3750 packet loss passthrough

[CobbyJ]

Hello,

We have a 3750 stack and an ip on it when we MTR to that ip we dont see any packet loss but once we get past that to a server for example connected directly to that 3750 we are seing packet loss of around 10% on the 3750.

There are no CRC errors and CPU is fine and tried with multple servers and so on as soon as it passes through the 3750 we see the loss on it which is very strange

Any ideas or has anyone else seen this?

[gilberto_cardenas]

- Take simultaneos packet capture at ingress/egress of the 3750X, and compare.

- In case is confirmed the packet loss worth to take a look into CPU proccessing, you can run the command show proc cpu history, just to take a look into current switch proccessing.

[Joseph W. Doherty]

The 3750 buffer allocations (especially using defaults) often drop packets. (NB: even "optimal" buffer configuration can be insufficient as 3750 doesn't have a lot of physical RAM for this purpose. [The switch is more oriented for edge user hosts usage, not for sever hosts.]) Possibly that's what's happening to you.

(As an example, I had a couple 3750 server ports showing multiple drops per seconds, but after buffer configuration changes, it was reduced to several drops per day.)