Subject: [spring] SID Related Algorithm in draft-peng-idr-segment-routing-te-policy-attr

From: <[email-masked]>
Date: Wed, 30 Mar 2022 17:03:50 +0800 (CST)

Hi all,

We presented https://datatracker.ietf.org/doc/draft-peng-idr-segment-routing-te-policy-attr  on IDR's session last week. 
This document defines two kinds of new Segment Sub-TLVs to carry SID related algorithm when delivering SR Policy via BGP. One is for SR-MPLS adjacency with algorithm, another kind is defined for carrying the algo along with the SR-MPLS or SRv6 SID value.

While we believe that the former kind is necessary, considering draft-ietf-lsr-algorithm-related-adjacency-sid complements that in scenarios where multiple algorithm share the same link resource, the algorithm can be also included as part of an Adj-SID advertisement for SR-MPLS. 
We'd like to request the WG's opinion especially about the delivering SR-MPLS or SRv6 SID value with optional algorithm. (Thanks for Ketan's suggestion about this.)
Segment Sub-TLVs carrying SID value with optional algorithm are defined in this draft because we think it may benefit the scenarios below:
Scenario 1: For verification purposes. The headend can check if the SID value and the related algorithm received can be found in its SR-DB if requested to do so.
Scenario 2: The headend may not know about the SID-related algorithm especially in the inter-domain scenario.  Providing the algorithm  info benefits troubleshooting and network management.

Any comments and suggestions are welcome.

Thanks,
Yao