Cisco IOS Cookbook, 2nd Edition

Using Class-Based Weighted Fair Queuing

Problem

You want to use Class-Based Weighted Fair Queuing on an interface.

Solution

There are three steps to configuring Class-Based Weighted Fair Queuing (CBWFQ) on a router. First, you have to create one or more class maps that describe the traffic types. Then you create a policy map that tells the router what to do with these traffic types. Finally, you need to attach this policy map to one or more of the router’s interfaces:

Router#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#class-map highprec
Router(config-cmap)#description Highest priority Prec=5
Router(config-cmap)#match ip precedence 5
Router(config-cmap)#exit
Router(config)#class-map medhiprec
Router(config-cmap)#description Medium-high priority Prec=4
Router(config-cmap)#match ip precedence 4
Router(config-cmap)#exit
Router(config)#class-map medloprec
Router(config-cmap)#description Medium-low priority Prec=2,3
Router(config-cmap)#match ip precedence 2 3
Router(config-cmap)#exit
Router(config)#policy-map cbwfqpolicy
Router(config-pmap)#class highprec
Router(config-pmap-c)#bandwidth percent 25
Router(config-pmap-c)#exit
Router(config-pmap)#class medhiprec
Router(config-pmap-c)#bandwidth percent 25
Router(config-pmap-c)#exit
Router(config-pmap)#class medloprec
Router(config-pmap-c)#bandwidth percent 25
Router(config-pmap-c)#exit
Router(config-pmap)#class class-default
Router(config-pmap-c)#fair-queue 512
Router(config-pmap-c)#queue-limit ...