ovs-fields(7) Open vSwitch Manual ovs-fields(7)
ovs-fields - protocol header fields in OpenFlow and Open vSwitch
This document aims to comprehensively document all of the fields,
both standard and non-standard, supported by OpenFlow or Open
vSwitch, regardless of origin.
Fields
A field is a property of a packet. Most familiarly, data fields are
fields that can be extracted from a packet. Most data fields are
copied directly from protocol headers, e.g. at layer 2, the Ethernet
source and destination addresses, or the VLAN ID; at layer 3, the
IPv4 or IPv6 source and destination; and at layer 4, the TCP or UDP
ports. Other data fields are computed, e.g. ip_frag describes whether
a packet is a fragment but it is not copied directly from the IP
header.
Data fields that are always present as a consequence of the basic
networking technology in use are called called root fields. Open
vSwitch 2.7 and earlier considered Ethernet fields to be root fields,
and this remains the default mode of operation for Open vSwitch
bridges. When a packet is received from a non-Ethernet interfaces,
such as a layer-3 LISP tunnel, Open vSwitch 2.7 and earlier force-fit
the packet to this Ethernet-centric point of view by pretending that
an Ethernet header is present whose Ethernet type that indicates the
packet’s actual type (and whose source and destination addresses are
all-zero).
Open vSwitch 2.8 and later implement the ``packet type-aware
pipeline’’ concept introduced in OpenFlow 1.5. Such a pipeline does
not have any root fields. Instead, a new metadata field, packet_type,
indicates the basic type of the packet, which can be Ethernet, IPv4,
IPv6, or another type. For backward compatibility, by default Open
vSwitch 2.8 imitates the behavior of Open vSwitch 2.7 and earlier.
Later versions of Open vSwitch may change the default, and in the
meantime controllers can turn off this legacy behavior, on a port-by-
port basis, by setting options:packet_type to ptap in the Interface
table. This is significant only for ports that can handle non-
Ethernet packets, which is currently just LISP, VXLAN-GPE, and GRE
tunnel ports. See ovs-vwitchd.conf.db(5) for more information.
Non-root data fields are not always present. A packet contains ARP
fields, for example, only when its packet type is ARP or when it is
an Ethernet packet whose Ethernet header indicates the Ethertype for
ARP, 0x0806. In this documentation, we say that a field is applicable
when it is present in a packet, and inapplicable when it is not.
(These are not standard terms.) We refer to the conditions that
determine whether a field is applicable as prerequisites. Some VLAN-
related fields are a special case: these fields are always applicable
for Ethernet packets, but have a designated value or bit that
indicates whether a VLAN header is present, with the remaining values
or bits indicating the VLAN header’s content (if it is present).
An inapplicable field does not have a value, not even a nominal
``value’’ such as all-zero-bits. In many circumstances, OpenFlow and
Open vSwitch allow references only to applicable fields. For example,
one may match (see Matching, below) a given field only if the match
includes the field’s prerequisite, e.g. matching an ARP field is only
allowed if one also matches on Ethertype 0x0806 or the packet_type
for ARP in a packet type-aware bridge.
Sometimes a packet may contain multiple instances of a header. For
example, a packet may contain multiple VLAN or MPLS headers, and
tunnels can cause any data field to recur. OpenFlow and Open vSwitch
do not address these cases uniformly. For VLAN and MPLS headers, only
the outermost header is accessible, so that inner headers may be
accessed only by ``popping’’ (removing) the outer header. (Open
vSwitch supports only a single VLAN header in any case.) For tunnels,
e.g. GRE or VXLAN, the outer header and inner headers are treated as
different data fields.
Many network protocols are built in layers as a stack of concatenated
headers. Each header typically contains a ``next type’’ field that
indicates the type of the protocol header that follows, e.g. Ethernet
contains an Ethertype and IPv4 contains a IP protocol type. The
exceptional cases, where protocols are layered but an outer layer
does not indicate the protocol type for the inner layer, or gives
only an ambiguous indication, are troublesome. An MPLS header, for
example, only indicates whether another MPLS header or some other
protocol follows, and in the latter case the inner protocol must be
known from the context. In these exceptional cases, OpenFlow and Open
vSwitch cannot provide insight into the inner protocol data fields
without additional context, and thus they treat all later data fields
as inapplicable until an OpenFlow action explicitly specifies what
protocol follows. In the case of MPLS, the OpenFlow ``pop MPLS’’
action that removes the last MPLS header from a packet provides this
context, as the Ethertype of the payload. See Layer 2.5: MPLS for
more information.
OpenFlow and Open vSwitch support some fields other than data fields.
Metadata fields relate to the origin or treatment of a packet, but
they are not extracted from the packet data itself. One example is
the physical port on which a packet arrived at the switch. Register
fields act like variables: they give an OpenFlow switch space for
temporary storage while processing a packet. Existing metadata and
register fields have no prerequisites.
A field’s value consists of an integral number of bytes. For data
fields, sometimes those bytes are taken directly from the packet.
Other data fields are copied from a packet with padding (usually with
zeros and in the most significant positions). The remaining data
fields are transformed in other ways as they are copied from the
packets, to make them more useful for matching.
Matching
The most important use of fields in OpenFlow is matching, to
determine whether particular field values agree with a set of
constraints called a match. A match consists of zero or more
constraints on individual fields, all of which must be met to satisfy
the match. (A match that contains no constraints is always
satisfied.) OpenFlow and Open vSwitch support a number of forms of
matching on individual fields:
Exact match, e.g. nw_src=10.1.2.3
Only a particular value of the field is matched; for
example, only one particular source IP address. Exact
matches are written as field=value. The forms accepted
for value depend on the field.
All fields support exact matches.
Bitwise match, e.g. nw_src=10.1.0.0/255.255.0.0
Specific bits in the field must have specified values;
for example, only source IP addresses in a particular
subnet. Bitwise matches are written as
field=value/mask, where value and mask take one of the
forms accepted for an exact match on field. Some fields
accept other forms for bitwise matches; for example,
nw_src=10.1.0.0/255.255.0.0 may also be written
nw_src=10.1.0.0/16.
Most OpenFlow switches do not allow every bitwise
matching on every field (and before OpenFlow 1.2, the
protocol did not even provide for the possibility for
most fields). Even switches that do allow bitwise
matching on a given field may restrict the masks that
are allowed, e.g. by allowing matches only on
contiguous sets of bits starting from the most
significant bit, that is, ``CIDR’’ masks [RFC 4632].
Open vSwitch does not allows bitwise matching on every
field, but it allows arbitrary bitwise masks on any
field that does support bitwise matching. (Older
versions had some restrictions, as documented in the
descriptions of individual fields.)
Wildcard, e.g. ``any nw_src’’
The value of the field is not constrained. Wildcarded
fields may be written as field=*, although it is
unusual to mention them at all. (When specifying a
wildcard explicitly in a command invocation, be sure to
using quoting to protect against shell expansion.)
There is a tiny difference between wildcarding a field
and not specifying any match on a field: wildcarding a
field requires satisfying the field’s prerequisites.
Some types of matches on individual fields cannot be expressed
directly with OpenFlow and Open vSwitch. These can be expressed
indirectly:
Set match, e.g. ``tcp_dst ∈ {80, 443, 8080}’’
The value of a field is one of a specified set of
values; for example, the TCP destination port is 80,
443, or 8080.
For matches used in flows (see Flows, below), multiple
flows can simulate set matches.
Range match, e.g. ``1000 ≤ tcp_dst ≤ 1999’’
The value of the field must lie within a numerical
range, for example, TCP destination ports between 1000
and 1999.
Range matches can be expressed as a collection of
bitwise matches. For example, suppose that the goal is
to match TCP source ports 1000 to 1999, inclusive. The
binary representations of 1000 and 1999 are:
01111101000
11111001111
The following series of bitwise matches will match 1000
and 1999 and all the values in between:
01111101xxx
0111111xxxx
10xxxxxxxxx
110xxxxxxxx
1110xxxxxxx
11110xxxxxx
1111100xxxx
which can be written as the following matches:
tcp,tp_src=0x03e8/0xfff8
tcp,tp_src=0x03f0/0xfff0
tcp,tp_src=0x0400/0xfe00
tcp,tp_src=0x0600/0xff00
tcp,tp_src=0x0700/0xff80
tcp,tp_src=0x0780/0xffc0
tcp,tp_src=0x07c0/0xfff0
Inequality match, e.g. ``tcp_dst ≠ 80’’
The value of the field differs from a specified value,
for example, all TCP destination ports except 80.
An inequality match on an n-bit field can be expressed
as a disjunction of n 1-bit matches. For example, the
inequality match ``vlan_pcp ≠ 5’’ can be expressed as
``vlan_pcp = 0/4 or vlan_pcp = 2/2 or vlan_pcp = 0/1.’’
For matches used in flows (see Flows, below), sometimes
one can more compactly express inequality as a higher-
priority flow that matches the exceptional case paired
with a lower-priority flow that matches the general
case.
Alternatively, an inequality match may be converted to
a pair of range matches, e.g. tcp_src ≠ 80 may be
expressed as ``0 ≤ tcp_src < 80 or 80 < tcp_src ≤
65535’’, and then each range match may in turn be
converted to a bitwise match.
Conjunctive match, e.g. ``tcp_src ∈ {80, 443, 8080} and
tcp_dst ∈ {80, 443, 8080}’’
As an OpenFlow extension, Open vSwitch supports
matching on conditions on conjunctions of the
previously mentioned forms of matching. See the
documentation for conj_id for more information.
All of these supported forms of matching are special cases of bitwise
matching. In some cases this influences the design of field values.
ip_frag is the most prominent example: it is designed to make all of
the practically useful checks for IP fragmentation possible as a
single bitwise match.
Shorthands
Some matches are very commonly used, so Open vSwitch accepts
shorthand notations. In some cases, Open vSwitch also uses shorthand
notations when it displays matches. The following shorthands are
defined, with their long forms shown on the right side:
eth packet_type=(0,0) (Open vSwitch 2.8 and later)
ip eth_type=0x0800
ipv6 eth_type=0x86dd
icmp eth_type=0x0800,ip_proto=1
icmp6 eth_type=0x86dd,ip_proto=58
tcp eth_type=0x0800,ip_proto=6
tcp6 eth_type=0x86dd,ip_proto=6
udp eth_type=0x0800,ip_proto=17
udp6 eth_type=0x86dd,ip_proto=17
sctp eth_type=0x0800,ip_proto=132
sctp6 eth_type=0x86dd,ip_proto=132
arp eth_type=0x0806
rarp eth_type=0x8035
mpls eth_type=0x8847
mplsm eth_type=0x8848
Evolution of OpenFlow Fields
The discussion so far applies to all OpenFlow and Open vSwitch
versions. This section starts to draw in specific information by
explaining, in broad terms, the treatment of fields and matches in
each OpenFlow version.
OpenFlow 1.0
OpenFlow 1.0 defined the OpenFlow protocol format of a match as a
fixed-length data structure that could match on the following fields:
· Ingress port.
· Ethernet source and destination MAC.
· Ethertype (with a special value to match frames that
lack an Ethertype).
· VLAN ID and priority.
· IPv4 source, destination, protocol, and DSCP.
· TCP source and destination port.
· UDP source and destination port.
· ICMPv4 type and code.
· ARP IPv4 addresses (SPA and TPA) and opcode.
Each supported field corresponded to some member of the data
structure. Some members represented multiple fields, in the case of
the TCP, UDP, ICMPv4, and ARP fields whose presence is mutually
exclusive. This also meant that some members were poor fits for their
fields: only the low 8 bits of the 16-bit ARP opcode could be
represented, and the ICMPv4 type and code were padded with 8 bits of
zeros to fit in the 16-bit members primarily meant for TCP and UDP
ports. An additional bitmap member indicated, for each member,
whether its field should be an ``exact’’ or ``wildcarded’’ match (see
Matching), with additional support for CIDR prefix matching on the
IPv4 source and destination fields.
Simplicity was recognized early on as the main virtue of this
approach. Obviously, any fixed-length data structure cannot support
matching new protocols that do not fit. There was no room, for
example, for matching IPv6 fields, which was not a priority at the
time. Lack of room to support matching the Ethernet addresses inside
ARP packets actually caused more of a design problem later, leading
to an Open vSwitch extension action specialized for dropping
``spoofed’’ ARP packets in which the frame and ARP Ethernet source
addressed differed. (This extension was never standardized. Open
vSwitch dropped support for it a few releases after it added support
for full ARP matching.)
The design of the OpenFlow fixed-length matches also illustrates
compromises, in both directions, between the strengths and weaknesses
of software and hardware that have always influenced the design of
OpenFlow. Support for matching ARP fields that do fit in the data
structure was only added late in the design process (and remained
optional in OpenFlow 1.0), for example, because common switch ASICs
did not support matching these fields.
The compromises in favor of software occurred for more complicated
reasons. The OpenFlow designers did not know how to implement
matching in software that was fast, dynamic, and general. (A way was
later found [Srinivasan].) Thus, the designers sought to support
dynamic, general matching that would be fast in realistic special
cases, in particular when all of the matches were microflows, that
is, matches that specify every field present in a packet, because
such matches can be implemented as a single hash table lookup.
Contemporary research supported the feasibility of this approach: the
number of microflows in a campus network had been measured to peak at
about 10,000 [Casado, section 3.2]. (Calculations show that this can
only be true in a lightly loaded network [Pepelnjak].)
As a result, OpenFlow 1.0 required switches to treat microflow
matches as the highest possible priority. This let software switches
perform the microflow hash table lookup first. Only on failure to
match a microflow did the switch need to fall back to checking the
more general and presumed slower matches. Also, the OpenFlow 1.0 flow
match was minimally flexible, with no support for general bitwise
matching, partly on the basis that this seemed more likely amenable
to relatively efficient software implementation. (CIDR masking for
IPv4 addresses was added relatively late in the OpenFlow 1.0 design
process.)
Microflow matching was later discovered to aid some hardware
implementations. The TCAM chips used for matching in hardware do not
support priority in the same way as OpenFlow but instead tie priority
to ordering [Pagiamtzis]. Thus, adding a new match with a priority
between the priorities of existing matches can require reordering an
arbitrary number of TCAM entries. On the other hand, when microflows
are highest priority, they can be managed as a set-aside portion of
the TCAM entries.
The emphasis on matching microflows also led designers to carefully
consider the bandwidth requirements between switch and controller: to
maximize the number of microflow setups per second, one must minimize
the size of each flow’s description. This favored the fixed-length
format in use, because it expressed common TCP and UDP microflows in
fewer bytes than more flexible ``type-length-value’’ (TLV) formats.
(Early versions of OpenFlow also avoided TLVs in general to head off
protocol fragmentation.)
Inapplicable Fields
OpenFlow 1.0 does not clearly specify how to treat inapplicable
fields. The members for inapplicable fields are always present in the
match data structure, as are the bits that indicate whether the
fields are matched, and the ``correct’’ member and bit values for
inapplicable fields is unclear. OpenFlow 1.0 implementations changed
their behavior over time as priorities shifted. The early OpenFlow
reference implementation, motivated to make every flow a microflow to
enable hashing, treated inapplicable fields as exact matches on a
value of 0. Initially, this behavior was implemented in the reference
controller only.
Later, the reference switch was also changed to actually force any
wildcarded inapplicable fields into exact matches on 0. The latter
behavior sometimes caused problems, because the modified flow was the
one reported back to the controller later when it queried the flow
table, and the modifications sometimes meant that the controller
could not properly recognize the flow that it had added. In
retrospect, perhaps this problem should have alerted the designers to
a design error, but the ability to use a single hash table was held
to be more important than almost every other consideration at the
time.
When more flexible match formats were introduced much later, they
disallowed any mention of inapplicable fields as part of a match.
This raised the question of how to translate between this new format
and the OpenFlow 1.0 fixed format. It seemed somewhat inconsistent
and backward to treat fields as exact-match in one format and forbid
matching them in the other, so instead the treatment of inapplicable
fields in the fixed-length format was changed from exact match on 0
to wildcarding. (A better classifier had by now eliminated software
performance problems with wildcards.)
The OpenFlow 1.0.1 errata (released only in 2012) added some
additional explanation [OpenFlow 1.0.1, section 3.4], but it did not
mandate specific behavior because of variation among implementations.
OpenFlow 1.1
The OpenFlow 1.1 protocol match format was designed as a
type/length/value (TLV) format to allow for future flexibility. The
specification standardized only a single type OFPMT_STANDARD (0) with
a fixed-size payload, described here. The additional fields and
bitwise masks in OpenFlow 1.1 cause this match structure to be over
twice as large as in OpenFlow 1.0, 88 bytes versus 40.
OpenFlow 1.1 added support for the following fields:
· SCTP source and destination port.
· MPLS label and traffic control (TC) fields.
· One 64-bit register (named ``metadata’’).
OpenFlow 1.1 increased the width of the ingress port number field
(and all other port numbers in the protocol) from 16 bits to 32 bits.
OpenFlow 1.1 increased matching flexibility by introducing arbitrary
bitwise matching on Ethernet and IPv4 address fields and on the new
``metadata’’ register field. Switches were not required to support
all possible masks [OpenFlow 1.1, section 4.3].
By a strict reading of the specification, OpenFlow 1.1 removed
support for matching ICMPv4 type and code [OpenFlow 1.1, section
A.2.3], but this is likely an editing error because ICMP matching is
described elsewhere [OpenFlow 1.1, Table 3, Table 4, Figure 4]. Open
vSwitch does support ICMPv4 type and code matching with OpenFlow 1.1.
OpenFlow 1.1 avoided the pitfalls of inapplicable fields that
OpenFlow 1.0 encountered, by requiring the switch to ignore the
specified field values [OpenFlow 1.1, section A.2.3]. It also implied
that the switch should ignore the bits that indicate whether to match
inapplicable fields.
Physical Ingress Port
OpenFlow 1.1 introduced a new pseudo-field, the physical ingress
port. The physical ingress port is only a pseudo-field because it
cannot be used for matching. It appears only one place in the
protocol, in the ``packet-in’’ message that passes a packet received
at the switch to an OpenFlow controller.
A packet’s ingress port and physical ingress port are identical
except for packets processed by a switch feature such as bonding or
tunneling that makes a packet appear to arrive on a ``virtual’’ port
associated with the bond or the tunnel. For such packets, the ingress
port is the virtual port and the physical ingress port is, naturally,
the physical port. Open vSwitch implements both bonding and
tunneling, but its bonding implementation does not use virtual ports
and its tunnels are typically not on the same OpenFlow switch as
their physical ingress ports (which need not be part of any switch),
so the ingress port and physical ingress port are always the same in
Open vSwitch.
