Re: [spring] Beyond SRv6.

["Zafar Ali (zali)" <[e-mail]>]

Dear Chairs and the WG,

As asked by the chairs ...

Cisco ASIC is capable of reading and writing an SRH of up to 9 (nine) “128-bit” SIDs at the line rate performance. Furthermore, SRv6 performance is at par with that is observed during an IPv6 packet processing.

Thanks

Regards ... Zafar

From: spring <[e-mail]> on behalf of Rob Shakir <robjs=[e-mail]>
Date: Sunday, August 4, 2019 at 5:03 PM
To: SPRING WG List <[e-mail]>
Subject: [spring] Beyond SRv6.


Hi SPRING WG,


Over the last 5+ years, the IETF has developed Source Packet Routing in NetworkinG (SPRING) aka Segment Routing for both the MPLS (SR-MPLS) and IPv6 (SRv6) data planes. SR-MPLS may also be transported over IP in UDP or GRE.


These encapsulations are past WG last call (in IESG or RFC Editor).


During the SPRING WG meeting at IETF 105, two presentations were related to the reduction of the size of the SID for IPv6 dataplane:

  *
  *   SRv6+ / CRH --
  *   https://tools.ietf.org/html/draft-bonica-spring-srv6-plus-04
  *
  *
  *   uSID --
  *   https://tools.ietf.org/html/draft-filsfils-spring-net-pgm-extension-srv6-usid-01
  *


During the IETF week, two additional drafts have been proposed:

  *
  *   https://tools.ietf.org/html/draft-li-spring-compressed-srv6-np-00
  *
  *
  *   https://tools.ietf.org/html/draft-mirsky-6man-unified-id-sr-03
  *


As we expressed during the meeting, it is important for the WG to understand what the aims of additional encapsulations are. Thus, we think it is important that the WG should first get to a common understanding on the requirements for a new IPv6 data plane with a smaller SID - both from the perspective of operators that are looking to deploy these technologies, and from that of the software/hardware implementation.


Therefore, we would like to solicit network operators interested in SR over the IPv6 data plane to briefly introduce their:

  *
  *   use case (e.g. Fast Reroute, explicit routing/TE)
  *
  *
  *   forwarding performance and scaling requirements
  *

     *
     *   e.g., (number of nodes, network diameter,
     *   number of SID required in max and average). For the latter, if possible using both SRv6 128-bit SIDs and shorter (e.g. 32-bit) SIDs as the number would typically be different (*).
     *

  *
  *   if the existing SRv6 approach is not deployable
  *   in their circumstances, details of the requirement of a different solution is required and whether this solution is needed for the short term only or for the long term.
  *


As well as deployment limitations, we would like the SPRING community to briefly describe the platform limitations that they are seeing which limit the deployment of SRv6  In particular limitations related to the number of SIDs which can be pushed and forwarded and how much the use of shorter SIDs would improve the deployments .


For both of these sets of feedback if possible, please post this to the SPRING WG. If the information cannot be shared publicly, please send it directly to the chairs & AD (Martin).


This call for information will run for four weeks, up to 2019/09/03. As a reminder, you can reach the SPRING chairs via [e-mail]<mailto:[e-mail]> and ADs via [e-mail]<mailto:[e-mail]>.


Thank you,

-- Rob & Bruno


(*) As expressed on the mailing list, a 128 bit SID can encode two instructions a node SID and an adjacency SID hence less SID may be required.