Routing And Switching Questions Long
There are three main types of routing protocols: distance vector, link-state, and hybrid. Each type operates differently to determine the best path for data packets to travel through a network.
1. Distance Vector Routing Protocols:
Distance vector protocols, such as Routing Information Protocol (RIP) and Interior Gateway Routing Protocol (IGRP), work by exchanging routing information between neighboring routers. Each router maintains a routing table that contains information about the distance (or metric) to reach a particular network. The distance is typically measured in terms of hop count, which represents the number of routers a packet must traverse to reach its destination. Distance vector protocols periodically exchange their routing tables with neighboring routers, allowing them to update their own tables accordingly. This process continues until all routers have the most up-to-date routing information. Distance vector protocols use the Bellman-Ford algorithm to calculate the best path based on the lowest metric value.
2. Link-State Routing Protocols:
Link-state protocols, such as Open Shortest Path First (OSPF) and Intermediate System to Intermediate System (IS-IS), work by exchanging information about the state of their links with other routers in the network. Each router creates a detailed map of the network, known as a link-state database, which includes information about the status and cost of each link. This information is then flooded throughout the network, allowing all routers to have a complete view of the network topology. Using this information, routers independently calculate the shortest path to each network by employing the Dijkstra's algorithm. Link-state protocols provide faster convergence and better scalability compared to distance vector protocols.
3. Hybrid Routing Protocols:
Hybrid protocols, such as Enhanced Interior Gateway Routing Protocol (EIGRP), combine elements of both distance vector and link-state protocols. They use distance vector algorithms to determine the best path within a particular autonomous system (AS), while also utilizing link-state information to exchange routing updates. Hybrid protocols maintain a topology table similar to link-state protocols, which contains detailed information about the network's topology. This table is used to calculate the best path based on metrics such as bandwidth, delay, reliability, and load. Hybrid protocols offer a balance between simplicity and efficiency, making them popular in larger networks.
In summary, distance vector protocols exchange routing tables to determine the best path based on hop count, link-state protocols exchange information about link status to create a network map and calculate the shortest path, and hybrid protocols combine elements of both distance vector and link-state protocols to determine the best path based on various metrics.