Tagging issues with non-Cisco phones 1

[atascoman]

First, I am very rusty in the Cisco switching arena so bear with me.

The Cisco network gear has the switchport voice vlan xxx option activated on the ports. I believe this work with the CDP on the Cisco phones so it knows how to tag their packets.

So, when I configured a Shoretel phone and activated 802.1Q and entered the VLAN ID, the switch appears to ignore that tag and puts the phone in the data vlan and does some other strange stuff like changing the FTP IP to 0.0.0.0 even though it's been entered on the phone. The FTP thing may be due to a DHCP option being on that I was not told about.

I have verified I am using the correct VLAN ID and if we configure the port to be only in the VLAN for the phones it works. ANything I am missing? They do not appear to be using LLDP.

 

[ADB100]

I have never dealt with Shoretel IP Phones but I assume the process is the same as with other phones that don't do CDP or LLDP to discover the Voice VLAN in that they require DHCP options to be configured on the Access VLAN DHCP Scope so the phone does a 'double-DHCP' boot. The process is pretty simple in that a vanilla phone is set for DHCP by default and has no knowledge of the Voice VLAN. It will request a specific DHCP option (in the Shoretel case it requests DHCP Option 156) and this option will inform the phone about a few things it needs - one of these is typically the Voice VLAN Tag. Once the phone has this information it will release the IP address from the Native VLAN and then start again using the Tag received from DHCP. It then goes through DHCP again on the Tagged VLAN.

I quickly googled Shoretel & DHCP and found this:

http://forums.untangle.com/networking/19016-how-config-dhcp-options-shoretel-voip.html

I am sure there are lots of other examples.

Andy