The show policy-map interface command output is showing too many random drops for the mission-critical traffic class. What can be changed to reduce the random drops?

A.
Increase the WRED max-threshold value for the mission-critical traffic class.

B.
Increase the WRED min-threshold value for the mission-critical traffic class.

C.
Decrease the WRED drop probability denominator for the mission-critical traffic class.

D.
Decrease the queue-limit for the mission-critical traffic class.

E.
Enable fair-queue within the mission-critical traffic class.

Explanation:

Weighted Fair Queuing (WFQ) is a dynamic process that divides bandwidth among queues based on weights. The process is designed to be fair, such that WFQ ensures that all traffic is treated fairly, with regard to its weight.

There are several forms of WFQ, including Class-based Weighted Fair Queuing (CBWFQ) and Low Latency Queuing (LLQ).

CBWFQ is probably the form of WFQ that is most commonly being deployed these days. CBWFQ works quite a bit like CQ, but the algorithm is more efficient and the configuration is quite a bit easier to understand. With CBWFQ, classes are created and traffic is assigned to those classes, as explained earlier in this chapter. Bandwidth is then assigned to those classes, and the amount of bandwidth assigned to a given class determines the amount of scheduling that class receives. In other words, the bandwidth statement on a given class determines the minimum amount of bandwidth that packets belonging to that class receive in the event of congestion. In the recent past, a PQ was added to the CBWFQ mechanism, specifically to handle VoIP traffic. This addition was necessary because, although CBWFQ did an excellent job of dividing up the available bandwidth, CBWFQ did not give any specific regard to the delay or jitter being introduced by queuing packets.

The LLQ mechanism is CBWFQ with a single PQ, which receives strict scheduling priority. To go back to airline analogies, this is the equivalent of preboarding courtesies that are often offered to persons with special needs or those traveling with small children. In spite of the fact that these people may not be in first class, or elite frequent fliers, they are moved directly to the front of the line and put on the plane first because they have special needs. In the case of VoIP traffic, it may not be the most important traffic on your network, but it has very specific requirements for delay and jitter and, therefore, must be moved to the front of the line for transmission. Catalyst switches use classification to appropriate queuing frames for transmission. Although Catalyst switches only support the Cisco IOS features WFQ, CBWFQ, and LLQ on WAN interfaces, Ethernet interfaces use similar forms of queuing but vary in configuration and behavior.