350-001 Cisco Certified Internetworking Expert Exam Actual Test

Demo Question 16.

Answer: A

Explanation: WRR allows bandwidth sharing at the egress port. This command defines the bandwidths for egress WRR through scheduling weights. Four queues participate in the WRR unless you enable the egress expedite queue. The expedite queue is a strict-priority queue that is used until it is empty before using one of the WRR queues. There is no order of dependencies for the wrr-queue bandwidth command. If you enable the egress priority, the weight ratio is calculated with the first three parameters; otherwise, all four parameters are used. The WRR weights are used to partition the bandwidth between the queues in the event all queues are nonempty. For example, entering weights of 1:3 means that one queue gets 25 percent of the bandwidth and the other queue gets 75 percent as long as both queues have data. Entering weights of 1:3 do not necessarily lead to the same results as entering weights at 10:30. Weights at 10:30 mean that more data is serviced from each queue and the latency of packets being serviced from the other queue goes up. You should set the weights so that at least one packet (maximum size) can be serviced from the lower priority queue at a time. For the higher priority queue, set the weights so that multiple packets are serviced at any one time. To map CoS values to drop thresholds for a queue, use the wrr-queue cos-map command. Use the no form of this command to return to the default settings. wrr-queue cos-map queue-id threshold-id cos-1 ... cos-n no wrr-queue cos-map Syntax Description queue-id Queue number; the valid value is 1. threshold-id Threshold ID; valid values are from 1 to 4. cos-1 ... cos-n CoS value; valid values are from 0 to 7. Defaults The defaults are as follows: Receive queue1/drop threshold 1 and transmit queue1/drop threshold 1:CoS 0 and 1. Receive queue1/drop threshold 2 and transmit queue1/drop threshold 2:CoS 2 and 3. Receive queue2/drop threshold 3 and transmit queue2/drop threshold 1:CoS 4 and 6. Receive queue2/drop threshold 4 and transmit queue2/drop threshold 2:CoS 7.