As jonathanjo said in his answer and the comments afterwards, there are no special test traps for testing connectivity. Often, one of the RFC-defined traps (like
warmstart) is used.
However, there is also MIB
188.8.131.52.4.1.8072.9999.9999, named netSnmpPlaypen. It was introduced by the net-SNMP project as a playground environment to introduce traps which only have meaning within your own network.
You could consider picking an OID within that MIB and using that to test if SNMP traps are working. However, two things are required then:
- your network device needs to be able to send SNMP traps with a customized OID
- your SNMP trap handler has to be configured to properly handle these customized traps
Since it's often hard to arrange these two things, one of the RFC-defined traps (like the ones jonathanjo mentioned) is commonly used.