On Catalyst 9300 switches running IOS XE 17.15, the default trust mode for a port is DSCP-based, falling back to CoS when the incoming packet is a pure Layer 2 packet.
Checked 2026-10-02
Note that the default trust mode for a port is DSCP based.
- 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 Behavior for Wired and Wireless Ports
Cite this note
APA
WarmTransfer. (2026, October 2). Troubleshooting voice QoS markings that are stripped or ignored: source note voice-qos-troubleshooting-c9300-default-trust-dscp. WarmTransfer. https://warmtransfer.net/knowledge/claims/voice-qos-troubleshooting-c9300-default-trust-dscp
BibTeX
@misc{warmtransfer-claim-voice-qos-troubleshooting-c9300-default-trust-dscp,
title = {Troubleshooting voice QoS markings that are stripped or ignored: source note voice-qos-troubleshooting-c9300-default-trust-dscp},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/voice-qos-troubleshooting-c9300-default-trust-dscp},
note = {Source note voice-qos-troubleshooting-c9300-default-trust-dscp, checked 2026-10-02}
}