[c-nsp] Best practice - Core vs Access Router

Tom Sands tsands at rackspace.com
Mon Feb 15 08:19:37 EST 2010

David Freedman wrote:
> Hash: SHA1
> Andy B. wrote:
>> On Wed, Feb 10, 2010 at 7:48 PM, David Freedman
>> <david.freedman at uk.clara.net> wrote:
>>> So, are you checking your interfaces for incrementing drop/error counters?
>>> Are you seeing any of this when there is the problem occuring?
>>> (clear counters , sh int summ etc..)
>> I am having input drops all the time, no matter how high or low I set
>> the incoming hold-queue.
>> The OSPF and IBGP interfaces approx. 30 minutes after I cleared the counters:
>> TenGigabitEthernet8/1 is up, line protocol is up (connected)
>>   Input queue: 0/2000/622/622 (size/max/drops/flushes); Total output drops: 0
>> TenGigabitEthernet9/1 is up, line protocol is up (connected)
>>   Input queue: 0/4096/1664/1664 (size/max/drops/flushes); Total output drops: 0
>> TenGigabitEthernet9/2 is up, line protocol is up (connected)
>>   Input queue: 0/4096/1916/1916 (size/max/drops/flushes); Total output drops: 0
>> These links are not congested! Te9/1 is the busiest with maybe 6.5 out
>> of 10 Gig. The other two are below 5 Gig.
> Are these supervisor ports or on a card (i.e 6704/6708?)
> Things I would check:
> - - That I understand 6704 has pathetically small per port buffers

The 6704 looks like the biggest problem in this setup.  We avoid them at 
all cost.

> - - Hold queue input appropriate (for punt to MSFC), usually set to 4096
> for these
> - - No IGP hello padding (if you have large MTU and pad then you must punt
> these big things
> - - Check SPD headroom (show ip spd)
> - - The drops are not being reported on input due to lack of transmit
> buffer on output (i.e to lower speed card), check traffic flows/pps to
> low speed interfaces and adjust buffers appropriately
> Dave.

Tom Sands			  				
Chief Network Engineer				

Confidentiality Notice: This e-mail message (including any attached or
embedded documents) is intended for the exclusive and confidential use of the
individual or entity to which this message is addressed, and unless otherwise
expressly indicated, is confidential and privileged information of Rackspace.
Any dissemination, distribution or copying of the enclosed material is prohibited.
If you receive this transmission in error, please notify us immediately by e-mail
at abuse at rackspace.com, and delete the original message.
Your cooperation is appreciated.

More information about the cisco-nsp mailing list