Routing:
Routing is the process of determining the path that data packets should take from the source to the destination in a computer network. It involves making decisions about the optimal routes based on various metrics and network conditions. Routing is a critical aspect of network communication as it ensures efficient and reliable data transfer.
Desirable Characteristics of Routing Algorithms:
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Correctness: The routing algorithm should correctly determine the paths to destinations, ensuring that data reaches the intended recipients.
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Simplicity: Routing algorithms should be simple to understand, implement, and maintain to facilitate efficient network management.
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Robustness: The algorithm should be robust enough to handle changes in network topology, link failures, or other dynamic conditions.
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Scalability: Routing algorithms should scale effectively with the size of the network, supporting a growing number of nodes and links.
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Optimality: The algorithm should strive to find optimal paths based on predefined metrics, such as minimizing hop count, latency, or maximizing available bandwidth.
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Adaptability: The routing algorithm should adapt to changes in the network, adjusting routes dynamically in response to varying conditions.
Distance Vector Routing:
Distance Vector Routing is a type of routing algorithm where each node maintains a table (vector) that contains the distance (cost) to every other node in the network. The distance vector is periodically exchanged with neighboring nodes. A common distance vector algorithm is the Bellman-Ford algorithm.
Example:
Consider a small network with four nodes (A, B, C, D) and the following initial distance vector table for node A:
| Destination |
Cost (A to Destination) |
| A |
0 |
| B |
1 |
| C |
3 |
| D |
∞ |
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In this table, the cost from A to A is 0, and the cost to B, C, and D is initially set to 1, 3, and infinity (∞), respectively.
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Node A periodically shares its distance vector with its neighbors (B, C, D).
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Upon receiving the distance vectors from its neighbors, A updates its own distance vector based on the received information and the known costs.
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This process repeats iteratively until convergence, with nodes updating their distance vectors and exchanging information until a consistent and stable routing table is achieved.
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The algorithm aims to minimize the cost to reach each destination and converge to a state where no further updates are needed.
