Resolve the dynamic routing protocol used in network communication

With the development of China's routing industry, it also promotes the continuous improvement of dynamic routing protocols. Here we mainly introduce the dynamic routing protocol used in network communication, computer networks) it is a complex system with many technologies, and each technology plays an irreplaceable role like other technologies.

Many international organizations and companies have set network standards independently and are not fully compatible with each other. Many enterprises have also launched a variety of products and network services that use unconventional network technologies and their dynamic network routing protocols. Computer networks are becoming more and more complex. The reason is that there are a variety of network technologies and various network dynamic routing protocols used to connect two or more networks, this leads to multiple possible connection methods between networks. For example, CISCO routers have self-developed dynamic routing protocols IGRP and VPN. When the dynamic routing protocol is used on the three layers of the Wan for PACKET routing, the destination router must be a CISCO router and use the IGRP or OSPF dynamic routing protocol. Otherwise, the router cannot communicate with the destination host, because IGRP and OSPF are CISCO proprietary routing protocols.

We can imagine that if there is only one road in Wuhan, every car, every bicycle, every motorcycle, and every pedestrian must use the only road. Traffic caused by thousands of vehicles will cause congestion in all places. Obviously, too much traffic needs to be transferred to different roads to break it down into manageable parts. Roads still need to be crossed so that people can still reach any destination they need. Multiple intersections can also provide redundant routes to avoid huge traffic delays. By sending traffic volumes on different routes, You can minimize traffic congestion. In the same way, interconnect network traffic needs to be broken down to avoid network traffic congestion. Routing is used to route the communication traffic to different networks ). Routing protocol Routing Protocols): This protocol is used to establish and maintain a route table and forward data packets based on the Optimal Path to the Data Packet Destination. For example, r1_1, IGRP, and OSPF.

Routed protocols: the selected routing protocol is used by the final node to encapsulate the data and network-layer address allocation information in the data packet, the purpose is that it can relay through an interconnected network. AppleTalk, IP, and IPX are both selected routing protocols. Note: When a protocol does not support network-layer addresses, it is not a routing protocol. The router uses the routing protocol (routing protocols) to establish and maintain the route table and forward data packets according to the optimal path to the Data Packet Destination. The routing protocol allows the router to understand the status of the network that is not directly connected and to communicate with other routers to understand the network they are concerned about. This communication continues, so that the information in the route selection table can be updated at any time when the communication network changes.

The routing algorithm is the calculation method used by the routing protocol to determine the optimal path to the target network. The simpler the routing algorithm, the smaller the processing capability the router uses. This will reduce the daily cost of the router. There are three main objectives of the routing selection algorithm: The Metric value (Metric) is the value used to determine which route is the optimal. Depending on the routing protocol used, different factors can determine the degree of a route, including the number of relay, link speed, latency, reliability, and load ).

Dynamic Route Selection protocol Dynamic Routing Protocols) Classification

Distance Vector routing protocols include r1_1, r1_2, and IGRP. (RIP Routing Information Protocols, IGRP Interior Gateway Routing Protocols) the vector router regularly sends their entire routing table to neighboring routers ). Establish a route selection information table based on the information received by the neighboring router. Regardless of the type of routing selection algorithm used, all routers on the interconnect network need time to update the changes in their routing selection table. This process is called convergence ).

Distance Vector routing is the oldest and simplest dynamic routing protocol algorithm. There is a serious disadvantage in Distance Vector dynamic Routing protocol. slow convergence time may cause Routing Loop ). Solution: horizontal segmentation, defining the maximum number of hops, route virus killing, reverse virus killing, and suppression time. Note: The real distance vector routing protocols are only r1_1 and r1_2, because they only use HOP Hops as the only method to calculate routes. IGRP is a proprietary dynamic distance vector routing protocol of CISCO. It uses the number of hops, but it mainly determines the route factor as link bandwidth, latency, load, maximum transmission unit, and equipment reliability, capabilities .)

The purpose of link status dynamic routing protocol is to map the topology of the Interconnect Network. It is a routing selection protocol that is more complex than distance vector, currently, the most popular dynamic routing protocol is a link Status Protocol: OSPF. OSPF is becoming more popular because of the emergence of Multi-Protocol Label Switching MPLS. The link status Router does not broadcast all information contained in their route tables. The link status routing protocol only sends information about the modified routes. The link status router sends a call message to its neighbor, which is called the link status notification (LSA ). Then, the neighbor copies the LSA to their routing selection table and transmits the information to the remaining part of the network. This process is called flooding ). The link status dynamic routing protocol uses a method called cost (cost) instead of hop ). The cost is automatically or manually assigned values. One of the main advantages of the Link State routing protocol is that the routing selection cycle cannot be formed. There are 2nd advantages. aggregation in the Link State interconnection network is very fast. These advantages release vro resources because the processing capability and bandwidth consumption for poor routing information are very small.

(Note: VPN is a hybrid dynamic routing protocol. It integrates two routing Methods: distance vector and link status. But we still think it belongs to an advanced distance vector routing protocol, HYBRID). We will not discuss it too much here. Both VPN and IGRP are proprietary routing protocols of CISCO. They can only be used in CISCO or its authorized routing products .)

In a large network, such as the Internet, a very small Interconnect Network is divided into autonomous systems (ASAutonomous System ). Each AS is considered to be a self-managed interconnected network. An autonomous system uses the same routing rules and routing algorithms. A large company's network connected to the Internet is its own autonomous system, because other hosts on the Internet are not managed by it, and it and the Internet Router do not share the internal route selection information. The routing selection protocol is developed for the management system in an autonomous system. They are also called the Internal Gateway Protocol (IGP Interior Gateway Protocols ). Internal Gateway protocols are also called intra-domain protocols because they work within the domain rather than between domains. These protocols hold that the routers they process are part of their systems and can freely exchange routing selection information. The Internal Gateway Routing Protocols include r00001, r00002, IGRP, OSPF, IS, and so on.

Some dynamic routing protocols are also developed to connect to autonomous systems in a large interconnected network. These are called dynamic routing protocols of external gateways (EGP-Exterior Gateway Protocls ). External gateway protocols are called Inter-Domain protocols because they work between domains. These protocols hold that they are on the edge of the system and only exchange the minimum required information to maintain the ability to provide routes for information. The external Gateway routing protocols are EGP and BGP4Border Gateway protocol 4 ).

Summary

In summary, the dynamic routing protocol is a dynamic algorithm and Method for Finding routes in router forwarding groups of layer-3 network devices. A good dynamic routing algorithm not only increases the available bandwidth of the network, but also reduces the CPU utilization of the router, it also improves the Network Stability of forwarding groups. The development and continuous improvement of dynamic routing protocols is an important part of the computer wide area network.