Robert,
On 25/07/2023 22:19, Robert Raszuk wrote:
Hey Peter and Lsr,
At the risk of being called troublemaker by Les again :) can you refresh
my failing memory how UPA would work in case of Inter-AS option C (where
original next hops are maintained for service routes across two or more
ASNs) and reachability to next hops is redistributed (often with labels)
between ASBRs ?
If the redistrubuted next hop is not summarized, there is no need for
UPA. If you would summarize the next-hop during the redistribution, then
you could use the UPA to signal its unreachbaility in case the summary
is still advertised due to other prefixes still being redistributed. UPA
can be used for summarization used during both inter-area propagation
and inetr-domain redistribution.
On a similar note how UPAs travel (if at all) between backbone area and
remote areas in the single AS case ?
UPA is propagated as any other prefix. See section 2.2.
While reading mail from Bruno I also realized a bit more complex case
where someone may use service routes in service BGP over "seamless MPLS
3107/LU routes by BGP over IGP. In such cases signalling remote PE going
down is not going to help much I am afraid.
- - -
As to the draft I think just adding a sentence that it should be
used/enabled only for encapsulated services at ingress to the service
nodes.
we can certainly say that above is the primary use-case.
thanks,
Peter
And actually to expand on what Bruno mentioned in the last note next hop
validation can in some implementations be enabled to resolve in
different RIBs on a per SAFI basis.
But how BGP (or any other app) takes such triggers is indeed outside of
scope of the current draft IMO.
Thx,
R,
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