Hi, Folks: As I recall, the loopbacks and their metrics need to be propagated individually to the whole network (including leaking from Level 2 to Level 1) for the following reasons:
1) Path selection: in case there are multiple Level 2 / Level 1 routers in an area. 2) Export IGP metric : when the IGP metrics are exported to BGP as MED for symmetric routing. Not sure if there is still a problem to be solved. Regards, -- Enke ---------- Forwarded message ---------- From: Tony Li <[email protected]> To: "Les Ginsberg (ginsberg)" <[email protected]> Cc: Gyan Mishra <[email protected]>, lsr <[email protected]> Bcc: Date: Wed, 13 Oct 2021 22:50:33 -0700 Subject: Re: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension for Event Notification" Les, If you’re advertising loopbacks that are outside of the summarized space, then you end up with reachability and liveness. Yes, there’s a cost in scalability… it ain’t free. Tony
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