Switch & AP configuration problem with DHCP

[A.K.M. Sayeed]

I am using more than 15 of Cisco switches in my office. Till yesterday we used to have only one DHCP scope on our Windows 2003 DHCP server an that is 145.17.59.0/24, Start Ip: 145.17.59.31; End IP: 145.17.59.254.

We dont have any other VLN configured on my swtiches and APs expect the default VLAN1. Beyond that the DHCP scope has already been finished. Yesterday I have defined another DHCP scope in my DHCP server that is 152.108.52.0/25.

Now the problem is Whenever I connect a host to the Switch or AP it gets IP from first scope that is 145.17.59.0 but not from second scope 152.109.52.0/25. So then If I want a host to get IP from secondary scope what should I do or configure on Cisco switches or APs?

Please help.

[Kasiraman S]

Hi Sayeed,

I believe the DHCP server is also in the Vlan 1. The new subnet you asigned in DHCP server belongs to different VLAN.

Ok, here are the question for you.

Have you assigned the appropriate VLAN (not VLAN 1) to the ports that you would to get the 152.X.Y.Z IP?

If the DHCP server and the DHCP client are in different VLAN then the switch does not send the broadcast to the another VLAN to get to the DHCP server.

Have you configured the defauly Gateway for the VLAN X (152.108.52.0/25) and placed the  "ip helper address " configuration to convert the broascast into unicast and forward the DHCP discover to the DHCP server in the other VLAN ?

Eg:

inter vlan 1

ip add 145.17.59.1 255.255.255.0

inter vlan X

ip add 152.108.52.1 255.255.255.128

ip helper-address

Thanks,
Kasi