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Cisco AVVID Network Infrastructure Enterprise Quality of Service Design
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Chapter 3 QoS in an AVVID-Enabled Campus Network
Selecting a Distribution-Layer Switch
Step 2
Create classes based on the ACL.
4006-SUPIII-Dist(config)#class-map match-all GOLD-DATA
4006-SUPIII-Dist(config-cmap)#description Mission Critical Traffic
4006-SUPIII-Dist(config-cmap)#match access-group name GOLD-DATA
4006-SUPIII-Dist(config)#class-map match-all VOICE
4006-SUPIII-Dist(config-cmap)#description VoIP Bearer Traffic
4006-SUPIII-Dist(config-cmap)#match access-group name VOICE
4006-SUPIII-Dist(config)#class-map match-all VOICE-CONTROL
4006-SUPIII-Dist(config-cmap)#description VoIP Control Traffic (SCCP, H225, H254, MGCP)
4006-SUPIII-Dist(config-cmap)#match access-group name VOICE-CONTROL
Configuring Service Policy
Create a service policy that uses the classes for admission criteria and sets the appropriate DSCP PHB
label.
Step 1
Create a policy to set the DSCP PHB label/value for the classes.
4006-SUPIII-Dist(config)#policy-map DISTRIBUTION-C4006-UPLINK-IN
4006-SUPIII-Dist(config-pmap)#description Set DSCP PerHopBehavior Label for VOIP Control
and Bearer Traffic
4006-SUPIII-Dist(config-pmap)#class VOICE-CONTROL
4006-SUPIII-Dist(config-pmap-c)#set ip dscp 26
4006-SUPIII-Dist(config-pmap)#class VOICE
4006-SUPIII-Dist(config-pmap-c)#set ip dscp 46
4006-SUPIII-Dist(config-pmap)#class GOLD-DATA
4006-SUPIII-Dist(config-pmap-c)#set ip dscp 18
Step 2
Apply the policy to the physical interface.
4006-SUPIII-Dist(config)#int fa 4/1
4006-SUPIII-Dist(config-if)#service-policy input DISTRIBUTION-C4006-UPLINK-IN
Configuring CoS or DSCP Trust
Additionally, you need to enable the Catalyst 4000 Supervisor III to trust DSCP or CoS depending on
the capabilities of the access-layer switch attached. In this example, port 3/1 is attached to a Layer
3-aware access device and can trust DSCP arriving from it. Ports 3/2 and 3/3 are attached to Layer 2 only
access devices, so the switch needs to trust CoS.
Step 1
Configure trust for DSCP.
4006-SUPIII-Dist(config)#int g 3/1
4006-SUPIII-Dist(config-if)#qos trust dscp
Step 2
Configure trust for CoS.
4006-SUPIII-Dist(config-if)#int g 3/2
4006-SUPIII-Dist(config-if)#qos trust cos
4006-SUPIII-Dist(config-if)#int g 3/3
4006-SUPIII-Dist(config-if)#qos trust cos