Re: [Lsr] Prefix Unreachable Announcement Use Cases

Robert Raszuk <> Sun, 15 November 2020 16:44 UTC

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From: Robert Raszuk <>
Date: Sun, 15 Nov 2020 17:44:05 +0100
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To: Aijun Wang <>
Cc: lsr <>, "Acee Lindem (acee)" <>
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Subject: Re: [Lsr] Prefix Unreachable Announcement Use Cases
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Hi Aijun,

I would in fact only propose that the presented mechanism is narrowed down
to invalidate BGP (service) routes - in fact their next hops.

The reason being that the moment you make the solution generic, moreover
the moment you want it to be used in RIB and data plane I am afraid you are
running into similar (even if local) deaggregation mechanism like recently
described in RIFT. That would kill all the scalability of advertising
summary routes in the first place and I bet would face lots of opposition.


> I would actually trim most use cases leaving just one - to signal remote
> service node (ex: PE) going down in the presence of summary route being
> advertised from remote area or pop.
>  [WAJ] Yes, this may be the most useful use case, but the PUA mechanism
can also apply to other scenarios. We want to make it one general solution.