330 Chapter 8: QoS Support on the Catalyst 6500
Port-Specific Auto-QoS
The port-specific Auto-QoS functions define, in one of two ways, the classification method
used for traffic ingress to a specific port. One way involves specifying the type of device
attached to the port, either a Cisco IP Phone or Cisco IP Softphone. The other method
requires specifying the trust state for a particular port, either trust DSCP or trust CoS.
Configuring port-specific Auto-QoS also assigns extended trust capabilities and CoS
assignments to attached IP Phones using Cisco Discovery Protocol (CDP) version 2. If
CDP version 2 is not enabled, the information cannot be communicated to an attached
Cisco IP Phone. Refer to the section “Voice VLANs and Extended Trust” in Chapter 2 for
additional information on CDP and extended port-based QoS capabilities. A PFC is a
prerequisite for using either the trust DSCP or IP Softphone Auto-QoS option. To configure
port-specific Auto-QoS, use one of the following commands:
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The “Classification and Marking” section within this chapter discusses trust and internal
DSCP in further detail. The trust dscp and trust cos classification keywords are used to
classify all traffic based on arriving DSCP or CoS values. You can use the cos keyword for
trusted uplink ports attached to devices capable of only modifying the trunk header of an
Ethernet frame. This ensures previously assigned CoS values are honored at the arriving
switch port, and subsequently mapped to a corresponding internal DSCP value. You can use
the dscp keyword for uplink ports attached to devices capable of altering the DSCP field in
the IP header. This capability is relevant, for instance, when connecting to a 3550, another
set qos txq-ratio 1p2q1t 75 15 15
set qos wrr 1p2q1t 50 255
set qos wred 1p2q1t queue 1 70:100
set qos wred 1p2q1t queue 2 70:100
set qos map 1p1q8t rx 1 1 cos 0
set qos map 1p1q8t rx 1 5 cos 1,2
set qos map 1p1q8t rx 1 8 cos 3,4
set qos map 1p1q8t rx 2 cos 5,6,7
set qos wred 1p1q8t queue 1 1 40:70
set qos wred 1p1q8t queue 1 5 60:90
set qos wred 1p1q8t queue 1 8 70:100
set qos rxq-ratio 1p1q8t 80 20
Table 8-22 Added Global Auto-QoS Port Type Configuration Commands (Continued)