VLANs - moving from class B to C network

[nunzeo]

We are running a flat class B network with no VLANs. Our network is broken down to 10.1.0.0 – 10.2.0.0 – 10.3.0.0 / 255.255.0.0. Each 10 network is separate LAN behind its own router. I am looking to implement class C VLANs to cut down on broadcasts on the LAN.

Example

10.1.1.0 / 24 switches
10.1.2.0 / 24 servers
10.1.3.0 / 24 clients
10.1.4.0 / 24 printers

10.2.1.0 / 24 switches
Etc.

All servers, clients, printers are statically configured with 255.255.0.0 masks and a gateway of 10.1.1.1 or 10.2.1.1. How can I go about configuring VLANs on our switch network while the servers, clients, and printers all have a subnet mask of 255.255.0.0 and a default gateway statically assigned? I’m guessing I would need a day of downtime to change all the devices gateways and subnet masks for their VLANs after they are configured on the switches?

Also, I am using a layer 3 switch for the interVLAN routing, but would I have to change anything on the WAN router for each location? Or can that be left alone as long as I have a game plan and implement correctly?

Any suggestions would be helpful.

Thanks.

 

[brianinms]

I would have a plan to do a hard cutover. Additionally I would move to a 10.10.1.x , 10.10.2.x and so on scheme so it is very easy to tell if you are on the old network or the new network.