CIDR abandon the concept of the IP address assignment and the management process, and the RFCs 1518 and 1519 describe it. CIDR does not use predefined, clear boundaries, but assigns the address that uses the start address and a range to define the available space more efficiently. This range defines the network part of the address. For example, ISP is assigned to an enterprise client's address representation: 10.57.1.128 / 25. It supplies 128 address blocks locally, where the top 25 is the network identifier part of the address. The address of the old classification is expressed as:
For a given classification system, the initial CIDR implementation is an address segment that connects Class C. This process is called "Creating Super Network". Supernet is used to merge multiple C network addresses into a logical network. To create a super network, the merged IP network addresses must have the same high, and the subnet mask should be reduced to reduce the network part of the address and add them to the host part. For example, you can combine C network addresses 199.199.4.0, 199.6.0, 199.199.6.0 and 199.199.7.0, each address uses subnet masks 255.255.252.0:
NET 199.199.4 (1100 0111.1100 0111.0000 0100.0000 0000) NET 199.199.5 (1100 0111.1100 0111.0000 0101.0000 0000) NET 199.199.6 (1100 0111.1100 0111.0000 0110.0000 0000) NET 199.199.7 (1100 0111.1100 0111.0000 0111.0000 0000) MASK 255.255.252.0 (1111 1111.11111 1111.111 1100.0000 0000)
When determining the route, only the bits of the subnet mask shield, so that from the perspective of the route, all of these addresses are on the same network. Any route to use must also support CIDR and may require special configuration. Windows 2000 TCP / IP supports 0 bits and 1 subnet, which is detailed in RFC 1878.
