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Để cung cấp sử dụng tài nguyên hiệu quả hơn. Phương pháp quản lý bảng định tuyến yêu cầu không có băng thông mạng để quảng cáo các tuyến đường giữa các thiết bị lân cận. Nó cũng sử dụng bộ nhớ xử lý ít hơn và chu kỳ CPU để tính toán mạng lưới đường lối. | To provide more efficient resource utilization. This method of routing table management requires no network bandwidth to advertise routes between neighboring devices. It also uses less processor memory and CPU cycles to calculate network paths. 5.2.2 Distance vector routing Distance vector algorithms are examples of dynamic routing protocols. These algorithms allow each device in the network to automatically build and maintain a local IP routing table. The principle behind distance vector routing is simple. Each router in the internetwork maintains the distance or cost from itself to every known destination. This value represents the overall desirability of the path. Paths associated with a smaller cost value are more attractive to use than paths associated with a larger value. The path represented by the smallest cost becomes the preferred path to reach the destination. This information is maintained in a distance vector table. The table is periodically advertised to each neighboring router. Each router processes these advertisements to determine the best paths through the network. The main advantage of distance vector algorithms is that they are typically easy to implement and debug. They are very useful in small networks with limited redundancy. However there are several disadvantages with this type of protocol During an adverse condition the length of time for every device in the network to produce an accurate routing table is called the convergence time. In large complex internetworks using distance vector algorithms this time can be excessive. While the routing tables are converging networks are susceptible to inconsistent routing behavior. This can cause routing loops or other types of unstable packet forwarding. To reduce convergence time a limit is often placed on the maximum number of hops contained in a single route. Valid paths exceeding this limit are not usable in distance vector networks. Distance vector routing tables are periodically transmitted .
