[c-nsp] OSPF question

[Ivan Pepelnjak]

It's actually quite simple: you need an EEM applet that triggers on X
occurences of a well-known SYSLOG message (OSPF neighbor going down) within
Y seconds, modifies the configuration (to insert "passive-interface X" into
the "router ospf Y") and alerts the operators via an e-mail.

You'll find a few similar applets in my blog and my wiki:

http://wiki.nil.com/Category:EEM_applet
http://blog.ioshints.info/search/label/EEM

Ivan
 
http://www.ioshints.info/about
http://blog.ioshints.info/


> -----Original Message-----
> From: Tony Baade [mailto:Tony at bobbroadband.com] 
> Sent: Friday, July 24, 2009 6:01 PM
> To: Rodney Dunn
> Cc: cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] OSPF question
> 
> Does anyone know if it's available in another IGP?
> 
> Or does anyone have any sample scripts I might able to try out?
> 
> 
> 
> Anthony J Baade
> Network Engineer
> Business Only Broadband, LLC
> O (630) 590-6011
> C (630) 340-0696
> tony at bobbroadband.com
> www.bobbroadband.com
>  
> 
> -----Original Message-----
> From: Rodney Dunn [mailto:rodunn at cisco.com]
> Sent: Thursday, July 23, 2009 9:33 PM
> To: Tony Baade
> Cc: cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] OSPF question
> 
> 
> 
> Tony Baade wrote:
> > We experienced an issue on our network where we have a link 
> between 2 cisco ME6524s.  There was packet loss across the 
> link, but the interfaces on either side never actually 
> dropped.  The packet loss however was severe enough to cause 
> problems w/ our OSPF (the neighbor session kept dropping up 
> and down) and as a result this caused our iBGP hellos to 
> timeout, causing an outage affecting several routers.
> > 
> > My question is there some way to dampen a flapping neighbor 
> in OSPF? 
> 
> Not natively. I tried to get that in a few years ago but 
> couldn't make 
> it happen. If you wanted it bad enough you could code it up 
> with EEM and 
> a TCL script to watch for a neighbor flap and passive that 
> interface for 
> some time.
> 
> Interface event dampening covers the link flap but just for the OSPF 
> transport we don't do it.
> 
> The enhancement request to track it was:
> 
> CSCsi29746    Routing protocol neighbor dampening request
> 
> 
>   So if the interface doesn't actually go down, but there is 
> X amount of 
> packet loss in Y amount of time (or if the neighbor goes up 
> and down a 
> certain number of times) the switch will recognize this issue 
> and stop 
> using that link? We are already using IP Event Dampening, 
> which didn't 
> kick in because the interfaces never actually went down.
> > 
> > If there's no way in OSPF to do this, is there support for 
> this in another IGP, or is there any other workaround for 
> this kind of situation?
> > 
> > Any advice is appreciated, thanks in advance,
> > 
> > t. baade
> > 
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