Cisco Certification Exam Review:

Class-Based Weighted Fair Queueing (CBWFQ)

By Chris Bryant, CCIE #12933

Steps To Configuring Class-Based Weighted Fair Queueing:

1. Define the traffic to be queued with access-lists.

R1(config)#access-list 120 permit tcp 172.10.10.0 0.0.0.255 any
R1(config)#access-list 130 permit tcp 172.20.20.0 0.0.0.255 any eq ftp

2. Create the class maps.

R1(config)#class-map TCP_TRAFFIC
R1(config-cmap)#match access-group 120
R1(config-cmap)#class-map FTP_TRAFFIC
R1(config-cmap)#match access-group 130

3. Create the policy map.

R1(config-cmap)#policy-map TRAFFIC_POLICY
R1(config-pmap)#class TCP_TRAFFIC
R1(config-pmap-c)#bandwidth ?
<8-2000000> Kilo Bits per second
percent % of Available Bandwidth

R1(config-pmap-c)#bandwidth 400
R1(config-pmap-c)#queue-limit 50
R1(config-pmap-c)#class FTP_TRAFFIC
R1(config-pmap-c)#bandwidth 200
R1(config-pmap-c)#queue-limit 25

4. Verify the policy map with show policy-map.

R1#show policy-map
Policy Map TRAFFIC_POLICY
Weighted Fair Queueing
Class TCP_TRAFFIC
Bandwidth 400 (kbps) Max Threshold 50 (packets)
Class FTP_TRAFFIC
Bandwidth 200 (kbps) Max Threshold 25 (packets)

5. Apply the policy to the interface with service output.

R1(config)#int serial0
R1(config-if)#service ?
input Assign policy-map to the input of an interface
output Assign policy-map to the output of an interface

R1(config-if)#service output TRAFFIC_POLICY
Must remove fair-queue configuration first.
R1(config-if)#no fair-queue
R1(config-if)#service output TRAFFIC_POLICY

6. Adjust the reservable bandwidth as needed with max-reserved-bandwidth.

R1(config-if)#max-reserved-bandwidth ?
<1-100> Max. reservable bandwidth as % of interface bandwidth
<cr>

R1(config-if)#max-reserved-bandwidth 90

To your success,

Chris Bryant

CCIE #12933

chris@thebryantadvantage.com