Algorithm type of routing in industrial routers

 1.Static and dynamic

The static routing algorithm is hard to be regarded as an algorithm, it is just a table mapping established by the network manager before starting the routing. These mappings themselves do not change unless the network manager changes them. Algorithms that use static routing are easier to design and work well in networks where network communication is predictable and simple.

Because static routing systems cannot reflect network changes, they are generally considered not suitable for large and volatile networks. The main routing algorithms in the 1990s were all dynamic routing algorithms, adapting to changes in the network environment by analyzing the received routing update information. If the information indicates that the network has changed, the routing software recalculates the route and sends out new routing updates. This information infiltrates the network, prompting the router to recalculate and make corresponding changes to the routing table.

Dynamic routing algorithms can be supplemented by static routing where appropriate. For example, the router of last resort, as the way out for all non-routable packets, ensures that all data has at least a way to process.

2.Single path and multipath

Some complex routing protocols support multiple paths to the same destination. Unlike single-path algorithms, these multi-path algorithms allow data to be multiplexed on multiple lines. The advantages of multipath algorithms are obvious: they can provide better throughput and reliability.

3. Flat and layered

Some routing protocols operate in a flat space, while others have routing levels. In a flat routing system, each router is equal to all other routers; in a hierarchical routing system, some routers form the routing backbone, and data flows from non-backbone routers to backbone routers, and then transmits on the backbone until they are Reach the target area, where they reach the destination from the last backbone router through one or more non-backbone routers.

Routing systems are usually designed with logical node groups, called domains, autonomous systems, or intervals. In a hierarchical system, some routers can communicate with routers in other domains, while others can only communicate with routers in the domain. In a very large network, there may be other levels, and the most advanced router constitutes the routing backbone.

The main advantage of hierarchical routing is that it simulates the structure of most companies, which can well support their communications. Most network communication occurs in the group (domain). Because the routers in the domain only need to know other routers in the domain, their routing algorithms can be simplified. According to the routing algorithm used, the amount of communication for routing updates can be reduced accordingly.

4. Host intelligence and router intelligence

Some routing algorithms assume that the source node determines the entire path, which is usually called source routing. In the source routing system, the router only serves as a storage and forwarding device, unconsciously sending packets to the next hop. Other routing algorithms assume that the host knows nothing about the path. In these algorithms, the router determines the path through the network based on its own calculations. In the former system, the host has the intelligence to determine the route, while the latter has the ability for the router.

The compromise between host intelligence and router intelligence is actually a balance between optimal routing and additional overhead. Host intelligent systems can usually choose the better path because they explore all possible paths before sending data, and then select the best path based on the specific system’s definition of “optimization”. However, determining the behavior of all paths usually requires a lot of exploration traffic and a long time.

5. Intra-domain and inter-domain

Some routing algorithms only work within domains, while others work both within and between domains. The essence of these two algorithms is different. The reason for its compliance is that the optimized intra-domain routing algorithm is not necessary and becomes an optimized inter-domain routing algorithm.

6. Link status and distance vector

The link state algorithm (also called the short path first algorithm) spreads routing information to each node of the network, but each router only sends the part of the routing table that describes its own link state. In the distance vector algorithm (also called the Bellman-Ford algorithm), each router sends all or part of the routing table, but only to its neighbors. In other words, the link state algorithm sends less update information everywhere, while the distance vector algorithm only sends more update information to neighboring routers.

Since link state algorithms converge faster, they have less tendency to generate routing loops than distance algorithms. On the other hand, the link state algorithm requires more CPU and memory resources, so the implementation and support of the link state algorithm is more expensive.

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