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New Member

DHCP for different VLANS

Hi All,

I have a issue with dhcp clients communicating with DHCP server on windowds 2003.

Layer 3 switch is configured with IP helper to forward request to DHCP server on /24 subnet users can get IP address from dhcp server when they are in particulae vlan but when a user moves from one vlan to other user is not getting IP address from dhcp server,Can anyone help me out here....


Re: DHCP for different VLANS

How do you have your DHCP scopes set up?

Where exactly did you put the IP-Helper command?

You could also try running Ethereal on one of the affected clients to see how much of the DHCP dialog is being completed.

Let us know



Re: DHCP for different VLANS

New Member

Re: DHCP for different VLANS

Sorry for the reply posting... Look at the link from previous post (jackyoung).


Re: DHCP for different VLANS

sounds like perhaps you have an 'ip helper' on the one subnet,, but maybe not on the other subnet/interface where a PC is moved to.

every router interface/subnet that needs to forward DHCP requests must be configured with an IP Helper command. if you have one dhcp server and 10 different subnets that use that server, then you will have at least 9 subnets/interfaces that require the IP Helper command.

put the same IP Helper command on the router subnet/interface where you have a PC that does not get an address. (of course, this requires that you have a DHCP Scope defined for this subnet, on the dhcp server)

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