OpenFlow 1.2
OpenFlow 1.2 abandoned the fixed-length approach to matching. One
reason was size, since adding support for IPv6 address matching (now
seen as important), with bitwise masks, would have added 64 bytes to
the match length, increasing it from 88 bytes in OpenFlow 1.1 to over
150 bytes. Extensibility had also become important as controller
writers increasingly wanted support for new fields without having to
change messages throughout the OpenFlow protocol. The challenges of
carefully defining fixed-length matches to avoid problems with
inapplicable fields had also become clear over time.
Therefore, OpenFlow 1.2 adopted a flow format using a flexible type-
length-value (TLV) representation, in which each TLV expresses a
match on one field. These TLVs were in turn encapsulated inside the
outer TLV wrapper introduced in OpenFlow 1.1 with the new identifier
OFPMT_OXM (1). (This wrapper fulfilled its intended purpose of
reducing the amount of churn in the protocol when changing match
formats; some messages that included matches remained unchanged from
OpenFlow 1.1 to 1.2 and later versions.)
OpenFlow 1.2 added support for the following fields:
· ARP hardware addresses (SHA and THA).
· IPv4 ECN.
· IPv6 source and destination addresses, flow label,
DSCP, ECN, and protocol.
· TCP, UDP, and SCTP port numbers when encapsulated
inside IPv6.
· ICMPv6 type and code.
· ICMPv6 Neighbor Discovery target address and source and
target Ethernet addresses.
The OpenFlow 1.2 format, called OXM (OpenFlow Extensible Match), was
modeled closely on an extension to OpenFlow 1.0 introduced in Open
vSwitch 1.1 called NXM (Nicira Extended Match). Each OXM or NXM TLV
has the following format:
type
<---------------->
16 7 1 8 length bytes
+------------+-----+--+------+ +------------+
|vendor/class|field|HM|length| | body |
+------------+-----+--+------+ +------------+
The most significant 16 bits of the NXM or OXM header, called vendor
by NXM and class by OXM, identify an organization permitted to
allocate identifiers for fields. NXM allocates only two vendors,
0x0000 for fields supported by OpenFlow 1.0 and 0x0001 for fields
implemented as an Open vSwitch extension. OXM assigns classes as
follows:
0x0000 (OFPXMC_NXM_0).
0x0001 (OFPXMC_NXM_1).
Reserved for NXM compatibility.
0x0002 to 0x7fff
Reserved for allocation to ONF members, but none yet
assigned.
0x8000 (OFPXMC_OPENFLOW_BASIC)
Used for most standard OpenFlow fields.
0x8001 (OFPXMC_PACKET_REGS)
Used for packet register fields in OpenFlow 1.5 and
later.
0x8002 to 0xfffe
Reserved for the OpenFlow specification.
0xffff (OFPXMC_EXPERIMENTER)
Experimental use.
When class is 0xffff, the OXM header is extended to 64 bits by using
the first 32 bits of the body as an experimenter field whose most
significant byte is zero and whose remaining bytes are an
Organizationally Unique Identifier (OUI) assigned by the IEEE [IEEE
OUI], as shown below.
type experimenter
<----------> <---------->
16 7 1 8 8 24 (length - 4) bytes
+------+-----+--+------+ +------+-----+ +------------------+
|class |field|HM|length| | zero | OUI | | body |
+------+-----+--+------+ +------+-----+ +------------------+
0xffff 0x00
OpenFlow says that support for experimenter fields is optional. Open
vSwitch 2.4 and later does support them, so that it can support the
following experimenter classes:
0x4f4e4600 (ONFOXM_ET)
Used by official Open Networking Foundation extensions
in OpenFlow 1.3 and later. e.g. [TCP Flags Match Field
Extension].
0x005ad650 (NXOXM_NSH)
Used by Open vSwitch for NSH extensions, in the absence
of an official ONF-assigned class. (This OUI is
randomly generated.)
Taken as a unit, class (or vendor), field, and experimenter (when
present) uniquely identify a particular field.
When hasmask (abbreviated HM above) is 0, the OXM is an exact match
on an entire field. In this case, the body (excluding the
experimenter field, if present) is a single value to be matched.
When hasmask is 1, the OXM is a bitwise match. The body (excluding
the experimenter field) consists of a value to match, followed by the
bitwise mask to apply. A 1-bit in the mask indicates that the
corresponding bit in the value should be matched and a 0-bit that it
should be ignored. For example, for an IP address field, a value of
192.168.0.0 followed by a mask of 255.255.0.0 would match addresses
in the 196.168.0.0/16 subnet.
· Some fields might not support masking at all, and some
fields that do support masking might restrict it to
certain patterns. For example, fields that have IP
address values might be restricted to CIDR masks. The
descriptions of individual fields note these
restrictions.
· An OXM TLV with a mask that is all zeros is not useful
(although it is not forbidden), because it is has the
same effect as omitting the TLV entirely.
· It is not meaningful to pair a 0-bit in an OXM mask
with a 1-bit in its value, and Open vSwitch rejects
such an OXM with the error OFPBMC_BAD_WILDCARDS, as
required by OpenFlow 1.3 and later.
The length identifies the number of bytes in the body, including the
4-byte experimenter header, if it is present. Each OXM TLV has a
fixed length; that is, given class, field, experimenter (if present),
and hasmask, length is a constant. The length is included explicitly
to allow software to minimally parse OXM TLVs of unknown types.
OXM TLVs must be ordered so that a field’s prerequisites are
satisfied before it is parsed. For example, an OXM TLV that matches
on the IPv4 source address field is only allowed following an OXM TLV
that matches on the Ethertype for IPv4. Similarly, an OXM TLV that
matches on the TCP source port must follow a TLV that matches an
Ethertype of IPv4 or IPv6 and one that matches an IP protocol of TCP
(in that order). The order of OXM TLVs is not otherwise restricted;
no canonical ordering is defined.
A given field may be matched only once in a series of OXM TLVs.
OpenFlow 1.3
OpenFlow 1.3 showed OXM to be largely successful, by adding new
fields without making any changes to how flow matches otherwise
worked. It added OXMs for the following fields supported by Open
vSwitch:
· Tunnel ID for ports associated with e.g. VXLAN or keyed
GRE.
· MPLS ``bottom of stack’’ (BOS) bit.
OpenFlow 1.3 also added OXMs for the following fields not documented
here and not yet implemented by Open vSwitch:
· IPv6 extension header handling.
· PBB I-SID.
OpenFlow 1.4
OpenFlow 1.4 added OXMs for the following fields not documented here
and not yet implemented by Open vSwitch:
· PBB UCA.
OpenFlow 1.5
OpenFlow 1.5 added OXMs for the following fields supported by Open
vSwitch:
· Packet type.
· TCP flags.
· Packet registers.
· The output port in the OpenFlow action set.
The following sections document the fields that Open vSwitch
supports. Each section provides introductory material on a group of
related fields, followed by information on each individual field. In
addition to field-specific information, each field begins with a
table with entries for the following important properties:
Name The field’s name, used for parsing and formatting the
field, e.g. in ovs-ofctl commands. For historical
reasons, some fields have an additional name that is
accepted as an alternative in parsing. This name, when
there is one, is listed as well, e.g. ``tun (aka
tunnel_id).’’
Width The field’s width, always a multiple of 8 bits. Some
fields don’t use all of the bits, so this may be
accompanied by an explanation. For example, OpenFlow
embeds the 2-bit IP ECN field as as the low bits in an
8-bit byte, and so its width is expressed as ``8 bits
(only the least-significant 2 bits may be nonzero).’’
Format How a value for the field is formatted or parsed by,
e.g., ovs-ofctl. Some possibilities are generic:
decimal
Formats as a decimal number. On input, accepts
decimal numbers or hexadecimal numbers prefixed
by 0x.
hexadecimal
Formats as a hexadecimal number prefixed by 0x.
On input, accepts decimal numbers or hexadecimal
numbers prefixed by 0x. (The default for parsing
is not hexadecimal: only a 0x prefix causes
input to be treated as hexadecimal.)
Ethernet
Formats and accepts the common Ethernet address
format xx:xx:xx:xx:xx:xx.
IPv4 Formats and accepts the dotted-quad format
a.b.c.d. For bitwise matches, formats and
accepts address/length CIDR notation in addition
to address/mask.
IPv6 Formats and accepts the common IPv6 address
formats, plus CIDR notation for bitwise matches.
OpenFlow 1.0 port
Accepts 16-bit port numbers in decimal, plus
OpenFlow well-known port names (e.g. IN_PORT) in
uppercase or lowercase.
OpenFlow 1.1+ port
Same syntax as OpenFlow 1.0 ports but for 32-bit
OpenFlow 1.1+ port number fields.
Other, field-specific formats are explained along with
their fields.
Masking
For most fields, this says ``arbitrary bitwise masks,’’
meaning that a flow may match any combination of bits
in the field. Some fields instead say ``exact match
only,’’ which means that a flow that matches on this
field must match on the whole field instead of just
certain bits. Either way, this reports masking support
for the latest version of Open vSwitch using OXM or NXM
(that is, either OpenFlow 1.2+ or OpenFlow 1.0 plus
Open vSwitch NXM extensions). In particular, OpenFlow
1.0 (without NXM) and 1.1 don’t always support masking
even if Open vSwitch itself does; refer to the OpenFlow
1.0 and OpenFlow 1.1 rows to learn about masking with
these protocol versions.
Prerequisites
Requirements that must be met to match on this field.
For example, ip_src has IPv4 as a prerequisite, meaning
that a match must include eth_type=0x0800 to match on
the IPv4 source address. The following prerequisites,
with their requirements, are currently in use:
none (no requirements)
VLAN VID
vlan_tci=0x1000/0x1000 (i.e. a VLAN header is
present)
ARP eth_type=0x0806 (ARP) or eth_type=0x8035 (RARP)
IPv4 eth_type=0x0800
IPv6 eth_type=0x86dd
IPv4/IPv6
IPv4 or IPv6
MPLS eth_type=0x8847 or eth_type=0x8848
TCP IPv4/IPv6 and ip_proto=6
UDP IPv4/IPv6 and ip_proto=17
SCTP IPv4/IPv6 and ip_proto=132
ICMPv4 IPv4 and ip_proto=1
ICMPv6 IPv6 and ip_proto=58
ND solicit
ICMPv6 and icmp_type=135 and icmp_code=0
ND advert
ICMPv6 and icmp_type=136 and icmp_code=0
ND ND solicit or ND advert
The TCP, UDP, and SCTP prerequisites also have the
special requirement that nw_frag is not being used to
select ``later fragments.’’ This is because only the
first fragment of a fragmented IPv4 or IPv6 datagram
contains the TCP or UDP header.
Access Most fields are ``read/write,’’ which means that common
OpenFlow actions like set_field can modify them. Fields
that are ``read-only’’ cannot be modified in these
general-purpose ways, although there may be other ways
that actions can modify them.
OpenFlow 1.0
OpenFlow 1.1
These rows report the level of support that OpenFlow 1.0
or OpenFlow 1.1, respectively, has for a field. For
OpenFlow 1.0, supported fields are reported as either
``yes (exact match only)’’ for fields that do not support
any bitwise masking or ``yes (CIDR match only)’’ for
fields that support CIDR masking. OpenFlow 1.1 supported
fields report either ``yes (exact match only)’’ or simply
``yes’’ for fields that do support arbitrary masks. These
OpenFlow versions supported a fixed collection of fields
that cannot be extended, so many more fields are reported
as ``not supported.’’
OXM
NXM These rows report the OXM and NXM code points that
correspond to a given field. Either or both may be
``none.’’
A field that has only an OXM code point is usually one
that was standardized before it was added to Open
vSwitch. A field that has only an NXM code point is
usually one that is not yet standardized. When a field
has both OXM and NXM code points, it usually indicates
that it was introduced as an Open vSwitch extension under
the NXM code point, then later standardized under the OXM
code point. A field can have more than one OXM code point
if it was standardized in OpenFlow 1.4 or later and
additionally introduced as an official ONF extension for
OpenFlow 1.3. (A field that has neither OXM nor NXM code
point is typically an obsolete field that is supported in
some other form using OXM or NXM.)
Each code point in these rows is described in the form
``NAME (number) since OpenFlow spec and Open vSwitch
version,’’ e.g. ``OXM_OF_ETH_TYPE (5) since OpenFlow 1.2
and Open vSwitch 1.7.’’ First, NAME, which specifies a
name for the code point, starts with a prefix that
designates a class and, in some cases, a vendor, as
listed in the following table:
Prefix Vendor Class
─────────────── ─────────── ───────
NXM_OF (none) 0x0000
NXM_NX (none) 0x0001
OXM_OF (none) 0x8000
OXM_OF_PKT_REG (none) 0x8001
NXOXM_ET 0x00002320 0xffff
NXOXM_NSH 0x005ad650 0xffff
ONFOXM_ET 0x4f4e4600 0xffff
For more information on OXM/NXM classes and vendors,
refer back to OpenFlow 1.2 under Evolution of OpenFlow
Fields. The number is the field number within the class
and vendor. The OpenFlow spec is the version of OpenFlow
that standardized the code point. It is omitted for NXM
code points because they are nonstandard. The version is
the version of Open vSwitch that first supported the code
point.
Summary:
Name Bytes Mask RW? Prereqs NXM/OXM Support
──────── ────── ───── ──── ──────── ────────────────
conj_id 4 no no none OVS 2.4+
An individual OpenFlow flow can match only a single value for each
field. However, situations often arise where one wants to match one
of a set of values within a field or fields. For matching a single
field against a set, it is straightforward and efficient to add
multiple flows to the flow table, one for each value in the set. For
example, one might use the following flows to send packets with IP
source address a, b, c, or d to the OpenFlow controller:
ip,ip_src=a actions=controller
ip,ip_src=b actions=controller
ip,ip_src=c actions=controller
ip,ip_src=d actions=controller
Similarly, these flows send packets with IP destination address e, f,
g, or h to the OpenFlow controller:
ip,ip_dst=e actions=controller
ip,ip_dst=f actions=controller
ip,ip_dst=g actions=controller
ip,ip_dst=h actions=controller
Installing all of the above flows in a single flow table yields a
disjunctive effect: a packet is sent to the controller if ip_src ∈
{a,b,c,d} or ip_dst ∈ {e,f,g,h} (or both). (Pedantically, if both of
the above sets of flows are present in the flow table, they should
have different priorities, because OpenFlow says that the results are
undefined when two flows with same priority can both match a single
packet.)
Suppose, on the other hand, one wishes to match conjunctively, that
is, to send a packet to the controller only if both ip_src ∈
{a,b,c,d} and ip_dst ∈ {e,f,g,h}. This requires 4 × 4 = 16 flows, one
for each possible pairing of ip_src and ip_dst. That is acceptable
for our small example, but it does not gracefully extend to larger
sets or greater numbers of dimensions.
The conjunction action is a solution for conjunctive matches that is
built into Open vSwitch. A conjunction action ties groups of
individual OpenFlow flows into higher-level ``conjunctive flows’’.
Each group corresponds to one dimension, and each flow within the
group matches one possible value for the dimension. A packet that
matches one flow from each group matches the conjunctive flow.
To implement a conjunctive flow with conjunction, assign the
conjunctive flow a 32-bit id, which must be unique within an OpenFlow
table. Assign each of the n ≥ 2 dimensions a unique number from 1 to
n; the ordering is unimportant. Add one flow to the OpenFlow flow
table for each possible value of each dimension with conjunction(id,
k/n) as the flow’s actions, where k is the number assigned to the
flow’s dimension. Together, these flows specify the conjunctive
flow’s match condition. When the conjunctive match condition is met,
Open vSwitch looks up one more flow that specifies the conjunctive
flow’s actions and receives its statistics. This flow is found by
setting conj_id to the specified id and then again searching the flow
table.
The following flows provide an example. Whenever the IP source is one
of the values in the flows that match on the IP source (dimension 1
of 2), and the IP destination is one of the values in the flows that
match on IP destination (dimension 2 of 2), Open vSwitch searches for
a flow that matches conj_id against the conjunction ID (1234),
finding the first flow listed below.
conj_id=1234 actions=controller
ip,ip_src=10.0.0.1 actions=conjunction(1234, 1/2)
ip,ip_src=10.0.0.4 actions=conjunction(1234, 1/2)
ip,ip_src=10.0.0.6 actions=conjunction(1234, 1/2)
ip,ip_src=10.0.0.7 actions=conjunction(1234, 1/2)
ip,ip_dst=10.0.0.2 actions=conjunction(1234, 2/2)
ip,ip_dst=10.0.0.5 actions=conjunction(1234, 2/2)
ip,ip_dst=10.0.0.7 actions=conjunction(1234, 2/2)
ip,ip_dst=10.0.0.8 actions=conjunction(1234, 2/2)
Many subtleties exist:
· In the example above, every flow in a single dimension
has the same form, that is, dimension 1 matches on
ip_src and dimension 2 on ip_dst, but this is not a
requirement. Different flows within a dimension may
match on different bits within a field (e.g. IP network
prefixes of different lengths, or TCP/UDP port ranges
as bitwise matches), or even on entirely different
fields (e.g. to match packets for TCP source port 80 or
TCP destination port 80).
· The flows within a dimension can vary their matches
across more than one field, e.g. to match only specific
pairs of IP source and destination addresses or L4 port
numbers.
· A flow may have multiple conjunction actions, with
different id values. This is useful for multiple
conjunctive flows with overlapping sets. If one
conjunctive flow matches packets with both ip_src ∈
{a,b} and ip_dst ∈ {d,e} and a second conjunctive flow
matches ip_src ∈ {b,c} and ip_dst ∈ {f,g}, for example,
then the flow that matches ip_src=b would have two
conjunction actions, one for each conjunctive flow. The
order of conjunction actions within a list of actions
is not significant.
· A flow with conjunction actions may also include note
actions for annotations, but not any other kind of
actions. (They would not be useful because they would
never be executed.)
· All of the flows that constitute a conjunctive flow
with a given id must have the same priority. (Flows
with the same id but different priorities are currently
treated as different conjunctive flows, that is,
currently id values need only be unique within an
OpenFlow table at a given priority. This behavior isn’t
guaranteed to stay the same in later releases, so
please use id values unique within an OpenFlow table.)
· Conjunctive flows must not overlap with each other, at
a given priority, that is, any given packet must be
able to match at most one conjunctive flow at a given
priority. Overlapping conjunctive flows yield
unpredictable results.
· Following a conjunctive flow match, the search for the
flow with conj_id=id is done in the same general-
purpose way as other flow table searches, so one can
use flows with conj_id=id to act differently depending
on circumstances. (One exception is that the search for
the conj_id=id flow itself ignores conjunctive flows,
to avoid recursion.) If the search with conj_id=id
fails, Open vSwitch acts as if the conjunctive flow had
not matched at all, and continues searching the flow
table for other matching flows.
· OpenFlow prerequisite checking occurs for the flow with
conj_id=id in the same way as any other flow, e.g. in
an OpenFlow 1.1+ context, putting a mod_nw_src action
into the example above would require adding an ip
match, like this:
conj_id=1234,ip actions=mod_nw_src:1.2.3.4,controller
· OpenFlow prerequisite checking also occurs for the
individual flows that comprise a conjunctive match in
the same way as any other flow.
