DHCP VLAN Option 132
- Kelli Higdon
Sangoma S-Series IP phones support VLAN discovery via DHCP Option 132; other series of Sangoma phones do not. When the VLAN Discovery method is set to DHCP, the IP phone will detect DHCP option for a valid VLAN ID. The predefined option 132 is used to supply the VLAN ID by default. You can customize the DHCP option used to detect the VLAN ID. Before using DHCP VLAN feature on IP phones, you must make sure that the DHCP option on the DHCP server is setup properly.
By default Sangoma IP Phones from the factory are not enabled for DHCP Option 132 but are enabled for LLDP. The phone can not support both LLDP and Option 132 at the same time as they conflict. We have two ways we can enable option 132 and disable LLDP on the phone as outlined below.
Automated Way to Setup Option 132
This method is the easiest but it assume the phone can reach the PBX to get its original configuration file from the PBX on a default untagged network.
Enable Phone for DHCP Option 132 and Disable LLDP
Log into your PBX and navigate to the template(s) that your phones will use.
Under the VLAN Tab set the following options
Disable LLDP
Enable VLAN DHCP
Save, Rebuild and Update Phones as shown below
It will only update existing phones that are registered to the PBX that use this template.
If you have not mapped your phones Mac address to a extension and template you will need to do that now. If you have already then the config for those phones should be updated and you can skip to the steps below.
Go into Extension Mapping and Map your Mac Address to an extension, brand, model and template. This will build a configuration file for your phones mac address that enables DHCP Vlan and disables LLDP.
Boot the phone and have it retrieve the updating configuration file from a non tagged vlan using our redirect server as outlined here or option 66 on your DHCP server as outlined here.
Recap on what will happen
Phone boots up on untagged network and option 66 or redirect server is set to send the phone to the PBX for a configuration file.
In the template that the phone will use, you have option 132 enabled as shown above in the VLAN DHCP and disabled LLDP
The boot will pull its configuration on boot and receive the information to enable options 132 and disable LLDP
The IP phone broadcasts a DHCP Discover message to find out if there is a DHCP server available.
If the DHCP server sends a DHCP Offer message with the Option 132, the phone will accept the Offer, send a DHCP Request, and save the VLAN ID provided by the DHCP server in the DHCP option 132.
After the DHCP server has sent the ACK message to the phone, the phone will release the leased IP address and start a new DHCP Discover cycle using the now known Voice VLAN ID tag.
After this process, the phone will send all packets with the VLAN ID learned from the DHCP server in the DHCP option 132.
Manually Enabling Option 132
Log into the Web GUI of each phone from your browser with username of admin and password of admin
Click on the Network > Advanced Tab
Disable LLDP and Enable DHCP Vlan
Save your changes and reboot the phone.
Make sure in End Point Manager (EPM) you set in your templates as shown above to disable LLDP and Enable DHCP Vlan otherwise when the phone gets a configruation file it will disable what you just set in the GUI of the phone.