[c-nsp] Dreaded FIB Exception on Sup2

[Church, Charles]

I got curious last week when I saw this thread.  From my (AS 26296)
point of view, there aren't a whole lot of routes in the /25 to /29
range, maybe a couple hundred total when I looked at it last week.   The
/24s were huge, about 142,000.  I'm curious how many of those /24s are
covered by larger aggregates.  Might be a fun experiment figuring out a
safe way to filter those.  Probably involve AS path length, maybe RIR
allocations.  

Chuck 

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Rubens Kuhl Jr.
Sent: Sunday, September 14, 2008 8:12 PM
To: Rick Kunkel
Cc: Cisco-nsp
Subject: Re: [c-nsp] Dreaded FIB Exception on Sup2


On Wed, Sep 3, 2008 at 2:58 PM, Rick Kunkel <kunkel at w-link.net> wrote:
> Well, I've hit the dreaded error message on my Sup2:
>
> %MLSCEF-SP-7-FIB_EXCEPTION: FIB TCAM exception, Some entries will be
> software switched

1) Try filtering on anything less than /24s and pointing default
routes to your providers, see if that helps.
2) Try filtering on RIR boundaries, if (1) has failed.
3) Try filtering on overlapping prefixes (will need software to find
those), if (2) has failed
4)  Try filtering on longer AS paths, which means you are likely to be
very far off to do useful traffic engineering, if (3) or (2) failed

Beware that pointing a defaul-route might do some damage if you use
uRPF, but you use uRPF, you would have probably posted this message
some years ago... :-)


Rubens
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