DHCP / RELAY AGENT for 3 Networks

The new network in our new office has 3 segments to it. I need to have 1 dhcp
server that can provide ip's for 3 seperate networks. Each network is
segmented on our catalyst cluster via VLAN. We have setup VLANS to point DHCP
traffic using cisco ip helper but I need to know how to setup the DHCP server
to hand out IP's to the proper VLAN based upon where the request is coming
from in the network.

Can Windows 2000/2003 DHCP and DHCP Relay agent help me dish out IP's in
this manner? I have skeched an a little diagram of how I think it should work
on the Windows side. represented by users 0, 1 and 2 which are all from
different networks and need to optain an IP from a single windows 2X machine
that will assign the proper IP based upon location in the network.


(E-Mail Removed) (E-Mail Removed) (E-Mail Removed)
| | |
VLAN1 VLAN2 VLAN3
--------------Catalyst 2950 X 8 ----------------
|
|
Win2X DHCP
Scope1 10.0.2X assigned to VLAN 1

Scope2 10.0.3.X assigned to VLAN2

Scope 3 10.0.4.X assigned to VLAN3


--
Devin M.
Network Engineer

No takers on this project? No comments? No thoughts? Surely someone must know
the answer to this question!
--
Devin M.
Network Engineer
Digital Planet
Detroit, MI.


"Devin M." wrote:

> The new network in our new office has 3 segments to it. I need to have 1 dhcp
> server that can provide ip's for 3 seperate networks. Each network is
> segmented on our catalyst cluster via VLAN. We have setup VLANS to point DHCP
> traffic using cisco ip helper but I need to know how to setup the DHCP server
> to hand out IP's to the proper VLAN based upon where the request is coming
> from in the network.
>
> Can Windows 2000/2003 DHCP and DHCP Relay agent help me dish out IP's in
> this manner? I have skeched an a little diagram of how I think it should work
> on the Windows side. represented by users 0, 1 and 2 which are all from
> different networks and need to optain an IP from a single windows 2X machine
> that will assign the proper IP based upon location in the network.
>
>
> (E-Mail Removed) (E-Mail Removed) (E-Mail Removed)
> | | |
> VLAN1 VLAN2 VLAN3
> --------------Catalyst 2950 X 8 ----------------
> |
> |
> Win2X DHCP
> Scope1 10.0.2X assigned to VLAN 1
>
> Scope2 10.0.3.X assigned to VLAN2
>
> Scope 3 10.0.4.X assigned to VLAN3
>
>
> --
> Devin M.
> Network Engineer
>

"Devin M." <(E-Mail Removed).(hold-the-spam)> wrote in message
news:09587A88-79BC-4836-A487-(E-Mail Removed)...
> No takers on this project? No comments? No thoughts? Surely someone must
know
> the answer to this question!

I never saw the question till now. We don't always see it
"instantly",...this stuff isn't "live", it is not a "chat".
We're overworked and underpai....er,...not paid at all. :-)

All you do is create a separate, distinct, independent Scope for each subnet
on the DHCP Server. No Superscopes!,...those are only for multi-netting and
VLANs are not multi-nets even thought they may physically look like they
are.

If the router forwards the queries properly then all is well,...that is all
there is to it,...you are done.

--
Phillip Windell [MCP, MVP, CCNA]
www.wandtv.com
-----------------------------------------------------
Understanding the ISA 2004 Access Rule Processing
http://www.isaserver.org/articles/IS...cessRules.html

Microsoft Internet Security & Acceleration Server: Guidance
http://www.microsoft.com/isaserver/t...dance/2004.asp
http://www.microsoft.com/isaserver/t...dance/2000.asp

Microsoft Internet Security & Acceleration Server: Partners
http://www.microsoft.com/isaserver/partners/default.asp
-----------------------------------------------------

Hey thanks Phil, I didn't mean to be snappy but I am a little under the gun
since we let our Linux guy go and this would normally be on him. Ok so this
DHCP server is sitting in one of the VLANs and the Catalysts are set to pass
DHCP requests to this one box, how does this single Windows Server know which
scope to parse out IP's to which VLAN network? Do I not have to set an
identifier somehow that scope 1 responds only to requests from this VLAN and
so on? And do I need to run relay agent at all? Any detailed as possible help
is most appreciated!~

Many Thanks

Devin M.
Network Engineer
Digital Planet
Detroit, MI.


