Sams Teach Yourself TCP/IP in 24 Hours, Third Edition

Divided Networks

As previous hours have mentioned, network access methods such as CSMA/CD (ethernet) and token passing (token ring) are designed to serve limited numbers of computers. A large network must provide some means of filtering and directing network traffic to prevent an overload of the transmission medium. Large networks, therefore, are divided into smaller segments. Each segment is isolated from the rest of the network by some filtering device.

If the source and the destination of a transmission are within the segment, the filtering device stops the transmission from passing to the greater network (see Figure 9.1). In a practical sense, this segmenting concept stops a considerable amount of traffic, because computers that are in close ...