Routing is the process of determining the paths that packets should follow in order to reach their destinations efficiently within a computer network. This involves the creation of a routing table that contains information about the routes that packets should take. Various routing algorithms are utilized to find the best possible path for packets to travel.

In this article at OpenGenus, we have explored the concept of Adaptive and Non-Adaptive Routing Algorithms along with examples for both types.

Table of Contents:

1.Classification of Routing Algorithms
2.Adaptive Routing Algorithms and Types
3.Non-Adaptive Routing Algorithms and Types
4.Differences
5.Advantages and Disadvantages of Both
6.Real-life Examples

Classification of Routing Algorithms

Routing algorithms can be broadly categorized into two types:

Adaptive Routing Algorithms:

These algorithms are dynamic and capable of adjusting their paths based on real-time network conditions. They use current network information, such as link status, traffic load, and congestion levels, to make routing decisions. The adaptive nature allows them to continuously update and optimize the routes for data packet delivery. These algorithms are particularly useful in large and dynamic networks where topology and traffic patterns may change frequently.

Types of Adaptive Routing Algorithms:

• Isolated: In this method, nodes make decisions based on the information they have without consulting other nodes. A disadvantage is that packets might be sent through congested networks, resulting in delays.
• Centralized: This type is also known as the link-state network, where a central node maintains information about the entire routing system. However, if this central node fails, finding an optimized route becomes challenging.
• Distributed: In this approach, nodes obtain information about the network from other packets. They decide the path based on the information received and what they have. A disadvantage is that the packet may be delayed if there are changes between the intervals of receiving information and sending packets.

Non-Adaptive Routing Algorithms

These algorithms use predetermined paths that do not change in response to network dynamics. They are statically configured and do not take real-time network conditions into account.
Types of Non-Adaptive Routing Algorithms:

• Flooding: In this method, every incoming packet is sent on every outgoing line until the entire network is covered. One problem is that packets may go in a loop, resulting in nodes receiving duplicate packets. This can be overcome with the help of sequence numbers, hop count, and spanning trees.
• Random Walk: In this approach, packets are sent node by node to one of their neighbors randomly. This is a highly robust method, usually implemented by sending packets onto the link with the least queuing.

Differences

• Adaptability: Adaptive routing algorithms have the ability to adjust and modify their behavior based on changing conditions or input data. Non-adaptive routing algorithms, on the other hand, follow predefined rules or fixed procedures without adapting to changes.
• Real-Time Response: Adaptive routing algorithms offer real-time responses as they actively adjust to the current situation or input data. Non-adaptive algorithms lack real-time responsiveness as they do not modify their behavior during execution.
• Complexity and Overhead: Adaptive routing algorithms often come with a higher level of complexity due to the need for continuous monitoring, feedback, and decision-making. Non-adaptive algorithms tend to be simpler as they rely on fixed rules and do not require continuous monitoring or complex decision-making during runtime.
• Performance in Changing Environments: Adaptive routing algorithms excel in dynamic and unpredictable environments where conditions can change frequently. Non-adaptive algorithms may struggle to perform optimally in rapidly changing scenarios where fixed rules become less suitable.
• Learning Capability: Adaptive routing algorithms often involve learning mechanisms that allow them to acquire knowledge from experience, training data, or feedback. Non-adaptive algorithms do not possess inherent learning capabilities and do not improve through experience or training.

Advantages and Disadvantages

Advantages of Adaptive Routing Algorithms:

1. Dynamic behavior, allowing adjustment to changing network conditions.
2. Load balancing, optimizing traffic distribution across the network.
3. Fault tolerance, accommodating network failures by rerouting packets.
4. Improved performance in dynamic and unpredictable environments.

Disadvantages of Adaptive Routing Algorithms:

1. Increased complexity due to continuous monitoring and decision-making.
2. Overhead in managing dynamic behavior.
3. Risk of routing loops that can cause delays or packet loss.
4. Potential delays in decision-making due to gathering real-time network information.

Advantages of Non-Adaptive Routing Algorithms:

1. Simplicity, as they follow predetermined paths without complex decision-making.
2. Low overhead, as they do not require real-time monitoring and adaptation.
3. Avoidance of routing loops, which helps prevent duplication and packet loss.
4. Fast routing decisions, ensuring efficient packet delivery.

Disadvantages of Non-Adaptive Routing Algorithms:

1. Inefficiency in dynamic networks with changing conditions.
2. Lack of flexibility to adapt to real-time network changes.
3. Limited responsiveness to dynamic traffic patterns.
4. Uneven traffic distribution, potentially leading to network congestion.

Real-Life Examples

Adaptive Routing Algorithms:

1. Dynamic Source Routing (DSR): DSR is commonly used in mobile ad hoc networks (MANETs), where nodes communicate without a fixed infrastructure. DSR allows nodes to dynamically update their routing tables based on neighboring nodes' availability and the changing network topology.
2. Border Gateway Protocol (BGP): BGP is used in the Internet to exchange routing information between autonomous systems (ASes). It allows routers to adapt to changes in network topology, traffic conditions, and policy decisions made by network administrators.

Non-Adaptive Routing Algorithms:

1. Dijkstra's Shortest Path Algorithm: Dijkstra's algorithm is a classic example of a non-adaptive routing algorithm used to find the shortest path between two nodes in a graph. It is used in various applications, such as GPS navigation systems, where the roads' distances and connections remain relatively constant.
2. Fixed Routing in Data Centers: In large-scale data centers, some traffic flows follow predetermined non-adaptive paths. For instance, there may be dedicated links or switches for specific types of traffic (e.g., storage traffic, management traffic), and these paths remain fixed to ensure predictable and efficient communication.