VLAN & DHCP server

Simon Hobson dhcp1 at thehobsons.co.uk
Thu Dec 13 08:13:59 UTC 2007

Suhaime Raeze wrote:

>Im new at configuring dhcp server for vlan. I tried to find sources 
>from the net and there are various ways which i admit is too 
>complicated or i couldnt comprehend the instructions.
>I using the 3COM 5500G as the vlan switch  and intend to use one (1) 
>linux server as the DHCP server for the whole network. The plan is 
>that my organization should have 4 vlans and all the dhcp request 
>should come from the dhcp server
>Question is whats the step-by-step to implement this? Any help, 
>guides, URl is appreacited

You don't "configure dhcp for vlan", you simply configure your dhcp 
server for the network - the vlans are irrelevant. As for any real 
(not virtual) lan, you simply need to :

a) properly define the subnet for dhcp server.
b) either directly attach the subnet to the server or install a relay 
agent in the subnet.

So you can either install a relay agent in each vlan (may be a 
function of some vlan capable kit), or you simply configure a vlan 
port on the dhcp server. This actually turns out to be very easy 
under Linux, and once configured, each vlan appears as a new 
interface (eg eth0.101 - NOT to be confused with a secondary IP as in 

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