OpenFlow 1.2规格：IPv6支持与增强功能

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OpenFlow-spec-v1.2是Open Networking Foundation (ONF) 发布的一个关键版本，它标志着SDN（Software-Defined Networking）领域的重要进展。这份规范于2011年12月发布，旨在提供一个开放和标准化的方式来控制网络设备的行为，特别是交换机。与早期版本（如1.1和1.0）相比，OpenFlow 1.2代表了一次重要的演进，不仅增加了对IPv6的支持，而且还扩展了对IPv4、MPLS（Multiprotocol Label Switching）以及第二层（L2）头的处理能力。在OpenFlow 1.2中，核心内容是Switch Specification，它定义了OpenFlow交换机与控制器之间通信的格式和协议。这种通信机制使得控制器能够指导交换机如何处理进入的数据包，从而实现网络流量的灵活控制。通过OpenFlow协议，控制器可以远程配置交换机的行为，包括设置流量转发规则、策略和安全措施。与前代版本相比，OpenFlow 1.2的主要改进点包括： 1. IPv6支持：这是重大升级，因为IPv6已成为下一代互联网协议的关键组成部分。新版本允许交换机匹配IPv6源地址和目的地址，以及网络层协议类型（protocol），这为支持IPv6网络的部署和管理提供了必要功能。 2. 增强的灵活性：OpenFlow 1.2允许更精细的网络流量控制，通过增强的匹配规则，可以针对不同类型的数据包执行不同的操作，比如基于源或目的IP地址、端口、协议等的差异化处理。 3. 一致性与标准性：随着OF-Config、OF-Test等组件的引入，OpenFlow 1.2不仅关注交换机的核心功能，还考虑到了网络配置和管理的标准化，以及性能测试和互操作性的验证，确保不同厂商的产品能够兼容并协同工作。 4. 扩展性：OpenFlow标准家族不断壮大，随着需求的增长，未来将会有更多组件如计费、自动化、安全等相关规范加入，以满足日益复杂和动态的网络环境。 OpenFlow-spec-v1.2是SDN发展中的一个重要里程碑，它通过增强功能和标准化流程，促进了网络架构的简化和灵活性，为网络管理员提供了更大的控制权，并推动了网络技术的演进。随着网络技术的不断进步，OpenFlow协议将继续扮演着关键角色，为未来的网络创新奠定基础。

OpenFlow Switch Speciﬁcation Version 1.2

support all counters, just those marked “Required” in Table 3.

Duration refers to the amount of t im e the ﬂ ow has been installed in the switch, and must be tracked with

second pr e ci si on . The Receive Errors ﬁeld is the total of all receive and coll is i on errors deﬁned in Table 3,

as well as any others not called out in t h e table.

Counters are unsign ed and wrap around with no overﬂow i nd i cat or . If a speciﬁc numeric counter is

not available in the s wi t ch, its value should be set to the maximum ﬁeld value (the unsigned equivalent of

-1).

Counter Bits

Per T able

Reference count (active entries) 32 Required

Packet Lookups 64 Optional

Packet Matches 64 Optional

Per Flow

Received Packets 64 Optional

Received Bytes 64 Optional

Duration (seconds) 32 Required

Duration (nanoseconds) 32 Optional

Per Port

Received Packets 64 Required

Transmitted Packets 64 Required

Received Bytes 64 Optional

Transmitted Bytes 64 Optional

Receive Drops 64 Optional

Transmit Drops 64 Optional

Receive Errors 64 Optional

Transmit Errors 64 Optional

Receive Frame Alignment Erro rs 64 Op tio na l

Receive Overrun Errors 64 Optional

Receive CRC Errors 64 Optional

Collisions 64 Optional

Per Queue

Transmit Packets 64 Required

Transmit Bytes 64 Optional

Transmit Overrun Errors 64 Optional

Per Group

Reference Count (ﬂow entries) 32 Optional

Packet Count 64 Optional

Byte Count 64 Optional

Per Bucket

Packet Count 64 Optional

Byte Count 64 Optional

Table 3: List of counters

5.6 Instructions

Each ﬂow entry contains a set of instruc t i ons that are executed when a packet matches the entry. These

instructions result in changes to the packet, action set and/or pipeline processing.

A switch is not required to support all action types , just those marked “Required Instruction” below. The

OpenFlow Switch Speciﬁcation Version 1.2

controller can also query the switch about which of the “Optional Instr u ctio n” it supports.

