DHCP Relay and IP Scopes

  • Thread starter Thread starter T Shilo
  • Start date Start date
T

T Shilo

Hi,
My network looks like this

R1,R2,R3 - Devices (similar to routers) with a class C behind them
R4 - Another device, with 4 physical ports, three of them connected to R1,R2,R3
R4's fourth physical port connects to a network with a DHCP server (Win2k) in it.

The goal: PCs behind R1-R3 will issue a DHCP request which will be relayed
by the relevant Rx to the DHCP server.

Problem: How can the DHCP server assign three different scopes ?

Optimally, I would like to tell the server: If the relay is done by R1
use scope1, etc. I couldn't find anything like it.

Any other solution ?
Are there DHCP servers out there that can do the job ?

TIA
 
If you configure the routers 1, 2, and 3 to relay dhcp requests to the DHCP
server, they will add their address to the GIADDR field of the DHCP packets
so the DHCP server will know which scope to use. You need no extra
configuration on the DHCP server.

--

Thanks,
Marc Reynolds
Microsoft Technical Support

This posting is provided "AS IS" with no warranties, and confers no rights.
 
So, what you are saying, is that if I configure scopes 1.1.1.0/24 and
2.2.2.0/24 and router A is 1.1.1.1 and B is 2.2.2.1 then the allocations
would be done accordingly ?
How does this "magic" happen ?
Is this some internal logic of the DHCP server ?
Anywhere you can point me in official documenation ?

What happens if A is 3.3.3.1 ? Which address is chosen for the allocation ?
 
Yes.
There's no "magic" it the design of DHCP.
Yes, it is written to work this way
120932 DHCP: Spanning Multiple Subnets
http://support.microsoft.com/?id=120932

If you have a scope for 3.3.3.x an address will be assigned.

Remember you also need to configure routers to do DHCP relay (or Bootp
relay).

--

Thanks,
Marc Reynolds
Microsoft Technical Support

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


T Shilo said:
So, what you are saying, is that if I configure scopes 1.1.1.0/24 and
2.2.2.0/24 and router A is 1.1.1.1 and B is 2.2.2.1 then the allocations
would be done accordingly ?
How does this "magic" happen ?
Is this some internal logic of the DHCP server ?
Anywhere you can point me in official documenation ?

What happens if A is 3.3.3.1 ? Which address is chosen for the allocation ?


"Marc Reynolds [MSFT]" <[email protected]> wrote in message
If you configure the routers 1, 2, and 3 to relay dhcp requests to the DHCP
server, they will add their address to the GIADDR field of the DHCP packets
so the DHCP server will know which scope to use. You need no extra
configuration on the DHCP server.

--

Thanks,
Marc Reynolds
Microsoft Technical Support

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


(Win2k)
in it.
Click to expand...
Click to expand...
 
If the routers do not support bootp or relay agents, you can configure RRAS
on a 2K or 2K3 server on each subnet to do this.

Marc Reynolds said:
Yes.
There's no "magic" it the design of DHCP.
Yes, it is written to work this way
120932 DHCP: Spanning Multiple Subnets
http://support.microsoft.com/?id=120932

If you have a scope for 3.3.3.x an address will be assigned.

Remember you also need to configure routers to do DHCP relay (or Bootp
relay).

--

Thanks,
Marc Reynolds
Microsoft Technical Support

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


T Shilo said:
So, what you are saying, is that if I configure scopes 1.1.1.0/24 and
2.2.2.0/24 and router A is 1.1.1.1 and B is 2.2.2.1 then the allocations
would be done accordingly ?
How does this "magic" happen ?
Is this some internal logic of the DHCP server ?
Anywhere you can point me in official documenation ?

What happens if A is 3.3.3.1 ? Which address is chosen for the
Click to expand...
allocation
?


"Marc Reynolds [MSFT]" <[email protected]> wrote in message
If you configure the routers 1, 2, and 3 to relay dhcp requests to the DHCP
server, they will add their address to the GIADDR field of the DHCP packets
so the DHCP server will know which scope to use. You need no extra
configuration on the DHCP server.

--

Thanks,
Marc Reynolds
Microsoft Technical Support

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


Hi,
My network looks like this

R1,R2,R3 - Devices (similar to routers) with a class C behind them
R4 - Another device, with 4 physical ports, three of them connected to
R1,R2,R3
R4's fourth physical port connects to a network with a DHCP server (Win2k)
in it.

The goal: PCs behind R1-R3 will issue a DHCP request which will be relayed
by the relevant Rx to the DHCP server.

Problem: How can the DHCP server assign three different scopes ?

Optimally, I would like to tell the server: If the relay is done by R1
use scope1, etc. I couldn't find anything like it.

Any other solution ?
Are there DHCP servers out there that can do the job ?

TIA
Click to expand...
Click to expand...
Click to expand...
 
Hello All,

Yes you can have a RRAS server as a DHCP relay agent.

232703 How to Use DHCP to Provide Routing and Remote Access Clients with
http://support.microsoft.com/?id=232703



Shane Brasher
MCSE (2003,2000,NT),MCSA Security, N+, A+
Microsoft Platforms Support
Windows NT/2000 Networking
 
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