[Tsv-art] Tsvart early review of draft-ietf-idr-sr-policy-safi-00

[David Black via Datatracker <[e-mail]>]

Reviewer: David Black
Review result: On the Right Track

The result of this early TSV-ART review's is "On the Right Track" rather than
some form of "Ready" for the sole reason that the scope of this review is
limited to the requested scope, namely:
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INT/Transport Area Review team:
This routing document (draft-ietf-idr-sr-policy-safi) extends the color
functions in the BGP Extended Community Color to aid the steering of traffic
flows into particular routing paths.  Color tagging is part of the Intent-based
signaling of upper-layer desire for VPNs within routing technology. Other
drafts that provide functions to carry Intent are draft-ietf-idr-bgp-car (via
color) and draft-ietf-idr-bgp-ct (via class).

It would be good to get a transport reviewer to help see if we are really
Transport/INT functions being defined.
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In addition to the drafts noted in that request, RFC 9256 (Segment Routing
Policy Architecture) has already introduced the use of color in SR Policy
(Segment Routing Policy).  Section 2.1 of RFC 9256 requires use of color for SR
Policy identification, and section 8 of RFC 9256 makes extensive use of color
in procedures for BGP steering of traffic based on SR Policies.  I don't
believe that RFC 9256's extension of color to this sort of BGP steering poses
any serious transport-related concerns, even if that BGP functionality is used
to realize QoS differences among portions of traffic to the same destination. 
That's just as well, as any such concern would almost certainly also need to be
raised against RFC 9256, a Proposed Standard RFC, and not just against this
draft.

This draft is primarily concerned with how BGP carries SR Policy information
needed to realize the SR Policy functionality defined in RFC 9256.  That does
not raise any transport-related concerns beyond RFC 9256.