Static Vs. Dynamic Routing

The term routing encapsulates two tasks―deciding the paths for data transferred, and sending the packets on these paths. Routing is a function carried out at the 3rd layer of the OSI reference model. A routing algorithm decides the output line to transfer the incoming packets; algorithms are based on the routing protocol, that uses metrics―bandwidth, delay, and reliability-to assess whether a particular path is the optimal path available for transfer of the data packets.

Routing tables maintain all information related to routing. There are various routing algorithms and depending on these algorithms, the information stored in the routing table varies. Every router has its own routing table and it fills this table with the required information to calculate the optimal path between the source router and the destination router.

To understand the basic points of difference between the two routing algorithms, let us take a brief look at routing tables.

A routing table is either a document stored in the router or on a network computer in the form of a database, or is simply a file stored in the router. The data entered in the routing table is referred to when the best possible path to transfer information across two computers in a network is to be determined.

The two classifications, viz., static and dynamic, are based on the way in which routing tables are updated every time they are used. Routers in which the data is stored and updated manually are called static routers.

On the other hand, routers in which the information is changed dynamically, by the router itself, are referred to as dynamic routers. Let us compare the two types of routing algorithms below.

• Static routing manually sets up optimal paths between the source and destination computers. On the other hand, dynamic routing uses dynamic protocols to update the routing table and to find the optimal path between the source and the destination computers.

Routers that use static routing do not have any controlling mechanism if they come across any faults in the routing paths. These routers do not sense faulty computers encountered while finding the path between two computers or routers in a network.

Dynamic routing algorithms can sense a faulty router in the network. Also, dynamic routers eliminate the faulty router and find out another optimal path from the source to the destination.

If any router is down or faulty due to certain reasons, this fault is circulated in the entire network. Due to this quality of dynamic routers, they are also called adaptive routers.

Static routing is suitable for very small networks; they cannot be used in large networks. As against this, dynamic routing is used for larger networks.

Manual routing has no specific routing algorithm. Dynamic routers are based on various routing algorithms like OSPF (Open Shortest Path First), IGRP (Interior Gateway Routing Protocol) and RIP (Routing Information Protocol).

Static routing is the simplest way of routing data packets from a source to a destination in a network. Dynamic routing uses complex algorithms for routing data packets.

Static routers have an advantage as they require minimal memory. Dynamic routers, however, have quite a few memory overheads, depending on the algorithms used.

In case of static routing, network administrators find out the optimal path and make changes in the routing table. In dynamic routing, the algorithm and the protocol is responsible for routing the packets and making the changes accordingly in the routing table.

Nowadays, static routing is seldom used. With many technological advancements, dynamic routing routes packets in the network more efficiently.