• Optional Instruction: Apply-Actions action(s): Applie s the speciﬁc action(s) immediately, without

any change to the Action Set. This inst r u ct i on may be used to modify the packet between two tables

or to execute multiple actions of the same type. The actions are speciﬁed as an action list ( se e 5.8).

• Optional Instruction: Clear-A ction s : Clears all the actions in the action se t immediately.

• Required Instruct ion : Write-Actions action(s): Merges th e speciﬁed act i on( s ) into the current

action set (see 5.7). If an ac t ion of the gi ven type exists in the curre nt set, overwrite it, otherwise add

it.

• Optional Instruction: Write-Metadata metadata / mask : Writes the masked metadata value into

the met ad at a ﬁeld. The mask speciﬁes which bits of the metadata register should be modiﬁed (i.e.

new metadata = old metadata & ˜mask | value & mask).

• Required Instruction: Goto-Table next-table-id : Indicates the next table in the processing pipeline.

The tabl e -i d must be greater than the current table-id. The ﬂows of last table of the pipeline can not

include this instruction (see 5.1).

The inst ru ct i on set associated with a ﬂow entry contains a maximum of one instruction of each type.

The instructions of the set execute in the order speciﬁed by this above list . In practice, the onl y constraints

are that the Clear-Actions instruction is execut ed before the Write-Actions instruction, and that Goto-Table

is ex ec ut e d last.

A switch may reject a ﬂow entry if it is unable to execute the instructions associated with the ﬂow

entry. In this case, the switch must r et u rn an unsupported ﬂow error (see 6.7). Flow tables may not support

every match, every instruction and every actions.

5.7 Action Set

An action set is associated with each packet. This set is empty by default. A ﬂow entry can modify the

action set using a Write-Action instruction or a Clear-Action i n st r uc t ion associated with a particular match.

The action set is carried between ﬂow tables. When the in st r uc ti on set of a ﬂow entry does not contain a

Goto-Table instruct i on , pipeline processing stops and the actions in the action set of t h e packet are executed.

An acti on set contains a maximum of one action of each type. The set-ﬁeld actions are identiﬁed

by their ﬁeld types, therefore the action set contains a maximum of one set-ﬁeld action for each ﬁeld

type (i.e. multiple ﬁelds can be set). Whe n multiple actions of the same type are required, e.g. pushing

multiple MPLS labels or popping multiple MPLS labe l s, the Apply-Actions instructi on may be used (see 5.8).

The action s in an action set are applied in the order speciﬁed below, regardless of the order that

they were added to the set. If an action set contains a group action, the actions in the appropriate action

bucket of the group are also applied i n the order speciﬁed below. The switch may support arbitrary action

execution order through the action list of the Apply-Actions instruction.

1. copy TTL inwards: apply copy TTL inward actions to the packet

2. pop: apply all tag pop actions to the packet

3. push: apply all tag push actions to the packet

4. copy TTL outwards: apply copy TTL outwards action to the packet

5. decrement TTL: apply decrement TTL action to the packet

OpenFlow Switch Speciﬁcation Version 1.2

6. set: apply all set-ﬁeld actions to the p acket

7. qos: apply all QoS actions, such as set queue to the packet

8. group: if a group ac ti on is speciﬁed, apply the actions of the relevant group bucket(s) in the order

speciﬁed by this list

9. output: if no group action is speciﬁed, forward the packet on the port speciﬁed by the output action

The output action in the action set is executed last. If both an out pu t action and a group action are

speciﬁed in an action set, the output action is ignored and the group acti on takes precedence. If n o output

action and n o group action were speciﬁed in an action set, the packet is dropped. The execution of groups

is recursive if the switch supports it ; a group bucket may spe ci fy anot h er group , in which case the execution

of act ion s traverses all the groups speciﬁed by the group conﬁguration.

5.8 Action List

The Apply-Acti ons instruction and the Packet-out message include an action list. The semantic of the

action list is identical to the OpenFlow 1.0 speciﬁcation. The actions of an action list are executed in the

order sp ec iﬁ ed by the list, and are applied immediately to the packet.

The execution of an action list start with the ﬁrst action in the list and each action is executed on

the packet in sequence. The eﬀect of those actions is cumulative, if the action list contains two Push VLAN

actions, two VLAN headers are added to the packet. If the action list c ontains an output act ion , a c opy of

the packet is forwarded in its current state to the desired port. If the list contains a group actions, a copy

of th e packet in its current state is processed by the relevant group buckets.

