Distance-vector routing

Definition

Distance-vector routing is a type of routing protocol used in networks where routers exchange information about the distance to various network destinations and the direction (vector) to reach them. This method relies on each router sharing its knowledge of the network with neighboring routers, allowing them to build and maintain a routing table that reflects the shortest paths to various destinations based on metrics such as hop count.

5 Must Know Facts For Your Next Test

1. In distance-vector routing, each router shares its entire routing table with its immediate neighbors at regular intervals, leading to eventual convergence where all routers have a consistent view of the network.
2. Distance-vector protocols can be susceptible to routing loops, which can cause packets to circulate indefinitely if not properly managed with techniques like split horizon and route poisoning.
3. Common distance-vector routing protocols include RIP (Routing Information Protocol) and IGRP (Interior Gateway Routing Protocol), both of which use hop count as their primary metric for determining the best path.
4. Distance-vector routing is simpler and requires less computational power compared to link-state protocols, making it suitable for smaller networks or less complex routing scenarios.
5. The convergence time for distance-vector protocols can be slower than link-state protocols, leading to temporary inconsistencies in routing tables during changes in the network.

Review Questions

• How does distance-vector routing manage information sharing among routers, and what are its implications for network stability?
  • Distance-vector routing manages information sharing by having each router periodically send its entire routing table to its neighboring routers. This process allows routers to learn about various paths and distances within the network. However, it can lead to stability issues, such as routing loops or inconsistent views of the network during periods of change, unless precautions like split horizon are implemented.
• Compare and contrast distance-vector routing with link-state routing in terms of efficiency and convergence speed.
  • Distance-vector routing is generally simpler and consumes fewer resources compared to link-state routing, making it easier to implement in smaller networks. However, it often suffers from slower convergence speeds because routers rely on periodic updates from their neighbors, leading to potential inconsistencies during network changes. In contrast, link-state routing creates a complete map of the network and allows for faster convergence since changes are propagated immediately throughout the entire network.
• Evaluate the impact of using distance-vector protocols like RIP on modern networks, considering scalability and performance.
  • Using distance-vector protocols like RIP in modern networks can be limiting due to their scalability issues and performance constraints. As networks grow larger and more complex, the reliance on periodic updates increases the risk of slow convergence and potential routing loops. Furthermore, metrics based solely on hop count do not account for bandwidth or latency differences between links. Consequently, while distance-vector protocols can serve smaller networks adequately, they may struggle in larger environments where more sophisticated protocols like link-state are necessary for optimal performance.

Related terms

Link-State Routing: A routing protocol that maintains a complete map of the network topology, allowing routers to make more informed routing decisions based on the state of all links in the network.

Routing Table: A data table stored in a router that contains information about the paths and distances to different network destinations, used to forward packets efficiently.

Bellman-Ford Algorithm: An algorithm used in distance-vector routing protocols to calculate the shortest path from a source node to all other nodes in a weighted graph.