Going from a /24 to a /23 subnet on LAN

[xendrome]

Hey guys,

 

Trying to work out anything before hand. But I am running out of IP address on a LAN of 172.16.50.1/24 (255.255.255.0) and want to change it to a 172.16.50.1/23 (255.255.254.0) to be at a total of 510 usable IPs.

 

My DHCP server i running on Windows Server 2008 R2 and all of the static clients are DHCP reservations, except the main router (Sonicwall), layer 3 switches and maybe a couple of other devices.

 

I have manually set my workstation to be on the 255.255.254.0 network with the existing IP it has, and communication seems fine between everything on this subnet.

 

My main question is, can I just modify the DHCP server scope to be Start IP 172.16.50.25 End IP 172.16.51.253 and apply it or do I have to delete and make a new scope? Secondary question, then will I need to quickly modify the Sonicwall, L3 switches, and anything else still using 255.255.255.0?

[+BudMan MVC]

.1/24 or .1/23 is not really a valid way to express a network.  That would be expressing a host address and its mask.

 

I think you mean your going from

 

172.168.50.0/24 to 172.16.50.0/23

 

Your going to want to modify everything to use the new mask.  Using different masks can cause you all kinds of issues - depending..  Especially when you start using the address space that is in the /23 but not in the /24.. So while say 172.16.51.14/23 would know that 172.16.50.123 is inside his network.. If you have 172.16.50.123/24 he would think that 51.14 is different network and send the traffic to its gateway.

 

As to editing scope to be /23 vs /24 - hmmm, its windows might have to create new scope.

 

So you sure you want to increase your broadcast domain, its quite often easier to just bring up the next /24 and route between devices.  Do these devices even really need to talk to each other?  Are they servers or users boxes.  Its rare to see lot of client to client traffic - so its normally simpler to just bring up a new vlan vs expanding one, etc.