Subnetting Subnetting is a method for getting the most out of the limited 32-bit IP addressing space. With any address class, subnetting provides a means of allocating a part of the host address space to network addresses, which lets you have more networks. The part of the host address space allocated to new network addresses is known as the subnet number. The InterNIC assigned the University of Windsor one class B Network address, which is 137.207.0.0 with network number part 137.207. The Host number part is left to be assigned at the discretion of the owner of the network number (local management - The Computing Services)

Subnetting

Subnetting In class B IP address, the 2 right-hand bytes assigned for the host number, can be subdivided into 254 subnetworks and 254 hosts to each subnetwork number. Which bits in the host address bytes will be applied to subnet addresses and which to host addresses is determined by a subnet mask, or netmask.(/etc/netmasks) The netmask can be applied to an IP address using the bitwise logical AND operator. If a netmask 255.255.255.0 (or FF.FF.FF.00) is applied to the address 137.207.192.003 (or 89 CF C0 03), the result is a network number 137.207.192.0 i.e.:     137.207.192.003 & 255.255.255.000 = 137.207.192.000 or,    89 CF C0 03 & FF FF FF 00 = 89 CF C0 00.

Subnetting In binary form, the operation is: 10001001 11001111 11000000 00000011 (IP address ) AND 11111111 11111111 11111111 00000000 (netmask) ------------------------------------------------------------------------ 10001001 11001111 11000000 00000000 (masked number) Now the system (router or server) will look for a network number of 137.207.192.000 instead of a network number of 137.207., then the router (or the server) will now locate the host, (workstation) , from its table, and adds the corresponding machine number, to arrive to 137.207.192.003.  To increase the host number from 254, a different mask number could be used for less subnetworks and more hosts

Subnetting