Running out of IP addresses

[xearow]

Hey guys, as the title says I am running out of IP addresses on my network. Our DCHP server is ran by a windows 2012 R2 server, and we have a single domain and right now our subnet mask is 255.255.255.0 and our ip range on the scope we currently have set up is 192.168.0.30-245 (with 1-29 being static devices [like printers, sonic walls, etc], same with the numbers above 245).

 

What would be the best way to increase the number of IP addresses we have? I've been trying to learn about changing the subnet masking and all that but I seem to be falling short on how it all....connects.

[Skiiwee29]

Should be able to add a 2nd DHCP pool in there. 

[xearow]

2 minutes ago, Skiiwee29 said:

Should be able to add a 2nd DHCP pool in there. 

What would this be? Do you have any articles you could link on how to do this/what exactly that would do?

[Mbowen]

8 minutes ago, Skiiwee29 said:

Should be able to add a 2nd DHCP pool in there. 

Either this or add a new subnet and organize your devices. 

[xearow]

1 minute ago, Mbowen said:

Either this or add a new subnet and organize your devices. 

And how exactly would I be able to go about doing this?

[scotartt]

can you make your subnet mask a /16 instead of a /24 (i.e. 255.255.0.0 not 255.255.255.0) ?

 

Then you've got 65,000 IP addresses.

[xearow]

For reference, this is what I'm looking at right now, and I'm not entirely sure Which properties need to be changed, what needs to be added, and so forth for anything to end up working.

[scotartt]

yeah, sorry man, windows ... i've got no idea.

[Lurick]

Unfortunately there isn't a quick and simple answer. Microsoft does have an article about this that outlines a few options though:

https://support.microsoft.com/en-us/help/255999/increasing-the-number-of-ip-addresses-on-a-subnet-in-dhcp-server

[xearow]

10 minutes ago, Lurick said:

Unfortunately there isn't a quick and simple answer. Microsoft does have an article about this that outlines a few options though:

https://support.microsoft.com/en-us/help/255999/increasing-the-number-of-ip-addresses-on-a-subnet-in-dhcp-server

Thanks Lurick, I'll read into this. Looks like it's going to be a bigger project than initially anticipated, but that's alright.

[leadeater]

4 hours ago, xearow said:

Thanks Lurick, I'll read into this. Looks like it's going to be a bigger project than initially anticipated, but that's alright.

Expanding a DHCP scope always is because there are a lot of steps you have to take care of to get it done correctly without breaking connectivity for devices.

 

First I would decrease your DHCP lease time to something very short, then go to all your static devices and update their subnet mask to 255.255.254.0 which is safe to do so, then on your DHCP server configure reservations for each of your static devices (you need their MAC addresses) so these will not be handed out and I find this better than range exclusions, now for the DHCP scope change the subnet mask to 255.255.254.0 and range to 192.168.0.30 - 192.168.1.245. Now put your DHCP lease time back to something longer/more standard.

[tech.guru]

at a certain point having a flat network you will run into issues.

you should setup subnets,

 

i would switch to a bigger address space

 

if i were you i would setup

      server vlan -  network 10.100.1.0  subnet 255.255.255.0 gw 10.100.1.1 (static)

      multiple client vlan - 

                           network 10.10.1.0 subnet 255.255.255.0 gw 10.10.1.1  (dhcp)

                           network 10.10.2.0 subnet 255.255.255.0 gw 10.10.2.1 (dhcp)

 

then you can from the dhcp server setup multiple scopes for client vlans

               10.10.1.0

                10.10.2.0

 

afterwards, use ip helpers to forward the dhcp broadcasts from the client vlans to the dhcp server.

yes its a big project but at a certain point you need to use subnets take the pain now