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Running DHCP in two locations

ahmad1467 asked
Currently my company has two sites, site A and site B these sites are connected wirelessly and have their own subnet. My site B gets its DHCP from site A, what I want to do is add a DCHP server to my site B so that the users in site get DHCP in site B. Is it possible to have both DHCP servers running?
If I can do this can I still leave DNS where it is which is site A?
The way that I think this would work is disable that scope for site B in my site A DHCP scope and only add that scope to my DHCP scope in site B. I am running Windows 2003 Server Standard in both sites, does this sound doable?

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Kent WSr. Network / Systems Admin

It will work fine, as long as you are not using the same IP network, or, they are at least separated by NAT.
Sounds like you somehow site B talking to the DHCP server at site A, so, it depends really on how these two networks are connected.  Do they share data / servers / mail, etc. that is located at either site A or B?

I would say hes probably using DHCP Relay for the remote network.. Disable it and then you should be set

Also there would have to be a second scope in the DHCP server for the remote subnet.. Delete the scope and then turn on DHCP locally for remote network


The way they are connected is in Site A I have a Windows 2003 that also runs my Firewall, on this Server I have Physical NIC cards connected with different subnets which are plugged into switch ports that are Tagged for different VLANS, example the Site A subnet is connected to VLAN11 and Site A subnet is connected to VLAN16 so these cards are the gateways. Site B gets does share Data with Site A and gets its internet from Site A, Site B gets everything from site A.  These connections are bridged by the wireless connections.
You will also want to copy the DHCP database from site A to site B so you can retain the DHCP leases and not run into a duplicate IP problem.


Then you need to turn off dhcp relay. Look at this: http://www.computerperformance.co.uk/w2k3/services/DHCP_Relay_Agent.htm


I already deleted the Site  B Scope From my Site A Windows DHCP server  it wasn’t being  used for Site B,  Site B was getting its address from the DHCP on the firewall witch I’m turning off so that I can use the Windows DHCP but after looking at your message I see something  about the use of DHCP relay this kind of seems like an option for me to use instead of setting up another DHCP server on Subnet B. Correct me if I’m wrong but before I started using my Firewall to serve up DHCP to Site B my Router used IP helpers that told Site B to look for DHCP over on my DHCP server in Site A. I found an article about DHCP Relay at http://technet.microsoft.com/en-us/library/cc758865(WS.10).aspx
that sounds like it’s doing the same thing my router did before we took it out of the configuration. What do you think?

I use it now, 5 scopes, 5 vlans, some of the vlans cross over, some dont.


I got DHCP to work in my site B but my scope options are not working like they should.

The reason for me using Windows DHCP is because I am running VOIP phones and some of my users have PCs that plug into the phone, all my IP phones are on the same Subnet in Site A and B but for data thy have different  subnets controlled by VLANs. In my Scopes I use Scope options 176 and 242 which allow my phones and PCs to use DHCP. It works in Site A but not Site B Site I can only get DHCP for the phones coming of the port if it It’s untagged for that VLAN. Do think this is because I only have the Data VLAN scope on my Site B DHCP Server?

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