The whole world is digitalized and connected over the network. Packets, which are the atomic unit of information in packet-switched communication networks, are exchanged between the nodes (a node might be an end device, a router or a data generating device, etc.). The process of transferring these packets of information from their source node to the destination node with one or more hops in between along the most optimum path is called as ‘Routing’. Routers and switches are the devices that are used for the purpose which work on the routing protocols and algorithms they are configured with. The routing of packets is taken care of by the L3 layer or the network layer of the OSI Reference Model.
The Internet would not be the one we know today, if it was not routed.
When a packet is introduced in the network and received by one of the routers, it reads the headers of the packet to understand the destination and checks its routing table marked with routing metrics to see what would be the next best hope for the packet to optimally reach the destination. Then, it pushes the packet to the next node and the above process repeats at the new node too until the packet reaches the destination node.
Routing metrics –
Routing tables have the information based on which packet switching takes place in the most optimal path. And this information is different metrics or variables which the routing algorithms look for and then decide their path. The standard metrics include –
- Path Length – In this, the administrator will assign costs to each path (between two nodes). The path length will be the sum of all the path costs. The path with the less path length will be chosen as the most optimal one.
- Delay – This is the measure of time it takes for the packet to route from source to destination. This depends on many factors like network bandwidth, the number of intermediate nodes, congestion at nodes, etc. Sooner the transfer, better the Quality of Service (QoS).
- Bandwidth – This refers to the amount of data a link can transfer through it. Usually, the enterprise lease the network line to achieve a higher link and bandwidth.
- Load – Load refers to the traffic which a router or a link is handling. The unbalanced or unhandled load might cause congestion and a lower rate of transmission packet losses.
- Communication Cost – This is the operational expense which the company incurs by sending the packets on the leased line between the nodes.
- Resilience and Reliability – This refers to the error handling capacity of the router and the routing algorithms. If some nodes in the network fail then the resilience and reliability measure will show us how well the other nodes can handle the traffic.
