On Catalyst 9300 with the trust device command, if the connected peer does not match the trusted device type, both CoS and DSCP are set to 0 and any input policy does not take effect.
Checked 2026-10-02
both CoS and DSCP values are set to '0' and any input policy will not take effect
- Vendor
- Cisco
- Product
- Catalyst 9300
- Subsystem
- QoS trust
- Deployment
- on-premises
- Region
- not restricted
- Release range
- IOS XE 17.15.x
- Checked
- 2026-10-02
Sources
- Quality of Service Configuration Guide, Cisco IOS XE 17.15.x (Catalyst 9300 Switches) - Configuring QoS — Cisco · tier 2 current vendor documentation · Trust device / Auto-QoS trust discussion
Cite this note
APA
WarmTransfer. (2026, October 2). Troubleshooting voice QoS markings that are stripped or ignored: source note voice-qos-troubleshooting-c9300-trust-device-zero. WarmTransfer. https://warmtransfer.net/knowledge/claims/voice-qos-troubleshooting-c9300-trust-device-zero
BibTeX
@misc{warmtransfer-claim-voice-qos-troubleshooting-c9300-trust-device-zero,
title = {Troubleshooting voice QoS markings that are stripped or ignored: source note voice-qos-troubleshooting-c9300-trust-device-zero},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/voice-qos-troubleshooting-c9300-trust-device-zero},
note = {Source note voice-qos-troubleshooting-c9300-trust-device-zero, checked 2026-10-02}
}