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Question
Thursday, April 21, 2016 10:48 AM
Hi. We have a single /24 network and need to expand.
We are thinking to have a /21 network with 2046 usable IP addresses
We would like to segment this, so that we have for example printers on 192.168.0.x, phones on 192.168.1.x, network gear on 192.168.2.x, workstations on 192.168.3.x, servers on 192.168.4.x etc. You get the idea. We would like to have one DHCP server assigning all the appropriate IP addresses for appropriate clients/devices. Obviously things like servers and workstations need need to communicate.
How best to go about this? How would the DHCP server know what type of client it is, and assign an IP address in the appropriate range?
Thanks
All replies (10)
Thursday, April 21, 2016 10:58 AM ✅Answered
Hi
We would like to have one DHCP server assigning all the appropriate IP addresses >>> You should configure VLANs...
Then you can configure Dhcp relay agent,check article for "Support multiple subnets with one DHCP server by configuring DHCP relay agents"
https://technet.microsoft.com/en-us/library/cc771390.aspx?f=255&MSPPError=-2147217396
This posting is provided AS IS with no warranties or guarantees,and confers no rights. Best regards Burak Uğur
Thursday, April 21, 2016 11:42 AM
DHCP server can identify target scope for the request using either "gateway ip address" specified in request by the relay agent or by subnet of the interface that received the request. So you can either configure relay agent (ip helper) on router interfaces connected to your new networks or connect DHCP server to each new subnet directly using additional NICs on DHCP server.
Since you mention that there will be routing between all subnets, then you need to configure IP helper address on router interfaces to point to DHCP server.
Gleb.
Thursday, April 21, 2016 1:17 PM
"DHCP server can identify target scope for the request using either "gateway ip address" specified in request by the relay agent "
Where exactly do you configure this "gateway ip address"?
Thanks
Thursday, April 21, 2016 2:55 PM
Is it possible to do this with one big /21 network. ie no routing? Just one relay agent for the whole network?
Thursday, April 21, 2016 3:06 PM
Hi
We would like to have one DHCP server assigning all the appropriate IP addresses >>> You should configure VLANs...
Then you can configure Dhcp relay agent,check article for "Support multiple subnets with one DHCP server by configuring DHCP relay agents"
https://technet.microsoft.com/en-us/library/cc771390.aspx?f=255&MSPPError=-2147217396
This posting is provided AS IS with no warranties or guarantees,and confers no rights. Best regards Burak Uğur
Dİd you check the article which i provide,if you should configure VLANs,then you can configure DHcp relay agent for multiple subnets...
This posting is provided AS IS with no warranties or guarantees,and confers no rights. Best regards Burak Uğur
Thursday, April 21, 2016 4:33 PM
Still reading up on VLANs. I'm completely lost.
Thursday, April 21, 2016 5:00 PM
Hi
OK,check the article for vlan sample,
http://www.michaelriccioni.com/how-to-multiple-vlans-single-dhcp-server-multiple-dhcp-scopes-2/
and check this conversation about Multiple VLAN's using a single DHCP Server via DHCP Relay Agent,
This posting is provided AS IS with no warranties or guarantees,and confers no rights. Best regards Burak Uğur
Friday, April 22, 2016 5:21 AM
Hi tim_dk,
This article might also be of help:
Understanding relay agents:
https://technet.microsoft.com/en-us/library/cc779610(v=ws.10).aspx
Best Regards,
Anne
Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Support, contact [email protected].
Friday, April 22, 2016 9:59 AM
OK, I think understand what you're suggesting. Different devices on different VLANs, each VLAN with an IP helper/Relay Agent address of DHCP server, which has a different scope for each VLAN, thereby devices on each VLAN get an IP address from the appropriate scope, because IP helper/Relay Agent tells DHCP server the IP address of the VLAN the request came from. Is that about right?
Since I want one big network (subnet mask 255.255.248.0), will each VLAN talk to each other? Can computers on VLAN1 print to printers on VLAN2 if they are in the same subnet (within the IP range defined by the subnet mask), and without configuring any routing on the router? Do you configure a subnet mask on the each of the vlans themselves. Is it necessary/possible? Does the switch "route" between VLANs? If you did want isolated networks, would you just have a /24 network with subnet mask 255.255.255.0 on each VLAN?
You might say why do I want separate VLAN networks if everything's on the same subnet? I don't. I want separate ranges of IP addresses for each group of devices, within the same subnet, and you've suggested VLANs as a way to do it.
Thanks
Tuesday, April 26, 2016 1:57 AM
OK, I think understand what you're suggesting. Different devices on different VLANs, each VLAN with an IP helper/Relay Agent address of DHCP server, which has a different scope for each VLAN, thereby devices on each VLAN get an IP address from the appropriate scope, because IP helper/Relay Agent tells DHCP server the IP address of the VLAN the request came from. Is that about right?
Hi tim_dk,
Yes, you are right, configure different DHCP relay agents for clients in different subnets.
>Since I want one big network (subnet mask 255.255.248.0), will each VLAN talk to each other?
Different VLANs are isolated from broadcast packets, VLAN 2 can't receive broadcast packets from VLAN 1, if we want VLAN2 to communicate with VLAN 1, then we need to configure routers.
>Can computers on VLAN1 print to printers on VLAN2 if they are in the same subnet (within the IP range defined by the subnet mask), and without configuring any routing on the router?
In theory, it could, if they are in same subnets, we do not need a gateway. You may use ping command to check if they can ping each other.
Best Regards,
Anne
Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Support, contact [email protected].