[Idr] new thread regarding capabilities handling

Mikael Abrahamsson <swmike@swm.pp.se> Thu, 27 April 2017 05:18 UTC

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Date: Thu, 27 Apr 2017 07:18:24 +0200 (CEST)
From: Mikael Abrahamsson <swmike@swm.pp.se>
To: idr@ietf.org
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Subject: [Idr] new thread regarding capabilities handling
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Hi,

disregard the part in my last email about asking why all bgp sessions in a 
peer group are flapped when one changes the config of that peer group. 
Let's discuss that here instead.

If I add "address-family ipv4 multicast" to my peer-group and it wasn't 
there before, all router OSes I know will just reset all the sessions. 
This is baffling.

I see two problems:

1. Why can't capabilities be renegotiated without BGP session restaart?

2. Why doesn't it require a command to flap the sessions to adapt to the 
new configuration? If I want to run-through my changed policy-map, I have 
to "clear soft in" (or out). Why isn't there a "clear 
all-sessions-where-capabilities-have-changed" (paraphrasing).

Current behaviour is very disruptive. You change a line of config that you 
might think is a minor change, and BOOM, all your sessions are reset and 
you have a many-minutes outage.

-- 
Mikael Abrahamsson    email: swmike@swm.pp.se