DHCP Server

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I got a DHCP server serving 2 subnets (192.168.1.0 & 192.168.2.0) I got a client now running Win XP and i wanted to know how do you make sure that the client gets an IP from the 2.0 range and not the 1.0 like it is?

Make any sense?

Thanks guys

 

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That's easy on Debian - but you didn't want to know that I suspect!

Can't help with Windows servers.

Harry.

 

What subnet is the servers address on?

Not sure, if you can specify which subnet the client takes the address from unless you specify it in a reservation.

 

Im trying to get linux out of my head! Seriously how is it done? Lets say i put them into a superscope and the above happens? And no reserving the MAC address!

 

You all agree a DHCP Server and serve 2 subnets right? - is the correct word remote multinets?

 

if anyone has the MS Press 291 book - 1st edition look at pages 7-26 to 7-30... maybe im not understanding something correctly...

 

That's how I would have done it!

My personal view is that trying to do this 'nicely' is a mistake in network design. Each network should have its own DHCP server.

Harry.

 

so there is no way a DHCP can serve 2 subnets and give specific IP's to specific clients?

 

Zimbo,

Looking around it seems exactly as Harry has already said - one DHCP server per subnet.

I did stumble across this article for this URL;

Q. If a physical LAN has more than one logical subnet, how can different groups of clients be allocated addresses on different subnets?

A. One way to do this is to preconfigure each client with information about what group it belongs to. A DHCP feature designed for this is the user class option. To do this, the client software must allow the user class option to be preconfigured and the server software must support its use to control which pool a client's address is allocated from.

Si

 

It *is* possible for one DHCP server to handle multiple subnets, but you have to have a physical interface on each subnet.

Harry.

 

I see.
I suppose this is one of the many things that crop up for the exams/theory that is not always practical in a business networked environment.

Si

 

Ok so lets say our DHCP server has 2 NIC's one for each subnet. So the DHCP Server has the IP address 192.168.1.10 and 192.168.2.10.

Now how is it done? Is the relay agent going to come into play now?

 

In the dhcpd.conf file (I'm talking Unix here) you enter the range of addresses that can be handed out on each subnet, along with the IP address of the server on that subnet. Then if a NIC gets a DHCP request it must be on that subnet!

Harry.

 

it still doesnt make sense to me! Throughout this book there is mention of a DHCP Server serving more than one subnet - i still dont understand how the DHCP Server gives the correct address to the correct client?

 

OK - try a little fragment from dhcpd.conf:

subnet 192.168.1.10 netmask 255.255.255.0 {
range 192.168.1.32 192.168.1.63;
}

subnet 192.168.2.10 netmask 255.255.255.0 {
range 192.168.2.32 192.168.2.63;
}

Now when a request comes in on (say) the .2 network the server matches that against the subnet statement, and uses the range from that section.

Harry.

 

Zimbo,

Came across this - see what you think.

Si

Edit;

Replying at same time as Harry.

 

thanks harry but in the Windows World? This is a concept im seeing now that im studying for 291 otherwise i would have laid to rest long ago with your Unix solution! One day we will do it your day too!

 

Looks like the three of us were typing at the same time! Zimbo - have you seen the link ^ above ?

Si

 

here is some light in the tunnel!

now there isnt much in the book on this so im going to try do it quickly here on my lab also something about relay agents!

cheers si! lets see what we can do...

 

Interesting. I've not had much experience of DHCP forwarding, so didn't know how it worked. Most illuminating. Thanks.

Harry.