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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 an Access-Layer Switch
Step 4
Apply the policy to a physical interface.
4006-SUPIII-Access(config)#int fa 4/1
4006-SUPIII-Access(config-if)#service-policy input ACCESS-C4006-LAN-EDGE-IN
Configuring Access-Layer Phone Support
When the Catalyst 4000 with Supervisor III is connected to an IP phone, do the following:
Step 1
Configure the switch to trust CoS from the IP Phone.
4006-SUPIII-Access(config)#int fa 4/5
4006-SUPIII-Access(config-if)#qos trust cos
Step 2
Enable the voice and data VLANs.
4006-SUPIII-Access(config-if)#switchport voice vlan 111
4006-SUPIII-Access(config-if)#switchport access vlan 11
Step 3
Set the IP Phones trust boundary.
4006-SUPIII-Access(config-if)#switchport priority extend cos 0
Step 4
While in interface configuration mode, enable priority queueing on the port.
Note
In the Catalyst 4000 with Supervisor III, only queue number 3 can be enabled for priority
queuing.
4006-SUPI(config-if-tx-queue)#tx-queue 3
4006-SUPI(config-if-tx-queue)#priority high
Configuring the Uplink to the Distribution Switch
The ports attached to the distribution layer require a slightly different configuration. These ports must
be configured to trust DSCP or CoS depending on the capabilities of the distribution-layer switch
attached. In the following configuration, port 3/1 is attached to a Layer 3-aware distribution device and
can trust DSCP arriving from it. Port 3/2 illustrates an example where CoS-only classification is used.
Note
The system-wide CoS-to-DSCP mapping and DSCP-to-queue admission criteria configurations must
have been completed and the priority queue must be enabled for these ports in order for the access-layer
uplink ports to perform QoS as expected.
Step 1
Configure DSCP trust.
4006-SUPIII-Access(config)#int g 3/1
4006-SUPIII-Access(config-if)#qos trust dscp
Step 2
Enable the priority queue on this interface.
4006-SUPI(config-if-tx-queue)#tx-queue 3
4006-SUPI(config-if-tx-queue)#priority high