[c-nsp] Funny (and hard to describe) AWOL routes

[Jared Mauch]

Your tcam is full. It may not log that, you likely need 12.2sxe or sxf  
to see the logs on sup2. Cut down the number of routes you listen to  
from your upstreams, having them send you just their customer routes  
and use default for the rest.

In sup720 and sup1a when the tcam is full it would then process  
switch. Not sure on sup2 but I presume it's the same.

Jared Mauch

On Aug 13, 2009, at 8:30 PM, Rick Kunkel <kunkel at w-link.net> wrote:

> Hello all,
>
> I've got a problem that I unfortunately don't know a heck of a lot  
> about, which I understand makes answering this question difficult.   
> But I thought I'd pick people's brains in the hopes of at least  
> getting pointed in the right direction.
>
> Here's the deal.  I run EIGRP for the internal network, and BGP to  
> talk to the outside world.  Occasionally, I go to add a new block or  
> router to the EIGRP network, and it just won't work.  Strangely, all  
> the "show ip route" commands look good, but traffic just won't get  
> where it's supposed to go. Crazily, sometimes I can get 20-40% of  
> packets through to the internet, but traffic to the internal network  
> is usually lost.  However, it sometimes seems as if the traffic  
> might be lost at a border router we have, which is currently getting  
> two full route tables on a Sup2 running IOS 12.1(26)E8.  (Yes, I  
> know, impossible.)  In an effort to minimize downtime, I can only  
> poke around at things for so long, before performing the wonky fix.
>
> The fix...  Usually I can do something that will withdraw or  
> otherwise change the new announcement, and then put it back, and it  
> will work.
>
> The LAST time this happened, however, when I re-added the new block,  
> suddenly another block on our network became unreachable.  It was as  
> if the new block kicked the old one out.
>
> To me, this smacks of a memory shortage somewhere, and it's occurred  
> to me that it may be that border router that has a bunch of EIGRP  
> stuff AND the BGP stuff.  I've heard tell of the TCAM filling, but  
> that's supposed to log messages, and I've seen none of those.  And  
> does EIGRP use the TCAM? Perhaps an OS bug?
>
> Anyhow, I don't expect anyone to solve the mystery for me (unless  
> they immediately know what's causing it), but I was hoping for some  
> direction. Any commands I can run to quickly show me exhausted  
> space, etc.?  I know the Sup2 needs to be upgraded, but I find  
> myself wondering if that will fix the problem, or if this is a  
> result of something else entirely.
>
> This is not a horrendous problem, but it rears its head from time to  
> time, and makes things difficult.  Most frustrating of all is that I  
> can't get a bead on it, and have minimal time to troubleshoot on a  
> production network.
>
> Any ideas and/or pointers?
>
> Thanks much!
>
> Rick Kunkel
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