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 2 VLANs that comprises either:
Native VLAN, which carries both data and voice traffic, or
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 has a VLAN ID (which may or may 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.
Cumulus Linux Voice VLAN Example
You can configure the topology above using the following NCLU commands. In this configuration:
swp1 data traffic traverses the bridge’s native VLAN 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 bridge’s native VLAN
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
These commands create the following configuration snippet in the
/etc/network/interfaces file:
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, so 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 reboots of the
switch.
Troubleshooting
The bridge-vids can be reviewed with 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
You can get MAC address information using 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
You can capture LLDP information by checking syslog or using tcpdump
on an interface.
Caveats and Errata
A static voice VLAN configuration overwrites a switch port’s existing configuration.
Removing the
bridge-vidsorbridge-pvidconfiguration from a voice VLAN does not remove the VLAN from the bridge.