Total Output Drops on 7606 Gig interface when flow control in on.

amitmarathe · ‎06-18-2009

on gig interface(200 mbps)we have turned flow control on. We observed Pause input frame and total output drops are increasing rapidly. When flow control is off we were not observing there issues. Kindly suggest is it possible queue pause input frames in the interface buffer. Appreciate quick reply.

Giuseppe Larosa · ‎06-18-2009

Hello Amit,

the 7606 port on receiving the pause frames has to hold frames that otherwise it would send on wire.

There are chances that given the bursty nature of traffic the output queue(s) are overwhelmed causing output drops.

When flow control is off the port doesn't care of input pause frames if received and frames are sent on wire but this can mean that it is the receiving side that will be overwhelmed in this case.

see

http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.2SX/configuration/guide/intrface.html#wp1041210

Hope to help

Giuseppe

amitmarathe · ‎06-18-2009

Thanks for the reply this will help us to convince customer there is no issue with router. Our issue will sort out.