[c-nsp] changing buffer size on 4900M - discards

[Holemans Wim]

We are seeing discards on a newly installed 4900M, probably coming from the fact that most input to the C4900M is coming from routers connected to it on 10G lines and is going out on a 2G etherchannel, although the total load on the 2G channel is just about 250-300 Mb/s. The 2G connection goes to an IPS that will be replaced before the end of the year but until then I have to find a way around the discards.
Based on the fact that the 4900M is normally mentioned as a switch with a good buffer capacity (compared to 37xx switches, see also threads of begin this week), I wonder if  there is a way to change buffer size on the gigabit interfaces so that there will be less discards ? Anyone has a reference to a good document on buffer tuning (on 4900M) ? I know the 'buffers' command exists but for the moment I'm still trying to find out what buffers I should change (and into which values) to get rid of these discards.

Greetings,

Wim Holemans
Netwerkdienst Universiteit Antwerpen
Network Services University of Antwerp