"Phillip Windell" wrote:

> "Devin M." <(E-Mail Removed).(hold-the-spam)> wrote in message
> news:09587A88-79BC-4836-A487-(E-Mail Removed)...
> > No takers on this project? No comments? No thoughts? Surely someone must
> know
> > the answer to this question!
>
> I never saw the question till now. We don't always see it
> "instantly",...this stuff isn't "live", it is not a "chat".
> We're overworked and underpai....er,...not paid at all. :-)
>
> All you do is create a separate, distinct, independent Scope for each subnet
> on the DHCP Server. No Superscopes!,...those are only for multi-netting and
> VLANs are not multi-nets even thought they may physically look like they
> are.
>
> If the router forwards the queries properly then all is well,...that is all
> there is to it,...you are done.
>
> --
> Phillip Windell [MCP, MVP, CCNA]
> www.wandtv.com
> -----------------------------------------------------
> Understanding the ISA 2004 Access Rule Processing
> http://www.isaserver.org/articles/IS...cessRules.html
>
> Microsoft Internet Security & Acceleration Server: Guidance
> http://www.microsoft.com/isaserver/t...dance/2004.asp
> http://www.microsoft.com/isaserver/t...dance/2000.asp
>
> Microsoft Internet Security & Acceleration Server: Partners
> http://www.microsoft.com/isaserver/partners/default.asp
> -----------------------------------------------------
>
>
>
>

"Devin M." <(E-Mail Removed).(hold-the-spam)> wrote in message
news:8336BFBE-132D-4879-9AEF-(E-Mail Removed)...
> Hey thanks Phil, I didn't mean to be snappy but I am a little under the
gun
> since we let our Linux guy go and this would normally be on him.

No prob...

> DHCP server is sitting in one of the VLANs and the Catalysts are set to
pass
> DHCP requests to this one box,

Catalysts? Aren't those Layer2 Switches? That wouldn't apply,...layer2
already lets the queries pass since Layer2 is all in one subnet. It is
Layer3 Routers that have to relay the DHCP Queries since it is only the
"jump" over the subnets that the queries need the "help" with. Layer2
Switches create & acknowledge the VLANs, but they cannot "route" between the
VLANs.

> how does this single Windows Server know which scope to parse out IP's to
which
> VLAN network?

The packets created by the Router when it relays the Queries contains the
information required by the DHCP to know which Scope to pull from. It does
not require any intervention. Performing this relay has been a normal part
of the job a LAN Router does ever since DHCP was invented and the same can
be said for the DHCP Servers ability to know what to do with the packet when
it gets it.

--
Phillip Windell [MCP, MVP, CCNA]
www.wandtv.com
-----------------------------------------------------
Understanding the ISA 2004 Access Rule Processing
http://www.isaserver.org/articles/IS...cessRules.html

Microsoft Internet Security & Acceleration Server: Guidance
http://www.microsoft.com/isaserver/t...dance/2004.asp
http://www.microsoft.com/isaserver/t...dance/2000.asp

Microsoft Internet Security & Acceleration Server: Partners
http://www.microsoft.com/isaserver/partners/default.asp
-----------------------------------------------------

Hey Phillip thanks, I actually left one important part out, We have 1 3750
Layer3 Catalyst that has all the VLANs and each 2950 connected to a port on
the 3750 with DHCP relay enabled so that it will jsut pass any/all DHCP
request on to the one single DHCP server located on one of the 3 VLAN's. So
what your saying is that the DHCP server will just send the right IP's based
upon the VLAN the client is coming from then by default because the DHCP is
smart enough to know what to do without me assigning a VLAN header/identifier?

Think I got it...

Thanks!
--
Devin M.
Network Engineer
Digital Planet
Detroit, MI.


