Re: [Lsr] Prefix Unreachable Announcement Use Cases Tue, 17 November 2020 06:31 UTC

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Date: Mon, 16 Nov 2020 22:31:12 -0800
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Cc: Jeff Tantsura <>, Robert Raszuk <>, lsr <>, "Acee Lindem (acee)" <>
To: Aijun Wang <>
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Subject: Re: [Lsr] Prefix Unreachable Announcement Use Cases
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>> And how would that help connectivity restoration ? 
>> [WAJ] This action will trigger the path protection procedures, which will divert the traffic to other backup path.

This seems to be making some major assumptions about how path protection features operate. Those assumptions need to be
very explicitly called out.

The path protection features that I’m familiar with are triggered by topological changes along the existing operable path. A PUA
does not provide that.  Rather, it’s something of a temporary signal saying ’this broke’. Without more specifics about the failure, it’s difficult to 
understand exactly what path protection should make of this.  If a prefix is unreachable, the obvious implication is that the associated link has
failed.  Path protection in a remote area is highly unlikely to have the topological details necessary to find an alternate path to that prefix.