
136 Chapter 6: Per-Hop Behavior: Congestion Avoidance and Packet Drop Policy
network and hence, it doesn’t want to randomly drop any of its critical application traffic,
although tail drop can be applied at the queue’s maximum threshold.
Listing 6-3 excludes the critical UDP-based application traffic before applying WRED on
the router’s interface.
As shown in Listing 6-3, you first define a noncritical traffic class that includes all traffic
except the critical UDP traffic. Next, use an access-list 101 command (not shown in Listing
6-3) to match all traffic, except the critical UDP application traffic. Follow this with the
match access-group 101 command, ...