You will need a network ID for each physical segment and one for each
wide-area connection (line b/w routers).

VLSM
	When ISP assigns you a block of IP addresses with a subnet mask,
	internally, you can break that down into more subnets and change
	the netmask. VLSM supports routing protocols: RIPv2 and OSPF.

	You will need a hierchical routers -> Master router -> sub routers