Distance Vector Routing Protocol is designed for small network environments. In large network environments, such protocols will generate more traffic and consume too much bandwidth when learning routes and keeping routes. If it does not receive a routing table update sent by a neighboring site within 90 seconds, it considers the neighboring site unreachable. Every 30 seconds, the distance vector routing protocol will send the entire routing table to neighboring sites, updating the routing tables of the neighboring sites. In this way, it can collect a list of networks from other sites (directly connected or otherwise connected) for routing purposes. The distance vector routing protocol uses the number of hops as a measure to calculate the number of routers to pass through to reach the destination.