Running out of IP addresses - best (easiest?) way to increase available IPs in DHCP?
Posted on 2010-01-06
We have a new client that is a private school and after a recent purchase of new computers, we are several IP addresses short in our DHCP scope. Here is the setup we inherited:
Windows 2008 Server Enterprise (DC) running DHCP
DHCP Scope of 192.168.168.1 - 192.168.168.252 with .1-.75 excluded from distribution for servers, printers, etc. that need static IPs. (Realistically we don't need that many static IPs and as a short term fix could reduce that to about 50 IPs excluded for static assignment, but we're looking for a longer term solution)
There are two routers for the purpose of sharing two cable internet connections. One is a SonicWALL NSA 240 which serves the bulk of the computers and the other is a Cisco ASA 5505 which also gives a handful of admin people VPN access for the purpose of using remote desktop to login to their computers from home. The Sonicwall is the default gateway and is 192.168.168.254 and the handful of systems that are on the Cisco have their Gateway statically assigned in advanced IP settings which is 192.168.168.253.
There are a couple of wiring closets connected by a fiber link. Most of the switches are 3Com but there are a number of smaller switches thrown into the mix both in one of the wiring closets as well as little 5 port switches in several classrooms allowing several computers to share one network jack in the wall.
We have a theoretical general understanding of what needs to happen to increase the number of available IPs through DHCP, but no practical knowledge or expertise in that area. Our average size customer is about 20 PCs so this is by far our largest in terms of network nodes.
We're looking for a best practice tutorial in how to do this right. Thanks.