Network layer: Route selection algorithm (1)--Overview

The purpose of the routing algorithm is to determine the optimal path from sender to receiver through router network, which is the shortest path.

　　

Terms:

Default router: The router directly connected to the end system host is called the default router.

SOURCE Router: The default router for the source host.

Destination router: The default router for the destination host.

Optimal path: The lowest cost path for the sender to the receiver through the router network.

Generalized classification of routing algorithms:

1. Differentiate by global or distributed:

Global routing algorithm: With all node connectivity and the cost of all links as input, each node has a complete network of information, the information is passed through the router through the protocol, because each router has a complete and identical information, can guarantee consistency of results. The algorithm used: Link state (link states, LS) algorithm.

Decentralized routing algorithm: calculate the minimum cost path in an iterative and distributed way. The calculation of each node is based on the cost knowledge that is directly connected to it. After the node calculates the information, it gradually converges the cost to the minimum cost, thus calculating the shortest path. Use algorithm: Distance vector (Distance-vector, DV) algorithm.

2. Differentiate according to static or dynamic mode:

Static route selection algorithm: Routing changes slowly, usually manually adjusted.

Dynamic routing algorithm: The change of routing varies with network traffic load or topology, and can be run periodically or respond to changes. But it is easy to get the influence of routing cycle and route oscillation.

3. Differentiate according to load sensitivity or load retardation:

Load-sensitive algorithms: Link costs change dynamically to reflect congestion levels, creating a number of challenges.

The load retardation algorithm, the link cost does not obviously reflect the congestion level, the current Internet route Choice algorithm is the load retardation algorithm.

　　　　

Network layer: Route selection algorithm (1)--Overview