Source note · Voice VLAN and LLDP-MED and CDP and PoE for IP phones
Per the Catalyst 9300 guide, untagged traffic from a device attached to the Cisco IP phone's PC port passes through the phone unchanged, whatever the trust state of the phone's access port.
Checked 2026-09-24
Untagged traffic from the device attached to the Cisco IP Phone passes through the phone unchanged, regardless of the trust state of the access port on the phone.
- Vendor
- Cisco
- Product
- Catalyst 9300 Series Switches
- Subsystem
- PC port pass-through
- Deployment
- on-premises
- Region
- not restricted
- Release range
- IOS XE 17.15.x
- Checked
- 2026-09-24
Sources
- VLAN Configuration Guide, Cisco IOS XE 17.15.x (Catalyst 9300 Switches) - Configuring Voice VLANs — Cisco Systems · tier 2 current vendor documentation · Configuring Voice VLANs > Cisco IP Phone Data Traffic
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-pc-untagged-passthrough. WarmTransfer. https://warmtransfer.net/knowledge/claims/voice-vlan-lldp-poe-c9300-pc-untagged-passthrough
BibTeX
@misc{warmtransfer-claim-voice-vlan-lldp-poe-c9300-pc-untagged-passthrough,
title = {Voice VLAN and LLDP-MED and CDP and PoE for IP phones: source note voice-vlan-lldp-poe-c9300-pc-untagged-passthrough},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/voice-vlan-lldp-poe-c9300-pc-untagged-passthrough},
note = {Source note voice-vlan-lldp-poe-c9300-pc-untagged-passthrough, checked 2026-09-24}
}