DHCp with two vlans in a CXi-II

[dbabiano]

Hi,

I'm trying to configure in a Mitel CXi-II system, two DHCP scopes, one for phones and one for PC (i have two vlans configured in the scenario), the telephony system it's working fine but in the data vlan I have a problem, I only get the CXi-II is leasing to the clients IP address from the voice scope.

I has tried to configure the port 17 in trunk mode with the two vlans tagged and the voice vlan tagged and the data vlan untagged, i try to do a dhcp relay from the switch to the CXi, but the result is ever the same, the system lease an IP address from voice scope.

It´s possible to do this with this system?? How?? If i use a router how dhcp server, the system works fine in the two vlan but my client doesn't have a dhcp server in his office (it's a little office) where i have to install the CXi....

Any idea..... If this doesn't works we can talk wiht the MPLS supplier for to do the gateway works how a dhcp server, but i don't like this idea....

Thanks to all and sorry but my english isn't good 

[ucx]

As far as I know, you can't do this with the in-built DHCP server on the Mitel.
Generally, what you do is have the CXi serving DHCP to the voice VLAN devices and have it connected to your network on an tagged voice-VLAN port. You then have your other DHCP server on an untagged data-VLAN port serving the data VLAN DHCP range, with the Option125 in that server having the vlan option pointing to the voice VLAN.
This way, your phones will send out a DHCP Request on the data VLAN, the data VLAN DHCP server will send an offer with Option 125 embedded. The phone will then drop the offer, set itself to the voice VLAN and send out another request. Because it's now on the voice VLAN, the Mitel sees the offer and not the other DHCP server, thus the phone gets the DHCP offer from the Mitel.
Meanwhile, your computer (or other network device) will send out a DHCP Request on the data vlan and get the offer by the data DHCP server - it doesn't see nor hear from the Mitel DHCP server at all.

[bobcheese]

You CAN do this on the 3300 you need to have two scopes set up with two defines DHCP subnets and you also need to make sure you have 2 sets of DHCP options for Gateway etc (as the two scope will be on different VLAN's they will have different gateways. You need to make sure your options 'scope' are set to 'subnet' not 'global'. Then set up DHCP relay/IP Helper and point to the 3300. The 3300 looks at the subnet it receives the request from and if that subnet matches a subnet in its DHCP subnets form it issues a DHCP address and rules for that subnet.

[ucx]

Ah, you learn something new every day. Thanks, bobcheese, for that info

[ralph]

Thanks bobcheese.
I was wonder (and couldn't quite get the thought together) is it could be done with the option (can't remember which one) that says "IP Phone" with the tick box that said the string must match.
Sorry for that sounding convoluted.  Like I said, I couldn't quite get that thought to gel.

Ralph

[dbabiano]

Thanks to all, but still isn't working fine... I have to tag the 2 vlans at Mitel Cxi port??? or isn't necessary....

[bobcheese]

not necessary if you have routing between VLANs and IP Helper/DHCP Relay set up correctly. Dont forget there needs to be a route between the two networks for the DHCP Helper/DHCP Relay to work.

Can you post screen shots of DHCP config?

Ralph - The 'Vendors Class must match' option can be used to only serve Mitel IP sets but I dont generally use this option to be honest as you need to disable every time you add a new handset.