te mode, as shown in Figure 6.12, because, in essence, you are try- ing to connect remote locations by using a WAN link, which is expensive in terms of bandwidth. You pay for every bit sent, so sending messages to LAN segments that don't need to see them across a WAN link that doesn't need to be congested is inefficient. Although bridges can operate in local and remote areas, today they are mostly used in the local environment. They operate at OSI Layer 2, and they are point to point-they do not understand networking or routing and relaying through a series of nodes. Bridges are protocol independent (Layer 3 and up), which keeps Bridge Figure 6.11 An example of a local bridge Chapter 6 Local Area Networking Figure 6.12 An example of remote bridges the software simple and inexpensive. Bridges cannot translate between different Layer 2 protocols (e.g., between Ethernet and Token Ring). They are primarily used to isolate traffic loads in the local environment because they offer fast throughput; because a bridge doesn't have to do intelligent routing, it is faster and less expensive than a traditional router. Over time, the best features of bridges and routers have been merged SO that some of the problems with each have begun to disappear. Flat Networks Flat networks are constructed by using bridges or Layer 2 LAN switches. This type of net- work is easy to configure, and it promises better performance than hierarchical networks because it offers higher throughput with lower latencies. However, the scalability of a flat network is limited, and a flat network is subject to broadcast storms. Routers The most popular internetworking device today is the router (see Figure 6.13). The applications for routers are quite similar to those for bridges. You use them for network segmentation and connection; that is, you use them either to segment larger networks into smaller ones or to connect smaller networks into a larger vir- tual whole. You can use a router to switch and route packets across multiple com- munications paths a