Strange intermodule SNMP communication on Cat6500

p.hruby · ‎03-01-2013

I'm trying to search for cause of CPU load on our Cat6500 (VSS) switch.

I've discovered strange SNMP communication from 127.0.0.11 (ASA-SM is in slot1, switch 1) to 127.0.0.51 (Sup720 is in slot 5)

This communication occurs each minute and lasts cca 7seconds. During this session ASA(?) reads state of all interfaces on Cat6500 and when finds out that interface is up, it reads several interface parameters (bytes in/out, etc). SNMP community string in packets is set to value which is not configured on Cat6500.

This communication causes 20% one minute CPU utilization.

There are periods during the day when one minute CPU util. is on cca 13% and there is no such SNMP communication. (see 2day CPU load picture attached)

Can anyone explain me cause or purpose of this behaviour?

Thanks

Petr

p.hruby · ‎03-15-2013

SNMP communication was caused by NAM3 module in slot1, switch2. This NAM module use the same address 127.0.0.11 for intra-module communication as ASA in slot1, swich1.

Petr