· The flows that constitute a conjunctive flow do not
have useful statistics. They are never updated with
byte or packet counts, and so on. (For such a flow,
therefore, the idle and hard timeouts work much the
same way.)
· Sometimes there is a choice of which flows include a
particular match. For example, suppose that we added an
extra constraint to our example, to match on ip_src ∈
{a,b,c,d} and ip_dst ∈ {e,f,g,h} and tcp_dst = i. One
way to implement this is to add the new constraint to
the conj_id flow, like this:
conj_id=1234,tcp,tcp_dst=i actions=mod_nw_src:1.2.3.4,controller
but this is not recommended because of the cost of the
extra flow table lookup. Instead, add the constraint to
the individual flows, either in one of the dimensions
or (slightly better) all of them.
· A conjunctive match must have n ≥ 2 dimensions
(otherwise a conjunctive match is not necessary). Open
vSwitch enforces this.
· Each dimension within a conjunctive match should
ordinarily have more than one flow. Open vSwitch does
not enforce this.
Conjunction ID Field
Name: conj_id
Width: 32 bits
Format: decimal
Masking: not maskable
Prerequisites: none
Access: read-only
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_CONJ_ID (37) since Open vSwitch 2.4
Used for conjunctive matching. See above for more information.
Summary:
Name Bytes Mask RW? Prereqs NXM/OXM Support
───────────────── ──────────────── ───── ──── ──────── ─────────────────────
nsh_flags 1 yes yes NSH OF 1.3+ and OVS 2.8+
nsh_mdtype 1 no no NSH OF 1.3+ and OVS 2.8+
nsh_np 1 no no NSH OF 1.3+ and OVS 2.8+
nsh_spi aka nsp 4 (low 24 bits) no yes NSH OF 1.3+ and OVS 2.8+
nsh_si aka nsi 1 no yes NSH OF 1.3+ and OVS 2.8+
nsh_c1 aka nshc1 4 yes yes NSH OF 1.3+ and OVS 2.8+
nsh_c2 aka nshc2 4 yes yes NSH OF 1.3+ and OVS 2.8+
nsh_c3 aka nshc3 4 yes yes NSH OF 1.3+ and OVS 2.8+
nsh_c4 aka nshc4 4 yes yes NSH OF 1.3+ and OVS 2.8+
flags field (8 bits) Field
Name: nsh_flags
Width: 8 bits
Format: decimal
Masking: arbitrary bitwise masks
Prerequisites: NSH
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: NXOXM_NSH_FLAGS (1) since OpenFlow 1.3 and Open
vSwitch 2.8
NXM: none
mdtype field (8 bits) Field
Name: nsh_mdtype
Width: 8 bits
Format: decimal
Masking: not maskable
Prerequisites: NSH
Access: read-only
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: NXOXM_NSH_MDTYPE (2) since OpenFlow 1.3 and Open
vSwitch 2.8
NXM: none
np (next protocol) field (8 bits) Field
Name: nsh_np
Width: 8 bits
Format: decimal
Masking: not maskable
Prerequisites: NSH
Access: read-only
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: NXOXM_NSH_NP (3) since OpenFlow 1.3 and Open vSwitch
2.8
NXM: none
spi (service path identifier) field (24 bits) Field
Name: nsh_spi (aka nsp)
Width: 32 bits (only the least-significant 24 bits may be nonzero)
Format: hexadecimal
Masking: not maskable
Prerequisites: NSH
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: NXOXM_NSH_SPI (4) since OpenFlow 1.3 and Open vSwitch 2.8
NXM: none
si (service index) field (8 bits) Field
Name: nsh_si (aka nsi)
Width: 8 bits
Format: decimal
Masking: not maskable
Prerequisites: NSH
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: NXOXM_NSH_SI (5) since OpenFlow 1.3 and Open vSwitch
2.8
NXM: none
c1 (Network Platform Context) field (32 bits) Field
Name: nsh_c1 (aka nshc1)
Width: 32 bits
Format: hexadecimal
Masking: arbitrary bitwise masks
Prerequisites: NSH
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: NXOXM_NSH_C1 (6) since OpenFlow 1.3 and Open vSwitch
2.8
NXM: none
c2 (Network Shared Context) field (32 bits) Field
Name: nsh_c2 (aka nshc2)
Width: 32 bits
Format: hexadecimal
Masking: arbitrary bitwise masks
Prerequisites: NSH
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: NXOXM_NSH_C2 (7) since OpenFlow 1.3 and Open vSwitch
2.8
NXM: none
c3 (Service Platform Context) field (32 bits) Field
Name: nsh_c3 (aka nshc3)
Width: 32 bits
Format: hexadecimal
Masking: arbitrary bitwise masks
Prerequisites: NSH
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: NXOXM_NSH_C3 (8) since OpenFlow 1.3 and Open vSwitch
2.8
NXM: none
c4 (Service Shared Context) field (32 bits) Field
Name: nsh_c4 (aka nshc4)
Width: 32 bits
Format: hexadecimal
Masking: arbitrary bitwise masks
Prerequisites: NSH
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: NXOXM_NSH_C4 (9) since OpenFlow 1.3 and Open vSwitch
2.8
NXM: none
Summary:
Name Bytes Mask RW? Prereqs NXM/OXM Support
───────────────────── ─────────────── ───── ──── ──────── ─────────────────────
tun_id aka tunnel_id 8 yes yes none OF 1.3+ and OVS 1.1+
tun_src 4 yes yes none OVS 2.0+
tun_dst 4 yes yes none OVS 2.0+
tun_ipv6_src 16 yes yes none OVS 2.5+
tun_ipv6_dst 16 yes yes none OVS 2.5+
tun_gbp_id 2 yes yes none OVS 2.4+
tun_gbp_flags 1 yes yes none OVS 2.4+
tun_metadata0 124 yes yes none OVS 2.5+
tun_metadata1 124 yes yes none OVS 2.5+
tun_metadata2 124 yes yes none OVS 2.5+
tun_metadata3 124 yes yes none OVS 2.5+
tun_metadata4 124 yes yes none OVS 2.5+
tun_metadata5 124 yes yes none OVS 2.5+
tun_metadata6 124 yes yes none OVS 2.5+
tun_metadata7 124 yes yes none OVS 2.5+
tun_metadata8 124 yes yes none OVS 2.5+
tun_metadata9 124 yes yes none OVS 2.5+
tun_metadata10 124 yes yes none OVS 2.5+
tun_metadata11 124 yes yes none OVS 2.5+
tun_metadata12 124 yes yes none OVS 2.5+
tun_metadata13 124 yes yes none OVS 2.5+
tun_metadata14 124 yes yes none OVS 2.5+
tun_metadata15 124 yes yes none OVS 2.5+
tun_metadata16 124 yes yes none OVS 2.5+
tun_metadata17 124 yes yes none OVS 2.5+
tun_metadata18 124 yes yes none OVS 2.5+
tun_metadata19 124 yes yes none OVS 2.5+
tun_metadata20 124 yes yes none OVS 2.5+
tun_metadata21 124 yes yes none OVS 2.5+
tun_metadata22 124 yes yes none OVS 2.5+
tun_metadata23 124 yes yes none OVS 2.5+
tun_metadata24 124 yes yes none OVS 2.5+
tun_metadata25 124 yes yes none OVS 2.5+
tun_metadata26 124 yes yes none OVS 2.5+
tun_metadata27 124 yes yes none OVS 2.5+
tun_metadata28 124 yes yes none OVS 2.5+
tun_metadata29 124 yes yes none OVS 2.5+
tun_metadata30 124 yes yes none OVS 2.5+
tun_metadata31 124 yes yes none OVS 2.5+
tun_metadata32 124 yes yes none OVS 2.5+
tun_metadata33 124 yes yes none OVS 2.5+
tun_metadata34 124 yes yes none OVS 2.5+
tun_metadata35 124 yes yes none OVS 2.5+
tun_metadata36 124 yes yes none OVS 2.5+
tun_metadata37 124 yes yes none OVS 2.5+
tun_metadata38 124 yes yes none OVS 2.5+
tun_metadata39 124 yes yes none OVS 2.5+
tun_metadata40 124 yes yes none OVS 2.5+
tun_metadata41 124 yes yes none OVS 2.5+
tun_metadata42 124 yes yes none OVS 2.5+
tun_metadata43 124 yes yes none OVS 2.5+
tun_metadata44 124 yes yes none OVS 2.5+
tun_metadata45 124 yes yes none OVS 2.5+
tun_metadata46 124 yes yes none OVS 2.5+
tun_metadata47 124 yes yes none OVS 2.5+
tun_metadata48 124 yes yes none OVS 2.5+
tun_metadata49 124 yes yes none OVS 2.5+
tun_metadata50 124 yes yes none OVS 2.5+
tun_metadata51 124 yes yes none OVS 2.5+
tun_metadata52 124 yes yes none OVS 2.5+
tun_metadata53 124 yes yes none OVS 2.5+
tun_metadata54 124 yes yes none OVS 2.5+
tun_metadata55 124 yes yes none OVS 2.5+
tun_metadata56 124 yes yes none OVS 2.5+
tun_metadata57 124 yes yes none OVS 2.5+
tun_metadata58 124 yes yes none OVS 2.5+
tun_metadata59 124 yes yes none OVS 2.5+
tun_metadata60 124 yes yes none OVS 2.5+
tun_metadata61 124 yes yes none OVS 2.5+
tun_metadata62 124 yes yes none OVS 2.5+
tun_metadata63 124 yes yes none OVS 2.5+
tun_flags 2 (low 1 bits) yes yes none OVS 2.5+
The fields in this group relate to tunnels, which Open vSwitch
supports in several forms (GRE, VXLAN, and so on). Most of these
fields do appear in the wire format of a packet, so they are data
fields from that point of view, but they are metadata from an
OpenFlow flow table point of view because they do not appear in
packets that are forwarded to the controller or to ordinary (non-
tunnel) output ports.
Open vSwitch supports a spectrum of usage models for mapping tunnels
to OpenFlow ports:
``Port-based’’ tunnels
In this model, an OpenFlow port represents one tunnel:
it matches a particular type of tunnel traffic between
two IP endpoints, with a particular tunnel key (if keys
are in use). In this situation, in_port suffices to
distinguish one tunnel from another, so the tunnel
header fields have little importance for OpenFlow
processing. (They are still populated and may be used
if it is convenient.) The tunnel header fields play no
role in sending packets out such an OpenFlow port,
either, because the OpenFlow port itself fully
specifies the tunnel headers.
The following Open vSwitch commands create a bridge
br-int, add port tap0 to the bridge as OpenFlow port 1,
establish a port-based GRE tunnel between the local
host and remote IP 192.168.1.1 using GRE key 5001 as
OpenFlow port 2, and arranges to forward all traffic
from tap0 to the tunnel and vice versa:
ovs-vsctl add-br br-int
ovs-vsctl add-port br-int tap0 -- set interface tap0 ofport_request=1
ovs-vsctl add-port br-int gre0 --
set interface gre0 ofport_request=2 type=gre \
options:remote_ip=192.168.1.1 options:key=5001
ovs-ofctl add-flow br-int in_port=1,actions=2
ovs-ofctl add-flow br-int in_port=2,actions=1
``Flow-based’’ tunnels
In this model, one OpenFlow port represents all
possible tunnels of a given type with an endpoint on
the current host, for example, all GRE tunnels. In this
situation, in_port only indicates that traffic was
received on the particular kind of tunnel. This is
where the tunnel header fields are most important: they
allow the OpenFlow tables to discriminate among tunnels
based on their IP endpoints or keys. Tunnel header
fields also determine the IP endpoints and keys of
packets sent out such a tunnel port.
The following Open vSwitch commands create a bridge
br-int, add port tap0 to the bridge as OpenFlow port 1,
establish a flow-based GRE tunnel port 3, and arranges
to forward all traffic from tap0 to remote IP
192.168.1.1 over a GRE tunnel with key 5001 and vice
versa:
ovs-vsctl add-br br-int
ovs-vsctl add-port br-int tap0 -- set interface tap0 ofport_request=1
ovs-vsctl add-port br-int allgre --
set interface gre0 ofport_request=3 type=gre \
options:remote_ip=flow options:key=flow
ovs-ofctl add-flow br-int \
’in_port=1 actions=set_tunnel:5001,set_field:192.168.1.1->tun_dst,3’
ovs-ofctl add-flow br-int ’in_port=3,tun_src=192.168.1.1,tun_id=5001 actions=1’
Mixed models.
One may define both flow-based and port-based tunnels
at the same time. For example, it is valid and possibly
useful to create and configure both gre0 and allgre
tunnel ports described above.
Traffic is attributed on ingress to the most specific
matching tunnel. For example, gre0 is more specific
than allgre. Therefore, if both exist, then gre0 will
be the ingress port for any GRE traffic received from
192.168.1.1 with key 5001.
On egress, traffic may be directed to any appropriate
tunnel port. If both gre0 and allgre are configured as
already described, then the actions 2 and
set_tunnel:5001,set_field:192.168.1.1->tun_dst,3 send
the same tunnel traffic.
Intermediate models.
Ports may be configured as partially flow-based. For
example, one may define an OpenFlow port that
represents tunnels between a pair of endpoints but
leaves the flow table to discriminate on the flow key.
ovs-vswitchd.conf.db(5) describes all the details of tunnel
configuration.
These fields do not have any prerequisites, which means that a flow
may match on any or all of them, in any combination.
These fields are zeros for packets that did not arrive on a tunnel.
Tunnel ID Field
Name: tun_id (aka tunnel_id)
Width: 64 bits
Format: hexadecimal
Masking: arbitrary bitwise masks
Prerequisites: none
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: OXM_OF_TUNNEL_ID (38) since OpenFlow 1.3 and Open
vSwitch 1.10
NXM: NXM_NX_TUN_ID (16) since Open vSwitch 1.1
Many kinds of tunnels support a tunnel ID:
· VXLAN and Geneve have a 24-bit virtual network
identifier (VNI).
· LISP has a 24-bit instance ID.
· GRE has an optional 32-bit key.
· STT has a 64-bit key.
When a packet is received from a tunnel, this field holds the tunnel
ID in its least significant bits, zero-extended to fit. This field is
zero if the tunnel does not support an ID, or if no ID is in use for
a tunnel type that has an optional ID, or if an ID of zero received,
or if the packet was not received over a tunnel.
When a packet is output to a tunnel port, the tunnel configuration
determines whether the tunnel ID is taken from this field or bound to
a fixed value. See the earlier description of ``port-based’’ and
``flow-based’’ tunnels for more information.
The following diagram shows the origin of this field in a typical
keyed GRE tunnel:
Ethernet IPv4 GRE Ethernet
<-----------> <---------------> <------------> <---------->
48 48 16 8 32 32 16 16 32 48 48 16
+---+---+-----+ +---+-----+---+---+ +---+------+---+ +---+---+----+
|dst|src|type | |...|proto|src|dst| |...| type |key| |dst|src|type| ...
+---+---+-----+ +---+-----+---+---+ +---+------+---+ +---+---+----+
0x800 47 0x6558
Tunnel IPv4 Source Field
Name: tun_src
Width: 32 bits
Format: IPv4
Masking: arbitrary bitwise masks
Prerequisites: none
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_TUN_IPV4_SRC (31) since Open vSwitch 2.0
When a packet is received from a tunnel, this field is the source
address in the outer IP header of the tunneled packet. This field is
zero if the packet was not received over a tunnel.
When a packet is output to a flow-based tunnel port, this field
influences the IPv4 source address used to send the packet. If it is
zero, then the kernel chooses an appropriate IP address based using
the routing table.
The following diagram shows the origin of this field in a typical
keyed GRE tunnel:
Ethernet IPv4 GRE Ethernet
<-----------> <---------------> <------------> <---------->
48 48 16 8 32 32 16 16 32 48 48 16
+---+---+-----+ +---+-----+---+---+ +---+------+---+ +---+---+----+
|dst|src|type | |...|proto|src|dst| |...| type |key| |dst|src|type| ...
+---+---+-----+ +---+-----+---+---+ +---+------+---+ +---+---+----+
0x800 47 0x6558
Tunnel IPv4 Destination Field
Name: tun_dst
Width: 32 bits
Format: IPv4
Masking: arbitrary bitwise masks
Prerequisites: none
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_TUN_IPV4_DST (32) since Open vSwitch 2.0
When a packet is received from a tunnel, this field is the
destination address in the outer IP header of the tunneled packet.
This field is zero if the packet was not received over a tunnel.
When a packet is output to a flow-based tunnel port, this field
specifies the destination to which the tunnel packet is sent.
The following diagram shows the origin of this field in a typical
keyed GRE tunnel:
Ethernet IPv4 GRE Ethernet
<-----------> <---------------> <------------> <---------->
48 48 16 8 32 32 16 16 32 48 48 16
+---+---+-----+ +---+-----+---+---+ +---+------+---+ +---+---+----+
|dst|src|type | |...|proto|src|dst| |...| type |key| |dst|src|type| ...
+---+---+-----+ +---+-----+---+---+ +---+------+---+ +---+---+----+
0x800 47 0x6558
Tunnel IPv6 Source Field
Name: tun_ipv6_src
Width: 128 bits
Format: IPv6
Masking: arbitrary bitwise masks
Prerequisites: none
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_TUN_IPV6_SRC (109) since Open vSwitch 2.5
Similar to tun_src, but for tunnels over IPv6.
Tunnel IPv6 Destination Field
Name: tun_ipv6_dst
Width: 128 bits
Format: IPv6
Masking: arbitrary bitwise masks
Prerequisites: none
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_TUN_IPV6_DST (110) since Open vSwitch 2.5
Similar to tun_dst, but for tunnels over IPv6.
VXLAN Group-Based Policy Fields
The VXLAN header is defined as follows [RFC 7348], where the I bit
must be set to 1, unlabeled bits or those labeled reserved must be
set to 0, and Open vSwitch makes the VNI available via tun_id:
VXLAN flags
<------------->
1 1 1 1 1 1 1 1 24 24 8
+-+-+-+-+-+-+-+-+--------+---+--------+
| | | | |I| | | |reserved|VNI|reserved|
+-+-+-+-+-+-+-+-+--------+---+--------+
VXLAN Group-Based Policy [VXLAN Group Policy Option] adds new
interpretations to existing bits in the VXLAN header, reinterpreting
it as follows, with changes highlighted:
GBP flags
<------------->
1 1 1 1 1 1 1 1 24 24 8
+-+-+-+-+-+-+-+-+---------------+---+--------+
| |D| | |A| | | |group policy ID|VNI|reserved|
+-+-+-+-+-+-+-+-+---------------+---+--------+
Open vSwitch makes GBP fields and flags available through the
following fields. Only packets that arrive over a VXLAN tunnel with
the GBP extension enabled have these fields set. In other packets
they are zero on receive and ignored on transmit.
