The queue-depth command configures the buffer size of the queues.
The undo queue-depth command restores the buffer size of the queues to the default value.
The default queue buffer size is 1000 Kbytes in flow-wred view, and the default queue buffer size is 8000 Kbytes in port-wred view.
Usage Scenario
When traffic is congested, packets accumulate in the buffer and wait to be forwarded. The delay greatly prolongs. The interval from the time when a packet enters the buffer to the time when the packet is forwarded is called the buffer delay or queue delay.
The buffer delay is determined by the buffer size for a queue and the output bandwidth allocated to the queue. The format is as follows: Buffer Size for a Queue(bytes) = Traffic shaping rate(bit/s)x maximum delay that is allowed(s)/8 High-priority services require that the delay be shorter than 10 ms, and Low-priority services require that the delay be shorter than or equal to 100 ms. Therefore, setting the buffer size to a value (10 ms x traffic shaping rate(bit/s)/8) is recommended for high-priority queues(CS7, CS6, and EF); setting the buffer size to a value (100 ms x traffic shaping rate(bit/s)/8) is recommended for low-priority queues.Configuration Impact
When traffic congestion occurs, adjusting the queue's buffer size affects the traffic latency.
The depth of a queue is determined by the packet traffic volume, packet size, and packet transmission delay.Precautions
When no flow-WRED profile is configured, queues on boards or subcards of different types have different default buffer sizes.
When no port-WRED profile is configured, queues on boards or subcards of different types have different default buffer sizes. Changing the buffer size of a queue affects the traffic transmission delay. The effective buffer size of a queue is different from its default one. You can obtain the effective buffer size through the current queue-length field in the display port-queue configuration command output. To obtain the default buffer size of a queue on a board or subcard, contact Huawei technical support.<HUAWEI> system-view [~HUAWEI] flow-wred test [*HUAWEI-flow-wred-test] queue-depth 100
<HUAWEI> system-view [~HUAWEI] port-wred pw [*HUAWEI-port-wred-pw] queue-depth 2048