Inter-Tel Phone Doesn't Get A DHCP IP Address

[Anonymous]

With a Ip helper address configure on the 1531 as below the Inter-Tel Phone never gets an IP address from the DHCP server.  It will see the Offer from the server but never sends the request.  Here is the switch config from the port level and vlan level:

interface gigabit-switchport 0/8

  spanning-tree edgeport

  no shutdown

  switchport mode trunk

  switchport access vlan 192

  switchport voice vlan 192 cos 6 dscp 46

  qos trust cos

!

interface gigabit-switchport 0/9

  no shutdown

  switchport mode trunk

  switchport trunk allowed vlan 1,192

...

interface vlan 192

  ip address  192.168.100.2  255.255.255.0

  ip helper-address  10.1.0.5

  ip helper-address  10.1.0.6

  ip route-cache express

  no shutdown

Does the switch need something else configured to make this work.  We can plug in a Mitel phone and it works right away but the InterTel phone does not.  The InterTel is a know working phone as it comes right up on a HP Switch.

[jayh]

Verify that the Inter-Tel phone is negotiating the voice VLAN properly, either via LLDP or by manual configuration to VLAN 192 in your example. It may be using CDP rather than LLDP. CDP is Cisco-proprietary but some vendors such as HP and Polycom (and perhaps Inter-Tel) interoperate with it. Ensure that LLDP is enabled on the switch and the phone. If LLDP is not an option on the phone, you may need to manually configure the phone's voice VLAN to match the switch.

[Anonymous · Accepted solution]

Looks like i have found the resolutions to this issue.  The Inter-tel 8662 and 8622 phones have an issues with LLDP.  To fix this on the AOS on the port the phone is connected to run this command:

     "no lldp send-and-receive". 

This will disable LLDP on the port and allow the phone to complete the DHCP negotiation.  Here is an out line of the issue as posted in the Mitel Support forums:

Mitel Support:

When the phone receives an LLDP frame from the switch, it seems to no longer process DHCP Offers. Similarly, if the phone has an IP address manually set, it will not process ARP Requests.

Disabling LLDP on the switch globally or at the interface level resolves the symptoms.

Root-Cause of Symptoms Theory:

If the Inter-Tel 8622 phone receives an LLDP frame where the sum of the System_Name and System_Description TLVs  is greater than 147 bytes, the phone seems to then stops processing DHCP Offers, and never acquires its IP address.