VXLAN Group-Based Policy ID Field
Name: tun_gbp_id
Width: 16 bits
Format: decimal
Masking: arbitrary bitwise masks
Prerequisites: none
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_TUN_GBP_ID (38) since Open vSwitch 2.4
For a packet tunneled over VXLAN with the Group-Based Policy (GBP)
extension, this field represents the GBP policy ID, as shown above.
VXLAN Group-Based Policy Flags Field
Name: tun_gbp_flags
Width: 8 bits
Format: hexadecimal
Masking: arbitrary bitwise masks
Prerequisites: none
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_TUN_GBP_FLAGS (39) since Open vSwitch 2.4
For a packet tunneled over VXLAN with the Group-Based Policy (GBP)
extension, this field represents the GBP policy flags, as shown
above.
The field has the format shown below:
GBP Flags
<------------->
1 1 1 1 1 1 1 1
+-+-+-+-+-+-+-+-+
| |D| | |A| | | |
+-+-+-+-+-+-+-+-+
Unlabeled bits are reserved and must be transmitted as 0. The VXLAN
GBP draft defines the other bits’ meanings as:
D (Don’t Learn)
When set, this bit indicates that the egress tunnel
endpoint must not learn the source address of the
encapsulated frame.
A (Applied)
When set, indicates that the group policy has already
been applied to this packet. Devices must not apply
policies when the A bit is set.
Geneve Fields
These fields provide access to additional features in the Geneve
tunneling protocol [Geneve]. Their names are somewhat generic in the
hope that the same fields could be reused for other protocols in the
future; for example, the NSH protocol [NSH] supports TLV options
whose form is identical to that for Geneve options.
Generic Tunnel Option 0 Field
Name: tun_metadata0
Width: 992 bits (124 bytes)
Format: hexadecimal
Masking: arbitrary bitwise masks
Prerequisites: none
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_TUN_METADATA0 (40) since Open vSwitch 2.5
The above information specifically covers generic tunnel option 0,
but Open vSwitch supports 64 options, numbered 0 through 63, whose
NXM field numbers are 40 through 103.
These fields provide OpenFlow access to the generic type-length-value
options defined by the Geneve tunneling protocol or other protocols
with options in the same TLV format as Geneve options. Each of these
options has the following wire format:
header body
<-------------------> <------------------>
16 8 3 5 4×(length - 1) bytes
+-----+----+---+------+--------------------+
|class|type|res|length| value |
+-----+----+---+------+--------------------+
0
Taken together, the class and type in the option format mean that
there are about 16 million distinct kinds of TLV options, too many to
give individual OXM code points. Thus, Open vSwitch requires the user
to define the TLV options of interest, by binding up to 64 TLV
options to generic tunnel option NXM code points. Each option may
have up to 124 bytes in its body, the maximum allowed by the TLV
format, but bound options may total at most 252 bytes of body.
Open vSwitch extensions to the OpenFlow protocol bind TLV options to
NXM code points. The ovs-ofctl(8) program offers one way to use these
extensions, e.g. to configure a mapping from a TLV option with class
0xffff, type 0, and a body length of 4 bytes:
ovs-ofctl add-tlv-map br0 "{class=0xffff,type=0,len=4}->tun_metadata0"
Once a TLV option is properly bound, it can be accessed and modified
like any other field, e.g. to send packets that have value 1234 for
the option described above to the controller:
ovs-ofctl add-flow br0 tun_metadata0=1234,actions=controller
An option not received or not bound is matched as all zeros.
Tunnel Flags Field
Name: tun_flags
Width: 16 bits (only the least-significant 1 bits may be nonzero)
Format: tunnel flags
Masking: arbitrary bitwise masks
Prerequisites: none
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_TUN_FLAGS (104) since Open vSwitch 2.5
Flags indicating various aspects of the tunnel encapsulation.
Matches on this field are most conveniently written in terms of
symbolic names (given in the diagram below), each preceded by either
+ for a flag that must be set, or - for a flag that must be unset,
without any other delimiters between the flags. Flags not mentioned
are wildcarded. For example, tun_flags=+oam matches only OAM packets.
Matches can also be written as flags/mask, where flags and mask are
16-bit numbers in decimal or in hexadecimal prefixed by 0x.
Currently, only one flag is defined:
oam The tunnel protocol indicated that this is an OAM
(Operations and Management) control packet.
The switch may reject matches against unknown flags.
Newer versions of Open vSwitch may introduce additional flags with
new meanings. It is therefore not recommended to use an exact match
on this field since the behavior of these new flags is unknown and
should be ignored.
For non-tunneled packets, the value is 0.
Summary:
Name Bytes Mask RW? Prereqs NXM/OXM Support
────────────── ────── ───── ──── ──────── ─────────────────────
in_port 2 no yes none OVS 1.1+
in_port_oxm 4 no yes none OF 1.2+ and OVS 1.7+
skb_priority 4 no no none
pkt_mark 4 yes yes none OVS 2.0+
actset_output 4 no no none OF 1.3+ and OVS 2.4+
packet_type 4 no no none OF 1.5+ and OVS 2.8+
These fields relate to the origin or treatment of a packet, but they
are not extracted from the packet data itself.
Ingress Port Field
Name: in_port
Width: 16 bits
Format: OpenFlow 1.0 port
Masking: not maskable
Prerequisites: none
Access: read/write
OpenFlow 1.0: yes (exact match only)
OpenFlow 1.1: yes (exact match only)
OXM: none
NXM: NXM_OF_IN_PORT (0) since Open vSwitch 1.1
The OpenFlow port on which the packet being processed arrived. This
is a 16-bit field that holds an OpenFlow 1.0 port number. For
receiving a packet, the only values that appear in this field are:
1 through 0xfeff (65,279), inclusive.
Conventional OpenFlow port numbers.
OFPP_LOCAL (0xfffe or 65,534).
The ``local’’ port, which in Open vSwitch is always
named the same as the bridge itself. This represents a
connection between the switch and the local TCP/IP
stack. This port is where an IP address is most
commonly configured on an Open vSwitch switch.
OpenFlow does not require a switch to have a local
port, but all existing versions of Open vSwitch have
always included a local port. Future Directions: Future
versions of Open vSwitch might be able to optionally
omit the local port, if someone submits code to
implement such a feature.
OFPP_NONE (OpenFlow 1.0) or OFPP_ANY (OpenFlow 1.1+) (0xffff
or 65,535).
OFPP_CONTROLLER (0xfffd or 65,533).
When a controller injects a packet into an OpenFlow
switch with a ``packet-out’’ request, it can specify one
of these ingress ports to indicate that the packet was
generated internally rather than having been received on
some port.
OpenFlow 1.0 specified OFPP_NONE for this purpose.
Despite that, some controllers used OFPP_CONTROLLER, and
some switches only accepted OFPP_CONTROLLER, so OpenFlow
1.0.2 required support for both ports. OpenFlow 1.1 and
later were more clearly drafted to allow only
OFPP_CONTROLLER. For maximum compatibility, Open vSwitch
allows both ports with all OpenFlow versions.
Values not mentioned above will never appear when receiving a packet,
including the following notable values:
0 Zero is not a valid OpenFlow port number.
OFPP_MAX (0xff00 or 65,280).
This value has only been clearly specified as a valid
port number as of OpenFlow 1.3.3. Before that, its
status was unclear, and so Open vSwitch has never
allowed OFPP_MAX to be used as a port number, so
packets will never be received on this port. (Other
OpenFlow switches, of course, might use it.)
OFPP_UNSET (0xfff7 or 65,527)
OFPP_IN_PORT (0xfff8 or 65,528)
OFPP_TABLE (0xfff9 or 65,529)
OFPP_NORMAL (0xfffa or 65,530)
OFPP_FLOOD (0xfffb or 65,531)
OFPP_ALL (0xfffc or 65,532)
These port numbers are used only in output actions and
never appear as ingress ports.
Most of these port numbers were defined in OpenFlow 1.0,
but OFPP_UNSET was only introduced in OpenFlow 1.5.
Values that will never appear when receiving a packet may still be
matched against in the flow table. There are still circumstances in
which those flows can be matched:
· The resubmit Open vSwitch extension action allows a
flow table lookup with an arbitrary ingress port.
· An action that modifies the ingress port field (see
below), such as e.g. load or set_field, followed by an
action or instruction that performs another flow table
lookup, such as resubmit or goto_table.
This field is heavily used for matching in OpenFlow tables, but for
packet egress, it has only very limited roles:
· OpenFlow requires suppressing output actions to
in_port. That is, the following two flows both drop all
packets that arrive on port 1:
in_port=1,actions=1
in_port=1,actions=drop
(This behavior is occasionally useful for flooding to a
subset of ports. Specifying actions=1,2,3,4, for
example, outputs to ports 1, 2, 3, and 4, omitting the
ingress port.)
· OpenFlow has a special port OFPP_IN_PORT (with value
0xfff8) that outputs to the ingress port. For example,
in a switch that has four ports numbered 1 through 4,
actions=1,2,3,4,in_port outputs to ports 1, 2, 3, and
4, including the ingress port.
Because the ingress port field has so little influence on packet
processing, it does not ordinarily make sense to modify the ingress
port field. The field is writable only to support the occasional use
case where the ingress port’s roles in packet egress, described
above, become troublesome. For example,
actions=load:0->NXM_OF_IN_PORT[],output:123 will output to port 123
regardless of whether it is in the ingress port. If the ingress port
is important, then one may save and restore it on the stack:
actions=push:NXM_OF_IN_PORT[],load:0->NXM_OF_IN_PORT[],output:123,pop:NXM_OF_IN_PORT[]
or, in Open vSwitch 2.7 or later, use the clone action to save and
restore it:
actions=clone(load:0->NXM_OF_IN_PORT[],output:123)
The ability to modify the ingress port is an Open vSwitch extension
to OpenFlow.
OXM Ingress Port Field
Name: in_port_oxm
Width: 32 bits
Format: OpenFlow 1.1+ port
Masking: not maskable
Prerequisites: none
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: yes (exact match only)
OXM: OXM_OF_IN_PORT (0) since OpenFlow 1.2 and Open
vSwitch 1.7
NXM: none
OpenFlow 1.1 and later use a 32-bit port number, so this field
supplies a 32-bit view of the ingress port. Current versions of Open
vSwitch support only a 16-bit range of ports:
· OpenFlow 1.0 ports 0x0000 to 0xfeff, inclusive, map to
OpenFlow 1.1 port numbers with the same values.
· OpenFlow 1.0 ports 0xff00 to 0xffff, inclusive, map to
OpenFlow 1.1 port numbers 0xffffff00 to 0xffffffff.
· OpenFlow 1.1 ports 0x0000ff00 to 0xfffffeff are not
mapped and not supported.
in_port and in_port_oxm are two views of the same information, so all
of the comments on in_port apply to in_port_oxm too. Modifying
in_port changes in_port_oxm, and vice versa.
Setting in_port_oxm to an unsupported value yields unspecified
behavior.
Output Queue Field
Name: skb_priority
Width: 32 bits
Format: hexadecimal
Masking: not maskable
Prerequisites: none
Access: read-only
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: none
Future Directions: Open vSwitch implements the output queue as a
field, but does not currently expose it through OXM or NXM for
matching purposes. If this turns out to be a useful feature, it could
be implemented in future versions. Only the set_queue, enqueue, and
pop_queue actions currently influence the output queue.
This field influences how packets in the flow will be queued, for
quality of service (QoS) purposes, when they egress the switch. Its
range of meaningful values, and their meanings, varies greatly from
one OpenFlow implementation to another. Even within a single
implementation, there is no guarantee that all OpenFlow ports have
the same queues configured or that all OpenFlow ports in an
implementation can be configured the same way queue-wise.
Configuring queues on OpenFlow is not well standardized. On Linux,
Open vSwitch supports queue configuration via OVSDB, specifically the
QoS and Queue tables (see ovs-vswitchd.conf.db(5) for details). Ports
of Open vSwitch to other platforms might require queue configuration
through some separate protocol (such as a CLI). Even on Linux, Open
vSwitch exposes only a fraction of the kernel’s queuing features
through OVSDB, so advanced or unusual uses might require use of
separate utilities (e.g. tc). OpenFlow switches other than Open
vSwitch might use OF-CONFIG or any of the configuration methods
mentioned above. Finally, some OpenFlow switches have a fixed number
of fixed-function queues (e.g. eight queues with strictly defined
priorities) and others do not support any control over queuing.
The only output queue that all OpenFlow implementations must support
is zero, to identify a default queue, whose properties are
implementation-defined. Outputting a packet to a queue that does not
exist on the output port yields unpredictable behavior: among the
possibilities are that the packet might be dropped or transmitted
with a very high or very low priority.
OpenFlow 1.0 only allowed output queues to be specified as part of an
enqueue action that specified both a queue and an output port. That
is, OpenFlow 1.0 treats the queue as an argument to an action, not as
a field.
To increase flexibility, OpenFlow 1.1 added an action to set the
output queue. This model was carried forward, without change, through
OpenFlow 1.5.
Open vSwitch implements the native queuing model of each OpenFlow
version it supports. Open vSwitch also includes an extension for
setting the output queue as an action in OpenFlow 1.0.
When a packet ingresses into an OpenFlow switch, the output queue is
ordinarily set to 0, indicating the default queue. However, Open
vSwitch supports various ways to forward a packet from one OpenFlow
switch to another within a single host. In these cases, Open vSwitch
maintains the output queue across the forwarding step. For example:
· A hop across an Open vSwitch ``patch port’’ (which does
not actually involve queuing) preserves the output
queue.
· When a flow sets the output queue then outputs to an
OpenFlow tunnel port, the encapsulation preserves the
output queue. If the kernel TCP/IP stack routes the
encapsulated packet directly to a physical interface,
then that output honors the output queue.
Alternatively, if the kernel routes the encapsulated
packet to another Open vSwitch bridge, then the output
queue set previously becomes the initial output queue
on ingress to the second bridge and will thus be used
for further output actions (unless overridden by a new
``set queue’’ action).
(This description reflects the current behavior of Open
vSwitch on Linux. This behavior relies on details of
the Linux TCP/IP stack. It could be difficult to make
ports to other operating systems behave the same way.)
Packet Mark Field
Name: pkt_mark
Width: 32 bits
Format: hexadecimal
Masking: arbitrary bitwise masks
Prerequisites: none
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_PKT_MARK (33) since Open vSwitch 2.0
Packet mark comes to Open vSwitch from the Linux kernel, in which the
sk_buff data structure that represents a packet contains a 32-bit
member named skb_mark. The value of skb_mark propagates along with
the packet it accompanies wherever the packet goes in the kernel. It
has no predefined semantics but various kernel-user interfaces can
set and match on it, which makes it suitable for ``marking’’ packets
at one point in their handling and then acting on the mark later.
With iptables, for example, one can mark some traffic specially at
ingress and then handle that traffic differently at egress based on
the marked value.
Packet mark is an attempt at a generalization of the skb_mark concept
beyond Linux, at least through more generic naming. Like
skb_priority, packet mark is preserved across forwarding steps within
a machine. Unlike skb_priority, packet mark has no direct effect on
packet forwarding: the value set in packet mark does not matter
unless some later OpenFlow table or switch matches on packet mark, or
unless the packet passes through some other kernel subsystem that has
been configured to interpret packet mark in specific ways, e.g.
through iptables configuration mentioned above.
Preserving packet mark across kernel forwarding steps relies heavily
on kernel support, which ports to non-Linux operating systems may not
have. Regardless of operating system support, Open vSwitch supports
packet mark within a single bridge and across patch ports.
The value of packet mark when a packet ingresses into the first Open
vSwich bridge is typically zero, but it could be nonzero if its value
was previously set by some kernel subsystem.
Action Set Output Port Field
Name: actset_output
Width: 32 bits
Format: OpenFlow 1.1+ port
Masking: not maskable
Prerequisites: none
Access: read-only
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: ONFOXM_ET_ACTSET_OUTPUT (43) since OpenFlow 1.3 and
Open vSwitch 2.4; OXM_OF_ACTSET_OUTPUT (43) since
OpenFlow 1.5 and Open vSwitch 2.4
NXM: none
Holds the output port currently in the OpenFlow action set (i.e. from
an output action within a write_actions instruction). Its value is an
OpenFlow port number. If there is no output port in the OpenFlow
action set, or if the output port will be ignored (e.g. because there
is an output group in the OpenFlow action set), then the value will
be OFPP_UNSET.
Open vSwitch allows any table to match this field. OpenFlow, however,
only requires this field to be matchable from within an OpenFlow
egress table (a feature that Open vSwitch does not yet implement).
Packet Type Field
Name: packet_type
Width: 32 bits
Format: packet type
Masking: not maskable
Prerequisites: none
Access: read-only
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: OXM_OF_PACKET_TYPE (44) since OpenFlow 1.5 and Open
vSwitch 2.8
NXM: none
The type of the packet in the format specified in OpenFlow 1.5:
Packet type
<--------->
16 16
+---+-------+
|ns |ns_type| ...
+---+-------+
The upper 16 bits, ns, are a namespace. The meaning of ns_type
depends on the namespace. The packet type field is specified and
displayed in the format (ns,ns_type).
Open vSwitch currently supports the following classes of packet types
for matching:
(0,0) Ethernet.
(1,ethertype)
The specified ethertype. Open vSwitch can forward
packets with any ethertype, but it can only match on
and process data fields for the following supported
packet types:
(1,0x800)
IPv4
(1,0x806)
ARP
(1,0x86dd)
IPv6
(1,0x8847)
MPLS
(1,0x8848)
MPLS multicast
(1,0x8035)
RARP
(1,0x894f)
NSH
Consider the distinction between a packet with packet_type=(0,0),
dl_type=0x800 and one with packet_type=(1,0x800). The former is an
Ethernet frame that contains an IPv4 packet, like this:
Ethernet IPv4
<-----------> <--------------->
48 48 16 8 32 32
+---+---+-----+ +---+-----+---+---+
|dst|src|type | |...|proto|src|dst| ...
+---+---+-----+ +---+-----+---+---+
0x800
The latter is an IPv4 packet not encapsulated inside any outer frame,
like this:
IPv4
<--------------->
8 32 32
+---+-----+---+---+
|...|proto|src|dst| ...
+---+-----+---+---+
Matching on packet_type is a pre-requisite for matching on any data
field, but for backward compatibility, when a match on a data field
is present without a packet_type match, Open vSwitch acts as though a
match on (0,0) (Ethernet) had been supplied. Similarly, when Open
vSwitch sends flow match information to a controller, e.g. in a reply
to a request to dump the flow table, Open vSwitch omits a match on
packet type (0,0) if it would be implied by a data field match.
