Devil's Advocate - Segment Routing, Why?

Robert Raszuk robert at
Sun Jun 21 20:21:58 UTC 2020

> I should point out that all of my input here is based on simple MPLS
> forwarding of IP traffic in the global table. In this scenario, labels
> are only assigned to BGP next-hops, which is typically an IGP Loopback
> address.

Well this is true for one company :) Name starts with j ....

Other company name starting with c - at least some time back by default
allocated labels for all routes in the RIB either connected or static or
sourced from IGP. Sure you could always limit that with a knob if desired.

The issue with allocating labels only for BGP next hops is that your
IP/MPLS LFA breaks (or more directly is not possible) as you do not have a
label to PQ node upon failure.  Hint: PQ node is not even running BGP :).

Sure selective folks still count of "IGP Convergence" to restore
connectivity. But I hope those will move to much faster connectivity
restoration techniques soon.

> Labels don't get assigned to BGP routes in a global table. There is no
> use for that.

Sure - True.

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