FCS errors when using SPAN on Catalyst 3550

[jzwaanswijk]

I've a host connected to int fa 0/24, this is a web server.

This port is the span source.

The SPAN destination is int fa0/9, where a IDS is connected.

Sometimes when the combined traffic rx/tx to the SPAN destination, rise above 70Mbit the source SPAN port is experiencing a lot of FCS errors, and the SPAN destination is experiencing output buffer failures.

Is there someone that has seen this before.

Regards, John Zwaanswijk.

[vkapoor5]

It might be due to bug id "CSCea28611" for 3550 switches. It's saying about the performance issue while transmitting traffic between 2 ports of the 3550-12 or 3550-48 switch.

[jzwaanswijk]

This bug is not the issue with this porblem.

We experiencing the problems at about 70% wire rate.

On port fa 0/24 ~50Mb out and ~20Mb in.

On port fa 0/9 ~70Mb out to IDS.

When the output buffers on port fa0/9 are increasing (which could be normal on high load), the FCS on FA0/24 are also increasing (which is not normal).

Regards, John Zwaanswijk.