dhcp config - 2 subnets on one phys net
dhcp1 at thehobsons.co.uk
Fri Sep 29 07:37:26 UTC 2006
Igor Antokhin wrote:
>Sorry for a question from a newbie, but I could not find a clear answer to
>mu problem - only pieces of the puzzle...
>I have a computer on a physical network 220.127.116.11. It runs Linux
>Fedora Core 5. It is just a client machine not providing any general
>use services like dns printing etc. Now for some reasons I want to create
>a private network for my department using the same physical ethernet.
>I understand that what I have to do is this:
The problem is that you CANNOT provide DHCP to only one of the
subnets - at least not without co-ordination with the admin of the
The problem is that even though you can apparently run two interfaces
(one 'real', one 'virtual'), DHCP relies on broadcasts which do not
respect the distinction between the subnets/interfaces.
To make it work you will have to be able to identify every client
that will be part of your private network (MAC address is usually
easiest). On your new dhcp server you will have to service ONLY those
clients and ignore all others. The admin of the existing dhcp server
will have to explicitly ignore your clients. If you don't do this
then you will have two dhcp servers fighting each other - yours will
offer a private address, the other will offer a public address, and
whichever the client decides to accept, one or other dhcp server will
reply with a NAK.
Unless you specifically want to play with the dhcp, you might be
better talking with the network admin and see if he can just set up
the dhcp for your private network on the existing server - be a whole
lot less effort overall.
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