Apply the approved switch QoS policy
When a switch port is untrusted it rewrites inbound DSCP to 0 and strips voice priority. The fix is to trust DSCP on that access port (not CoS, which is Layer 2), then confirm the trust state by reading it back. This lab uses the simulated switch console; a real switch uses the same mls qos trust dscp configuration. This page teaches a job procedure. These are not exam questions, this is not a score predictor, and nothing here is taken from any exam.
Steps
- 1
Confirm the access port is untrusted before you change it: run show mls qos interface GigabitEthernet1/0/24 and read the trust state.
- 2
Enter configuration for the access-facing uplink: enable, then configure terminal, then interface GigabitEthernet1/0/24.
- 3
Trust the Layer 3 marking on the port with mls qos trust dscp (not CoS, which is Layer 2; not disabling QoS, which drops prioritization).
- 4
Return and verify the end state: end, then show running-config interface GigabitEthernet1/0/24 and show mls qos interface GigabitEthernet1/0/24, confirming the port now reads trust dscp.
What you should see
After applying, the access port reads trust dscp and the DSCP marking is preserved end to end; applying trust CoS or disable instead would not complete the lab.