Supernetwork

Under Supernetting refers to the combining of multiple networks with partially the same network share to a single route. The underlying technology is the opposite to subnetting and in principle means a method of addressing a larger number of hosts within an IP network. Supernetting works by reducing the network share and thereby resulting increase in the host part of an IP address. For the hosts changes usually nothing, just the router different networks through the use of similarities in the network portion actually saved routing entries.

Supernetting described in RFC 1338 and was a transitional technology that was replaced by CIDR ( RFC 1519) in 1993, which uses no more network classes. The option Supernetting combine multiple networks into a route is referred to in CIDR, with route aggregation.

Examples

For a Class C network with the associated standard netmask 255.255.255.0 are available 254 available host addresses. If more addresses are needed in a network, either a class B network ( subnet mask 255.255.0.0 ) can be used with 65536 possible addresses or by using Supernetting the size of the network are changed.

In the above table, the netmask is shown in decimal and binary notation. Differentiating here is between network and host portion. Offer the 8 bits of the host part 256 ( 2 ^ 8 ) possible IP addresses, but are restricted to less network and broadcast address to be assigned to a total of 254 addresses for hosts.

Shall be within a Class C network with the network address of 192.168.176.0 for example 1000 hosts without a router reachable, so you have to reduce the network portion of the subnet mask, depending on the number of hosts. With 10 bits (2 ^ 10), it is possible to reach 1024 hosts.

The host part has been extended by two bits. The lowest to addresses in the IP address of the network is

192.168.176.1

11000000.10101000.10110000.00000001

And the highest

192 168 179 254

11000000.10101000.10110011.11111110

This form of Supernettings works independently from the example above in all power classes and greater or lesser reduction of the network share.