Routing Metrics and Protocols

The purpose of routing protocols is to learn about all the available paths to route data packets, build routing table and take routing decisions based on some specified metrics. There are two primary types of routing protocols rest of them ideate from these two only.

1. Distance Vector Routing

In this type of routing protocol, all the nodes that are a part of the network advertise their routing table to their adjacent nodes (nodes that are directly connected to each other) at regular intervals. With each router getting updated at regular intervals, it may take time for all the nodes to have the same accurate network view.

• Uses fixed length sub-net, not suitable for scaling.
• Algorithm used: Bellman Ford Algorithm to find the shortest path.

2. Link State Routing

Link State Routing is another type of dynamic routing protocol in which routes advertise their updated routing tables only when some new updates are added. This results in effective use of bandwidth. All the routers keep exchanging the information dynamically regarding different links such as cost and hop count to find the best possible path.

• Uses variable length sub-net mask, which is scalable and uses addressing more effectively.
• Algorithm used: Djikstra’s Algorithm to find the shortest path.

Let’s look at the metrics used to measure the cost to travel one node to another :-

1. Hop Count: Hop count refers to the number of nodes a data packet has to traverse to reach its intended destination. Transmitting from one node to another node counts as 1 – hop count. The goal is to minimize the hop count and find the shortest path.

2. Bandwidth Consumption: Bandwidth is the ability of a network to transmit data typically measured in (Kilobits per second)kbps, mbps(Megabits per second) or Gbps (Gigabits per second). The bandwidth depends on a number of factors such as – the volume of data, traffic on a network, network speed etc. Routing decision is made in a way to ensure efficient bandwidth consumption.

3. Delay: Delay is the time it takes for a data packet to travel from source node to its destination node. There are different types of delay such as – propagation delay, transmission delay, queing delay.

4. Load: Load refers to the network traffic on a certain path in the context of routing. A data packet will be routed to the path with lesser load so that it reaches its destination in the specified time.

5. Reliability: Reliability refers to the assured delivery of the data packet to its intended destination although there are certain other factors, the data packet is routed in such a way so that it reaches its destination. The stability and availability of the link in the network is looked over before routing the data packet from a specific path.

The process of choosing a path across one or more networks is known as network routing. Any kind of network, including public transit and phone networks, can use the routing principles. Routing chooses the routes along which Internet Protocol (IP) packets get from their source to their destination in packet-switching networks, such as the Internet. Routers are specialized pieces of network hardware that make these judgments about Internet routing.