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Author Topic: Changing DHCP servers  (Read 4377 times)

rbanksy

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Changing DHCP servers
« on: March 11, 2010, 07:09:20 PM »
We have a 5000 with data and voice vlans.

The phones obtain IP's from the same DHCP server but a different scope.
I want to replace our DHCP server,  I copied the config accross to the new 2003 dhcp server.

Computers connect to it fine but the phones get stuck in DHCP discovery mode...

If I enable the old DHCP server than it works perfectly!  But I can't upgrade my server in this sitation.

I have tried rebooting the router and hp poe switch but that made no difference.


Offline Chakara

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Re: Changing DHCP servers
« Reply #1 on: March 11, 2010, 09:04:06 PM »
  Was the old DHCP server windows as well?

  Is the switchport the new DHCP server plugged into set for both the data and voice vlan?  It should be data only.

  Is the DHCP helper on the switch (or whatever is doing layer 3 routing) configured to relay the DHCP request to the new server?

Those are my best guesses from the description....

-Chak

rbanksy

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Re: Changing DHCP servers
« Reply #2 on: March 12, 2010, 08:00:56 AM »
Both windows.

Port is data only...
I even tried putting the new DHCP server in the same port that the old one was in.

DHCP helper on the switch...
How can I check that?

Offline Chakara

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Re: Changing DHCP servers
« Reply #3 on: March 13, 2010, 11:40:00 AM »
  Whatever device is doing your layer 3 routing - likely the switch or a router.  It is probably whatever device is your default gateway.  In there should be the DHCP (sometimes called IP Helper) address setting.  This is what relays the DHCP request across VLAN's to your DHCP server.  It will be set to the IP address of your DHCP server.

-Chak

Offline StarLog

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Re: Changing DHCP servers
« Reply #4 on: March 14, 2010, 09:15:14 PM »
Do you have option 43 setup on the NEW DHCP server?

This is the code section of my option 43;

Code: [Select]
.com;sw_tftp=192.168.99.1;call_srv=192.168.99.1;vlan=99;l2p=6;dscp=46

My 5K Mitel is at 192.168.99.1 on vlan 99
« Last Edit: March 14, 2010, 09:24:39 PM by StarLog »


 

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