etted network, a proper VLSM network, and an invalid VLSM network. In the invalid example, the network 192.168.1.200/28 is not permitted by the rules of subnetting. Remember, a subnet must exist where would normally fit had you subnetted the entire network with that subnet mask. If you were to configure an IP address of 192.168.1.200/28, the network address would be 192.168.1.192 and the broadcast address would be 192.168.1.207. The benefits of VLSM should be apparent. In the old days, we used to have to put aside entire classful networks just for /30 subnets (once a /30 subnet was allocated within a classful network, the entire network had to be allocated with the same subnet mask). Often, 80 percent of the network was wasted because it had to be allocated as /30 subnets, when only 10 or SO /30 subnets were needed. With VLSM, you can use 25 percent of a network for /30 subnets, another 25 percent for /27 subnets, and SO on. Needless to say, VLSM has had a serious impact on the allocation of IP space, both on the Internet and in private networks. Chapter 36: IP Design 192.168.1.0/30 192.168.1.0/29 192.168.1.4/30 192.168.1.0/28 192.168.1.8/30 192.168.1.8/29 192.168.1.12/30 192.168.1.0/27 192.168.1.16/30 192.168.1.16/29 192.168.1.20/30 192.168.1.16/28 192.168.1.24/30 192.168.1.24/29 192.168.1.28/30 192.168.1.0/26 192.168.1.32/30 192.168.1.32/29 192.168.1.36/30 192.168.1.32/28 192.168.1.40/30 192.168.1.40/29 192.168.1.44/30 192.168.1.32/27 192.168.1.48/30 192.168.1.48/29 192.168.1.52/30 192.168.1.48/28 192.168.1.56/30 192.168.1.56/29 192.168.1.60/30 192.168.1.0/25 192.168.1.64/30 192.168.1.64/29 192.168.1.68/30 192.168.1.64/28 192.168.1.72/30 192.168.1.72/29 192.168.1.76/30 192.168.1.64/27 192.168.1.80/30 192.168.1.80/29 192.168.1.84/30 192.168.1.80/28 192.168.1.88/30 192.168.1.88/29 192.168.1.92/30 192.168.1.64/26 192.168.1.96/30 192.168.1.96/29 192.168.1.100/30 192.168.1.96/28 192.168.1.104/30 192.168.1.104/29 192.168.1.108/30 192.168.1.96/27 192.168.1.112/30 192.168.1.112/29 192.168.1.116/30 192.168.1.112/28 192.