Traditionally when working with voice and data vlans you normally have to either have DHCP voice options set up in your data scope or you manually untag the voice ports onto the voice vlan both of these come with their own disadvantages, this guide utilises Link Layer Discovery Protocol (LLDP) which is a vendor independent link layer protocol used by network devices for advertising their identity and capabilities to neighbors on a LAN segment. This guide shows you how to configure LLDP on Extreme EXOS switching to detect IP phones when plugged in and move them to the correct VLAN before reaching the initial DHCP stage.
Before configuring this, the VLAN that is being used for VOIP traffic needs to have the port the phone is connected to added to it as tagged:
configure vlan <VOIP vlan> add ports <port numbers> tagged
Use the following commands to configure and allow the switch to communicate with the phone via LLDP:
Configure the LLDP port to advertise to its neighbors.
configure lldp port all advertise system-name
Configures the LLDP port to advertise MAC and physical layer capabilities to its neighbors. The capabilities include duplex and bit rate.
configure lldp port all advertise vendor-specific dot3 mac-phy
Configures the LLDP port to advertise MED capabilities. This TLV must be enabled before any of the other MED TLVs can be enabled. Also, this TLV must be set to no-advertise after all other MED TLVs are set to no-advertise.
configure lldp port all advertise vendor-specific med capabilities
Configures the LLDP port to advertise MED power requirement details. This TLV can only be enabled on a PoE-capable port and is used for advanced power management between the MED network connectivity and endpoint devices.
configure lldp port all advertise vendor-specific med power-via-mdi
Configure all ports to advertise voice on the VLAN video with a DSCP of 46 to neighbours
configure lldp port all advertise vendor-specific med policy application voice vlan <voice vlan> dscp 46
Enables LLDP transmit mode, receive mode, or transmit and receive mode. If the transmit-only or receive-only option is not specified, both transmit and receive modes are enabled.
enable lldp ports <port numbers>
An example configuration for ports 1 to 44 on each switch in a 2 switch stack would look like;
create vlan DATA tag 100 create vlan VOICE tag 200 configure DATA add ports 1:1-44,2:1-44 untagged configure VOICE add ports 1:1-44,2:1-44 tagged configure lldp port 1:1-44,2:1-44 advertise system-name configure lldp port 1:1-44,2:1-44 advertise vendor-specific dot3 mac-phy configure lldp port 1:1-44,2:1-44 advertise vendor-specific med capabilities configure lldp port 1:1-44,2:1-44 advertise vendor-specific med power-via-mdi configure lldp port 1:1-44,2:1-44 advertise vendor-specific med policy application voice vlan VOICE dscp 46 enable lldp ports 1:1-44,2:1-44
Test by plugging into a port which is untagged on data and tagged on voice, LLDP should tag phone traffic to connect to the voice vlan then pull an ip address from DHCP on this VLAN. The PC/laptop connected to the phone should be pulling its DHCP from the untagged data vlan.