I am not sure if this is a OSPF related problem but I recently encountered a
strange problem in my network. I have a WAN link that has been running on
frame relay encapsulation for the past few years without any problems. Just
today, I noticed that I lost connectivity between site A and site B (these
sites are directly connected) .The first thing I did was to do a show int on
both ends. I found both the line protocol and interface to be up. I however,
could not ping the two ends. I couldn't even ping the WAN interface of the
router that I am connected by console to. How is that possible? Should I do
a shut , no shut?
Another interesting thing I discovered on this router (7500) is that when I
ping the WAN IP address of other interfaces, I get a round trip delay. I
always thought that since the IP address is assigned on that router, the
ping should be less than 10ms ??
I run OSPF,BGP and MPLS. FR guys says that there is no problem with the PVC.
I would appreciate any help rendered.
Thanks!
Kevin
wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> I have had similar problems to this with OSPF. Wierd situations where
> adjacencies would drop out or could not form adjacencies, and yet
> everything looked good. In one instance it was a layer2 problem, and in
> the other it had to do with CEF (the feature I have a love/hate
> relationship with).
>
> If your running CEF, it could possibly be doing something here. To me
> however it smells of l2 problems. I assume you checked "sh frame pvc" and
> made sure the counters look ok?
>
> Brian
>
>
> On Thu, 10 May 2001, [EMAIL PROTECTED] wrote:
>
> > Hi all,
> > This isn't directly certification-related, but maybe people can practise
> > their trouble-shooting skills.
> >
> > I have a frame relay link that occasionally drops the OSPF adjacency
across
> > it (average once a day maybe, but it can go several days with no
problems
> > and then get several hits in a day). Apart from the brief disruption,
this
> > causes the ISDN backup to kick in, which is not something I want to
happen
> > unnecessarily since the call is from one side of Australia to the other
:-)
> > Each access supports other PVCs as well, which do not have problems.
> > The PVC does not drop out.
> >
> > I have debug ip ospf events and debug ip ospf adjacency turned on. One
> > side will announce that the other neighbour is dead, and start
rebuilding
> > the adjacency. The side that detects the problem first varies.
> > There are a small number of CRC errors at one end, and some broadcasts
are
> > dropped at the other end, but the numbers are consistent with links
> > throughout the rest of the network which are problem-free.
> > Both routers have had the cables re-seated and have been reloaded.
> > Traffic shaping is in effect and should be preventing traffic from
> > overloading the smaller access rate. There are some FECN/BECN/DE
packets,
> > but again, nothing at unusual levels. I have no reason to believe that
the
> > traffic pattern on this link is different to others in the network.
> >
> > IOS is 11.2. One router is a 7505, the other a 4700M.
> >
> > I assume that hellos are being dropped occassionally (and fairly
randomly)
> > across the link, and that sometimes enough in a row get dropped that the
> > timer expires. The links are monitored via MRTG, and there is some
> > correlation between increased usage and the problem, but there are
plenty
> > of times of higher utilisation with no problems. Very short-term bursty
> > traffic may not show up in MRTG, though.
> >
> > Any tips on what to check/fiddle with next? My thought is to get the
> > carrier to check out the link and see whether they can see any problems
in
> > their cloud. I have no doubt the answer will be 'no', but they may fix
> > something while they're looking :-).
> >
> > Ta,
> > JMcL
> > FAQ, list archives, and subscription info:
> http://www.groupstudy.com/list/cisco.html
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> >
>
>
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> Brian Feeny,CCDP,CCNP+VAS Scarlett Parria
> [EMAIL PROTECTED] [EMAIL PROTECTED]
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