Summary:
Name Bytes Mask RW? Prereqs NXM/OXM Support
──────────── ────── ───── ──── ──────── ────────────────
ct_state 4 yes no none OVS 2.5+
ct_zone 2 no no none OVS 2.5+
ct_mark 4 yes yes none OVS 2.5+
ct_label 16 yes yes none OVS 2.5+
ct_nw_src 4 yes no CT OVS 2.8+
ct_nw_dst 4 yes no CT OVS 2.8+
ct_ipv6_src 16 yes no CT OVS 2.8+
ct_ipv6_dst 16 yes no CT OVS 2.8+
ct_nw_proto 1 no no CT OVS 2.8+
ct_tp_src 2 yes no CT OVS 2.8+
ct_tp_dst 2 yes no CT OVS 2.8+
Open vSwitch 2.5 and later support ``connection tracking,’’ which
allows bidirectional streams of packets to be statefully grouped into
connections. Open vSwitch connection tracking, for example,
identifies the patterns of TCP packets that indicates a successfully
initiated connection, as well as those that indicate that a
connection has been torn down. Open vSwitch connection tracking can
also identify related connections, such as FTP data connections
spawned from FTP control connections.
An individual packet passing through the pipeline may be in one of
two states, ``untracked’’ or ``tracked,’’ which may be distinguished
via the ``trk’’ flag in ct_state. A packet is untracked at the
beginning of the Open vSwitch pipeline and continues to be untracked
until the pipeline invokes the ct action. The connection tracking
fields are all zeroes in an untracked packet. When a flow in the Open
vSwitch pipeline invokes the ct action, the action initializes the
connection tracking fields and the packet becomes tracked for the
remainder of its processing.
The connection tracker stores connection state in an internal table,
but it only adds a new entry to this table when a ct action for a new
connection invokes ct with the commit parameter. For a given
connection, when a pipeline has executed ct, but not yet with commit,
the connection is said to be uncommitted. State for an uncommitted
connection is ephemeral and does not persist past the end of the
pipeline, so some features are only available to committed
connections. A connection would typically be left uncommitted as a
way to drop its packets.
Connection tracking is an Open vSwitch extension to OpenFlow.
Connection Tracking State Field
Name: ct_state
Width: 32 bits
Format: ct state
Masking: arbitrary bitwise masks
Prerequisites: none
Access: read-only
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_CT_STATE (105) since Open vSwitch 2.5
This field holds several flags that can be used to determine the
state of the connection to which the packet belongs.
Matches on this field are most conveniently written in terms of
symbolic names (listed below), each preceded by either + for a flag
that must be set, or - for a flag that must be unset, without any
other delimiters between the flags. Flags not mentioned are
wildcarded. For example, tcp,ct_state=+trk-new matches TCP packets
that have been run through the connection tracker and do not
establish a new connection. Matches can also be written as
flags/mask, where flags and mask are 32-bit numbers in decimal or in
hexadecimal prefixed by 0x.
The following flags are defined:
new (0x01)
A new connection. Set to 1 if this is an uncommitted
connection.
est (0x02)
Part of an existing connection. Set to 1 if this is a
committed connection.
rel (0x04)
Related to an existing connection, e.g. an ICMP
``destination unreachable’’ message or an FTP data
connections. This flag will only be 1 if the connection
to which this one is related is committed.
Connections identified as rel are separate from the
originating connection and must be committed
separately. All packets for a related connection will
have the rel flag set, not just the initial packet.
rpl (0x08)
This packet is in the reply direction, meaning that it
is in the opposite direction from the packet that
initiated the connection. This flag will only be 1 if
the connection is committed.
inv (0x10)
The state is invalid, meaning that the connection
tracker couldn’t identify the connection. This flag is
a catch-all for problems in the connection or the
connection tracker, such as:
· L3/L4 protocol handler is not
loaded/unavailable. With the Linux kernel
datapath, this may mean that the
nf_conntrack_ipv4 or nf_conntrack_ipv6 modules
are not loaded.
· L3/L4 protocol handler determines that the
packet is malformed.
· Packets are unexpected length for protocol.
trk (0x20)
This packet is tracked, meaning that it has previously
traversed the connection tracker. If this flag is not
set, then no other flags will be set. If this flag is
set, then the packet is tracked and other flags may
also be set.
snat (0x40)
This packet was transformed by source address/port
translation by a preceding ct action. Open vSwitch 2.6
added this flag.
dnat (0x80)
This packet was transformed by destination address/port
translation by a preceding ct action. Open vSwitch 2.6
added this flag.
There are additional constraints on these flags, listed in decreasing
order of precedence below:
1.
If trk is unset, no other flags are set.
2.
If trk is set, one or more other flags may be set.
3.
If inv is set, only the trk flag is also set.
4.
new and est are mutually exclusive.
5.
new and rpl are mutually exclusive.
6.
rel may be set in conjunction with any other flags.
Future versions of Open vSwitch may define new flags.
Connection Tracking Zone Field
Name: ct_zone
Width: 16 bits
Format: hexadecimal
Masking: not maskable
Prerequisites: none
Access: read-only
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_CT_ZONE (106) since Open vSwitch 2.5
A connection tracking zone, the zone value passed to the most recent
ct action. Each zone is an independent connection tracking context,
so tracking the same packet in multiple contexts requires using the
ct action multiple times.
Connection Tracking Mark Field
Name: ct_mark
Width: 32 bits
Format: hexadecimal
Masking: arbitrary bitwise masks
Prerequisites: none
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_CT_MARK (107) since Open vSwitch 2.5
The metadata committed, by an action within the exec parameter to the
ct action, to the connection to which the current packet belongs.
Connection Tracking Label Field
Name: ct_label
Width: 128 bits
Format: hexadecimal
Masking: arbitrary bitwise masks
Prerequisites: none
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_CT_LABEL (108) since Open vSwitch 2.5
The label committed, by an action within the exec parameter to the ct
action, to the connection to which the current packet belongs.
Open vSwitch 2.8 introduced the matching support for connection
tracker original direction 5-tuple fields.
For non-committed non-related connections the conntrack original
direction tuple fields always have the same values as the
corresponding headers in the packet itself. For any other packets of
a committed connection the conntrack original direction tuple fields
reflect the values from that initial non-committed non-related
packet, and thus may be different from the actual packet headers, as
the actual packet headers may be in reverse direction (for reply
packets), transformed by NAT (when nat option was applied to the
connection), or be of different protocol (i.e., when an ICMP response
is sent to an UDP packet). In case of related connections, e.g., an
FTP data connection, the original direction tuple contains the
original direction headers from the master connection, e.g., an FTP
control connection.
The following fields are populated by the ct action, and require a
match to a valid connection tracking state as a prerequisite, in
addition to the IP or IPv6 ethertype match. Examples of valid
connection tracking state matches include ct_state=+new,
ct_state=+est, ct_state=+rel, and ct_state=+trk-inv.
Connection Tracking Original Direction IPv4 Source Address Field
Name: ct_nw_src
Width: 32 bits
Format: IPv4
Masking: arbitrary bitwise masks
Prerequisites: CT
Access: read-only
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_CT_NW_SRC (120) since Open vSwitch 2.8
Matches IPv4 conntrack original direction tuple source address. See
the paragraphs above for general description to the conntrack
original direction tuple. Introduced in Open vSwitch 2.8.
Connection Tracking Original Direction IPv4 Destination Address Field
Name: ct_nw_dst
Width: 32 bits
Format: IPv4
Masking: arbitrary bitwise masks
Prerequisites: CT
Access: read-only
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_CT_NW_DST (121) since Open vSwitch 2.8
Matches IPv4 conntrack original direction tuple destination address.
See the paragraphs above for general description to the conntrack
original direction tuple. Introduced in Open vSwitch 2.8.
Connection Tracking Original Direction IPv6 Source Address Field
Name: ct_ipv6_src
Width: 128 bits
Format: IPv6
Masking: arbitrary bitwise masks
Prerequisites: CT
Access: read-only
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_CT_IPV6_SRC (122) since Open vSwitch 2.8
Matches IPv6 conntrack original direction tuple source address. See
the paragraphs above for general description to the conntrack
original direction tuple. Introduced in Open vSwitch 2.8.
Connection Tracking Original Direction IPv6 Destination Address Field
Name: ct_ipv6_dst
Width: 128 bits
Format: IPv6
Masking: arbitrary bitwise masks
Prerequisites: CT
Access: read-only
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_CT_IPV6_DST (123) since Open vSwitch 2.8
Matches IPv6 conntrack original direction tuple destination address.
See the paragraphs above for general description to the conntrack
original direction tuple. Introduced in Open vSwitch 2.8.
Connection Tracking Original Direction IP Protocol Field
Name: ct_nw_proto
Width: 8 bits
Format: decimal
Masking: not maskable
Prerequisites: CT
Access: read-only
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_CT_NW_PROTO (119) since Open vSwitch 2.8
Matches conntrack original direction tuple IP protocol type, which is
specified as a decimal number between 0 and 255, inclusive (e.g. 1 to
match ICMP packets or 6 to match TCP packets). In case of, for
example, an ICMP response to an UDP packet, this may be different
from the IP protocol type of the packet itself. See the paragraphs
above for general description to the conntrack original direction
tuple. Introduced in Open vSwitch 2.8.
Connection Tracking Original Direction Transport Layer Source Port
Field
Name: ct_tp_src
Width: 16 bits
Format: decimal
Masking: arbitrary bitwise masks
Prerequisites: CT
Access: read-only
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_CT_TP_SRC (124) since Open vSwitch 2.8
Bitwise match on the conntrack original direction tuple transport
source, when MFF_CT_NW_PROTO has value 6 for TCP, 17 for UDP, or 132
for SCTP. When MFF_CT_NW_PROTO has value 1 for ICMP, or 58 for
ICMPv6, the lower 8 bits of MFF_CT_TP_SRC matches the conntrack
original direction ICMP type. See the paragraphs above for general
description to the conntrack original direction tuple. Introduced in
Open vSwitch 2.8.
Connection Tracking Original Direction Transport Layer Source Port
Field
Name: ct_tp_dst
Width: 16 bits
Format: decimal
Masking: arbitrary bitwise masks
Prerequisites: CT
Access: read-only
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_CT_TP_DST (125) since Open vSwitch 2.8
Bitwise match on the conntrack original direction tuple transport
destination port, when MFF_CT_NW_PROTO has value 6 for TCP, 17 for
UDP, or 132 for SCTP. When MFF_CT_NW_PROTO has value 1 for ICMP, or
58 for ICMPv6, the lower 8 bits of MFF_CT_TP_DST matches the
conntrack original direction ICMP code. See the paragraphs above for
general description to the conntrack original direction tuple.
Introduced in Open vSwitch 2.8.
Summary:
Name Bytes Mask RW? Prereqs NXM/OXM Support
───────── ────── ───── ──── ──────── ─────────────────────
metadata 8 yes yes none OF 1.2+ and OVS 1.8+
reg0 4 yes yes none OVS 1.1+
reg1 4 yes yes none OVS 1.1+
reg2 4 yes yes none OVS 1.1+
reg3 4 yes yes none OVS 1.1+
reg4 4 yes yes none OVS 1.3+
reg5 4 yes yes none OVS 1.7+
reg6 4 yes yes none OVS 1.7+
reg7 4 yes yes none OVS 1.7+
reg8 4 yes yes none OVS 2.6+
reg9 4 yes yes none OVS 2.6+
reg10 4 yes yes none OVS 2.6+
reg11 4 yes yes none OVS 2.6+
reg12 4 yes yes none OVS 2.6+
reg13 4 yes yes none OVS 2.6+
reg14 4 yes yes none OVS 2.6+
reg15 4 yes yes none OVS 2.6+
xreg0 8 yes yes none OF 1.3+ and OVS 2.4+
xreg1 8 yes yes none OF 1.3+ and OVS 2.4+
xreg2 8 yes yes none OF 1.3+ and OVS 2.4+
xreg3 8 yes yes none OF 1.3+ and OVS 2.4+
xreg4 8 yes yes none OF 1.3+ and OVS 2.4+
xreg5 8 yes yes none OF 1.3+ and OVS 2.4+
xreg6 8 yes yes none OF 1.3+ and OVS 2.4+
xreg7 8 yes yes none OF 1.3+ and OVS 2.4+
xxreg0 16 yes yes none OVS 2.6+
xxreg1 16 yes yes none OVS 2.6+
xxreg2 16 yes yes none OVS 2.6+
xxreg3 16 yes yes none OVS 2.6+
These fields give an OpenFlow switch space for temporary storage
while the pipeline is running. Whereas metadata fields can have a
meaningful initial value and can persist across some hops across
OpenFlow switches, registers are always initially 0 and their values
never persist across inter-switch hops (not even across patch ports).
OpenFlow Metadata Field
Name: metadata
Width: 64 bits
Format: hexadecimal
Masking: arbitrary bitwise masks
Prerequisites: none
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: yes
OXM: OXM_OF_METADATA (2) since OpenFlow 1.2 and Open
vSwitch 1.8
NXM: none
This field is the oldest standardized OpenFlow register field,
introduced in OpenFlow 1.1. It was introduced to model the limited
number of user-defined bits that some ASIC-based switches can carry
through their pipelines. Because of hardware limitations, OpenFlow
allows switches to support writing and masking only an
implementation-defined subset of bits, even no bits at all. The Open
vSwitch software switch always supports all 64 bits, but of course an
Open vSwitch port to an ASIC would have the same restriction as the
ASIC itself.
This field has an OXM code point, but OpenFlow 1.4 and earlier allow
it to be modified only with a specialized instruction, not with a
``set-field’’ action. OpenFlow 1.5 removes this restriction. Open
vSwitch does not enforce this restriction, regardless of OpenFlow
version.
Register 0 Field
Name: reg0
Width: 32 bits
Format: hexadecimal
Masking: arbitrary bitwise masks
Prerequisites: none
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_REG0 (0) since Open vSwitch 1.1
This is the first of several Open vSwitch registers, all of which
have the same properties. Open vSwitch 1.1 introduced registers 0, 1,
2, and 3, version 1.3 added register 4, version 1.7 added registers
5, 6, and 7, and version 2.6 added registers 8 through 15.
Extended Register 0 Field
Name: xreg0
Width: 64 bits
Format: hexadecimal
Masking: arbitrary bitwise masks
Prerequisites: none
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: OXM_OF_PKT_REG0 (0) since OpenFlow 1.3 and Open
vSwitch 2.4
NXM: none
This is the first of the registers introduced in OpenFlow 1.5.
OpenFlow 1.5 calls these fields just the ``packet registers,’’ but
Open vSwitch already had 32-bit registers by that name, so Open
vSwitch uses the name ``extended registers’’ in an attempt to reduce
confusion. The standard allows for up to 128 registers, each 64 bits
wide, but Open vSwitch only implements 4 (in versions 2.4 and 2.5) or
8 (in version 2.6 and later).
Each of the 64-bit extended registers overlays two of the 32-bit
registers: xreg0 overlays reg0 and reg1, with reg0 supplying the
most-significant bits of xreg0 and reg1 the least-significant.
Similarly, xreg1 overlays reg2 and reg3, and so on.
The OpenFlow specification says, ``In most cases, the packet
registers can not be matched in tables, i.e. they usually can not be
used in the flow entry match structure’’ [OpenFlow 1.5, section
7.2.3.10], but there is no reason for a software switch to impose
such a restriction, and Open vSwitch does not.
Double-Extended Register 0 Field
Name: xxreg0
Width: 128 bits
Format: hexadecimal
Masking: arbitrary bitwise masks
Prerequisites: none
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_XXREG0 (111) since Open vSwitch 2.6
This is the first of the double-extended registers introduce in Open
vSwitch 2.6. Each of the 128-bit extended registers overlays four of
the 32-bit registers: xxreg0 overlays reg0 through reg3, with reg0
supplying the most-significant bits of xxreg0 and reg3 the least-
significant. xxreg1 similarly overlays reg4 through reg7, and so on.
Summary:
Name Bytes Mask RW? Prereqs NXM/OXM Support
───────────────────── ────── ───── ──── ───────── ─────────────────────
eth_src aka dl_src 6 yes yes Ethernet OF 1.2+ and OVS 1.1+
eth_dst aka dl_dst 6 yes yes Ethernet OF 1.2+ and OVS 1.1+
eth_type aka dl_type 2 no no Ethernet OF 1.2+ and OVS 1.1+
Ethernet is the only layer-2 protocol that Open vSwitch supports. As
with most software, Open vSwitch and OpenFlow regard an Ethernet
frame to begin with the 14-byte header and end with the final byte of
the payload; that is, the frame check sequence is not considered part
of the frame.
Ethernet Source Field
Name: eth_src (aka dl_src)
Width: 48 bits
Format: Ethernet
Masking: arbitrary bitwise masks
Prerequisites: Ethernet
Access: read/write
OpenFlow 1.0: yes (exact match only)
OpenFlow 1.1: yes
OXM: OXM_OF_ETH_SRC (4) since OpenFlow 1.2 and Open
vSwitch 1.7
NXM: NXM_OF_ETH_SRC (2) since Open vSwitch 1.1
The Ethernet source address:
Ethernet
<---------->
48 48 16
+---+---+----+
|dst|src|type| ...
+---+---+----+
Ethernet Destination Field
Name: eth_dst (aka dl_dst)
Width: 48 bits
Format: Ethernet
Masking: arbitrary bitwise masks
Prerequisites: Ethernet
Access: read/write
OpenFlow 1.0: yes (exact match only)
OpenFlow 1.1: yes
OXM: OXM_OF_ETH_DST (3) since OpenFlow 1.2 and Open
vSwitch 1.7
NXM: NXM_OF_ETH_DST (1) since Open vSwitch 1.1
The Ethernet destination address:
Ethernet
<---------->
48 48 16
+---+---+----+
|dst|src|type| ...
+---+---+----+
Open vSwitch 1.8 and later support arbitrary masks for source and/or
destination. Earlier versions only support masking the destination
with the following masks:
01:00:00:00:00:00
Match only the multicast bit. Thus,
dl_dst=01:00:00:00:00:00/01:00:00:00:00:00 matches all
multicast (including broadcast) Ethernet packets, and
dl_dst=00:00:00:00:00:00/01:00:00:00:00:00 matches all
unicast Ethernet packets.
fe:ff:ff:ff:ff:ff
Match all bits except the multicast bit. This is
probably not useful.
ff:ff:ff:ff:ff:ff
Exact match (equivalent to omitting the mask).
00:00:00:00:00:00
Wildcard all bits (equivalent to dl_dst=*).
Ethernet Type Field
Name: eth_type (aka dl_type)
Width: 16 bits
Format: hexadecimal
Masking: not maskable
Prerequisites: Ethernet
Access: read-only
OpenFlow 1.0: yes (exact match only)
OpenFlow 1.1: yes (exact match only)
OXM: OXM_OF_ETH_TYPE (5) since OpenFlow 1.2 and Open
vSwitch 1.7
NXM: NXM_OF_ETH_TYPE (3) since Open vSwitch 1.1
The most commonly seen Ethernet frames today use a format called
``Ethernet II,’’ in which the last two bytes of the Ethernet header
specify the Ethertype. For such a frame, this field is copied from
those bytes of the header, like so:
Ethernet
<---------------->
48 48 16
+---+---+----------+
|dst|src| type | ...
