Does Junos OS impose any rate limiting on SNMP trap generation?
Junos OS implements a trap-queuing mechanism to limit the number of traps that are generated and sent.
If a trap delivery fails, the trap is added back to the queue, and the delivery attempt counter and the next delivery attempt timer for the queue are reset. Subsequent attempts occur at progressive intervals of 1, 2, 4, and 8 minutes. The maximum delay between the attempts is 8 minutes, and the maximum number of attempts is 10. After 10 unsuccessful attempts, the destination queue and all traps in the queue are deleted.
Junos OS also has a throttle threshold mechanism to control the number of traps sent (default 500 traps) during a particular throttle interval (default 5 seconds). This helps ensure consistency in trap traffic, especially when a large number of traps are generated due to interface status changes.
The throttle interval begins when the first trap arrives at the throttle. All traps within the throttle threshold value are processed, and traps exceeding the threshold value are queued. The maximum size of all trap queues (the throttle queue and the destination queue) is 40,000 traps. The maximum size of any one queue is 20,000 traps. When a trap is added to the throttle queue, or if the throttle queue has exceeded the maximum size, the trap is moved to the top of the destination queue. Further attempts to send the trap from the destination queue are stopped for a 30-second period, after which the destination queue restarts sending the traps.
NOTE: For the Juniper Networks EX Series Ethernet Switch, the maximum size of all trap queues (the throttle queue and the destination queue) is 1,000 traps. The maximum size for any one queue on the EX Series is 500 traps.
For more information, click SNMP MIBs and Traps.