DHCP for NEC DT700

[vontech615]

I have the Adtran Netvanta 1500 series switches.  Our office has 25 NEC DT700 phones and IPBX 8xxx series.  We are splitting the data and voice traffic by putting them on their own vlans.  We have a Windows 2003 server doing DHCP.  What information do I need to add to the DHCP scope for the phones?  Or will the switch push this info out using LLDP and ip helper-address command?

[jayh]

I haven't had good experience with Windows DHCP on multiple VLANs.  I'd enable DHCP on the switch for the phone VLAN and ensure that the port feeding the Windows DHCP server doesn't have the voice VLAN visible.

You'll need the typical DNS, gateway, and the like.  Also possibly FTFP server, NTP server, etc.

Can the 8xxx series IPBX serve DHCP for the voice VLAN?  This would ensure that any proprietary options would be included. 

[vontech615]

I realized after I submitted the question I was over thinking it.  Currently the phones get IP address, default router, and dns from the server so I don't really need anything else.  I will be putting the PBX on the voice vlan along with the phones.  We only have 25 phones and will have 2 vlans and it won't be scaling so the Windows server should be fine for this.

[jayh]

vontech615 wrote:

I realized after I submitted the question I was over thinking it.  Currently the phones get IP address, default router, and dns from the server so I don't really need anything else.  I will be putting the PBX on the voice vlan along with the phones.  We only have 25 phones and will have 2 vlans and it won't be scaling so the Windows server should be fine for this.

When you say "server" do you mean that the PBX on the voice VLAN will act as DHCP server for the phones?  If the PBX has DHCP capability, this is what I would recommend. 

Let the data devices use the Windows DHCP server and be sure to exclude the voice VLAN from its switch port.  Otherwise you may find that the Windows DHCP server will "hop" VLANs and assign IPs from the data subnet to the phones.

[Anonymous · Accepted solution]

I deal with the DT700 phones often.  The switch will do fine for DHCP.  If you program the ports as follows, they will automatically grab the correct VLAN. 

vlan 2

name Voice

int gigabit 0/1

switchport voice vlan 2 dscp 46 cos 6

no shutdown

No need to program the VLAN in the DT700.  It will receive the VLAN and tagging information via LLDP from the switch.

as far as DHCP goes, I think is right about letting the switch do DHCP for the phones and leaving your server handle the data connection.  Just remember that if you have more than one VLAN INTERFACE, in a Layer 3 environment, you should disable DHCP on the data VLAN interface.  Otherwise, the switch may answer up on the data network, but without a pool defined, it will not lease an address to the data device.  If you are not using the switch as a gateway, you need not worry about it. 

Example:

interface vlan 1

ip address 10.10.10.1 255.255.255.0

ip dhcp relay destination A.B.C.D  (dhcp server on the data network).

no shutdown

[vontech615]

Well my plan is to make the switch the default gateway for the data and the phones.  We'll have 2 vlans 1 for data and 1 for voice. Our phones have an adapter so we only have one cable run per users computer/phone. So how will that effect the phones picking up the correct vlan?  I'm thinking the switch smartly recognizes the voice traffic and tags that as voice vlan and via LLDP the phones recieve correct vlan tag?

I won't be enabling DHCP for the data vlan on the switch but will just let our Windows server handle that.  I've gotten advice from other sources that say using Windows server for dhcp should work just fine for the phones but jayh has advised me against this before.  However, I've enbled ip helper-address command so when phones reach switch it will forward broadcast to the Windows server?

My only other question is the phones have a SIP address.  How can they automatically pick this up?  The technician that installed the system manually input this into all of them and just left everything on our data vlan.

[Anonymous]

If you program the switchports with the "switchport voice vlan <vlan id>" statement, it will tell the DT700 to use that vlan for voice.  The pc port on the DT700 will use the native vlan (usually 1, unless set differently).  It works well.

With regards to the the sip address and port number, I think you have to create config files and put them on an FTP server.  Then you have to have a unique pool/reservation for each phone based on mac address.  I've always just manually put in the sip server and sip port settings.  It only takes a minute to do that on the phones.  NEC doesn't make it easy in that respect.  If you are using an SV8000 series PBX, they typically use port 5080 vs. the rest of the world that uses port 5060 for SIP. 

I found a manual that contains information on the auto configuration of the phones.  http://www.southwesterntel.com/necpdf/newpdf/DT700%20Resource%20Manual_1-0.pdf

I hope that helps.

[vontech615]

Thanks... you've been a big help.

[vontech615]

We switched everything over and make voice calls internally but voice calls that go outside the network connect but don't carry voice?