+---+---+----------+
≥0x600
Every Ethernet type has a value 0x600 (1,536) or greater. When the
last two bytes of the Ethernet header have a value too small to be an
Ethernet type, then the value found there is the total length of the
frame in bytes, excluding the Ethernet header. An 802.2 LLC header
typically follows the Ethernet header. OpenFlow and Open vSwitch only
support LLC headers with DSAP and SSAP 0xaa and control byte 0x03,
which indicate that a SNAP header follows the LLC header. In turn,
OpenFlow and Open vSwitch only support a SNAP header with
organization 0x000000. In such a case, this field is copied from the
type field in the SNAP header, like this:
Ethernet LLC SNAP
<------------> <------------> <----------------->
48 48 16 8 8 8 24 16
+---+---+------+ +----+----+----+ +--------+----------+
|dst|src| type | |DSAP|SSAP|cntl| | org | type | ...
+---+---+------+ +----+----+----+ +--------+----------+
<0x600 0xaa 0xaa 0x03 0x000000 ≥0x600
When an 802.1Q header is inserted after the Ethernet source and
destination, this field is populated with the encapsulated Ethertype,
not the 802.1Q Ethertype. With an Ethernet II inner frame, the result
looks like this:
Ethernet 802.1Q Ethertype
<------> <--------> <-------->
48 48 16 16 16
+----+---+ +------+---+ +----------+
|dst |src| | TPID |TCI| | type | ...
+----+---+ +------+---+ +----------+
0x8100 ≥0x600
LLC and SNAP encapsulation look like this with an 802.1Q header:
Ethernet 802.1Q Ethertype LLC SNAP
<------> <--------> <-------> <------------> <----------------->
48 48 16 16 16 8 8 8 24 16
+----+---+ +------+---+ +---------+ +----+----+----+ +--------+----------+
|dst |src| | TPID |TCI| | type | |DSAP|SSAP|cntl| | org | type | ...
+----+---+ +------+---+ +---------+ +----+----+----+ +--------+----------+
0x8100 <0x600 0xaa 0xaa 0x03 0x000000 ≥0x600
When a packet doesn’t match any of the header formats described
above, Open vSwitch and OpenFlow set this field to 0x5ff
(OFP_DL_TYPE_NOT_ETH_TYPE).
Summary:
Name Bytes Mask RW? Prereqs NXM/OXM Support
──────────── ──────────────── ───── ──── ───────── ─────────────────────
dl_vlan 2 (low 12 bits) no yes Ethernet
dl_vlan_pcp 1 (low 3 bits) no yes Ethernet
vlan_vid 2 (low 12 bits) yes yes Ethernet OF 1.2+ and OVS 1.7+
vlan_pcp 1 (low 3 bits) no yes VLAN VID OF 1.2+ and OVS 1.7+
vlan_tci 2 yes yes Ethernet OVS 1.1+
The 802.1Q VLAN header causes more trouble than any other 4 bytes in
networking. OpenFlow 1.0, 1.1, and 1.2+ all treat VLANs differently.
Open vSwitch extensions add another variant to the mix. Open vSwitch
reconciles all four treatments as best it can.
VLAN Header Format
An 802.1Q VLAN header consists of two 16-bit fields:
TPID TCI
<-------> <--------->
16 3 1 12
+---------+---+---+---+
|Ethertype|PCP|CFI|VID|
+---------+---+---+---+
0x8100 0
The first 16 bits of the VLAN header, the TPID (Tag Protocol
IDentifier), is an Ethertype. When the VLAN header is inserted just
after the source and destination MAC addresses in a Ethertype frame,
the TPID serves to identify the presence of the VLAN. The standard
TPID, the only one that Open vSwitch supports, is 0x8100. OpenFlow
1.0 explicitly supports only TPID 0x8100. OpenFlow 1.1, but not
earlier or later versions, also requires support for TPID 0x88a8
(Open vSwitch does not support this). OpenFlow 1.2 through 1.5 do not
require support for specific TPIDs (the ``push vlan header’’ action
does say that only 0x8100 and 0x88a8 should be pushed). No version of
OpenFlow provides a way to distinguish or match on the TPID.
The remaining 16 bits of the VLAN header, the TCI (Tag Control
Information), is subdivided into three subfields:
· PCP (Priority Control Point), is a 3-bit 802.1p
priority. The lowest priority is value 1, the second-
lowest is value 0, and priority increases from 2 up to
highest priority 7.
· CFI (Canonical Format Indicator), is a 1-bit field. On
an Ethernet network, its value is always 0. This led to
it later being repurposed under the name DEI (Drop
Eligibility Indicator). By either name, OpenFlow and
Open vSwitch don’t provide any way to match or set this
bit.
· VID (VLAN IDentifier), is a 12-bit VLAN. If the VID is
0, then the frame is not part of a VLAN. In that case,
the VLAN header is called a priority tag because it is
only meaningful for assigning the frame a priority. VID
0xfff (4,095) is reserved.
See eth_type for illustrations of a complete Ethernet frame with
802.1Q tag included.
Multiple VLANs
Open vSwitch can match only a single VLAN header. If more than one
VLAN header is present, then eth_type holds the TPID of the inner
VLAN header. Open vSwitch stops parsing the packet after the inner
TPID, so matching further into the packet (e.g. on the inner TCI or
L3 fields) is not possible.
OpenFlow only directly supports matching a single VLAN header. In
OpenFlow 1.1 or later, one OpenFlow table can match on the outermost
VLAN header and pop it off, and a later OpenFlow table can match on
the next outermost header. Open vSwitch does not support this.
VLAN Field Details
The four variants have three different levels of expressiveness:
OpenFlow 1.0 and 1.1 VLAN matching are less powerful than OpenFlow
1.2+ VLAN matching, which is less powerful than Open vSwitch
extension VLAN matching.
OpenFlow 1.0 VLAN Fields
OpenFlow 1.0 uses two fields, called dl_vlan and dl_vlan_pcp, each of
which can be either exact-matched or wildcarded, to specify VLAN
matches:
· When both dl_vlan and dl_vlan_pcp are wildcarded, the
flow matches packets without an 802.1Q header or with
any 802.1Q header.
· The match dl_vlan=0xffff causes a flow to match only
packets without an 802.1Q header. Such a flow should
also wildcard dl_vlan_pcp, since a packet without an
802.1Q header does not have a PCP. OpenFlow does not
specify what to do if a match on PCP is actually
present, but Open vSwitch ignores it.
· Otherwise, the flow matches only packets with an 802.1Q
header. If dl_vlan is not wildcarded, then the flow
only matches packets with the VLAN ID specified in
dl_vlan’s low 12 bits. If dl_vlan_pcp is not
wildcarded, then the flow only matches packets with the
priority specified in dl_vlan_pcp’s low 3 bits.
OpenFlow does not specify how to interpret the high 4
bits of dl_vlan or the high 5 bits of dl_vlan_pcp. Open
vSwitch ignores them.
OpenFlow 1.1 VLAN Fields
VLAN matching in OpenFlow 1.1 is similar to OpenFlow 1.0. The one
refinement is that when dl_vlan matches on 0xfffe (OFVPID_ANY), the
flow matches only packets with an 802.1Q header, with any VLAN ID. If
dl_vlan_pcp is wildcarded, the flow matches any packet with an 802.1Q
header, regardless of VLAN ID or priority. If dl_vlan_pcp is not
wildcarded, then the flow only matches packets with the priority
specified in dl_vlan_pcp’s low 3 bits.
OpenFlow 1.1 uses the name OFPVID_NONE, instead of OFP_VLAN_NONE, for
a dl_vlan of 0xffff, but it has the same meaning.
In OpenFlow 1.1, Open vSwitch reports error OFPBMC_BAD_VALUE for an
attempt to match on dl_vlan between 4,096 and 0xfffd, inclusive, or
dl_vlan_pcp greater than 7.
OpenFlow 1.2 VLAN Fields
OpenFlow 1.2+ VLAN ID Field
Name: vlan_vid
Width: 16 bits (only the least-significant 12 bits may be nonzero)
Format: decimal
Masking: arbitrary bitwise masks
Prerequisites: Ethernet
Access: read/write
OpenFlow 1.0: yes (exact match only)
OpenFlow 1.1: yes (exact match only)
OXM: OXM_OF_VLAN_VID (6) since OpenFlow 1.2 and Open vSwitch 1.7
NXM: none
The OpenFlow standard describes this field as consisting of ``12+1’’
bits. On ingress, its value is 0 if no 802.1Q header is present, and
otherwise it holds the VLAN VID in its least significant 12 bits,
with bit 12 (0x1000 aka OFPVID_PRESENT) also set to 1. The three most
significant bits are always zero:
OXM_OF_VLAN_VID
<------------->
3 1 12
+---+--+--------+
| |P |VLAN ID |
+---+--+--------+
0
As a consequence of this field’s format, one may use it to match the
VLAN ID in all of the ways available with the OpenFlow 1.0 and 1.1
formats, and a few new ways:
Fully wildcarded
Matches any packet, that is, one without an 802.1Q
header or with an 802.1Q header with any TCI value.
Value 0x0000 (OFPVID_NONE), mask 0xffff (or no mask)
Matches only packets without an 802.1Q header.
Value 0x1000, mask 0x1000
Matches any packet with an 802.1Q header, regardless of
VLAN ID.
Value 0x1009, mask 0xffff (or no mask)
Match only packets with an 802.1Q header with VLAN ID
9.
Value 0x1001, mask 0x1001
Matches only packets that have an 802.1Q header with an
odd-numbered VLAN ID. (This is just an example; one can
match on any desired VLAN ID bit pattern.)
OpenFlow 1.2+ VLAN Priority Field
Name: vlan_pcp
Width: 8 bits (only the least-significant 3 bits may be nonzero)
Format: decimal
Masking: not maskable
Prerequisites: VLAN VID
Access: read/write
OpenFlow 1.0: yes (exact match only)
OpenFlow 1.1: yes (exact match only)
OXM: OXM_OF_VLAN_PCP (7) since OpenFlow 1.2 and Open vSwitch
1.7
NXM: none
The 3 least significant bits may be used to match the PCP bits in an
802.1Q header. Other bits are always zero:
OXM_OF_VLAN_VID
<------------->
5 3
+--------+------+
| zero | PCP |
+--------+------+
0
This field may only be used when vlan_vid is not wildcarded and does
not exact match on 0 (which only matches when there is no 802.1Q
header).
See VLAN Comparison Chart, below, for some examples.
Open vSwitch Extension VLAN Field
The vlan_tci extension can describe more kinds of VLAN matches than
the other variants. It is also simpler than the other variants.
VLAN TCI Field
Name: vlan_tci
Width: 16 bits
Format: hexadecimal
Masking: arbitrary bitwise masks
Prerequisites: Ethernet
Access: read/write
OpenFlow 1.0: yes (exact match only)
OpenFlow 1.1: yes (exact match only)
OXM: none
NXM: NXM_OF_VLAN_TCI (4) since Open vSwitch 1.1
For a packet without an 802.1Q header, this field is zero. For a
packet with an 802.1Q header, this field is the TCI with the bit in
CFI’s position (marked P for ``present’’ below) forced to 1. Thus,
for a packet in VLAN 9 with priority 7, it has the value 0xf009:
NXM_VLAN_TCI
<---------->
3 1 12
+----+--+----+
|PCP |P |VID |
+----+--+----+
7 1 9
Usage examples:
vlan_tci=0
Match packets without an 802.1Q header.
vlan_tci=0x1000/0x1000
Match packets with an 802.1Q header, regardless of VLAN
and priority values.
vlan_tci=0xf123
Match packets tagged with priority 7 in VLAN 0x123.
vlan_tci=0x1123/0x1fff
Match packets tagged with VLAN 0x123 (and any
priority).
vlan_tci=0x5000/0xf000
Match packets tagged with priority 2 (in any VLAN).
vlan_tci=0/0xfff
Match packets with no 802.1Q header or tagged with VLAN
0 (and any priority).
vlan_tci=0x5000/0xe000
Match packets with no 802.1Q header or tagged with
priority 2 (in any VLAN).
vlan_tci=0/0xefff
Match packets with no 802.1Q header or tagged with VLAN
0 and priority 0.
See VLAN Comparison Chart, below, for more examples.
VLAN Comparison Chart
The following table describes each of several possible matching
criteria on 802.1Q header may be expressed with each variation of the
VLAN matching fields:
Criteria OpenFlow 1.0 OpenFlow 1.1 OpenFlow 1.2+ NXM
───────── ───────────── ───────────── ────────────── ──────────
[1] ????/1,??/? ????/1,??/? 0000/0000,-- 0000/0000
[2] ffff/0,??/? ffff/0,??/? 0000/ffff,-- 0000/ffff
[3] 0xxx/0,??/1 0xxx/0,??/1 1xxx/ffff,-- 1xxx/1fff
[4] ????/1,0y/0 fffe/0,0y/0 1000/1000,0y z000/f000
[5] 0xxx/0,0y/0 0xxx/0,0y/0 1xxx/ffff,0y zxxx/ffff
[6] (none) (none) 1001/1001,-- 1001/1001
[7] (none) (none) (none) 3000/3000
[8] (none) (none) (none) 0000/0fff
[9] (none) (none) (none) 0000/f000
[10] (none) (none) (none) 0000/efff
All numbers in the table are expressed in hexadecimal. The columns in
the table are interpreted as follows:
Criteria
See the list below.
OpenFlow 1.0
OpenFlow 1.1
wwww/x,yy/z means VLAN ID match value wwww with wildcard
bit x and VLAN PCP match value yy with wildcard bit z. ?
means that the given bits are ignored (and conventionally
0 for wwww or yy, conventionally 1 for x or z).
``(none)’’ means that OpenFlow 1.0 (or 1.1) cannot match
with these criteria.
OpenFlow 1.2+
xxxx/yyyy,zz means vlan_vid with value xxxx and mask
yyyy, and vlan_pcp (which is not maskable) with value zz.
-- means that vlan_pcp is omitted. ``(none)’’ means that
OpenFlow 1.2 cannot match with these criteria.
NXM xxxx/yyyy means vlan_tci with value xxxx and mask yyyy.
The matching criteria described by the table are:
[1] Matches any packet, that is, one without an 802.1Q
header or with an 802.1Q header with any TCI value.
[2] Matches only packets without an 802.1Q header.
OpenFlow 1.0 doesn’t define the behavior if dl_vlan is
set to 0xffff and dl_vlan_pcp is not wildcarded. (Open
vSwitch always ignores dl_vlan_pcp when dl_vlan is set
to 0xffff.)
OpenFlow 1.1 says explicitly to ignore dl_vlan_pcp when
dl_vlan is set to 0xffff.
OpenFlow 1.2 doesn’t say how to interpret a match with
vlan_vid value 0 and a mask with OFPVID_PRESENT
(0x1000) set to 1 and some other bits in the mask set
to 1 also. Open vSwitch interprets it the same way as a
mask of 0x1000.
Any NXM match with vlan_tci value 0 and the CFI bit set
to 1 in the mask is equivalent to the one listed in the
table.
[3] Matches only packets that have an 802.1Q header with
VID xxx (and any PCP).
[4] Matches only packets that have an 802.1Q header with
PCP y (and any VID).
OpenFlow 1.0 doesn’t clearly define the behavior for
this case. Open vSwitch implements it this way.
In the NXM value, z equals (y << 1) | 1.
[5] Matches only packets that have an 802.1Q header with
VID xxx and PCP y.
In the NXM value, z equals (y << 1) | 1.
[6] Matches only packets that have an 802.1Q header with an
odd-numbered VID (and any PCP). Only possible with
OpenFlow 1.2 and NXM. (This is just an example; one can
match on any desired VID bit pattern.)
[7] Matches only packets that have an 802.1Q header with an
odd-numbered PCP (and any VID). Only possible with NXM.
(This is just an example; one can match on any desired
VID bit pattern.)
[8] Matches packets with no 802.1Q header or with an 802.1Q
header with a VID of 0. Only possible with NXM.
[9] Matches packets with no 802.1Q header or with an 802.1Q
header with a PCP of 0. Only possible with NXM.
[10] Matches packets with no 802.1Q header or with an 802.1Q
header with both VID and PCP of 0. Only possible with
NXM.
Summary:
Name Bytes Mask RW? Prereqs NXM/OXM Support
─────────── ──────────────── ───── ──── ──────── ──────────────────────
mpls_label 4 (low 20 bits) no yes MPLS OF 1.2+ and OVS 1.11+
mpls_tc 1 (low 3 bits) no yes MPLS OF 1.2+ and OVS 1.11+
mpls_bos 1 (low 1 bits) no no MPLS OF 1.3+ and OVS 1.11+
mpls_ttl 1 no yes MPLS OVS 2.6+
One or more MPLS headers (more commonly called MPLS labels) follow an
Ethernet type field that specifies an MPLS Ethernet type [RFC 3032].
Ethertype 0x8847 is used for all unicast. Multicast MPLS is divided
into two specific classes, one of which uses Ethertype 0x8847 and the
other 0x8848 [RFC 5332].
The most common overall packet format is Ethernet II, shown below
(SNAP encapsulation may be used but is not ordinarily seen in
Ethernet networks):
Ethernet MPLS
<------------> <------------>
48 48 16 20 3 1 8
+---+---+------+ +-----+--+-+---+
|dst|src| type | |label|TC|S|TTL| ...
+---+---+------+ +-----+--+-+---+
0x8847
MPLS can be encapsulated inside an 802.1Q header, in which case the
combination looks like this:
Ethernet 802.1Q Ethertype MPLS
<------> <--------> <-------> <------------>
48 48 16 16 16 20 3 1 8
+----+---+ +------+---+ +---------+ +-----+--+-+---+
|dst |src| | TPID |TCI| | type | |label|TC|S|TTL| ...
+----+---+ +------+---+ +---------+ +-----+--+-+---+
0x8100 0x8847
The fields within an MPLS label are:
Label, 20 bits.
An identifier.
Traffic control (TC), 3 bits.
Used for quality of service.
Bottom of stack (BOS), 1 bit (labeled just ``S’’ above).
0 indicates that another MPLS label follows this one.
1 indicates that this MPLS label is the last one in the
stack, so that some other protocol follows this one.
Time to live (TTL), 8 bits.
Each hop across an MPLS network decrements the TTL by
1. If it reaches 0, the packet is discarded.
OpenFlow does not make the MPLS TTL available as a
match field, but actions are available to set and
decrement the TTL. Open vSwitch 2.6 and later makes the
MPLS TTL available as an extension.
