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how do i tell why my 36xx router are dropping UDP (SNMP) packets?

I have two 3640's and one 3660 on 100mb ports of a cat 6509. On another 100mb port (and VLAN) on the 6509 I have a pc doing ICMP pings and UDP SNMP queries to, and through, the 36xx routers. The routers are occasionally failing to respond. Even when the queries are to the routers (not just through). I cant see why they are dropping these packets.

The switch ports show zero errors.

CPU utilization is 0% on the 3660 and the 3640s are at 9-10%

They all have over 2mb of free i/o memory.

Show interfaces does not show any increase in drops or no buffers and no errors at all.

Show buffers has some misses and failures from the past but they do not go up as the packets are dropped.

Show snmp shows that the gets are received and an equal number of responses are sent indicating that the problem is in outputing the responses.

I cant think of anything else to check to see where these packets are disappearing to. Can anyone help?


Re: how do i tell why my 36xx router are dropping UDP (SNMP) pac

Use the debug ip snmp, if possible due to performance issues.

Put a sniffer on the ports to see what if anything hits the routers and if they reply.

Use snmp-server view Commands to cut the load on the routers.

Hope that helps.


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