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Routing Protocols

The set of predefined rules used by the routers to maintain the communication between the source and the destination are known as Routing Protocols. These protocols help to find the routes between two nodes on the computer network. The routing protocol doesn’t transmit the information directly from the source to the destination; rather, it updates the routing table that contains complete information.

The routing protocols determine the best path for packet delivery by using the metric. Here, the metric is the standard of measurement, such as bandwidth, delay, hop count, etc., which is used by the routing algorithm to get the optimal path to the destination.

Table of Contents

Purpose of Routing Protocols

There can be several reasons to opt Routing Protocol, and they are as follows:

o It provides ease in the configuration.

o It is beneficial for the large size of network routing.

o It adapts to changes.

o It helps in minimising and updating traffic.

o It has fast convergence.

o It allows optimal path selection.

o It allows loop-free routing.

o It is compatible with existing routers.

Types of Routing Protocols

There are three types of routing protocols. In this article, we will discuss more on these protocols.

• Static Routing Protocol

• Default Routing Protocol

• Dynamic Routing Protocol

Static Routing Protocol

The static routing protocol is a technique in which the router sends the packets to the destination with the route defined by the administrator. Nonadaptive routing is another name given to Static Routing. In this technique, the routing table is updated by the administrator, who manually adds the routes in it. Here, the routing decisions do not depend on the condition or the network topologies.

Advantages of Static Routing

  • Static routing doesn’t have any bandwidth usage between the routers.
  • As the system administrator can only control the route for a particular network, it leads to providing high security to the system.
  • The cheaper router can be used to implement static routing, as it has no overhead on the CPU.

Disadvantages of Static Routing

  • When it comes to a larger network, it is difficult to add each route to the routing table manually.
  • The administrator needs to have complete knowledge about the network topology as he is responsible for adding each route.

Default Routing Protocol

When the router sends all the packets to the same hop device, whether it belongs to a particular network or not, then it is known as a Default routing protocol. When a network has a single exit point, then default routing is used. Here, the packet is transmitted through default routing to the destination for which it is configured. The packet uses the default route only if no specific route is mentioned. This technique is also useful when there is a bulk of data to be transmitted.

Advantages of Default Routing Protocol

  • If there are no predefined routes in the routing table, the default route may be useful.
  • It can be applied to proxy servers and packet filtering, and firewalls.

Disadvantages of Default Routing Protocol

  • The setup will be challenging if the network is overly complicated.

Dynamic Routing Protocol

Dynamic routing is a technique in which the routing table is updated with a new route by the router when it adds a new route for each packet, leading to changes in the condition or the network topology. If any decided route fails, then the packet will automatically adjust and discover a new route to reach the destination. PIP and OSPF are the two main protocols in dynamic routing to discover new routes.

Features of Dynamic Routing Protocol

  • When it comes to exchanging the route, the router needs to have the same dynamic address.
  • The router broadcasts all the information to the other routers if it notices any changes in the condition or the network topology.

Advantages of Dynamic Routing Protocol

  • The Dynamic protocol is easy to configure.
  • It is more effective when it comes to finding the best route when there is a change in network topology.

Disadvantages of Dynamic Routing Protocol

  • When we talk about CPU and bandwidth usage, then it is expensive.
  • It is less secure in comparison to static and default routing.

Let’s discuss a few more essential protocols:

Distance Vector Routing Protocol (DVR)

Distance Vector Routing Protocol shares the routing table with each node which is a directly connected neighbour at a specific time but has slow convergence and high bandwidth. When the route is unavailable, the routing table gets updated with new information.

Internet Routing Protocol

An internet routing protocol allows data packets to find their route across the internet. The internet routing protocol is of two types:

Routing Information Protocol (RIP)

Routing information protocol works on the application layer of the OSI model. It is also used in both local area networks and wide area networks. RIP comes up with two versions, i.e. RIPv1 and RIPv2.

RIPv1 allows you to determine the network route according to the IP address and hop count. It broadcasts the IP address table to all the routers in the network and interacts with the devices. Whereas RIPv2 transmits its routing table to the multicast address.

Interior Gateway Protocol (IGP)

The Interior Gateway Protocol was built to overcome the shortcomings of RIP. IGP is majorly used by the routers to transit the data within the autonomous systems. They are more suitable for large-sized networks as it contains a count of 255 and broadcast after every 90-sec interval. It is fruitful for loop routing as it can automatically update the route whenever any kind of change takes place.

Link State Routing Protocol

The Link State Routing Protocol, as the name suggests, follows a unique method to get the best route by calculating the speed of the path for reaching the destination and the cost of resources. This protocol maintains a separate table to get the best and backup route information. Thus, it is appropriate for inter-network compared to any other distance vector protocol. It does not consume any extra bandwidth as it follows triggered updates. But when there is any change in the topology, it triggers a partial update. Therefore, there is no update required at the point where the whole routing table is exchanged.

Routing Protocol Tables

Link state routing protocol works on the following three tables and maintains them:

  • Neighbour table: The information about the neighbourhood router is held in this table.
  • Topology table: The whole information about the topology is carried out in this table.
  • Routing table: Routing table contains all the best routes to the advertised network.