Hello Michael.

Thanks for the info; very useful.

Considering this, could we say BGP is faster removing routes when
session is lost/closed/shut down than when they are added?

Even though you start receiving traffic right away you setup a BGP
session, we have seen it takes hours (even days) to fully propagate new
BGP upstream we added in the past.

Did you find this behavior too?

Thanks Michael.
Best Regards.

PD: Just to clarify point 2) Another solution is to just shutdown BGP
session but leave upstream connected and configured (so outdated
routers we still reach us...) AND unplug the cable after traffic disappears.

We are using option number 2.

After 600 seconds, all routes via the shutted down peer will get invalid.

So just wait 10 Minutes and your inbound traffic should stop.

.........

But there was a another thread with a feature request to send withdraws to your peer, so you can immediatley shutdown your network interface after shutting down the bgp session.

Am Sa., 8. Dez. 2018, 04:03 hat Francis Brosnan Blázquez <francis.brosnan@aspl.es> geschrieben:

Hello.

We are using bird with several upstream providers, all of them with a
share of traffic.

We are in the process of shutting down one of them but we are unsure
how to proceed to minimize loss of traffic.

We have been reading and looking for general recommendations but it is
not clear (besides using graceful shutdown which is not supported by
the upstream we want to shutdown).

We have been looking at mailing list but we haven't found anything
treating this matter.

So far, solutions we have come up are:

1) Use AS-path prepend to increase metric on the uptstream to be
shutted down and once nearly no traffic comes in through that link, shutdown
BGP and unplug. Something like:

    export filter {

          if source = RTS_STATIC then { # Export only static routes
                 # Assign our community
                 bgp_community.add((65000,64501));
                 # Artificially increase path length
                 # by advertising local AS number twice
                 if bgp_path ~ [= 65000 =] then
                      bgp_path.prepend(65000);
                      bgp_path.prepend(65000);
                 accept;
           }
          reject;
    };

2) Another solution is to just shutdown BGP session but leave upstream
connected and configured (so outdated routers we still reach us...).

3) And the obvious, just shutdown BGP session and unplug the cable.

It would be great to know your opinion and what's the recommended way
to proceed.

What do you think?

Many thanks
Best Regards.

-- 
Francis Brosnan Blázquez  -  ASPL
http://www.asplhosting.com/
http://www.aspl.es/
https://twitter.com/aspl_es
https://twitter.com/asplhosting
https://twitter.com/francisbrosnanb
https://es.linkedin.com/in/francis-brosnan-blázquez-1353a218

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