Dividing the Network

The address class system described in Hour 4 enables all hosts to identify the network ID in an IP address and send a datagram to the correct network. However, identifying a network segment by its Class A, B, or C network ID presents some limitations. The principal limitation of the address class system is that it doesn’t provide any logical subdivision of the address space beneath the network level.

Figure 5.1 shows a Class A network. As described in Hour 4, datagrams arrive efficiently at the gateway and pass into the 99.0.0.0 address space. However, the picture gets more complicated when you consider how to deliver the datagram after it passes into the 99.0.0.0 address space. A Class A network has room for over 16 million ...

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