Hi Gyan, 

> On May 17, 2021, at 1:50 PM, Gyan Mishra <[email protected]> wrote:
> 
> So if GW2 connection to external was down but GW1 still has its connection to 
> external.  GW2 would auto discover GW1 over iBGP and GW2 would advertise both 
> GW1 and GW2 as reachable gateways.  However GW2 has its external peer down.  
> So if GW1 continues to advertised GW2 as we stated GW1 will auto discover  
> GW2 over iBGP.  

Isn’t this scenario covered? From §3:

   If a gateway becomes disconnected from the backbone network, or if
   the SR domain operator decides to terminate the gateway's activity,
   it withdraws the advertisements described above.  This means that
   remote gateways at other sites will stop seeing advertisements from
   this gateway.

So when GW2’s external peering goes down, GW2 withdraws its auto discovery 
route, and therefore GW1 re-advertises its routes externally without GW2 listed 
in the tunnel attribute.

I will say that reviewing the above-quoted text — which seems tailor-made for a 
“MUST withdraw” — made me notice that the draft makes only sporadic and 
desultory use of RFC2119 keywords. In fact there are so few used, that it seems 
like it might be better to scrub those two SHOULD and two MUST out and remove 
the 2119 citation.

—John
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