Get to know the Principles and How Routing Works on a Computer Network

Routing is the path selection process carried out by the router to send data packets to the destination location. The location can be in one network or on another network, for example from the office network to the ISP network. In the process, the router tries to choose the best path. If it fails, then the router will use the path that is already listed in a table called the routing table.

The routing table itself is a collection of information stored in the router, and the information in question is needed by the router every time the router receives a data packet. This table is like a map that contains various paths to reach a destination.

The contents of the routing table should at least include information about destinations, interfaces, and metrics. The destination contains the IP address that is the destination of the data packet, the interface shows the location of the router that is closest to the destination network, and the metric is the calculation result of the routing algorithm to find the best route in sending data packets. The route that is considered the best is the route that has the lowest metric value. The value of this metric will later be used by the routing protocol in certain situations.

Routing Type

Principles and How Routing Works

There are three types of routing, namely default, static, and dynamic.

When a data packet has a destination whose route is not in the routing table, then the data packet will be sent via the default route. This is what is called default routing. If the route is added manually in the routing table, then this method is called static routing. This type of routing is more appropriate for small-scale networks because the configuration is quite time-consuming.

Route selection to send data packets can also be done dynamically by applying the dynamic routing method. The goal is to get the best route so that data packets can reach their destination faster. In the selection process, routers use routing protocols.

Routing Protocol

Principles and How Routing Works

RIP (Routing Information Protocol) is a distance vector based routing protocol. In this protocol, the shortest route is the best route and the route determination is done by relying on the Bellman Ford algorithm. The metric used is the number of hops, but the maximum number of hops supported is 15 so it is not recommended for large-scale networks.

EIGRP (Enhanced Interior Gateway Routing Protocol) is an improvement from IGRP (Interior Gateway Routing Protocol) which uses the DUAL algorithm (Diffusing Update Algorithm), has three tables (topology, neighbors, routing), and supports up to 255 hops so it is more appropriate for use on a network that is relatively large in scale than the RIP protocol.

OSPF (Open Shortest Path First) is a link state-based routing protocol that selects a route after calculating the cost of each available route. The best route is the route that has the lowest cost. Route selection is done using the Djikstra algorithm which was officially published in 1959 by Edsger W. Dijkstra.