[c-nsp] Persistent Loops?

[Bruce Pinsky]

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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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