[c-nsp] HighQueueDropRate ?

[Oliver Boehmer (oboehmer)]

If you suffer from input queue drops due to a high amount of BGP
traffic, you might want to consider increasing the TCP MSS by enabling
PMTUD on your iBGP peers ("ip tcp path-mtu-discovery", requires a
session reset to take effect), and increase the input hold-queue (1000
is a common value) if the PMTUD alone didn't help. 

	oli

Gregori Parker <> wrote on Tuesday, August 07, 2007 7:45 PM:

> Thanks for the reply - I did find that same information before
> posting, it just didn't help me arrive at any conclusions.
> 
> I took your advice however and ran the outputs of 'sh int' and 'sh
> buffers' thru CCO's OI...this led me to the following guide:
>
http://www.cisco.com/en/US/customer/products/hw/routers/ps133/products_t
> ech_note09186a0080094791.shtml#topic3
> 
> I was able to eliminate proc, mem and switching as potential issues -
> and it appears that I'm down to traffic destined for the router itself
> as the most likely culprit.  This router does act as a BGP neighbor at
> the edge of my network, so I believe it may have something to do with
> iBGP routing updates (this is an inside interface reporting the
> issue). This is further evidenced by being able to reproduce the
> alert by simulating an external link failure.  I'm continuing to
> investigate, but thought I'd add this information in hopes that it
> may spark some thoughts on the matter.  I'll know more the next time
> I'm able to catch it in the act :)
> 
> 
> 
> -----Original Message-----
> From: Oliver Boehmer (oboehmer) [mailto:oboehmer at cisco.com]
> Sent: Monday, August 06, 2007 11:32 PM
> To: Gregori Parker; NSP List
> Subject: RE: [c-nsp] HighQueueDropRate ?
> 
> Gregori Parker <> wrote on Monday, August 06, 2007 9:51 PM:
> 
>> I have CiscoWorks DFM complaining to me about HighQueueDropRate on
>> the inside interface of one of my edge routers (7200)...the alert
>> comes pretty infrequently (once a week or so), and I'm unable to
>> find much information about what exactly it means.  Has anyone run
>> into this alert or have some insight on this?
> 
> google brings up
> 
>
http://www.cisco.com/en/US/docs/net_mgmt/ciscoworks_device_fault_manager
> /2.0_IDU_2.0.3/user/guide/Events.html
> 
> HighQueueDropRate
> 
> Description: Number of packets discarded due to input or output queue
> overflow exceeding the Queue drop threshold. The input (or output)
> queue overflow is derived by dividing the number of packets
> designated to be sent (or received) that were discarded due to queue
> overflow, by the total number of packets in the queue.
> 
> Trigger: Exceeded Queue drop threshold.
> Severity: Critical.
> Device Type: All.
> Event Code: 1012.
> 
> Take a look at "show int" of the corresponding interface via CLI and
> go from there.. CCO's Output Interpreter can help you diagnose the
> issue.. 
> 
> 	oli
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