High "OutDiscards" on Cisco 6500 Series Switch

[inayathulla1]

Hi,

We are getting high outdiscards on gig interface of cisco6500 series switch.There is no much traffic passing through this interfaces.

version on siwthc;

WS-C6513 Software, Version NmpSW: 8.5(5)

cat6000-sup2k8.8-5-5.bin

[Prashanth Krishnappa]

What type of gig card is it? Probably you are seeing bursts of traffic which are filling up the buffers.

[paramvsi]

Hi,

The basic reason for seeing Out-Discard is that the number of outbound packets chosen to be discarded even though no packet errors have been detected due to a low or no buffer space available on the line cards. This could be caused due to some bursty traffic. Are there any servers that are used at the same time for a same function, like databcckup on a server farm or any such application. One of the suggestions would be using alternate ports on the line card di distrubute traffic processing on different ASIC's which will help us laod balance the traffic and better utilize the buffers. Also you can try using the command " set option flowcontrol enable" and this too should help you in this issue.

Hope this helps !!

Regards,

Param

[inayathulla1]

Hello Param

yes, I think we have bursty traffic here !!

yesterday I have checked on one of their Switches.

I did the following steps:

- clear counters

- after the counters were cleared, i saw no drops for 11 minutes (no 'ifOutDiscards')

- then, there were 439 drops within 30 seconds !!

that looks for me like a traffic peak.

traffic increased by 500% during the droptime:

-----------------traffic during there were no drops-------------------

Sw1#sh int g1/1 | include rate

Queueing strategy: fifo

30 second input rate 120903000 bits/sec, 21230 packets/sec

30 second output rate 111386000 bits/sec, 19406 packets/sec --> ca. 110 Mbit/s

-----------------------------------------------------------------

This is the average load, based on 30 seconds timeframe.

I think we have peak-times when the buffer was not able to handle all frames

Do you have an idea how to temporarily increase the size of the outbound buffers on a Cisco 6500 ?

Best regards,

Inayath

[paramvsi]

Hi Inayath,

Please let me know if you have executed the command "set option flowcontrol enable", as this should help youn in such situations wherein the controller ASIC will allow buffering simultaneously along with the edge ASIC.

Please let me know the staus if this command helped you.

Regards,

Para.