The company I work for is expanding and as such has just purchased a new building and we will be moving staff and resources over there as well as keep the current premises. As it's better to get the advice of others who have been through similar experiences rather than to learn the hard way, which could cost considerable downtime/money, I need some advice as to what to do with subnetting.
The current premises contains about 400 staff in a Windows environment and for some reason has been set up with a Class B (255.255.0.0). We are currently using internal range 192.168.1.0 - 192.168.4.0 and using about 60%.
The new building has 6 levels and there will be a direct 1Gbps link to the current premises and both premises will have 1Gbps links to our ISP, forming a redundant link and all Internet traffic will be to/from via the ISP.
Ideally, I would like to have a different subnet on each level like floor 0 = 192.168.100.0 and floor 5 = 192.168.105.0 etc. These ranges aren't going to work with the current premises range are they? Do I need to change the subnet mask on the current premises? There are so many locations that this subnet mask is specified. What would be the easiest thing in your experience to do? Have the new building in a totally different range (for example 10.10.10.0 - 10.10.10.5 ?) and leave the current premises the same?