[c-nsp] Graceful way to terminate BGP Session

[a. Rahman Isnaini r. sutan]

I used to do this way as we have many peers 'come and go'.

1. Incoming
    - Add more as path prepends to old one if using the similar prefix 
lenghth / Advertise (all) longer prefix to the new upstream
    - Ensure all traffic had moved
    - Shut BGP session then interface
    - Re-aggregate the prefix if still needed.

2. Outgoing manipulation local preference, prepend, weight & shutdown BGP 
Session then interface.


- a. rahman isnaini r. sutan

----- Original Message ----- 
From: "Ian Dickinson" <iand at eng.pipex.net>
To: "Gert Doering" <gert at greenie.muc.de>
Cc: <cisco-nsp at puck.nether.net>
Sent: Sunday, June 24, 2007 11:52 PM
Subject: Re: [c-nsp] Graceful way to terminate BGP Session


> Gert Doering wrote:
>> Hi,
>>
>> On Sat, Jun 23, 2007 at 01:45:27PM +0100, Ian Dickinson wrote:
>>>Doing weight or local pref tweaks inbound etc gives you the chance to 
>>>check
>>>that everything actually has migrated to other paths - you also get to 
>>>see
>>>that the traffic on that leg has moved - and all without turning it off. 
>>>Once
>>>you've checked this, you *know* your outbound traffic is sorted.
>>
>> That's why you shut down the BGP session, long before shutting down the
>> actual physical link.
>>
>> I can't see a good reason for explicitely configuring the running BGP 
>> session
>> to "send nothing, accept nothing" instead of just switching it off - it
>> will achieve the same thing with less effort.
>
> That's why I suggested weight or local-pref tweaks rather than accept 
> nothing.
> That way you still spot if there's anything still going out via that leg
> (e.g. de-aggs or routes missing from other feeds) prior to downing the
> session.  You're welcome to follow the less effort route - I'm just saying
> that *once* this saved my bacon, and it might again one day.
> -- 
> Ian Dickinson
> Senior Network Development Engineer
> Pipex Communications
> ian.dickinson at pipex.net
> INOC-DBA: 5413*426
> http://www.pipex.net
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