From: Mike O (mikeeo@email.msn.com)
Date: Wed Oct 05 2005 - 20:38:53 GMT-3
Well I think the flapping link was causing OSPF to re-calaculate and I
checked the log again and it looks like it was flapping every 5 seconds. I
also should mentioned this network has about 180,000 nodes.
----- Original Message -----
From: "Andrew Lissitz (alissitz)" <alissitz@cisco.com>
To: "Mike O" <mikeeo@msn.com>; <mandingo2073@yahoo.com>
Cc: <ccielab@groupstudy.com>
Sent: Wednesday, October 05, 2005 4:30 PM
Subject: RE: OSPF routing loop
> Hello,
>
> Multicast would have problems if the Unicast table is not right. RPFs
> etc... Incoming and outgoing interface problems...
>
> The reason I asked about redist is because OSPF, by itself, is pretty
> good about keeping loops from occurring. If you saw packets expiring
> and looping, then I would check your routing sources. Loops occur when
> routing data is not consistent / correct and up to date.
>
> The devices that bounced the packets around thought they had the correct
> route for the destinations. Why and where did they learn their routing
> information....
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Mike O
> Sent: Wednesday, October 05, 2005 3:38 PM
> To: mandingo2073@yahoo.com
> Cc: ccielab@groupstudy.com
> Subject: Re: OSPF routing loop
>
> Well we run mulitcast and it reported a unicast routing loop and when
> you did a traceroute it kept bouncing back till the TTL expired.
>
>
>>From: Carl Willias <mandingo2073@yahoo.com>
>>Reply-To: Carl Willias <mandingo2073@yahoo.com>
>>To: Mike O <mikeeo@msn.com>, alissitz@cisco.com, ccielab@groupstudy.com
>>Subject: Re: OSPF routing loop
>>Date: Wed, 5 Oct 2005 12:29:21 -0700 (PDT)
>>
>>Why do you think it was a routing loop? I have seen issues with a
> flood of
>>LSA's causing high CPU utilization on routers causing it to drop
> packets,
>>routing and otherwise.
>>
>>----- Original Message ----
>>From: Mike O <mikeeo@msn.com>
>>To: alissitz@cisco.com; ccielab@groupstudy.com
>>Sent: Wednesday, October 05, 2005 1:59:30 PM
>>Subject: RE: OSPF routing loop
>>
>>
>>Yes we redistbute OSPF into BGP for iBGP.
>>
>>We also use the command "timers throttle spf 400 400 4000" and I think
> it
>>was trying to flood out LSA's while the link was flapping and caused a
> loop
>>in the Area
>>
>>
>> >From: "Andrew Lissitz (alissitz)" <alissitz@cisco.com>
>> >Reply-To: "Andrew Lissitz (alissitz)" <alissitz@cisco.com>
>> >To: "Mike O" <mikeeo@msn.com>, <ccielab@groupstudy.com>
>> >Subject: RE: OSPF routing loop
>> >Date: Wed, 5 Oct 2005 14:34:22 -0400
>> >
>> >Mike, are you all performing any redistribution?
>> >
>> >
>> >-----Original Message-----
>> >From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> Of
>> >Mike O
>> >Sent: Wednesday, October 05, 2005 12:09 PM
>> >To: ccielab@groupstudy.com
>> >Subject: OSPF routing loop
>> >
>> >Can a rapidly flapping interface cause a routing loop with OSPF?
>> >yesterday we had an interface bounce every 90 seconds and caused a
>> >routing loop within the network until we shut it down. Shouldn't the
>> >hold-down timers prevent this?
>> >
>> >
>> >Thanks,
>> >
>> >Mike
>> >
>>
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