Hi Colin,
On 01/29/15 08:19, Colin Stubbs wrote:
Hi Richard
You're right, 2960C's are L2 only; and my understanding is the same in that they shouldn't be doing CEF at all.
That said they're a similar hardware flavour to 2960S/3560X/3750X hardware, which can have L3 features enabled, so the software release in use probably has CEF code riddled right the way thru it.
What happens when you attempt to run CEF related commands on the CLI, e.g.
- show cef background
This command isn't available.
- show platform ip unicast cef-idb
This command returns immediately with no output.
e.g. are they available, do they return anything, does the CPU spike with the CLI commands too?
Nope, no CPU spike.
The other obvious questions:
- Which IOS version are you running?
We've now tested on 12.2(55)EX, 15.0(2)SE7, and 15.2(1)E3. All have the same problem. I can use snmpbulkwalk to query CISCO-CEF-MIB::cefFIBSummaryEntry and the SNMP ENGINE process CPU use jumps to over 80%, and stays there for 20 to 50 seconds.
- Is it the latest stable/recommended release?
15.0(2)SE7 is.
-Colin
Hopefully this info will be useful to other Observium users. It's definitely a Cisco problem, not an Observium problem. As long as we remember to disable cisco-cef when installing a 2960C everything is fine.
- Richard