Tuesday, August 25, 2009

Switchport configuration for NEC DT700 for phone and PC

Last week I was struggling to find the switcport settings for the NEC DT700 for us to use with one cable going to the VOIP phone and PC with dual VLANS. After a couple of testing in my LAB I was able to to get the right configurations for the switchport. Below is a sample port settings in our Cisco 3750 switch for the NEC DT700.

interface GigabitEthernet1/0/1
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 2,3
switchport mode trunk
auto qos voip trust
spanning-tree portfast

During my test I couldn't get an ip address from the DHCP server and I had to put ip helper address to each of the VLAN interfaces.

For the NEC DT700 enable VLAN and set the LAN settings to your voice VLAN and PC settings to your data VLAN. You can also enable CDP on the NEC DT700 if you like to see the devices connected to the switch using show cdp neighbor command.


  1. What did you set on the phone for the VLAN priority? Does the phone do any actual prioritization or does it just mark the traffic for the switch to prioritize it?

  2. The LAN settings has a higher priority than the PC port settings. I also set the LAN settings to full/100 the example above should have speed 100 and duplex full this will prevent the phone from auto negotiating speed that makes the interface port to come up a little bit slower. I guess for IP phones, you want to get a dial tone as fast as possible. :-)

  3. Curious, but did you actually get to register this to a Cisco CallManager (CUCM)?

  4. We are not using a Call Manager at this site.

  5. Thanks for posting this info. I have enabled CDP on the DT700 and it shows up in cdp neighbors. However it only show the capability code of H(Host) not P (Phone). How does it show up on your network with cdp neighbors?

  6. It also shows as H on capability and SIP-ITL on Platform.