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How can I get DHCP ( layer 2 ) packets to forward between vlans on a network switch ?

We have 2 vlans and need to have the DHCP server on one vlan ( 500 ) and the dhcp clients on a different vlan ( 200 ).   Is there a way to forward the packets across the vlans ?   We want the vlan with the dhcp server to be isolated from the systems requesting the services except for DNCP and DNS.

Thank you all again.

D
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itguy411
Asked:
itguy411
1 Solution
 
that1guy15Commented:
The only way to get vlans to communicate is with inter-vlan routing. you either need a layer 3 switch or a router to accomplish this.

After setting that up you can create access list to filter the traffic you want
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ngravattCommented:
on a cisco switch there is a command you can type to forward DHCP requests to a DHCP server on a different VLAN.  the command is this.

ip helper-address 10.10.10.10

as that1guy said, this has to be done on the layer 3 device.  This particular command is entered in the VLAN config mode.
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ngravattCommented:
if i remember, you are using dell switches, so refer to this page for some info on the Dell version of the helper-address command:

http://systems.cs.colorado.edu/Manuals/Dell/Dell%20Power%20Connect%206024/Dell%20Power%20Connect%206024%20CLI/ipaddres.htm
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MikeKaneCommented:
If its a Microsoft DHCP setup, you could always just use the  DHCP Relay service running on a Microsoft box to forward the packets, but this only works if the Vlans can route  to each other.  
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itguy411Author Commented:
Mike:

Good suggestion and it is good to know, however in this case the microsoft server is in the other vlan thus would never see the packet to forward it.  
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ngravattCommented:
the helper command forwards all UDP broadcasts to the indicated address.  you need to configure this on your router that connects the two vlans.
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