p4srv6 ... proto-typing SRv6 functions with P4 lang.

• About p4srv6
• P4 Targets and Architectures
• Roadmap
  • List of SRv6 functions of interest and status
• Reference
• Archives

About p4srv6

At the time of its inception in 2018, the objective of this project was to implement SRv6 functions still under discussion at IETF using P4 Lang to make running code available for testing and demo.

After 5+ years, the standardization of SRv6 has progressed, and many specifications have become RFCs. Open Source implementation has also advanced. For switch type implementation, SONiC now (in 202211, 202305 release) supports many SRv6 functions including uSID. Switch Abstraction Interface (SAI), which is the de facto standard API for Switch ASICs, is used by SONiC to communicate with ASIC from multiple vendors. e.g. Intel/Barefoot Tofino, Cisco Silicon One, Broadcom, Marvell, etc.

Since SAI has become the de facto of Switch Object and Pipeline Model, p4srv6 is being refactored in a way that is (not perfect but some what) compatible with SAI, aiming to provide an implementation that serves as a educational reference for people who are interested in how packets are processed inside ASIC behind SAI.

P4 Targets and Architectures

• BMv2 v1model
  • The main target of this p4srv6 is switch based P4 target which is BMv2 using v1model.p4 architecture.
• Tofino Native Architecture (TNA)
  • Tofino Native Architecture is now public on GitHub Open-Tofino with architecture document(pdf) and P4 architecture file (tna.p4)
  • However, there are still some restrictions (e.g. doesn't have an ASIC simulator publically available so anyone can try)
  • Thus, the P4 code in this repo is written to be compatible with TNA as much as posible, but not intented to run full demo nor fully documented. (Since it's difficult to do so without violating Intel NDA/SLA)
• SmartNIC (FPGA, IPU, DPU, ARM-Manycore, etc.)
  • There is no plan to support SmartNIC type of targets. However, P4 work in this area is evolving very fast. Thus, I would recommend checking other projects for SRv6 implementation on SmartNIC.

Roadmap

Update after documenting SAI object / pipeline model

• Phase 1
  • Basic L3 features
  • Port Forwarding (for debug)
  • nexthop, neighbor
• Phase 2
  • Basic L2 features
  • VLAN Port/Tag
  • L2 (dmac) Table

List of SRv6 functions of interest and status

• Data Plane (P4) Switching

Feature	Schedule
Port Forwarding	TBD
L2 (dmac) forwarding	TBD
VLAN (port)	TBD
VLAN (Tag)	TBD
IPv4 forwarding (lpm/host)	TBD
IPv6 forwarding (lpm/host)	TBD

• Control Plane

| L2 learning agent | TBD | | Host Interface (ping/arp) | TBD |

• draft-ietf-dmm-srv6-mobile-uplane-24

Function	schedule	description
Args.Mob.Session
End.MAP
End.M.GTP6.D		GTP-U/IPv6 => SRv6
End.M.GTP6.Di		GTP-U/IPv6 => SRv6
End.M.GTP6.E		SRv6 => GTP-U/IPv6
End.M.GTP4.E		SRv6 => GTP-U/IPv4
T.M.GTP4.D		GTP-U/IPv4 => SRv6
End.Limit	-	Rate Limiting function

• draft-murakami-dmm-user-plane-message-encoding-05

Function	schedule	description
Args.Mob.Upmsg
Encoding of Tags Field
User Plane message IE

• RFC8986: SRv6 Network Programming

SR Policy Headend Behaviors

Function	schedule	description
H.Encaps		SR Headend with Encapsulation in an SR Policy
H.Encaps.Red		H.Encaps with Reduced Encapsulation
H.Encaps.L2		H.Encaps Applied to Received L2 Frames
H.Encaps.L2.Red		H.Encaps.Red Applied to Received L2 Frames

SR Endpoint Behaviors

Function	schedule	description
End
End.X		L3 Cross-Connect
End.T		Specific IPv6 Table Lookup
End.DX6		Decapsulation and IPv6 Cross-Connect
End.DX4		Decapsulation and IPv4 Cross-Connect
End.DT6		Decapsulation and Specific IPv6 Table Lookup
End.DT4		Decapsulation and Specific IPv4 Table Lookup
End.DT46		Decapsulation and Specific IP Table Lookup
End.DX2		Decapsulation and L2 Cross-Connect
End.DX2V		Decapsulation and VLAN L2 Table Lookup
End.DT2U		Decapsulation and Unicast MAC L2 Table Lookup
End.DT2M		Decapsulation and L2 Table Flooding
End.B6.Encaps		Endpoint Bound to an SRv6 Policy with Encapsulation
End.B6.Encaps.Red		End.B6.Encaps with Reduced SRH
End.BM		Endpoint Bound to an SR-MPLS Policy

Flavours

Function	schedule	description
PSP		Penultimate Segment Pop
USP		Ultimate Segment Pop
USD		Ultimate Segment Decapsulation

Reference

• SRv6 consortium is where many people in Japan interested in SRv6 gathers.

Archives

You can find old version of p4srv6 here

• [2019/03/03] Old P4-14 version is moved under archive/p4-14/ for archival purpose.
• demos presented at events and hackathon are archived as below
  • branch janog45
  • branch ietf104
  • branch ietf106
• [2023/03/31] branch v20191206 is created to archive pre-refactoring version started working from April 2023.
• [2023/04/01] All code, script, docs predates April 2023 refactoring are archived under archive/