The best collection performance is achieved if the SNMP manager keeps the SNMP input queue of the SR OS router filled, but without overflowing it. If maximum performance is required, then the SNMP manager should always have at least two outstanding requests toward the SR OS router: one request that the SR OS router is currently processing (but to which it has not replied yet), and one request that is waiting in the SNMP input queue of the SR OS router.
When the 7750 SR replies to the request, it immediately processes the next request if one is waiting in the input queue.
When the SNMP manager receives the reply, it immediately sends another request to the 7750 SR SNMP input queue.
If the round trip time (RTT) between the SNMP manager and the 7750 SR is significant, the SNMP manager may need to have more than two outstanding requests to maximize collection performance.
The SNMP manager must also avoid sending too many requests at a high rate without waiting for responses. A large number of outstanding requests can cause a backup in the SNMP input queue in SR OS. A backup can cause a long delay in response to the last item in the queue and a timeout on the SNMP manager. It can also cause discards at the SNMP input queue inSR OS.