[c-nsp] Cisco 7206VXR OSPF

[Ben Steele]

Going by the fact you see nothing obvious in the logs on the routers I  
was just curious to see whether it may be something on the switch like  
someone randomly plugging in a cable or interface that is causing a  
brief SPT loop or other various layer 2 issue, nothing in the switch  
logs I assume that correlates with the times?

On 13/03/2008, at 2:01 PM, Jason Berenson wrote:

> Ben,
>
> We have 3 7206's used as edge routers.  PA-MC-T3 in from our DAX and  
> ethernet out to our transport.  So there are a few adjacencies along  
> with iBGP and eBGP.  It seems like the router that goes down (flaps  
> OSPF/BGP instance 1) is the only one that takes a hit out of all of  
> them connected to the switches.
>
> I'm leaning away from thinking this is an ethernet issue, but I  
> definitely could be wrong.  Are there any helpful outputs I could  
> include?
>
> Thanks,
> Jason
>
> Ben Steele wrote:
>> Are any other hosts affected off the switch during this period  
>> aswell?
>>
>> Ben
>> On 13/03/2008, at 8:05 AM, Jason Berenson wrote:
>>
>>> Rodney,
>>>
>>> They connect back to a cisco switch.  No errors anywhere along the
>>> ethernet and no packet loss.  It also only flapped 3 times  
>>> yesterday and
>>> 2 times 5 days ago, so it's not a constant flap.
>>>
>>> It hasn't flapped yet today, so I'll turn on debugging and setup a  
>>> snoop
>>> and write back when I have something.  About the debugging - will
>>> turning on the commands suggested (ospf event or ospf adj)  have an
>>> averse affect on the routers performance?
>>>
>>> Thanks,
>>> Jason
>>>
>>> Rodney Dunn wrote:
>>>> What is the physical topology?
>>>>
>>>> Is it back to back ethernet?
>>>>
>>>> On Wed, Mar 12, 2008 at 11:37:42AM -0400, Jason Berenson wrote:
>>>>
>>>>> Joe,
>>>>>
>>>>> I checked the neighbors too.  I do see the session flap there  
>>>>> but again,
>>>>> no errors on the ethernet and nothing really obvious as to why it
>>>>> flapped.  This just started in the past few days.  I do see some  
>>>>> CPU
>>>>> spikes to 100% but it doesn't correlate exactly to when the flap  
>>>>> occurred.
>>>>>
>>>>> -Jason
>>>>>
>>>>> Joe Freeman wrote:
>>>>>
>>>>>> If OSPF is flapping, you should see it on the neighbor attached  
>>>>>> to
>>>>>> that interface as well, so you might look there for issues.
>>>>>>
>>>>>> Joe
>>>>>>
>>>>>> On 3/12/08, *Jason Berenson* <jason at pins.net <mailto:jason at pins.net 
>>>>>> >>
>>>>>> wrote:
>>>>>>
>>>>>>  Rodney,
>>>>>>
>>>>>>  The interface is clean.  No errors/drops at all.  I think I'll  
>>>>>> have to
>>>>>>  snoop that segment like you suggested and wait for it to flap  
>>>>>> again.
>>>>>>
>>>>>>  Thanks,
>>>>>>
>>>>>>  Jason
>>>>>>
>>>>>>
>>>>>>  Rodney Dunn wrote:
>>>>>>> Look for intput drops on the 'sh int'.
>>>>>>>
>>>>>>> If you don't see any you probably need a sniffer trace on the
>>>>>>> ethernet segment.
>>>>>>>
>>>>>>> On Tue, Mar 11, 2008 at 03:53:30PM -0400, Jason Berenson wrote:
>>>>>>>
>>>>>>>> Greetings,
>>>>>>>>
>>>>>>>> We have a few 7206's running OSPF/BGP for routing.  All of the
>>>>>>  routers
>>>>>>>> are fine except for one - I noticed a few times in the past
>>>>>>  week where
>>>>>>>> OSPF/BGP flapped and came back right away.
>>>>>>>>
>>>>>>>> I checked CPU and noticed it peaked in the past hour but that
>>>>>>  doesn't
>>>>>>>> really correlate to the time the routing sessions flapped.  I  
>>>>>>>> also
>>>>>>>> didn't see the ethernet connection go down and I don't see any
>>>>>>  errors on
>>>>>>>> either side of the ethernet.
>>>>>>>>
>>>>>>>> If there are any outputs anyone would expect please let me know
>>>>>>  and I'll
>>>>>>>> promptly reply.  This is the first time I'm faced with a
>>>>>>  problem like
>>>>>>>> this so I'm not really sure where to look other then the things
>>>>>>  I've
>>>>>>>> already tried.
>>>>>>>>
>>>>>>>> Much thanks in advance,
>>>>>>>> Jason Berenson
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