Distance Vector Routing，也称为Bellman-Ford shortest path algorithm。基本思想是：

每个路由器（路由结点）都维持一张路由表，包括路由的目的地(V)和路由的距离(D)。每个路由器都定期与相邻结点交换路由表信息，据此更新它们自己的路由表。所有结点都监听从其它结点传来的路由表，并按照下列规则更新其路由表：

-发现了一条到达某目的结点的新路由，而该路由在原来的路由表中不存在（即发现了一条新路由），则在路由表中增加该路由。

-发现了一条到达某目的结点的、距离更短的新路由，则用该路由替换原有的路由。

-到达某目的结点的一条路由，其后继结点到达该目的地的距离发生了变化，则需要更新该路由的距离。

本文件中包含详细的源代码和注释，以实现利用距离向量算法更新路由表的功能。-Distance Vector Routing, also known as the Bellman-Ford shortest path algorithm. The basic idea is : Each router (routing nodes) has maintained a routing table, the destinations include routing (V) and the routing of distance (D). Each router regularly with neighboring nodes to exchange routing table information, updated accordingly their own routing table. All nodes are monitored from other nodes sent a routing table, and in accordance with the following rules to update its routing table :- found a purpose to reach a node of the new routing, The routing of the original routing table does not exist (that is, found a new routing), the routing table to increase the routing.- Found a purpose to reach an end point, the short distance between the new routing, the router can be used to replace