Cisco WS-SUP32-GE-3B - Supervisor Engine 32 Software Configuration Manual page 628

Common QoS Scenarios
This is the QoS classification scheme for the traffic arriving on an access layer port:
Voice traffic: DSCP 46 (highest priority)
•
Voice signaling traffic: DSCP 24 (medium priority)
•
PC SAP traffic: DSCP 25 (medium priority)
•
All other PC traffic: DSCP 0 (best effort)
•
This classification strategy provides a way to support three different classes of service on the network:
High priority for voice traffic
•
Medium priority for voice signaling and important application traffic
•
Low priority for the remaining traffic
•
You can alter this model to fit other network environments.
PFC QoS can trust received priorities or assign new priorities by applying a QoS policy to the traffic.
You configure a QoS policy using the Modular QoS CLI (MQC). In the access switches, the traffic is
identified using ACLs, which differentiate the various traffic types entering the port. Once identified, a
QoS policy marks the traffic with the appropriate DSCP value. These assigned DSCP values will be
trusted when the traffic enters the distribution and core switches.
The port on the access switch where the phone and PC are attached has been configured for a voice
VLAN (VLAN 110), which is used to separate the phone traffic (subnet 10.1.110.0/24) from the PC
traffic (10.1.10.0/24). The voice VLAN subnet uniquely identifies the voice traffic. The UDP and TCP
port numbers identify the different applications.
This is the access port access control list (ACL) configuration:
Identify the Voice Traffic from an IP Phone (VVLAN)
ip access-list extended CLASSIFY-VOICE
permit udp 10.1.110.0 0.0.0.255 any range 16384 32767
Identify the Voice Signaling Traffic from an IP Phone (VVLAN)
ip access-list extended CLASSIFY-VOICE-SIGNAL
permit udp 10.1.110.0 0.0.0.255 any range 2000 2002
Identify the SAP Traffic from the PC (DVLAN)
ip access-list extended CLASSIFY-PC-SAP
permit tcp 10.1.10.0 0.0.0.255 any range 3200 3203
permit tcp 10.1.10.0 0.0.0.255 any eq 3600 any
ip access-list extended CLASSIFY-OTHER
permit ip any any
The next step in configuring the QoS policy is to define the class maps. These class maps associate the
identifying ACLs with the QoS actions that you want to perform (marking, in this case). This is the
syntax for the class maps:
class-map match-all CLASSIFY-VOICE
match access-group name CLASSIFY-VOICE
class-map match-all CLASSIFY-VOICE-SIGNAL
match access-group name CLASSIFY-VOICE-SIGNAL
class-map match-all CLASSIFY-PC-SAP
match access-group name CLASSIFY-PC-SAP
class-map match-all CLASSIFY-OTHER
match access-group name CLASSIFY-OTHER
Catalyst Supervisor Engine 32 PISA Cisco IOS Software Configuration Guide, Release 12.2ZY
38-94
Chapter 38 Configuring PFC QoS
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