[c-nsp] Persistent Loops?

[Christian Koch]

Bruce,

This is a customer router/t1's that's just how its been done here with
every customer..

.89 and .93 are each a serial interface on our border router 

We cant figure out what is causing this loop, being we can trace to the
ip's sourcing the customers ip on our side...

The only other thing is theres a lot of these messages in the log, but
that's it

Sep 27 20:37:30 GMT: %GENERAL-3-EREVENT: HWCEF: Failed to alloc Mtrie HW
node
-Traceback= 6008BCC8 6008CAFC 6008CFA4 6008E95C 601D6014 601D933C
601E1628 601E9BB0 6041C36C 603EF9BC 603F0138 60812938 6081381C 6089FC90
608138B8 607EA110

-----Original Message-----
From: Bruce Pinsky [mailto:bep at whack.org] 
Sent: Wednesday, September 27, 2006 2:47 PM
To: Christian Koch
Cc: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] Persistent Loops?

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Christian Koch wrote:
> i,
> 
> I am having an issue which looks like a persistent loop.
> 
> Check below for how this is setup
> 
> Router A has 2 serial interfaces which are 2 T1's which are load 
> sharing per packet Router B has 2 serial interfaces which the 2 T1's 
> connect to and are load sharing per packet
> 
> On Router A there is a default route out each interface
> 
> ip route 0.0.0.0 0.0.0.0 Serial0/0
> ip route 0.0.0.0 0.0.0.0 Serial0/1
> 
> When performing traceroute from router a I receive this
> 
> #trace 145.97.39.155
> 
> Type escape sequence to abort.
> Tracing the route to rr.knams.wikimedia.org (145.97.39.155)
> 
>   1 X.X.X.89 72 msec
>     X.X.X.93 36 msec
>     X.X.X.89 4 msec
>   2 X.X.X.89 !N 
>     X.X.X.93 !N  *
> #trace 155.94.60.236
> 
> Type escape sequence to abort.
> Tracing the route to imail-gv6.wyeth.com (155.94.60.236)
> 
>   1 X.X.X.89 12 msec 8 msec
>     X.X.X.93 8 msec
>   2 X.X.X.89 !N  * 
>     X.X.X.93 !N
> 
> 
> When tracing from Router B and sourching thr IP address that connects 
> to the other serial on Router A, I can get through..
> 
> 
> Anyone have any ideas???
> 
> I have been looking into this with a colleague for over 3hours..have 
> tried everything, have not seen anything that doesn't really look 
> right..
> 

Why do you have your default routes pointing at the interfaces and not
the nexthop IP addresses?

What routers are the .89 and .93?  Yours, your upstreams, something
else?

Looks to me like you've got a routing loop of some sort.  Without a bit
more detail, it's a bit difficult to diagnose.

- --
=========
bep

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