SnmpExtensionTrap has a size limit?

Question

I am working on a problem in SNMP extension agent in windows, which is passing traps to snmp.exe via SnmpExtensionTrap callback.

We added a couple of fields to the agent recently, and I am starting to see that some traps are getting lost. When I intercept the call in debugger and reduce the length of some strings, the same traps, that would have been lost, will go through.

I cannot seem to find any references to size limit or anything on the data passed via SnmpExtensionTrap. Does anyone know of one?

Answer 1

I would expect the trap size to be limited by the UDP packet size, since SNMP runs over the datagram-oriented UDP protocol.

The maximum size of a UDP packet is 64Kb but you'll have to take into account the SNMP overhead plus any limitations of the transport you're running over (e.g. ethernet).