Devil's Advocate - Segment Routing, Why?

Mon Jun 22 07:55:49 UTC 2020

> From: NANOG <nanog-bounces at nanog.org> On Behalf Of Masataka Ohta
> Sent: Friday, June 19, 2020 5:01 PM
> 
> Robert Raszuk wrote:
> 
> > So I think Ohta-san's point is about scalability services not flat
> > underlay RIB and FIB sizes. Many years ago we had requests to support
> > 5M L3VPN routes while underlay was just 500K IPv4.
> 
> That is certainly a problem. However, worse problem is to know label
values
> nested deeply in MPLS label chain.
> 
> Even worse, if route near the destination expected to pop the label chain
> goes down, how can the source knows that the router goes down and
> choose alternative router near the destination?
> 
Via IGP or controller, but for sub 50ms convergence there are edge node
protection mechanisms, so the point is the source doesn't even need to know
about for the restoration to happen. 

adam