Section 8: QoS (8 Points)

  • Configure your switch to trust DSCP QoS from the Cisco IP phones.

You first need to enable QoS for the 3550 with the command mls qos and then under the Cisco IP Phone interfaces (port 0/16 and 0/17), configure mls qos trust dscp. If you have configured this correctly, you have scored 2 points. Example 2-77 shows the Cisco IP phone port QoS summary.

Example 2-77. Switch1 Port 0/16 and 0/17 QoS Summary
Switch1#sh mls qos int fastEthernet 0/16
FastEthernet0/16
trust state: trust dscp
						trust mode: trust dscp
COS override: dis
default COS: 0
DSCP Mutation Map: Default DSCP Mutation Map
trust device: none

Switch1#sh mls qos int fastEthernet 0/17
FastEthernet0/17
trust state: trust dscp
						trust mode: trust dscp COS override: ...

Get CCIE Routing and Switching Practice Labs now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.

Start your free trial