Subject: [spring] Regarding Circuit Style Segment Routing Policies [draft-schmutzer-pce-cs-sr-policy]

From: Vishnu Pavan Beeram <[email-masked]>
Date: Fri, 25 Mar 2022 08:48:35 -0500

Authors,

This draft is introducing a specific type of transport profile for SR
policy paths. To be more precise, it is introducing "Bandwidth Constrained
Bidirectional Corouted Pinned Path SR policies" with restoration and/or
reversion features enabled. I'm not sure if "Circuit-Styled" is an apt name
for this specific profile, but I don't have a better alternative to offer .
It is interesting how all of these TE features are being reinvented for SR
policy paths.

Is "Bandwidth Constraint" the only reason for the dependency on a
PCE/Controller (because of the need for a centralized Resource Reservation
Manager)? Would a Bidirectional Corouted Pinned Path SR policy not be
classified as "Circuit Style" if it wasn't bandwidth constrained (in other
words, do you envision any "Circuit Style" SR policy without a controller
in place)?

If this work were to progress, I would suggest having one document in
SPRING WG that discusses just the profile without getting into any PCEP/BGP
specific details (TEAS WG participants would be interested given that you
are modeling/defining a specific type of TE path profile; would be useful
to keep them notified) and a document in PCE WG that discusses the PCEP
specific procedures for this type of SR policies. The "new" PCEP
protocol-extensions being proposed (in
draft-sidor-pce-circuit-style-pcep-extensions) are path-control technology
agnostic (don't quite agree with the proposed encodings -- but that would
be a mail on the PCE list) and can potentially be discussed separately.

Regards,
-Pavan