If a pending inform packet receives the response
packet and its request-id is equal to pending
packet's, this pending packet is discarded at
once. otherwise, it will try to retransmit the
Inform packet after snmpTargetAddrTimeout[RFC3413],
repeat this operation snmpTargetAddrRetryCount
[RFC3413] numbers if a response is not received
for a generated message. After this, this pending
packet will be discarded.