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Configuring Rate Limits on SONET/SDH OC48/STM16 IQE PICs


You can rate-limit all queues on SONET/SDH OC48/STM16 IQE PICs. However, overall you can have only 256 distinct policed rates. Without this limiting, traffic in higher-priority queues can block the transmission of lower-priority packets. If you do not rate-limit queues, higher-priority traffic is always sent before lower-priority traffic, causing the lower-priority queues to “starve,” which in turn leads to timeouts and unnecessary resending of packets.

On the SONET/SDH OC48/STM16 IQE PICs, you can rate-limit queues before the packets are queued for output (analogous to policing). All packets exceeding the configured rate limit are dropped, so care is required when establishing this limit. The rate-limit can be configured on the non strict-high queues also.


When the queue transmission rates are oversubscribed, the rate-limit option configured on any of the queues uses the configured rate limit values, although the transmission rates are oversubscribed.

To rate-limit queues, include the transmit-rate statement with the rate-limit option at the [edit class-of-service schedulers scheduler-name] hierarchy level: