Moving from class B to class C network

[nunzeo]

I would like to convert our network from a class B to C in order to reduce broadcasts.

Site A is configured as so –

Router IP
10.1.5.1 255.255.0.0

Router is broadcasting network via BGP which AT&T manages. We have 5 other sites on our MPLS.
Site A bgp is as so:
10.1.0.0 mask 255.255.0.0

Now 10.1.5.1 is the default router for site A and behind the router we have our switches configured as such:
10.1.5.5 255.255.0.0
10.1.5.6 255.255.0.0
10.1.5.7 255.255.0.0
Etc

Clients are
10.1.2.2-254 255.255.0.0
Servers are
10.1.3.2-254 255.255.0.0
Printers
10.1.4.2-254 255.255.0.0

I want to convert our network to a class C. Would the following scenario work?

Change our router IP to
10.1.5.1 255.255.255.0

Contact AT&T and have them modify our broadcast BGP from 10.1.0.0 to the following networks-

10.1.2.0 mask 255.255.255.0
10.1.3.0 mask 255.255.255.0
10.1.4.0 mask 255.255.255.0

Then on the L3 switch connected to the router, keep its VLAN1 IP as 10.1.5.5 but change from a 16 to 24 mask and then create VLAN 2 (10.1.2.1/24) VLAN 3 (10.1.3.1/24) etc and assign ports, trunk on switches and modify masks and GWs on clients, servers, printers.

Then create a default route on L3 switch for all other traffic for next hop of 0.0.0.0 0.0.0.0 10.1.5.1?

Hope I was detailed enough.

Thanks.

 

[VinceWhirlwind]

On your L3 switch, you will also need to enable DHCP relay for each subnet that your DHCP server isn't on.

It would also be a lot better if the link between your L3 switch & router wasn't on the same subnet as a bunch of other devices - ie create a new subnet to be just the transit subnet between L3 switch and router.