Source note · Voice VLAN and LLDP-MED and CDP and PoE for IP phones
On Catalyst 9300, auto qos voip cisco-phone trusts incoming QoS labels only when CDP detects a Cisco IP phone on the port (conditional trust), and does not trust them when no phone is detected.
Checked 2026-09-24
QoS labels of incoming packets are only trusted (conditional trust through CDP) when the telephone is detected.
- Vendor
- Cisco
- Product
- Catalyst 9300 Series Switches
- Subsystem
- auto-QoS / trust boundary
- Deployment
- on-premises
- Region
- not restricted
- Release range
- IOS XE 17.17.x
- Checked
- 2026-09-24
Sources
- Quality of Service Configuration Guide, Cisco IOS XE 17.17.x (Catalyst 9300 Switches) - Configuring Auto-QoS — Cisco Systems · tier 2 current vendor documentation · Configuring Auto-QoS > auto qos voip cisco-phone description
Cite this note
APA
WarmTransfer. (2026, September 24). Voice VLAN and LLDP-MED and CDP and PoE for IP phones: source note voice-vlan-lldp-poe-c9300-autoqos-cdp-trust. WarmTransfer. https://warmtransfer.net/knowledge/claims/voice-vlan-lldp-poe-c9300-autoqos-cdp-trust
BibTeX
@misc{warmtransfer-claim-voice-vlan-lldp-poe-c9300-autoqos-cdp-trust,
title = {Voice VLAN and LLDP-MED and CDP and PoE for IP phones: source note voice-vlan-lldp-poe-c9300-autoqos-cdp-trust},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/voice-vlan-lldp-poe-c9300-autoqos-cdp-trust},
note = {Source note voice-vlan-lldp-poe-c9300-autoqos-cdp-trust, checked 2026-09-24}
}