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Cisco ip helper address doesn't work for DHCP Packets

Last Modified: 2015-08-03
Hi Guys,
I have a Cisco 3750 Stack.
My goal is to change the IP range for Vlan1.

OLD IP RANGE:  (current)
NEW IP RANGE: (new IP range)

I just configured the following

interface Vlan1
 ip address secondary
 ip address
 ip helper-address

I have a new DHCP Server in the server (Vlan88) giving out IP addresses in the IP range that works, I have tested it with  a test vlan and connected a test computer to the test port and the ip helper worked on that test.

Now I disabled the current DHCP Server in Vlan1 (production environment) that is giving out IP addresses in the range ( and added the ip helper line as shown in the configuration above.

But this time it didn't work, meaning that none of the computers in vlan1 were able to see the DHCP Server.

Now that I'm writing this I'm thinking that it could be that the is a secondary IP address in Vlan1, may be it needs to be the primary IP address of that Vlan1 so that the DHCP Server identifies that the computers in Vlan1 can receive IPs in the range. But all this are just ideas.

Can somebody please shed some light on this issue?

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