[c-nsp] IOS: catch 22 when enabling new bgp neighbors

Dimitris Befas dimitris.befas at gmail.com
Fri Jun 20 13:11:10 EDT 2014


You can use peer-groups. Setup whatever setting you want for the peer-group
(neighbor peer-group-name shutdown) and enable the neighbor when you want.
But if you have multiple neighbors then you will affect all of them at once.

-----Original Message-----
From: Dimitris Befas [mailto:dimitris.befas at gmail.com] 
Sent: Friday, June 20, 2014 8:01 PM
To: 'Lukas Tribus'; 'cisco-nsp at puck.nether.net'
Subject: RE: [c-nsp] IOS: catch 22 when enabling new bgp neighbors

Use IOS-XR instead :-)

With IOS and XE you may just configure a wrong AS number (neighbor 2001::123
remote-as 6) so the adj won't come up, then shut it (neighbor 2001::123
shut) and while in a shut state, configure the correct AS (neighbor
2001::123 remote-as 65005). Now feel free to no shut (no neighbor 2001::123
remote-as shut)


-----Original Message-----
From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of
Lukas Tribus
Sent: Friday, June 20, 2014 5:40 PM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] IOS: catch 22 when enabling new bgp neighbors

Hey guys,


I feel like this is a stupid question with a simple solution, but I just not
see it:

When I configure a new BGP session, before I can shutdown the neighbor or
apply a specific peer-group/session-template/policy-template, I need to
configure the remote-as, so the first command in the address-family is:

 neighbor 2001::123 remote-as 65005


Now, if I don't specify the policies right away, or shutdown the session
right away (or the ssh terminal slows down for whatever reason), IOS will
establish the BGP session as-is (without any policies), until I manage to
configure the rest.

In that case, I'm leaking everything I have to the other side for a short
period of time, possibly triggering max-prefix limits or causing other
nastiness.

Especially when using SSH and configuring long IPv6 addresses on IOS-XE
here, this seams to be a problem, copy'n'pasting from notepad is not enough
in that situation (somehow, the terminal slows down when pasting the config
to some 2 - 3 chars per second).


Any way to make IOS(-XE) behave in a more sane way so I can configure
everything *before* the session brought up? Like defaulting to shutdown or
something like that?


Let me know how you guys avoid this problem.



Thanks!

Lukas

 		 	   		  
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