Shut down Windows and then turn off the computer and unplug it.

⻬ A basic rule of Ethernet life is that a signal can’t pass through more than three repeaters on its way from one node to another. That doesn’t mean you can’t have more than three repeaters or hubs, but if you do, you have to carefully plan the network cabling so that the three-repeater rule isn’t violated. ⻬ A two-port 10Base2 repeater costs about 200. Sheesh I guess that’s one of the reasons few people use coaxial cable anymore. ⻬ Repeaters are legitimate components of a by-the-book Ethernet network. They don’t extend the maximum length of a single segment; they just enable you to tie two segments together. Beware of the little black boxes that claim to extend the segment limit beyond the standard 185-meter limit for Thinnet or the 100-meter limit for 10100BaseT cable. These products usually work, but playing by the rules is better. Bridges A bridge is a device that connects two networks. Bridges are used to partition one large network into two smaller networks for performance reasons. You can think of a bridge as a kind of smart repeater. Repeaters listen to signals coming down one network cable, amplify them, and send them down the other cable. They do this blindly, paying no attention to the content of the messages that they repeat. In contrast, a bridge is a little smarter about the messages that come down the pike. For starters, most bridges have the capability to listen to the net- work and automatically figure out the address of each computer on both sides of the bridge. Then the bridge can inspect each message that comes from one side of the bridge and broadcast it on the other side of the bridge, but only if the message is intended for a computer that’s on the other side. This key feature enables bridges to partition a large network into two smaller, more efficient networks. Bridges work best in networks that are highly segre- gated. For example, suppose your network consists of two distinct groups of users: the Marketing Department and the Accounting Department, each with their own servers. A bridge would let you partition this network so that the Marketing side of the network isn’t bogged down by Accounting, and vice-versa. The bridge automatically learns which computers are on each side of the bridge and forwards messages from the one side to the other only when necessary. The overall performance of both networks improves, although the perfor- mance of any network operation that has to travel over the bridge slows down a bit. 126 Part II: Building Your Own Network