Do all your ~150 client PC's get their IP addresses from via DHCP from IpCop or other server ?
If yes, change your IpCop Green subnet settings, DHCP server settings, flip the switch, and tell them all to reboot.
thanks for the quick reply. DHCP is arranged by a Windows 2003 Server. The problem is that there are a lot of laser machines too, who have a static IP and it can take quite a while to let every supplier pass to reconfigure the machines with the new ip address.
I can easyly change the dhcp scope for all the computers in the network, but the problem is more related to machines and other equipment who have a fixed address and where we depend on the supplier to change something. So there will always be a time where we have temporarily 2 subnets.
Change DHCP is a good idea, but how to let the existing network communicate with the new range?