After the execution of the action l i st in an Apply-Actions instructi on , pipeline execution continues

on the modi ﬁ ed packet (see 5.1). The action set of the packet is unchanged by the execution of the action

list.

5.9 Actions

A switch is not required to support all action types, just those marked “Requi red Action” below. The

controller can also query the switch about which of the “Optional Action” it supports.

Required Action: Output. The Output action forwards a packet to a speciﬁe d OpenFlow port (see

4.1). OpenFlow switches must support forwarding to physical ports, switch-deﬁned logical ports and the

required reserved ports (see 4.5).

Optional Action: Set-Queue. The set-queue action set s the queue id for a packet. When the

packet is forwarded to a port using the output action, the queue id determines which queue attached to this

port is used for forwarding the packet. Forwarding behavior is dictated by the conﬁguration of the queue

and i s used to provide basic Quality-of-Service (QoS) support (see section A.2.2).

Required Action: Drop. There is no explicit action to represent drops. Instead, packets whose ac-

tion sets have no output actions should be dropped. This result c oul d come from empty instruct i on sets or

empty action buckets in the pr ocessing pipeline, or after executing a Clear-Actions instruction.

Required Action: Group. Process the packet through the speciﬁed group. The e x act interpret at i on

depends on group type.

Optional Action: Push-Tag/Pop-Tag. Switches may support the ability to push/pop tags as shown in

OpenFlow Switch Speciﬁcation Version 1.2

Table 4. To aid integration with exi st i n g networks, we suggest that the abil ity to push/pop VLAN tags be

supported.

The or de ri n g of header ﬁelds/tags is:

Ethernet VLAN MPLS ARP/IP TCP/UDP/SCTP (IP-only)

Newly pushed tags should always be inserted as the outermost tag in this ordering. When a new VLAN tag

is pushed, it should be the outermost VLAN tag inserted immediately after the Ethernet header. Likewise,

when a new M PLS tag is pushed, i t should be the outermost MPLS tag, inserted as a shim header after any

VLAN tags.

Note: Refer to section 5.9.1 for information on default ﬁeld values.

Action Associated Data Description

Push VLAN header Ethertype Push a new VLAN header onto the packet.

The Ethertype is used as the Ethertype for the tag. Only

Ethertype 0x8100 and 0x88a8 should be used .

Pop VLAN header - Pop the outer-mo st V LA N head er from the pa cket.

Push MPLS header Ethertype Push a new MPLS shim header onto the packet.

The Ethertype is used as the Ethertype for the tag. Only

Ethertype 0x8847 and 0x8848 should be used .

Pop MPLS header Ethertype Pop the outer-most MPLS tag or shim header from the

packet.

The Ethertype is used a s the Ethertype for the resulting

packet (Ethertype for the MPLS payload).

Table 4: Push/pop tag actions.

Optional Action: Set-Field. The various Set-Field actions are identiﬁed by their ﬁeld type an d modify the

values of respective heade r ﬁelds in the packet. While not strictly req ui r ed , the support of rewriting various

header ﬁelds using Set-Field actions greatly increase the usefulness of an OpenFlow imple mentation. To

aid integration with exist i ng networks, we suggest that VLAN modiﬁcation act i ons be supported. Set -F i el d

actions should always be applied to the outermost-possible header (e.g. a “Set VLAN ID” acti on always

sets the ID of the outermost VLAN tag), unless the ﬁeld type speciﬁes otherwise.

Optional Action: Change-TTL. The various Change-TTL actions modify the values of the IPv4

TTL, IPv6 Hop Limit or MPLS TTL in th e packet. While not strictly required, the actions shown in

Table 5 greatly increase the usefulness of an OpenFlow imp le mentation for i mp le m e nting routing fu nc t ion s.

Change-TTL actions shou l d always be applied to the outermost-possible header.

Action Associated Data Description

Set MPLS TTL 8bits:NewMPLSTTL Repla c e the existing MPLS TTL. Only applies to packets

with an existing MPLS shim header.

Decrement MPLS TTL - Decrement the MPLS TTL. Only ap p l ie s to packets with

an existing MPLS shim header.

Set IP TTL 8bits:NewIPTTL Replace the existing IPv4 TTL or IPv6 Hop Limit and up-

date the IP checksum. Only applies to IPv4 and IPv6 pack-

ets.

Table 5 – Continued on next page

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OpenFlow 1.2规格：IPv6支持与增强功能

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