Running Windows 2008 DHCP with 2 seperate scopes on the same physical network
Hi ,
I'm in the process of changing our company internal network from a public IP scheme to a private IP scheme. The reason for the change is that im installing a new windows 2008 sbs server as the domain controller replacing a linux DHCP server. How do i get windows 2008 DHCP to give the old IP scheme to specified clients and for all the other clients give them the new IP scheme?
Here's what ive tried so far. I have setup 2 scopes in DHCP below:
Old public scheme on 192.34.98.x
New private scheme on 192.168.50.x
I've noted all the clients MAC addresses which need to be on the old IP scheme and entered reservations under 192.34.98.x scope. However, the clients with reservations still receive ips from the 192.168.50.x scope, any ideas why? all clients are on the same physical network.
If the clients dont have a IP reservation under 192.34.98.x i want them to receive a 192.168.50.x scheme. How can i achieve this?
Any suggestions are welcome.
I'm in the process of changing our company internal network from a public IP scheme to a private IP scheme. The reason for the change is that im installing a new windows 2008 sbs server as the domain controller replacing a linux DHCP server. How do i get windows 2008 DHCP to give the old IP scheme to specified clients and for all the other clients give them the new IP scheme?
Here's what ive tried so far. I have setup 2 scopes in DHCP below:
Old public scheme on 192.34.98.x
New private scheme on 192.168.50.x
I've noted all the clients MAC addresses which need to be on the old IP scheme and entered reservations under 192.34.98.x scope. However, the clients with reservations still receive ips from the 192.168.50.x scope, any ideas why? all clients are on the same physical network.
If the clients dont have a IP reservation under 192.34.98.x i want them to receive a 192.168.50.x scheme. How can i achieve this?
Any suggestions are welcome.
James
Configure the lease on the 2 scopes this should work and also the range on the 2 scopes.
ASKER
by lease, do you mean reservation?
Yes.
ASKER
I'm sorry, I'm a little confused, I can't configure the lease on the 2 scopes. I've added the reservation to 192.34.98.222 to scope 192.34.98.x, it works fine. However, when I add reservation 192.34.98.222 to scope 192.168.98.x i receive the error "the specified DHCP client is not a reserved client".
Why would I want to configure the lease to the 2 scopes anyway? If the reservation is on 192.34.98.x scope i want dhcp to give the client its IP from the reservation. If there is no reservation on this scope, I want it to give a lease from the 192.168.50.x scope.
Why would I want to configure the lease to the 2 scopes anyway? If the reservation is on 192.34.98.x scope i want dhcp to give the client its IP from the reservation. If there is no reservation on this scope, I want it to give a lease from the 192.168.50.x scope.
I'm not sure if you'll be able to get this to work.
Having two DHCP servers advertising different subnets on the same physical network is going to cause the issues you've described.
The only suggestions I can think of, is investigating the use of Network Access Protection to restrict who is able to get an IP from the scope or having two DHCP servers and use MAC filtering to prevent them from obtaining a DHCP lease from the "wrong" DHCP server.
Both of these options (particular the NAP option) require a fair amount of configuration, so therefore may not be a viable solution.
Having two DHCP servers advertising different subnets on the same physical network is going to cause the issues you've described.
The only suggestions I can think of, is investigating the use of Network Access Protection to restrict who is able to get an IP from the scope or having two DHCP servers and use MAC filtering to prevent them from obtaining a DHCP lease from the "wrong" DHCP server.
Both of these options (particular the NAP option) require a fair amount of configuration, so therefore may not be a viable solution.
ASKER
We will have only one Windows 2008 DHCP server that will have the 2 scopes. There will be no other DHCP server on the network.
In DHCP the default lease time is 8 days. What you need to do is on the one of the PCs that you created a Reservation on the DHCP Server, is open the command prompt and then type ipconfig /release and then press enter and then type ipconfig /renew. See does the PC get the new IP address that you assigned on the DHCP Server. If this does not work, try clearing ARP cache on the PC. You can do this by right clicking on the Local Area Connection and select Repair, of from the command prompt type arp -d.
ASKER
Here's a table showing an example client showing the networks it was connected too and the reservations entered in the DHCP scopes and the ip received from the DHCP. As you can see as soon as a reservation is entered in 192.34.98.x scope, it takes presedence over the 192.168.50.x scope.
Address Given Client connected to LAN 50.x client connected to LAN 98.x Reservation on 50.x Reservation 98.x 192.168.50.110 yes no 192.168.50.110 no 192.34.98.2 yes yes 192.168.50.110 no 192.34.98.250 yes yes 192.168.50.110 192.34.98.250 192.34.98.250 yes yes no 192.34.98.250 192.34.98.250 no yes no 192.34.98.250
Address Given Client connected to LAN 50.x client connected to LAN 98.x Reservation on 50.x Reservation 98.x 192.168.50.110 yes no 192.168.50.110 no 192.34.98.2 yes yes 192.168.50.110 no 192.34.98.250 yes yes 192.168.50.110 192.34.98.250 192.34.98.250 yes yes no 192.34.98.250 192.34.98.250 no yes no 192.34.98.250
ASKER
If the clients dont have a IP reservation under 192.34.98.x i want them to receive a 192.168.50.x scheme. How can i achieve this?
ASKER
heres the spread sheet with the details.
DHCP-lease-details.xlsx
DHCP-lease-details.xlsx
ASKER CERTIFIED SOLUTION
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What I was trying to explain to you in my previous comment is that when a PC is given an IP address is holds on that IP address for 8 days which is the default period. It was not try to renew it's lease until half through it's lease. That's why I suggesting that you release the ip address and then renew the ip address ok?
ASKER
Thanks for your replys, its a apreciated!
OK, i think i understand you. Let me re-phrase it in my own words:
Make sure all IPs in 192.168.1.1 - 192.168.1.50 scope have reservations. Then the DHCP server will relise there are no more ips to give out in that scope so it will start to give out ips in the 192.168.2.1 - 192.168.2.50 scope?
I understand about the IP lease time period. I will instruct all users to switch off their machines at night and then switch it on again in the morning so they are forced to re-contact the DHCP server.
OK, i think i understand you. Let me re-phrase it in my own words:
Make sure all IPs in 192.168.1.1 - 192.168.1.50 scope have reservations. Then the DHCP server will relise there are no more ips to give out in that scope so it will start to give out ips in the 192.168.2.1 - 192.168.2.50 scope?
I understand about the IP lease time period. I will instruct all users to switch off their machines at night and then switch it on again in the morning so they are forced to re-contact the DHCP server.
Correct!
You can also set exclusions on the addresses that you are using for Reservations so DHCP will not give these addresses as oppose to creating 2 scopes. This is the other option you have.