Voice VLAN
In Cumulus Linux, a voice VLAN is a VLAN dedicated to voice traffic on a switch port. However, the term can mean different things to different vendors.
Voice VLAN is part of a trunk port with two VLANs that comprises either of the following:
- Native VLAN, which carries both data and voice traffic
- Voice VLAN, which carries the voice traffic, and a data or native VLAN, which carries the data traffic in a trunk port.
The voice traffic is an 802.1q-tagged packet with a VLAN ID (that might or might not be 0) and an 802.1p (3-bit layer 2 COS) with a specific value (typically 5 is assigned for voice traffic).
Data traffic is always untagged.
Voice VLAN Configuration Example

In this example configuration:
- swp1 data traffic traverses the native VLAN of the bridge and the voice traffic traverses VLAN 200
- swp2 data traffic traverses VLAN 10 and the voice traffic traverses VLAN 100
- swp3 data and voice traffic both traverse the native VLAN of the bridge
To configure the topology shown above:
cumulus@switch:~$ net add bridge bridge ports swp1-3
cumulus@switch:~$ net add bridge bridge vids 1-1000
cumulus@switch:~$ net add bridge bridge pvid 1
cumulus@switch:~$ net add interface swp1 bridge voice-vlan 200
cumulus@switch:~$ net add interface swp2 bridge voice-vlan 100 data-vlan 10
cumulus@switch:~$ net add interface swp3 bridge voice-vlan 300
cumulus@switch:~$ net pending
cumulus@switch:~$ net commit
Edit the /etc/network/interfaces
file and add the following configuration:
cumulus@switch:~$ sudo nano /etc/network/interfaces
auto swp1
iface swp1
bridge-vids 200
mstpctl-bpduguard yes
mstpctl-portadminedge yes
auto swp2
iface swp2
bridge-pvid 10
bridge-vids 100
mstpctl-bpduguard yes
mstpctl-portadminedge yes
auto swp3
iface swp3
bridge-vids 300
mstpctl-bpduguard yes
mstpctl-portadminedge yes
auto bridge
iface bridge
bridge-ports swp1 swp2 swp3
bridge-pvid 1
bridge-vids 1-1000
bridge-vlan-aware yes
Configure LLDP
Configuring voice VLAN with NCLU does not configure lldpd
in Cumulus Linux; therefore, LLDP-MED does not provide data and voice VLAN information. You can configure LLDP-MED for each interface in a new file in /etc/lldp.d
. In the following example, the file is called /etc/lldpd.d/voice_vlan.conf
:
cumulus@switch:~$ sudo nano /etc/lldpd.d/voice_vlan.conf
configure ports swp1 med policy application voice tagged vlan 200 priority voice dscp 46
configure ports swp2 med policy application voice tagged vlan 100 priority voice dscp 46
configure ports swp3 med policy application voice tagged vlan 300 priority voice dscp 46
You can also use the lldpcli
command to configure an LLDP-MED network policy. However, lldpcli
commands do not persist across switch reboots.
Troubleshooting
To show the bridge-vids:
Run the net show bridge vlan
command:
cumulus@switch:~$ net show bridge vlan
Interface VLAN Flags
----------- ------ ---------------------
swp1 1 PVID, Egress Untagged
200
swp2 10 PVID, Egress Untagged
200
swp3 1 PVID, Egress Untagged
300
Run the bridge fdb
show
command:
cumulus@switch:~$ bridge fdb show
44:38:39:00:12:9c dev swp2 VLAN 0 master bridge-A permanent
44:38:39:00:12:9b dev swp1 VLAN 0 master bridge-A permanent
44:38:39:00:12:9e dev swp4 VLAN 0 master bridge-B permanent
44:38:39:00:12:9d dev swp3 VLAN 0 master bridge-B permanent
To obtain MAC address information:
Run the net show bridge macs
command:
cumulus@switch:~$ net show bridge macs
VLAN Master Interface MAC TunnelDest State Flags LastSeen
-------- -------- ----------- ----------------- ------------- --------- ------- ----------
untagged bridge bridge 08:00:27:d5:00:93 permanent 00:13:54
untagged bridge swp1 08:00:27:6a:ad:da permanent 00:13:54
untagged bridge swp2 08:00:27:e3:0c:a7 permanent 00:13:54
untagged bridge swp3 08:00:27:9e:98:86 permanent 00:13:54
Run the sudo brctl showmacs <bridge>
command:
cumulus@switch:~$ sudo brctl showmacs my_bridge
port name mac addr is local? ageing timer
swp4 06:90:70:22:a6:2e no 19.47
swp1 12:12:36:43:6f:9d no 40.50
bond0 2a:95:22:94:d1:f0 no 1.98
swp1 44:38:39:00:12:9b yes 0.00
swp2 44:38:39:00:12:9c yes 0.00
swp3 44:38:39:00:12:9d yes 0.00
swp4 44:38:39:00:12:9e yes 0.00
bond0 44:38:39:00:12:9f yes 0.00
swp2 90:e2:ba:2c:b1:94 no 12.84
swp2 a2:84:fe:fc:bf:cd no 9.43
To capture LLDP information, check syslog
or use tcpdump
on an interface.
Caveats and Errata
- A static voice VLAN configuration overwrites the existing configuration for the switch port.
- Removing the
bridge-vids
orbridge-pvid
configuration from a voice VLAN does not remove the VLAN from the bridge.