DHCP Problem

I have a strange DHCP server issue...Let me explain the current setup...
I have 4 subnets:
172.21.136.0/24, 172.21.137.0/24, 172.21.138.0/24, 172.21.139.0/24
There is a DHCP server 172.21.136.21 (Windows 2003 Server). All subnets are
connected to workgroup
switches and these switches are connected to Layer-3 switches that also
perform the task of routing.
I have created 4 scopes for these 4 subnets with respective scope options.
DHCP relay agent is enabled on the Layer-3 switch so that this single DHCP
server can provide IP addresses
to clients.

Apart from these, we have few more subnets in another building connected
through metro-ethernet link of 6MBPS.
Subnets on other building are:
159.217.58.0/24, 139.54.132.0/24, 159.217.103/24
Now, what my problem is: sometimes my client get IP addresses from DHCP
server of 159.217.103.0 subnet,
sometimes from some other subnet in the intranet, i believe that im not
aware of (like 192.168.0.0/24).

I also periodically checks to make sure that scopes have enough IP addresses
to lease to clients.
How do I make sure that my clients gets IP from DHCP server here
(172.21.136.21)?

Thanks in advance for your kind reply.
Should you require any more input from me, do let me know...
Umesh

ptwilliams
Mon Mar 21 17:28:45 CST 2005

If I'm following your scenario correctly, you've multiple DHCP servers (one
each side of a L3 switch) and a relay. I would say you either don't need
the relay or the second DHCP server.

DHCP will bind to the first IP address of each NIC, and will provide
addresses to that range. Why do you need the second server if you have the
first with the multiple NICs and a relay?


--

Paul Williams

http://www.msresource.net/
http://forums.msresource.net/

UmeshThakur
Mon Mar 21 21:11:04 CST 2005

No, There is only 1 DHCP server with IP of 172.21.136.21.
Layer-3 switch is working as DHCP Relay agent relaying DHCP messages
between all 4 subnets. I dont have any other DHCP server in my network.


"ptwilliams" wrote:

> If I'm following your scenario correctly, you've multiple DHCP servers (one
> each side of a L3 switch) and a relay. I would say you either don't need
> the relay or the second DHCP server.
>
> DHCP will bind to the first IP address of each NIC, and will provide
> addresses to that range. Why do you need the second server if you have the
> first with the multiple NICs and a relay?
>
>
> --
>
> Paul Williams
>
> http://www.msresource.net/
> http://forums.msresource.net/
>
>
>

Athif
Mon Mar 21 23:40:11 CST 2005

Hi,
If you dont have other DHCP Server, then how is the client getting the
IP Address automatically outside of the scope of the only DHCP Server??

Good day,
Mohammed Athif Khaleel.

Todd
Tue Mar 22 00:45:03 CST 2005

The clients get a DHCP address lease from the first DHCP server which
replies. You may rogue DHCP servers on your network.

From a workstation that is receiving the wrong IP, run ipconfig /all (Or
winipcfg from 9x) and check the DHCP server. Use nbtstat -a to identify the
machine name and who is currently logged on to it. Alternatively use the
dhcploc.exe utility from the NT Resource Kit.

--
Todd J Heron, MCSE
Windows Server 2003/2000/NT; CCA
----------------------------------------------------------------------------
This posting is provided "as is" with no warranties and confers no rights.

Paul
Tue Mar 22 07:48:49 CST 2005

From what it sounds like to me the DHCP relay agent (Router) should only be
forwarding requests to the Windows dhcp server from the Windows sub-nets.
You make it sound like the relay agent is forwarding it to more than 1 DHCP
server. As far as I know the client is going to take the first offer given.

Look at the relay agent to resolve it.

--

Paul Bergson MCT, MCSE, MCSA, CNE, CNA, CCA

This posting is provided "AS IS" with no warranties, and confers no rights.



"Umesh Thakur" <UmeshThakur@discussions.microsoft.com> wrote in message
news:A8A03169-B58E-4148-BCB2-6DD8E361BCF1@microsoft.com...
> I have a strange DHCP server issue...Let me explain the current setup...
> I have 4 subnets:
> 172.21.136.0/24, 172.21.137.0/24, 172.21.138.0/24, 172.21.139.0/24
> There is a DHCP server 172.21.136.21 (Windows 2003 Server). All subnets
are
> connected to workgroup
> switches and these switches are connected to Layer-3 switches that also
> perform the task of routing.
> I have created 4 scopes for these 4 subnets with respective scope
options.
> DHCP relay agent is enabled on the Layer-3 switch so that this single DHCP
> server can provide IP addresses
> to clients.
>
> Apart from these, we have few more subnets in another building connected
> through metro-ethernet link of 6MBPS.
> Subnets on other building are:
> 159.217.58.0/24, 139.54.132.0/24, 159.217.103/24
> Now, what my problem is: sometimes my client get IP addresses from DHCP
> server of 159.217.103.0 subnet,
> sometimes from some other subnet in the intranet, i believe that im not
> aware of (like 192.168.0.0/24).
>
> I also periodically checks to make sure that scopes have enough IP
addresses
> to lease to clients.
> How do I make sure that my clients gets IP from DHCP server here
> (172.21.136.21)?
>
> Thanks in advance for your kind reply.
> Should you require any more input from me, do let me know...
> Umesh
>