Re: [spring] Beyond SRv6.

Hi,

the introduction of SRv6 as alternate data plane in addition to MPLS
has been an important step in SPRING, providing an encapsulation
for SPRING traffic that is native to IPv6.

The question about the necessity of work on alternate encapsulations
was fueled by concerns about encapsulation overhead when using 
full 128 bit SIDs in the SRv6 SRH.

Through the introduction of the uSID network instruction in SRv6
these concerns are now properly addressed and SRv6 with uSID
can now also be deployed in a very MTU-efficient manner. 

Therefore I do not see a necessity for any additional encapsulations.

Cheers
Dirk 

> Am 31.08.2019 um 06:05 schrieb Zafar Ali (zali) <zali@cisco.com>:
> 
> Dear Chairs and the WG: 
>  
> The SRv6 network programming solution and its SRH encapsulation is implemented on 12 hardware platforms including Merchant Silicon.
> Multiple providers have deployed the SRv6 network programming solution and its SRH encapsulation with line-rate performance carrying a significant amount of commercial traffic.
> Several independent interoperability reports documenting successful interoperability of implementation from multiple vendors exist.
> Implementation, deployment, and interoperability status is publicly documented in https://www.ietf.org/id/draft-matsushima-spring-srv6-deployment-status-01.txt <https://www.ietf.org/id/draft-matsushima-spring-srv6-deployment-status-01.txt>.
>  
> Most use-cases are expected to use very few SRv6 segments.
>  
> In some specific use-cases, one may desire to optimize the MTU usage further.
> The SRv6 network programming solution and its SRH encapsulation also support for this Optimization, through the uSID network instruction.
>  
> I do not see the need for any new encapsulation work.
>  
> Thanks
>  
> Regards … Zafar 
>  
> From: spring <spring-bounces@ietf.org <mailto:spring-bounces@ietf.org>> on behalf of Rob Shakir <robjs=40google.com@dmarc.ietf.org <mailto:robjs=40google.com@dmarc.ietf.org>>
> Date: Sunday, August 4, 2019 at 5:04 PM
> To: SPRING WG List <spring@ietf.org <mailto:spring@ietf.org>>
> 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 <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 <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-li-spring-compressed-srv6-np-00> 
>  
>  
> https://tools.ietf.org/html/draft-mirsky-6man-unified-id-sr-03 <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 spring-chairs@ietf.org <mailto:spring-chairs@ietf.org> and ADs via spring-ads@ietf.org <mailto:spring-ads@ietf.org>. 
>  
> 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.
>  
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