MPLS Label Stacks
Unlike the other encapsulations supported by OpenFlow and Open
vSwitch, MPLS labels are routinely used in ``stacks’’ two or three
deep and sometimes even deeper. Open vSwitch currently supports up to
three labels.
The OpenFlow specification only supports matching on the outermost
MPLS label at any given time. To match on the second label, one must
first ``pop’’ the outer label and advance to another OpenFlow table,
where the inner label may be matched. To match on the third label,
one must pop the two outer labels, and so on. The Open Networking
Foundation is considering support for directly matching on multiple
MPLS labels for OpenFlow 1.6.
MPLS Inner Protocol
Unlike all other forms of encapsulation that Open vSwitch and
OpenFlow support, an MPLS label does not indicate what inner protocol
it encapsulates. Different deployments determine the inner protocol
in different ways [RFC 3032]:
· A few reserved label values do indicate an inner
protocol. Label 0, the ``IPv4 Explicit NULL Label,’’
indicates inner IPv4. Label 2, the ``IPv6 Explicit NULL
Label,’’ indicates inner IPv6.
· Some deployments use a single inner protocol
consistently.
· In some deployments, the inner protocol must be
inferred from the innermost label.
· In some deployments, the inner protocol must be
inferred from the innermost label and the encapsulated
data, e.g. to distinguish between inner IPv4 and IPv6
based on whether the first nibble of the inner protocol
data are 4 or 6. OpenFlow and Open vSwitch do not
currently support these cases.
Open vSwitch and OpenFlow do not infer the inner protocol, even if
reserved label values are in use. Instead, the flow table must
specify the inner protocol at the time it pops the bottommost MPLS
label, using the Ethertype argument to the pop_mpls action.
Field Details
MPLS Label Field
Name: mpls_label
Width: 32 bits (only the least-significant 20 bits may be nonzero)
Format: decimal
Masking: not maskable
Prerequisites: MPLS
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: yes (exact match only)
OXM: OXM_OF_MPLS_LABEL (34) since OpenFlow 1.2 and Open vSwitch
1.11
NXM: none
The least significant 20 bits hold the ``label’’ field from the MPLS
label. Other bits are zero:
OXM_OF_MPLS_LABEL
<--------------->
12 20
+--------+--------+
| zero | label |
+--------+--------+
0
Most label values are available for any use by deployments. Values
under 16 are reserved.
MPLS Traffic Class Field
Name: mpls_tc
Width: 8 bits (only the least-significant 3 bits may be nonzero)
Format: decimal
Masking: not maskable
Prerequisites: MPLS
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: yes (exact match only)
OXM: OXM_OF_MPLS_TC (35) since OpenFlow 1.2 and Open vSwitch
1.11
NXM: none
The least significant 3 bits hold the TC field from the MPLS label.
Other bits are zero:
OXM_OF_MPLS_TC
<------------>
5 3
+--------+-----+
| zero | TC |
+--------+-----+
0
This field is intended for use for Quality of Service (QoS) and
Explicit Congestion Notification purposes, but its particular
interpretation is deployment specific.
Before 2009, this field was named EXP and reserved for experimental
use [RFC 5462].
MPLS Bottom of Stack Field
Name: mpls_bos
Width: 8 bits (only the least-significant 1 bits may be nonzero)
Format: decimal
Masking: not maskable
Prerequisites: MPLS
Access: read-only
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: OXM_OF_MPLS_BOS (36) since OpenFlow 1.3 and Open vSwitch
1.11
NXM: none
The least significant bit holds the BOS field from the MPLS label.
Other bits are zero:
OXM_OF_MPLS_BOS
<------------->
7 1
+--------+------+
| zero | BOS |
+--------+------+
0
This field is useful as part of processing a series of incoming MPLS
labels. A flow that includes a pop_mpls action should generally match
on mpls_bos:
· When mpls_bos is 1, there is another MPLS label
following this one, so the Ethertype passed to pop_mpls
should be an MPLS Ethertype. For example: table=0,
dl_type=0x8847, mpls_bos=1, actions=pop_mpls:0x8847,
goto_table:1
· When mpls_bos is 0, this MPLS label is the last one, so
the Ethertype passed to pop_mpls should be a non-MPLS
Ethertype such as IPv4. For example: table=1,
dl_type=0x8847, mpls_bos=0, actions=pop_mpls:0x0800,
goto_table:2
MPLS Time-to-Live Field
Name: mpls_ttl
Width: 8 bits
Format: decimal
Masking: not maskable
Prerequisites: MPLS
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_MPLS_TTL (30) since Open vSwitch 2.6
Holds the 8-bit time-to-live field from the MPLS label:
NXM_NX_MPLS_TTL
<------------->
8
+---------------+
| TTL |
+---------------+
Summary:
Name Bytes Mask RW? Prereqs NXM/OXM Support
────────────────────── ──────────────── ───── ──── ────────── ─────────────────────
ip_src aka nw_src 4 yes yes IPv4 OF 1.2+ and OVS 1.1+
ip_dst aka nw_dst 4 yes yes IPv4 OF 1.2+ and OVS 1.1+
ipv6_src 16 yes yes IPv6 OF 1.2+ and OVS 1.1+
ipv6_dst 16 yes yes IPv6 OF 1.2+ and OVS 1.1+
ipv6_label 4 (low 20 bits) yes yes IPv6 OF 1.2+ and OVS 1.4+
nw_proto aka ip_proto 1 no no IPv4/IPv6 OF 1.2+ and OVS 1.1+
nw_ttl 1 no yes IPv4/IPv6 OVS 1.4+
ip_frag 1 (low 2 bits) yes no IPv4/IPv6 OVS 1.3+
nw_tos 1 no yes IPv4/IPv6 OVS 1.1+
ip_dscp 1 (low 6 bits) no yes IPv4/IPv6 OF 1.2+ and OVS 1.7+
nw_ecn aka ip_ecn 1 (low 2 bits) no yes IPv4/IPv6 OF 1.2+ and OVS 1.4+
IPv4 Specific Fields
These fields are applicable only to IPv4 flows, that is, flows that
match on the IPv4 Ethertype 0x0800.
IPv4 Source Address Field
Name: ip_src (aka nw_src)
Width: 32 bits
Format: IPv4
Masking: arbitrary bitwise masks
Prerequisites: IPv4
Access: read/write
OpenFlow 1.0: yes (CIDR match only)
OpenFlow 1.1: yes
OXM: OXM_OF_IPV4_SRC (11) since OpenFlow 1.2 and Open
vSwitch 1.7
NXM: NXM_OF_IP_SRC (7) since Open vSwitch 1.1
The source address from the IPv4 header:
Ethernet IPv4
<-----------> <--------------->
48 48 16 8 32 32
+---+---+-----+ +---+-----+---+---+
|dst|src|type | |...|proto|src|dst| ...
+---+---+-----+ +---+-----+---+---+
0x800
For historical reasons, in an ARP or RARP flow, Open vSwitch
interprets matches on nw_src as actually referring to the ARP SPA.
IPv4 Destination Address Field
Name: ip_dst (aka nw_dst)
Width: 32 bits
Format: IPv4
Masking: arbitrary bitwise masks
Prerequisites: IPv4
Access: read/write
OpenFlow 1.0: yes (CIDR match only)
OpenFlow 1.1: yes
OXM: OXM_OF_IPV4_DST (12) since OpenFlow 1.2 and Open
vSwitch 1.7
NXM: NXM_OF_IP_DST (8) since Open vSwitch 1.1
The destination address from the IPv4 header:
Ethernet IPv4
<-----------> <--------------->
48 48 16 8 32 32
+---+---+-----+ +---+-----+---+---+
|dst|src|type | |...|proto|src|dst| ...
+---+---+-----+ +---+-----+---+---+
0x800
For historical reasons, in an ARP or RARP flow, Open vSwitch
interprets matches on nw_dst as actually referring to the ARP TPA.
IPv6 Specific Fields
These fields apply only to IPv6 flows, that is, flows that match on
the IPv6 Ethertype 0x86dd.
IPv6 Source Address Field
Name: ipv6_src
Width: 128 bits
Format: IPv6
Masking: arbitrary bitwise masks
Prerequisites: IPv6
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: OXM_OF_IPV6_SRC (26) since OpenFlow 1.2 and Open
vSwitch 1.1
NXM: NXM_NX_IPV6_SRC (19) since Open vSwitch 1.1
The source address from the IPv6 header:
Ethernet IPv6
<------------> <-------------->
48 48 16 8 128 128
+---+---+------+ +---+----+---+---+
|dst|src| type | |...|next|src|dst| ...
+---+---+------+ +---+----+---+---+
0x86dd
Open vSwitch 1.8 added support for bitwise matching; earlier versions
supported only CIDR masks.
IPv6 Destination Address Field
Name: ipv6_dst
Width: 128 bits
Format: IPv6
Masking: arbitrary bitwise masks
Prerequisites: IPv6
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: OXM_OF_IPV6_DST (27) since OpenFlow 1.2 and Open
vSwitch 1.1
NXM: NXM_NX_IPV6_DST (20) since Open vSwitch 1.1
The destination address from the IPv6 header:
Ethernet IPv6
<------------> <-------------->
48 48 16 8 128 128
+---+---+------+ +---+----+---+---+
|dst|src| type | |...|next|src|dst| ...
+---+---+------+ +---+----+---+---+
0x86dd
Open vSwitch 1.8 added support for bitwise matching; earlier versions
supported only CIDR masks.
IPv6 Flow Label Field
Name: ipv6_label
Width: 32 bits (only the least-significant 20 bits may be nonzero)
Format: hexadecimal
Masking: arbitrary bitwise masks
Prerequisites: IPv6
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: OXM_OF_IPV6_FLABEL (28) since OpenFlow 1.2 and Open vSwitch
1.7
NXM: NXM_NX_IPV6_LABEL (27) since Open vSwitch 1.4
The least significant 20 bits hold the flow label field from the IPv6
header. Other bits are zero:
OXM_OF_IPV6_FLABEL
<---------------->
12 20
+--------+---------+
| zero | label |
+--------+---------+
0
IPv4/IPv6 Fields
These fields exist with at least approximately the same meaning in
both IPv4 and IPv6, so they are treated as a single field for
matching purposes. Any flow that matches on the IPv4 Ethertype 0x0800
or the IPv6 Ethertype 0x86dd may match on these fields.
IPv4/v6 Protocol Field
Name: nw_proto (aka ip_proto)
Width: 8 bits
Format: decimal
Masking: not maskable
Prerequisites: IPv4/IPv6
Access: read-only
OpenFlow 1.0: yes (exact match only)
OpenFlow 1.1: yes (exact match only)
OXM: OXM_OF_IP_PROTO (10) since OpenFlow 1.2 and Open
vSwitch 1.7
NXM: NXM_OF_IP_PROTO (6) since Open vSwitch 1.1
Matches the IPv4 or IPv6 protocol type.
For historical reasons, in an ARP or RARP flow, Open vSwitch
interprets matches on nw_proto as actually referring to the ARP
opcode. The ARP opcode is a 16-bit field, so for matching purposes
ARP opcodes greater than 255 are treated as 0; this works adequately
because in practice ARP and RARP only use opcodes 1 through 4.
IPv4/v6 TTL/Hop Limit Field
Name: nw_ttl
Width: 8 bits
Format: decimal
Masking: not maskable
Prerequisites: IPv4/IPv6
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_IP_TTL (29) since Open vSwitch 1.4
The main reason to match on the TTL or hop limit field is to detect
whether a dec_ttl action will fail due to a TTL exceeded error.
Another way that a controller can detect TTL exceeded is to listen
for OFPR_INVALID_TTL ``packet-in’’ messages via OpenFlow.
IPv4/v6 Fragment Bitmask Field
Name: ip_frag
Width: 8 bits (only the least-significant 2 bits may be nonzero)
Format: frag
Masking: arbitrary bitwise masks
Prerequisites: IPv4/IPv6
Access: read-only
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: none
NXM: NXM_NX_IP_FRAG (26) since Open vSwitch 1.3
Specifies what kinds of IP fragments or non-fragments to match. The
value for this field is most conveniently specified as one of the
following:
no Match only non-fragmented packets.
yes Matches all fragments.
first Matches only fragments with offset 0.
later Matches only fragments with nonzero offset.
not_later
Matches non-fragmented packets and fragments with zero
offset.
The field is internally formatted as 2 bits: bit 0 is 1 for an IP
fragment with any offset (and otherwise 0), and bit 1 is 1 for an IP
fragment with nonzero offset (and otherwise 0), like so:
NXM_NX_IP_FRAG
<------------>
6 1 1
+----+-----+---+
|zero|later|any|
+----+-----+---+
0
Even though 2 bits have 4 possible values, this field only uses 3 of
them:
· A packet that is not an IP fragment has value 0.
· A packet that is an IP fragment with offset 0 (the
first fragment) has bit 0 set and thus value 1.
· A packet that is an IP fragment with nonzero offset has
bits 0 and 1 set and thus value 3.
The switch may reject matches against values that can never appear.
It is important to understand how this field interacts with the
OpenFlow fragment handling mode:
· In OFPC_FRAG_DROP mode, the OpenFlow switch drops all
IP fragments before they reach the flow table, so every
packet that is available for matching will have value 0
in this field.
· Open vSwitch does not implement OFPC_FRAG_REASM mode,
but if it did then IP fragments would be reassembled
before they reached the flow table and again every
packet available for matching would always have value
0.
· In OFPC_FRAG_NORMAL mode, all three values are
possible, but OpenFlow 1.0 says that fragments’
transport ports are always 0, even for the first
fragment, so this does not provide much extra
information.
· In OFPC_FRAG_NX_MATCH mode, all three values are
possible. For fragments with offset 0, Open vSwitch
makes L4 header information available.
Thus, this field is likely to be most useful for an Open vSwitch
switch configured in OFPC_FRAG_NX_MATCH mode. See the description of
the set-frags command in ovs-ofctl(8), for more details.
IPv4/IPv6 TOS Fields
IPv4 and IPv6 contain a one-byte ``type of service’’ or TOS field
that has the following format:
type of service
<------------->
6 2
+--------+------+
| DSCP | ECN |
+--------+------+
IPv4/v6 DSCP (Bits 2-7) Field
Name: nw_tos
Width: 8 bits
Format: decimal
Masking: not maskable
Prerequisites: IPv4/IPv6
Access: read/write
OpenFlow 1.0: yes (exact match only)
OpenFlow 1.1: yes (exact match only)
OXM: none
NXM: NXM_OF_IP_TOS (5) since Open vSwitch 1.1
This field is the TOS byte with the two ECN bits cleared to 0:
NXM_OF_IP_TOS
<----------->
6 2
+------+------+
| DSCP | zero |
+------+------+
0
IPv4/v6 DSCP (Bits 0-5) Field
Name: ip_dscp
Width: 8 bits (only the least-significant 6 bits may be nonzero)
Format: decimal
Masking: not maskable
Prerequisites: IPv4/IPv6
Access: read/write
OpenFlow 1.0: yes (exact match only)
OpenFlow 1.1: yes (exact match only)
OXM: OXM_OF_IP_DSCP (8) since OpenFlow 1.2 and Open vSwitch
1.7
NXM: none
This field is the TOS byte shifted right to put the DSCP bits in the
6 least-significant bits:
OXM_OF_IP_DSCP
<------------>
2 6
+-------+------+
| zero | DSCP |
+-------+------+
0
IPv4/v6 ECN Field
Name: nw_ecn (aka ip_ecn)
Width: 8 bits (only the least-significant 2 bits may be nonzero)
Format: decimal
Masking: not maskable
Prerequisites: IPv4/IPv6
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: yes (exact match only)
OXM: OXM_OF_IP_ECN (9) since OpenFlow 1.2 and Open vSwitch 1.7
NXM: NXM_NX_IP_ECN (28) since Open vSwitch 1.4
This field is the TOS byte with the DSCP bits cleared to 0:
OXM_OF_IP_ECN
<----------->
6 2
+-------+-----+
| zero | ECN |
+-------+-----+
0
Summary:
Name Bytes Mask RW? Prereqs NXM/OXM Support
──────── ────── ───── ──── ──────── ─────────────────────
arp_op 2 no yes ARP OF 1.2+ and OVS 1.1+
arp_spa 4 yes yes ARP OF 1.2+ and OVS 1.1+
arp_tpa 4 yes yes ARP OF 1.2+ and OVS 1.1+
arp_sha 6 yes yes ARP OF 1.2+ and OVS 1.1+
arp_tha 6 yes yes ARP OF 1.2+ and OVS 1.1+
In theory, Address Resolution Protocol, or ARP, is a generic protocol
generic protocol that can be used to obtain the hardware address that
corresponds to any higher-level protocol address. In contemporary
usage, ARP is used only in Ethernet networks to obtain the Ethernet
address for a given IPv4 address. OpenFlow and Open vSwitch only
support this usage of ARP. For this use case, an ARP packet has the
following format, with the ARP fields exposed as Open vSwitch fields
highlighted:
Ethernet ARP
<-----------> <---------------------------------->
48 48 16 16 16 8 8 16 48 16 48 16
+---+---+-----+ +---+-----+---+---+--+---+---+---+---+
|dst|src|type | |hrd| pro |hln|pln|op|sha|spa|tha|tpa|
+---+---+-----+ +---+-----+---+---+--+---+---+---+---+
0x806 1 0x800 6 4
The ARP fields are also used for RARP, the Reverse Address Resolution
Protocol, which shares ARP’s wire format.
ARP Opcode Field
Name: arp_op
Width: 16 bits
Format: decimal
Masking: not maskable
Prerequisites: ARP
Access: read/write
OpenFlow 1.0: yes (exact match only)
OpenFlow 1.1: yes (exact match only)
OXM: OXM_OF_ARP_OP (21) since OpenFlow 1.2 and Open
vSwitch 1.7
NXM: NXM_OF_ARP_OP (15) since Open vSwitch 1.1
Even though this is a 16-bit field, Open vSwitch does not support ARP
opcodes greater than 255; it treats them to zero. This works
adequately because in practice ARP and RARP only use opcodes 1
through 4.
