That's what Cisco told us also, Dennis. HP Procurve switches behave the same way.
Evan On Thu 11/09/08 11:06 , [email protected] sent: > At the University of British Columbia we have several thousand > switches, mostly Cisco 3750 stacks. > > In my experience with the Cisco switches we have so many interface > discards being reported that we tend to ignore interface discards > whenever and wherever they surface (by setting the "ignore interface > discards" behaviour in Intermapper). The discards happen in all > situations including under extremely light load. For whatever reason > the discards tend to occur mostly on larger switch stacks of 7, 8, or > 9 switches. > > I am sure there are cases where discards happen for legit reasons as > Pedro and Chris say, but in our case we spent a lot of time looking > and couldn't find the reason. It certainly wasn't anything obvious > like QoS, or rate limiting, or VLAN mismatch on an 802.1Q trunk, or > oversized frames (those get reported as real ethernet errors > (giants)), or network congestion (the discards happen under light > load). And when the discards are being reported if we do network > performance testing (iperf, ip sla) we can tell 0 packets are being > dropped in our test streams. Plus no users have ever reported > connectivity issues that correlate to the discards happening. > > I've opened several cases with Cisco about this, and after Cisco > investigated was told that the reason discards were incrementing was > a "cosmetic bug". That is, the discards didn't reflect a lack of > resources in the switches or dropped packets. > > So we really have no choice except to set "ignore interface > discards". I know several other large Intermapper shops that do the > same for the same reason. ____________________________________________________________________ List archives: http://www.mail-archive.com/intermapper-talk%40list.dartware.com/ To unsubscribe: send email to: [email protected]
