I'd say this is a start-from-zero and make sure that things as are
you think they are on the customer router.
Often this kind of thing occurs when "ip classless" falls out of a
config due to an upgrade or retrofit or boot accident.
ip classless went from being not-the-default, to the default, then
back to being not the default, but inserted automatically by the
setup script.
People saying "ip classless is now the default" are confused. 8-)
12.0.7S:
earth-angel#show run | inc class
ip classless
earth-angel#conf t
Enter configuration commands, one per line. End with CNTL/Z.
earth-angel(config)#default ip classless
earth-angel#show run | inc class
no ip classless
CEF problems are also possible, but most often observered on the 7500's,
current releases seem to be fairly problem free on the simple routers.
There are also some problems here and there with BGP and other routing
protocols.
1) is it "can't get to" from the perspective of the router or some box
out on their ethernet?
2) are other protocols involved?
3) is there another route for the /24 popping into existance?
Look at the route for the /30, /24 and /19 both as show ip route
and show IP BGP - make sure that're are no surprises as far as
the "best router" and also it's next-hop.
Check to make sure that auto-summary isn't making fun for you...
George
> From cisco-nsp-request@puck.nether.net Fri Oct 13 16:13:32 2000
> Resent-Date: Fri, 13 Oct 2000 16:09:13 -0400
> Received-Date: Fri, 13 Oct 2000 16:07:48 -0400
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> Date: Fri, 13 Oct 2000 16:07:47 -0400 (EDT)
> From: Andy Waltz <andy@one.net>
> X-Sender: aew@chrome.burn.net
> To: cisco-nsp@puck.nether.net
> Subject: [nsp] Weird peering/routing issue
> Resent-From: cisco-nsp@puck.nether.net
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>
> Good day,
>
> We have a customer that is peering with us using a 3640 ios 12.1.1T, our
> router is a 7507 12.0.9S. All the routing shows correctly via BGP. They
> are receiving a /19 (among the rest of the routing table) from us. Out of
> that /19 they have a /30. Basically they cannot get to any other hosts in
> the /24 (that the /30 came from). The rest of the /19 seems to work fine.
> I'm completely stumped. I'm thinking a bug in the 3640's ios, which i
> will be looking into. It is currently patched with a static route but
> obviously that isn't a permenant solution. This strange since the
> connection worked fine up to two days ago. The customer claims there have
> been no changes on their end, and the only thing i can notice that has
> happened is their connection flapped the other night (we reset bgp today
> just to make sure). One of our other customers with the same setup and
> /30 out of the same class C works fine.
>
> Obviously i could break up that aggragate i'm sending to them and send
> them the aggragate and a /24 but i'm not even confident that will work and
> obviously the other peers on that router will have to hear another /24 (as
> if there needs to be more routes in the routing table).
>
> Does anyone have any thoughts as to what might be the root cause of this
> and any possible remidies?
>
>
> Thanks for any assistance you can provide.
>
> andy
>
>
> ----
> Andy Waltz
> Network Administrator
> 513-618-1000 Fax 513-618-2000
> OneNet Communications
> andy@one.net
> ----
>
>
>
>
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