Early Review of draft-ietf-idr-nhc-00
review-ietf-idr-nhc-00-rtgdir-early-alston-2026-02-03-00

Having carefully review this draft, I believe that it is largely ready.  It's a
well written draft thats easy to understand and my compliments to the authors
on the good job done on the drafting of this.

That being said - before this is ready I believe that some additional text may
be required to address certain corner cases.

In section 2.5 of the draft, reference is made to anycast next-hops.  My
concern is that this text probably needs to be expanded to cover cases where
the next-hop is something indirectly resolved.  An example of this would be
where an IPv4 (or IPv6) prefix is advertised with an SR Label.  The SR label
may or may not correspond to the network address of the next-hop, so for
example, it is possible for a case to exist where a route has an SR label that
directs the traffic through multiple hops (with the SID only being popped once
it reaches the SR destination), and the next-hop specified in address terms
doesn't take this into account.

If router A announces a prefix with a next-hop of 10.10.20.1 for example - but
has a SID of 16010 - and SID 16010 is mapped to a router 5 hops down the line
with an entirely different address - the SID will be what is followed and the
NHC could well be invalid.

As such - I would advise adding text to the draft for dealing with cases where
the next-hop is "indirectly" resolved.

Beyond this, I think its a solid draft and once such text is added I would say
the draft is ready.