lastSubId or Instance returned with Trap

[Guest_imported]

I am trying to configure my ECS to filter out any matching linkDown and linkUp alerts that occur within 10 minutes.

I found the OID for these two events (both cisco and snmpTraps) but I dont understand where to get the lastSubId or the INST. According to the documentation, the events will look like 1.3.6.1.6.3.1.1.5.3.INST Where do I find this INST or is there some sort of variable that I use?

Thanks,

Carl