IMC SNMP issues

[pattap]

I've received a few complaints about SNMP not being able to communicate with Nortel CS1000E.

Now, the device is fully discovered and added in IMC, customer claims that it has gone down and it's been missed
by IMC. They started digging into it and noticed that they are not able to test SNMP for devices in question, see the below

Like I said above the device is added to IMC using auto discovery so it seems that IMC is able to communicate with it in certain cases but not when testing SNMP. I'm just not sure why it is failing the test.

[LindsayHill]

Since it's plaintext SNMP, I would start by capturing SNMP packets between IMC & the device when you're running that test. Check what it's sending, and what (if anything) the device is responding with. 

[pattap]

Just did that last night, it seems snmp requests are hitting the device but for some reason Nortel won't respond with anything.

Then we generated test SNMP traps from the Nortel kit and that finds IMC no problems

[NeilR]

Traps are a separate configuration on the device side. Check and make sure that the Notel will accept snmp from the address/subnet IMC is using. 

[pattap]

The thing is you can discover these Nortel hosts with IMC no problem - using auto discovery feature. In this case I'd assume Nortel does accept SNMP from IMC.

Also from wireshark capture I can see IMC talking to Nortel, it's only when trying to use that TEST feature it wouldn't work.

It doesn't seem to be affecting the way IMC monitors those hosts, apart from CPU not being monitored properly but that different story I believe - MIB missing etc

[pattap]

I have also went through nortel documentation and if I understand it correctly snmp v1 is used for traps and v2 for something else - weird

can you actually set IMC to work that way - listen for traps with snmp v1 and monitoring with v2 for the same device?

this is directly from the document

Trap – a one-way notification sent from the SNMP agent on a device to

the Network Management System (NMS) when a specific condition occurs,

such as the failure of a system component. In Nortel Communication

Server 1000 products, the traps are sent in the form of a SNMP V1

TRAP-TYPE Protocol Data Unit (PDU). The PDU type is TRAP-V1, and

the trap type is Enterprise-Specific.