All, With all the discussions about how to accomplish this I have one fundamental doubt.
Let's take SR and ISIS or OSPF extensions for it (say RFC8667). It seems that none of it works network wide if we instead of prefix reachability start advertising summary routes from ABRs to other areas/levels. That means no use for this there. For MPLS LDP FECs already must be /32 so if we want to keep this at the underlay level we have a way (and actually doing it today with ordered LDP mode) and signal liveness network wide. That means that the real practical use case has shrunk. That said it may be still very useful and can be done with BGP recursion when you have MPLS-over-UDP for your service tunneling. Essentially what we are trying to race here with is BGP service routes withdraws to speed up connectivity restoration time. Shouldn't we really try to understand the issue (if there is one in the protocol which I personally doubt) before we start investing essentially by building a workaround in LSR sandbox ? The ABR acting as state reflector directly to interested parties or via their local relays (local area ABRs) sounds like a cool pub-sub option. But that still only attempts to fix current proposals. The fact that in my local area there are /32s does not really mean I can reach those PEs from any remote sites. There can be fabric or LC data plane bugs on the way, accidental ACLs, broken SRH processors, misconfigurations etc .. which can drop (all or worse some) of my packets to a remote PE. Only inline data plane telemetry and reaction to it will allow me to choose a different path to a multihomed service. Again not a problem for LSR WG I think. Kind regards, Robert
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