Catalyst 295048 G Big Buffer Misses

cumiskeyp · ‎02-20-2007

We have a Cisco Catalyst 295048 G switch that shows a high number (2192) of Big Buffer Misses for today. This trend has occured for at least the last month.

I've read that large numbers of buffer misses can often be corrected by adjusting the Permanent or Min-Free parameters for the particular buffer size.

I'm curious to know if this is an exceptionally high number of misses, as the other buffers show 0 or less than 10 misses.

Tsasbrink · ‎02-21-2007

Buffer misses indicate that the switch has no memory block of the appropiate size available to store the incomming packet.

The question witch gets raised is what causes the in memory blocks witch are in use not to be emptied ?

I would suggest you take a look at the way the misses build up, do they come graduatly or a lot at a time.

If they come in large quantity's at a time buffer tuning will have virtualy no effect.

If the come all in a short period of time i expect some large packets to be directed to software functions of the switch managament.

To determine if this is a high number you should compare it to the total packet troughput of this switch. This number alone does not tell me mutch.

I hope this helps.