Before being transferred from source to destination, data in computer networks are converted into packets in computer networks. The network layer finds the best path to take for data packet transmission. The network layer is responsible for providing datagram and virtual circuit services and determining the best path to take from source to destination for packets. The network layers provide a routing protocol or routing algorithm to determine the best and shortest path from sender/source to destination for data transmission. This article describes routing algorithms and the various types of routing algorithms in computer networks.
There will be multiple paths to transfer data from source to destination in communication networks. To reach the destination, one path should be preferred over others. Routing refers to the process of selecting or displaying a path. Routers are network devices that use software to select the best route. In computer networks, it contains information about the best routes chosen for transferring data from source to destination.
A routing algorithm in computer networks is a routing protocol determined by the network layer to transmit data packets from source to destination. This algorithm determines the best, or least cost, path for data transmission from sender/source to receiver/destination.
The network layer performs operations that effectively and efficiently regulate internet traffic. In computer networks, this is known as a routing algorithm. It is used to find the best path or route mathematically.
Classification of a Routing algorithm in computer networks -
It is a routing protocol that determines the best path for data packets to reach their destination. It aids in the efficient transfer of data to the destination.
The Routing algorithms in computer networks are divided into two categories -
Adaptive Routing algorithm -
Centralized
Isolated
Distributed
Non-adaptive Routing algorithm -
Flooding
Random Walk
Adaptive Routing Algorithms -
It is also known as dynamic routing. The routing decisions and routes are determined by network traffic and topology. It calculates and optimizes parameters like hop count, path distance to destination, and estimated transit time. Dynamic data such as network topology, load, and delays are required to select the best route.
The three most common types of adaptive routing algorithms are as follows:
Centralized algorithm -
This algorithm is also known as global or link-state routing. Using complete network topology information, it calculates each path and finds the best least-cost route to transfer data packets between the source and receiver/destination. The connection between the nodes and the input as link cost is established before calculating routes.
Links between routers have an associated cost. In general, it could be determined by distance, bandwidth, average traffic, communication cost, mean queue length, measured delay, router processing speed, and so on.
The shortest path algorithm finds the least expensive path through the network based on the cost function.
If the centralized node fails, the entire network fails because it contains all of the network topology data required to make correct routing decisions. The main advantage is that only one node will have knowledge of the entire network.
Examples: The Dijkstra algorithm
Isolated algorithm -
Instead of gathering information from other nodes, this algorithm obtains routing information using local information. In this algorithm, each node makes its routing decisions based on its information without consulting other nodes. The sending nodes do not know the status of a specific link. The disadvantage is that packets may be routed through a congested network, causing delays.
Distributed algorithm −
Since it calculates the least-cost route between the destination and source, this type of algorithm is also known as decentralized or distance vector routing. The node receives information from its neighbors and decides how to route the data packets to their destination; if the time interval between receiving information changes, the sending of the data packet may be delayed.
The node that sends the data packets lacks information about the complete route between the source and destination and network links. It contains information about the cheapest path for data packets to be transferred.
One disadvantage is that the packet may be delayed if the intervals it receives information and sends packets change.
Non Adaptive Algorithms -
Non-adaptive routing algorithms, also known as static routing algorithms, build a static routing table to determine the path packets should take. When the network boots up, the routing information stored in the routers is used to build the static routing table. These algorithms do not change their routing decisions after being chosen. This is also known as static routing because the route to be taken is computed ahead of time and downloaded to routers when they boot up.
Non Adaptive routing algorithms are classified into two types:
Flooding −
When a data packet arrives at a router, it is sent to all outgoing links except the one on which it arrived. Flooding can be either uncontrolled, controlled, or selective. This technique adapts the technique of sending every incoming packet on every outgoing line except the one from which it arrived. One issue is that packets can get stuck in a loop, causing a node to receive duplicate packets. These issues can be solved using sequence numbers, hop counts, and spanning trees.
Random walks −
This is a probabilistic algorithm in which the router sends a data packet to any of its neighbors at random. Packets are sent node by node or host by host to one of its neighbors at random. This is a robust method usually implemented by sending packets onto the least queued link.
Conclusion
In this article, we discussed routing algorithms in computer networks. We begin with a brief introduction to routing and routing algorithms and then about the two types of routing algorithms: adaptive and non-adaptive routing algorithms. We also read about the various subtypes within the categories, which are Centralized, Isolated, Distributed, Flooding, and Random Walk.
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