"Phillip Windell" wrote:

> "Devin M." <(E-Mail Removed).(hold-the-spam)> wrote in message
> news:8336BFBE-132D-4879-9AEF-(E-Mail Removed)...
> > Hey thanks Phil, I didn't mean to be snappy but I am a little under the
> gun
> > since we let our Linux guy go and this would normally be on him.
>
> No prob...
>
> > DHCP server is sitting in one of the VLANs and the Catalysts are set to
> pass
> > DHCP requests to this one box,
>
> Catalysts? Aren't those Layer2 Switches? That wouldn't apply,...layer2
> already lets the queries pass since Layer2 is all in one subnet. It is
> Layer3 Routers that have to relay the DHCP Queries since it is only the
> "jump" over the subnets that the queries need the "help" with. Layer2
> Switches create & acknowledge the VLANs, but they cannot "route" between the
> VLANs.
>
> > how does this single Windows Server know which scope to parse out IP's to
> which
> > VLAN network?
>
> The packets created by the Router when it relays the Queries contains the
> information required by the DHCP to know which Scope to pull from. It does
> not require any intervention. Performing this relay has been a normal part
> of the job a LAN Router does ever since DHCP was invented and the same can
> be said for the DHCP Servers ability to know what to do with the packet when
> it gets it.
>
> --
> Phillip Windell [MCP, MVP, CCNA]
> www.wandtv.com
> -----------------------------------------------------
> Understanding the ISA 2004 Access Rule Processing
> http://www.isaserver.org/articles/IS...cessRules.html
>
> Microsoft Internet Security & Acceleration Server: Guidance
> http://www.microsoft.com/isaserver/t...dance/2004.asp
> http://www.microsoft.com/isaserver/t...dance/2000.asp
>
> Microsoft Internet Security & Acceleration Server: Partners
> http://www.microsoft.com/isaserver/partners/default.asp
> -----------------------------------------------------
>
>
>
>

"Devin M." <(E-Mail Removed).(hold-the-spam)> wrote in message
news:9D8244FB-1C19-4702-BE53-(E-Mail Removed)...
> Hey Phillip thanks, I actually left one important part out, We have 1 3750
> Layer3 Catalyst that has all the VLANs and each 2950 connected to a port
on
> the 3750 with DHCP relay enabled so that it will jsut pass any/all DHCP
> request on to the one single DHCP server located on one of the 3 VLAN's.

Yes. That is identical to what we do other than we use HP Procurve Switches
with a single "central" HP 5300 Series Layer3 Switch acting as both a
central Switch and LAN Router. It forwards all DHCP Queries to two specific
DHCP Servers. It sends the queries directly to both of their IP#s. Nothig
special is done on the DCHP Servers,..they are configured identically except
for the Exclusions in each Scope to avoid duplicate addesses

> what your saying is that the DHCP server will just send the right IP's
based
> upon the VLAN the client is coming from then by default because the DHCP
is
> smart enough to know what to do without me assigning a VLAN
header/identifier?

It should be fine. I don't know what you mean with "VLAN
header/identifier", you mean the Frame Tag? I dont' think that has any
relevance, the Frame Tags don't mean anything to any other devices except
the Switches,...the Switches are the only things that even pays attention to
them,...they are ignored by everything else. Also Frame Tags are only
relevant to the Dynamic VLANS,...Static VLANS don't use them and function
soley based on which physical switch port the cable is plugged into. Most
VLAN setups are a blend of Static and Dynamic VLANs, I know it is with ours.

In any case I don't think they are relevant to DHCP functionality, but I
would highly recommend that the "wire" that the DHCP Server "lives" on is a
Static VLAN so that the DHCP Service is "solidly" recognized as being on a
particluar "segment" based on the physical switch port it is plugged into.

--
Phillip Windell [MCP, MVP, CCNA]
www.wandtv.com
-----------------------------------------------------
Understanding the ISA 2004 Access Rule Processing
http://www.isaserver.org/articles/IS...cessRules.html

Microsoft Internet Security & Acceleration Server: Guidance
http://www.microsoft.com/isaserver/t...dance/2004.asp
http://www.microsoft.com/isaserver/t...dance/2000.asp

Microsoft Internet Security & Acceleration Server: Partners
http://www.microsoft.com/isaserver/partners/default.asp
-----------------------------------------------------