Understanding the Network: A Practical Guide to Internetworking

The Need for Network Switching

Enterprise networks traditionally have been built with shared transmission medium Layer 2 LAN protocols and point-to-point dedicated medium Layer 2 WAN protocols. Multiport repeaters, MAUs, and bridges were used to construct LANs, so that two connected end-stations would have momentary access to all the available LAN segment bandwidth to exchange data. These LANs were designed and operated using the 80/20 rule: 80 percent of the LAN segment traffic was local (on one side of a router), the other 20 percent was remote (on the other side of a router). On the WAN side, Transport-1 based PSTN links using synchronous serial interfaces were used to tie LANs together. In fact, much of the Internet backbone in the early ...