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Question on DHCP Relay and VLANs

I'm not sure if this is a Cisco problem or a Microsoft DHCP server problem. I have 6 VLANs setup being routed by a Catalyst 4507R and DHCP scopes configured for each. My problem occurs when I move a node off of one VLAN onto another. If Device A is assigned to VLAN 2 and has an address of 172.16.2.2 and I move it to VLAN 3 it will not pickup a new address on the 172.16.3.X subnet. I have even gone through and done a IPCONFIG/ RELEASE and manually deleted the address off of the DHCP server. I have the DHCP relay agent configured correctly (as far as I know at least) and the scopes are activated on the Microsoft DHCP server. Any thoughts on why the device would not be picking up a new IP address when it changes from one VLAN to another. Any help is appreciated.

One additional question as well on the IP Directed-Broadcast statement. Is this required on each VLAN in order to make DHCP work properly or should I have the No IP Directed-Broadcast statement configured?

Jo

3 REPLIES
Cisco Employee

Re: Question on DHCP Relay and VLANs

What software version are you running on the 4507R? Do you have helper addresses configured under the VLAN interfaces? If not, can you try with helper address? Also the following page should help

http://www.cisco.com/warp/public/473/100.html

New Member

Re: Question on DHCP Relay and VLANs

I'm running version 12.1.13EW1 . I do have the helper address assigned to all the VLAN interfaces as well.

Jo

New Member

Re: Question on DHCP Relay and VLANs

I have seen this problem with NT4.0 clients. The problem is with Microsoft. If you you issue the release command before you move the client to another Vlan things should work fine. The problem has been fixed in 2000 and XP.

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