Overview of routing protocols

Many of my friends are confused about the routing protocol. Here we will introduce all the routing protocols in detail. Let's take a look at the definition and classification of the routing protocol. A route consists of a static route table and a dynamic route table. The corresponding route table is called a static route table and a dynamic route table. The static route table is preset by the network administrator according to the network configuration during system installation. After the network structure changes, the network administrator manually modifies the route table. Dynamic Routing varies with the network operation. The router automatically calculates the optimal data transmission path based on the functions provided by the routing protocol, and obtains the dynamic route table.

Based on the Routing algorithm, the dynamic Routing Protocol can be divided into Distance Vector Routing Protocol) and Link State Routing Protocol ). The distance vector routing protocol is based on the Bellman-Ford algorithm, mainly including RIP and IGRPIGRP as private protocols of Cisco. The Link State routing protocol is based on the Dijkstra algorithm, which is very famous in graph theory, shortest Path First, SPF) algorithm, such as OSPF. In the distance vector routing protocol, routers transmit some or all route tables to their adjacent routers. In the link status routing protocol, the router transmits the link status information to all routers in the same region. Based on the position of the router in the autonomous system AS), the routing Protocol can be divided into the Internal Gateway Protocol Interior Gateway Protocol, IGP) and the External Gateway Protocol, EGP, is also called the Inter-Domain Routing Protocol ). There are two Inter-Domain Routing Protocols: the external gateway protocol EGP) and the Border Gateway Protocol BGP ). EGP is designed for a simple tree topology. It has obvious disadvantages when dealing with routing loops and setting routing policies. It has been replaced by BGP.

VPN is a private protocol of Cisco. It is a hybrid protocol. It not only has the characteristics of distance vector routing protocol, but also inherits the advantages of Link State routing protocol. Different routing protocols have their own characteristics and are suitable for different types of networks. The following sections describe them respectively.

Static Routing

The static route table is created by the network administrator before you start to select a route, and can only be changed by the network administrator. Therefore, it is only applicable to environments with simple network transmission statuses.

Static Routing has the following features:

◆ Static Routing does not require route switching, thus saving network bandwidth, CPU utilization, and vro memory.

◆ Static Routing provides higher security. In a network using a static route, all routers connected to the network must set their corresponding routes on the adjacent router. Therefore, network security is improved to some extent.

◆ In some cases, you must use static routes, such as DDR and the network environment using NAT technology.

Static Routing has the following Disadvantages:

◆ Managers must understand the network topology and correctly configure routes.

◆ Poor network scalability. To add a network to the network, the Administrator must add a route to all routers.

◆ Configuration is cumbersome, especially when it is necessary to communicate with several vrouters, the routing configuration is more complex.