ARP Source IPv4 Address Field
Name: arp_spa
Width: 32 bits
Format: IPv4
Masking: arbitrary bitwise masks
Prerequisites: ARP
Access: read/write
OpenFlow 1.0: yes (CIDR match only)
OpenFlow 1.1: yes
OXM: OXM_OF_ARP_SPA (22) since OpenFlow 1.2 and Open
vSwitch 1.7
NXM: NXM_OF_ARP_SPA (16) since Open vSwitch 1.1
ARP Target IPv4 Address Field
Name: arp_tpa
Width: 32 bits
Format: IPv4
Masking: arbitrary bitwise masks
Prerequisites: ARP
Access: read/write
OpenFlow 1.0: yes (CIDR match only)
OpenFlow 1.1: yes
OXM: OXM_OF_ARP_TPA (23) since OpenFlow 1.2 and Open
vSwitch 1.7
NXM: NXM_OF_ARP_TPA (17) since Open vSwitch 1.1
ARP Source Ethernet Address Field
Name: arp_sha
Width: 48 bits
Format: Ethernet
Masking: arbitrary bitwise masks
Prerequisites: ARP
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: OXM_OF_ARP_SHA (24) since OpenFlow 1.2 and Open
vSwitch 1.7
NXM: NXM_NX_ARP_SHA (17) since Open vSwitch 1.1
ARP Target Ethernet Address Field
Name: arp_tha
Width: 48 bits
Format: Ethernet
Masking: arbitrary bitwise masks
Prerequisites: ARP
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: OXM_OF_ARP_THA (25) since OpenFlow 1.2 and Open
vSwitch 1.7
NXM: NXM_NX_ARP_THA (18) since Open vSwitch 1.1
Summary:
Name Bytes Mask RW? Prereqs NXM/OXM Support
─────────────────── ──────────────── ───── ──── ──────── ─────────────────────
tcp_src aka tp_src 2 yes yes TCP OF 1.2+ and OVS 1.1+
tcp_dst aka tp_dst 2 yes yes TCP OF 1.2+ and OVS 1.1+
tcp_flags 2 (low 12 bits) yes no TCP OF 1.3+ and OVS 2.1+
udp_src 2 yes yes UDP OF 1.2+ and OVS 1.1+
udp_dst 2 yes yes UDP OF 1.2+ and OVS 1.1+
sctp_src 2 yes yes SCTP OF 1.2+ and OVS 2.0+
sctp_dst 2 yes yes SCTP OF 1.2+ and OVS 2.0+
For matching purposes, no distinction is made whether these protocols
are encapsulated within IPv4 or IPv6.
TCP
The following diagram shows TCP within IPv4. Open vSwitch also
supports TCP in IPv6. Only TCP fields implemented as Open vSwitch
fields are shown:
Ethernet IPv4 TCP
<-----------> <---------------> <------------------->
48 48 16 8 32 32 16 16 12
+---+---+-----+ +---+-----+---+---+ +---+---+---+-----+---+
|dst|src|type | |...|proto|src|dst| |src|dst|...|flags|...| ...
+---+---+-----+ +---+-----+---+---+ +---+---+---+-----+---+
0x800 6
TCP Source Port Field
Name: tcp_src (aka tp_src)
Width: 16 bits
Format: decimal
Masking: arbitrary bitwise masks
Prerequisites: TCP
Access: read/write
OpenFlow 1.0: yes (exact match only)
OpenFlow 1.1: yes (exact match only)
OXM: OXM_OF_TCP_SRC (13) since OpenFlow 1.2 and Open
vSwitch 1.7
NXM: NXM_OF_TCP_SRC (9) since Open vSwitch 1.1
Open vSwitch 1.6 added support for bitwise matching.
TCP Destination Port Field
Name: tcp_dst (aka tp_dst)
Width: 16 bits
Format: decimal
Masking: arbitrary bitwise masks
Prerequisites: TCP
Access: read/write
OpenFlow 1.0: yes (exact match only)
OpenFlow 1.1: yes (exact match only)
OXM: OXM_OF_TCP_DST (14) since OpenFlow 1.2 and Open
vSwitch 1.7
NXM: NXM_OF_TCP_DST (10) since Open vSwitch 1.1
Open vSwitch 1.6 added support for bitwise matching.
TCP Flags Field
Name: tcp_flags
Width: 16 bits (only the least-significant 12 bits may be nonzero)
Format: TCP flags
Masking: arbitrary bitwise masks
Prerequisites: TCP
Access: read-only
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: ONFOXM_ET_TCP_FLAGS (42) since OpenFlow 1.3 and Open
vSwitch 2.4; OXM_OF_TCP_FLAGS (42) since OpenFlow 1.5 and
Open vSwitch 2.3
NXM: NXM_NX_TCP_FLAGS (34) since Open vSwitch 2.1
This field holds the TCP flags. TCP currently defines 9 flag bits. An
additional 3 bits are reserved. For more information, see [RFC 793],
[RFC 3168], and [RFC 3540].
Matches on this field are most conveniently written in terms of
symbolic names (given in the diagram below), each preceded by either
+ for a flag that must be set, or - for a flag that must be unset,
without any other delimiters between the flags. Flags not mentioned
are wildcarded. For example, tcp,tcp_flags=+syn-ack matches TCP SYNs
that are not ACKs, and tcp,tcp_flags=+[200] matches TCP packets with
the reserved [200] flag set. Matches can also be written as
flags/mask, where flags and mask are 16-bit numbers in decimal or in
hexadecimal prefixed by 0x.
The flag bits are:
reserved later RFCs RFC 793
<---------------> <--------> <--------------------->
4 1 1 1 1 1 1 1 1 1 1 1 1
+----+-----+-----+-----+--+---+---+---+---+---+---+---+---+
|zero|[800]|[400]|[200]|NS|CWR|ECE|URG|ACK|PSH|RST|SYN|FIN|
+----+-----+-----+-----+--+---+---+---+---+---+---+---+---+
0
UDP
The following diagram shows UDP within IPv4. Open vSwitch also
supports UDP in IPv6. Only UDP fields that Open vSwitch exposes as
fields are shown:
Ethernet IPv4 UDP
<-----------> <---------------> <--------->
48 48 16 8 32 32 16 16
+---+---+-----+ +---+-----+---+---+ +---+---+---+
|dst|src|type | |...|proto|src|dst| |src|dst|...| ...
+---+---+-----+ +---+-----+---+---+ +---+---+---+
0x800 17
UDP Source Port Field
Name: udp_src
Width: 16 bits
Format: decimal
Masking: arbitrary bitwise masks
Prerequisites: UDP
Access: read/write
OpenFlow 1.0: yes (exact match only)
OpenFlow 1.1: yes (exact match only)
OXM: OXM_OF_UDP_SRC (15) since OpenFlow 1.2 and Open
vSwitch 1.7
NXM: NXM_OF_UDP_SRC (11) since Open vSwitch 1.1
UDP Destination Port Field
Name: udp_dst
Width: 16 bits
Format: decimal
Masking: arbitrary bitwise masks
Prerequisites: UDP
Access: read/write
OpenFlow 1.0: yes (exact match only)
OpenFlow 1.1: yes (exact match only)
OXM: OXM_OF_UDP_DST (16) since OpenFlow 1.2 and Open
vSwitch 1.7
NXM: NXM_OF_UDP_DST (12) since Open vSwitch 1.1
SCTP
The following diagram shows SCTP within IPv4. Open vSwitch also
supports SCTP in IPv6. Only SCTP fields that Open vSwitch exposes as
fields are shown:
Ethernet IPv4 SCTP
<-----------> <---------------> <--------->
48 48 16 8 32 32 16 16
+---+---+-----+ +---+-----+---+---+ +---+---+---+
|dst|src|type | |...|proto|src|dst| |src|dst|...| ...
+---+---+-----+ +---+-----+---+---+ +---+---+---+
0x800 132
SCTP Source Port Field
Name: sctp_src
Width: 16 bits
Format: decimal
Masking: arbitrary bitwise masks
Prerequisites: SCTP
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: yes (exact match only)
OXM: OXM_OF_SCTP_SRC (17) since OpenFlow 1.2 and Open
vSwitch 2.0
NXM: none
SCTP Destination Port Field
Name: sctp_dst
Width: 16 bits
Format: decimal
Masking: arbitrary bitwise masks
Prerequisites: SCTP
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: yes (exact match only)
OXM: OXM_OF_SCTP_DST (18) since OpenFlow 1.2 and Open
vSwitch 2.0
NXM: none
Summary:
Name Bytes Mask RW? Prereqs NXM/OXM Support
──────────── ────── ───── ──── ─────────── ─────────────────────
icmp_type 1 no yes ICMPv4 OF 1.2+ and OVS 1.1+
icmp_code 1 no yes ICMPv4 OF 1.2+ and OVS 1.1+
icmpv6_type 1 no yes ICMPv6 OF 1.2+ and OVS 1.1+
icmpv6_code 1 no yes ICMPv6 OF 1.2+ and OVS 1.1+
nd_target 16 yes yes ND OF 1.2+ and OVS 1.1+
nd_sll 6 yes yes ND solicit OF 1.2+ and OVS 1.1+
nd_tll 6 yes yes ND advert OF 1.2+ and OVS 1.1+
ICMPv4
Ethernet IPv4 ICMPv4
<-----------> <---------------> <----------->
48 48 16 8 32 32 8 8
+---+---+-----+ +---+-----+---+---+ +----+----+---+
|dst|src|type | |...|proto|src|dst| |type|code|...| ...
+---+---+-----+ +---+-----+---+---+ +----+----+---+
0x800 1
ICMPv4 Type Field
Name: icmp_type
Width: 8 bits
Format: decimal
Masking: not maskable
Prerequisites: ICMPv4
Access: read/write
OpenFlow 1.0: yes (exact match only)
OpenFlow 1.1: yes (exact match only)
OXM: OXM_OF_ICMPV4_TYPE (19) since OpenFlow 1.2 and Open
vSwitch 1.7
NXM: NXM_OF_ICMP_TYPE (13) since Open vSwitch 1.1
For historical reasons, in an ICMPv4 flow, Open vSwitch interprets
matches on tp_src as actually referring to the ICMP type.
ICMPv4 Code Field
Name: icmp_code
Width: 8 bits
Format: decimal
Masking: not maskable
Prerequisites: ICMPv4
Access: read/write
OpenFlow 1.0: yes (exact match only)
OpenFlow 1.1: yes (exact match only)
OXM: OXM_OF_ICMPV4_CODE (20) since OpenFlow 1.2 and Open
vSwitch 1.7
NXM: NXM_OF_ICMP_CODE (14) since Open vSwitch 1.1
For historical reasons, in an ICMPv4 flow, Open vSwitch interprets
matches on tp_dst as actually referring to the ICMP code.
ICMPv6
Ethernet IPv6 ICMPv6
<------------> <--------------> <----------->
48 48 16 8 128 128 8 8
+---+---+------+ +---+----+---+---+ +----+----+---+
|dst|src| type | |...|next|src|dst| |type|code|...| ...
+---+---+------+ +---+----+---+---+ +----+----+---+
0x86dd 58
ICMPv6 Type Field
Name: icmpv6_type
Width: 8 bits
Format: decimal
Masking: not maskable
Prerequisites: ICMPv6
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: OXM_OF_ICMPV6_TYPE (29) since OpenFlow 1.2 and Open
vSwitch 1.7
NXM: NXM_NX_ICMPV6_TYPE (21) since Open vSwitch 1.1
ICMPv6 Code Field
Name: icmpv6_code
Width: 8 bits
Format: decimal
Masking: not maskable
Prerequisites: ICMPv6
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: OXM_OF_ICMPV6_CODE (30) since OpenFlow 1.2 and Open
vSwitch 1.7
NXM: NXM_NX_ICMPV6_CODE (22) since Open vSwitch 1.1
ICMPv6 Neighbor Discovery
Ethernet IPv6 ICMPv6 ICMPv6 ND
<------------> <--------------> <--------------> <--------------->
48 48 16 8 128 128 8 8 128
+---+---+------+ +---+----+---+---+ +-------+----+---+ +------+----------+
|dst|src| type | |...|next|src|dst| | type |code|...| |target|option ...|
+---+---+------+ +---+----+---+---+ +-------+----+---+ +------+----------+
0x86dd 58 135/136 0
ICMPv6 Neighbor Discovery Target IPv6 Field
Name: nd_target
Width: 128 bits
Format: IPv6
Masking: arbitrary bitwise masks
Prerequisites: ND
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: OXM_OF_IPV6_ND_TARGET (31) since OpenFlow 1.2 and
Open vSwitch 1.7
NXM: NXM_NX_ND_TARGET (23) since Open vSwitch 1.1
ICMPv6 Neighbor Discovery Source Ethernet Address Field
Name: nd_sll
Width: 48 bits
Format: Ethernet
Masking: arbitrary bitwise masks
Prerequisites: ND solicit
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: OXM_OF_IPV6_ND_SLL (32) since OpenFlow 1.2 and Open
vSwitch 1.7
NXM: NXM_NX_ND_SLL (24) since Open vSwitch 1.1
ICMPv6 Neighbor Discovery Target Ethernet Address Field
Name: nd_tll
Width: 48 bits
Format: Ethernet
Masking: arbitrary bitwise masks
Prerequisites: ND advert
Access: read/write
OpenFlow 1.0: not supported
OpenFlow 1.1: not supported
OXM: OXM_OF_IPV6_ND_TLL (33) since OpenFlow 1.2 and Open
vSwitch 1.7
NXM: NXM_NX_ND_TLL (25) since Open vSwitch 1.1
Casado M. Casado, M. J. Freedman, J. Pettit, J. Luo, N.
McKeown, and S. Shenker, ``Ethane: Taking Control of
the Enterprise,’’ Computer Communications Review,
October 2007.
EXT-56 J. Tonsing, ``Permit one of a set of prerequisites to
apply, e.g. don’t preclude non-Ethernet media,’’
⟨https://rs.opennetworking.org/bugs/browse/EXT-56⟩ (ONF
members only).
EXT-112
J. Tourrilhes, ``Support non-Ethernet packets
throughout the pipeline,’’ ⟨https://
rs.opennetworking.org/bugs/browse/EXT-112⟩ (ONF members
only).
EXT-134
J. Tourrilhes, ``Match first nibble of the MPLS
payload,’’ ⟨https://rs.opennetworking.org/bugs/browse/
EXT-134⟩ (ONF members only).
Geneve J. Gross, I. Ganga, and T. Sridhar, editors, ``Geneve:
Generic Network Virtualization Encapsulation,’’
⟨https://datatracker.ietf.org/doc/
draft-ietf-nvo3-geneve/⟩ .
IEEE OUI
IEEE Standards Association, ``MAC Address Block Large
(MA-L),’’ ⟨https://standards.ieee.org/develop/regauth/
oui/index.html⟩ .
NSH P. Quinn and U. Elzur, editors, ``Network Service
Header,’’ ⟨https://datatracker.ietf.org/doc/
draft-ietf-sfc-nsh/⟩ .
OpenFlow 1.0.1
Open Networking Foundation, ``OpenFlow Switch Errata,
Version 1.0.1,’’ June 2012.
OpenFlow 1.1
OpenFlow Consortium, ``OpenFlow Switch Specification
Version 1.1.0 Implemented (Wire Protocol 0x02),’’
February 2011.
OpenFlow 1.5
Open Networking Foundation, ``OpenFlow Switch
Specification Version 1.5.0 (Protocol version 0x06),’’
December 2014.
OpenFlow Extensions 1.3.x Package 2
Open Networking Foundation, ``OpenFlow Extensions 1.3.x
Package 2,’’ December 2013.
TCP Flags Match Field Extension
Open Networking Foundation, ``TCP flags match field
Extension,’’ December 2014. In [OpenFlow Extensions
1.3.x Package 2].
Pepelnjak
I. Pepelnjak, ``OpenFlow and Fermi Estimates,’’
⟨http://blog.ipspace.net/2013/09/
openflow-and-fermi-estimates.html⟩ .
RFC 793
``Transmission Control Protocol,’’ ⟨http://
www.ietf.org/rfc/rfc793.txt⟩ .
RFC 3032
E. Rosen, D. Tappan, G. Fedorkow, Y. Rekhter, D.
Farinacci, T. Li, and A. Conta, ``MPLS Label Stack
Encoding,’’ ⟨http://www.ietf.org/rfc/rfc3032.txt⟩ .
RFC 3168
K. Ramakrishnan, S. Floyd, and D. Black, ``The Addition
of Explicit Congestion Notification (ECN) to IP,’’
⟨https://tools.ietf.org/html/rfc3168⟩ .
RFC 3540
N. Spring, D. Wetherall, and D. Ely, ``Robust Explicit
Congestion Notification (ECN) Signaling with Nonces,’’
⟨https://tools.ietf.org/html/rfc3540⟩ .
RFC 4632
V. Fuller and T. Li, ``Classless Inter-domain Routing
(CIDR): The Internet Address Assignment and Aggregation
Plan,’’ ⟨https://tools.ietf.org/html/rfc4632⟩ .
RFC 5462
L. Andersson and R. Asati, ``Multiprotocol Label
Switching (MPLS) Label Stack Entry: ``EXP’’ Field
Renamed to ``Traffic Class’’ Field,’’ ⟨http://
www.ietf.org/rfc/rfc5462.txt⟩ .
RFC 6830
D. Farinacci, V. Fuller, D. Meyer, and D. Lewis, ``The
Locator/ID Separation Protocol (LISP),’’ ⟨http://
www.ietf.org/rfc/rfc6830.txt⟩ .
RFC 7348
M. Mahalingam, D. Dutt, K. Duda, P. Agarwal, L.
Kreeger, T. Sridhar, M. Bursell, and C. Wright,
``Virtual eXtensible Local Area Network (VXLAN): A
Framework for Overlaying Virtualized Layer 2 Networks
over Layer 3 Networks, ’’ ⟨https://tools.ietf.org/html/
rfc7348⟩ .
Srinivasan
V. Srinivasan, S. Suriy, and G. Varghese, ``Packet
Classification using Tuple Space Search,’’ SIGCOMM
1999.
Pagiamtzis
K. Pagiamtzis and A. Sheikholeslami, ``Content-
addressable memory (CAM) circuits and architectures: A
tutorial and survey,’’ IEEE Journal of Solid-State
Circuits, vol. 41, no. 3, pp. 712-727, March 2006.
VXLAN Group Policy Option
M. Smith and L. Kreeger, `` VXLAN Group Policy
Option.’’ Internet-Draft. ⟨https://tools.ietf.org/
html/draft-smith-vxlan-group-policy⟩ .
Ben Pfaff, with advice from Justin Pettit and Jean Tourrilhes.
This page is part of the Open vSwitch (a distributed virtual
multilayer switch) project. Information about the project can be
found at ⟨http://openvswitch.org/⟩. If you have a bug report for
this manual page, send it to bugs@openvswitch.org. This page was
obtained from the project's upstream Git repository
⟨https://github.com/openvswitch/ovs.git⟩ on 2018-02-02. (At that
time, the date of the most recent commit that was found in the repos‐
itory was 2018-02-01.) If you discover any rendering problems in
this HTML version of the page, or you believe there is a better or
more up-to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not part
of the original manual page), send a mail to man-pages@man7.org
Open vSwitch 2.8.90 ovs-fields(7)
Pages that refer to this page: ovs-vswitchd.conf.db(5), ovn-architecture(7), ovn-trace(8), ovs-ofctl(8)
|
HTML rendering created 2018-02-02 by Michael Kerrisk, author of The Linux Programming Interface, maintainer of the Linux man-pages project. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH.
|
|