In-depth discussion on the functions and functions of Dynamic Routing Protocol

There are two types of routing protocols: static and dynamic. I believe everyone knows this. In dynamic routing, is the classification of dynamic routing protocol clear? Here we will mainly explain the classification and main functions of these dynamic routing protocols. As we all know, many international organizations and companies have set network standards independently, and they are not fully compatible with each other. Many enterprises have also launched a variety of products and network services using unconventional network technologies and their dynamic network routing protocols. computer networks are becoming more and more complex, the reason for the complexity is that there are multiple network technologies and various network dynamic routing protocols used to connect two or more networks, which 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 switching 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. The traffic caused by thousands of cars will cause congestion everywhere. Obviously, excessive traffic needs to be transferred to different roads to be divided into manageable parts. Roads still need to be crossed, in this way, people can still reach any destination they need. Multiple intersections can also provide surplus routes to avoid huge traffic delays. By sending traffic volumes on different routes, traffic congestion can be reduced to a minimum. communication traffic needs to be broken down according to the same method, to avoid network traffic congestion. The process of guiding the communication network traffic to reach different networks is called Routing. Routing Protocol (Routing Protocols ): it is used to establish and maintain a route table and forward data packets based on the Optimal Path to the destination of the data packets, such as 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 the interconnection network. Both AppleTalk, IP, and IPX are selected routing protocols. Note: When a protocol does not support network layer addresses, the router uses the routing protocol (routing protocols ), in order to establish and maintain the route table and forward data packets according to the optimal path to the Data Packet Destination, the router can understand the status of the network that is not directly connected and 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 interconnect network changes ｡

The routing algorithm is the calculation method used by the routing protocol to determine the optimal path for the target network. The simpler the routing algorithm, the smaller the processing capability that the router will use, which will reduce the daily cost of the router. The main objective of the routing algorithm is three: Metric value (Metric) is the value used to determine which route is the optimal. According to the routing selection protocol used, different factors can determine the degree of a route, including the number of relay, link speed, latency (delay), reliability and load )｡

Dynamic Route Selection protocol (Dynamic Routing Protocols) Classification

Distance Vector Routing Protocols include r00001, r00002, and IGRP. (RIP Routing Information Protocols, IGRP Interior Gateway Routing Protocols) the vector router regularly sends their entire routing table (routing table) to neighboring routers) the routing information table is created based on the information received from the neighboring router. No matter what type of routing algorithm is used, all routers on the interconnect network need time to update the changes in their route selection table. This process is called convergence )｡

Distance Vector routing is the oldest and simplest dynamic routing protocol algorithm, a slow process of convergence will result in a 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 for calculating routes. IGRP is a proprietary dynamic distance vector routing protocol of CISCO, it uses the number of hops, but mainly determines the link bandwidth, latency, load, maximum transmission unit, device reliability, and capabilities ｡)

The link status dynamic routing protocol is used to map the topology of the Interconnect Network. It is a routing selection protocol that is more complex than distance vector, at present, the most popular dynamic routing protocol is a link state protocol: OSPF) the link status Router does not broadcast all information contained in their route tables. The link status router only sends the information of the changed route. their neighbors send call messages, this is called the link state notice (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 instead of hop. The cost is automatically or manually assigned values, that is to say, the routing selection cycle cannot be formed. There are 2nd advantages, and aggregation in the Link State interconnection network is very fast. These advantages release the resources of the router, 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 state. However, we still think it belongs to an advanced distance vector routing protocol (HYBRID ), we won't discuss it too much here. Both VPN and IGRP are proprietary routing protocols of CISCO and 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 AS (Autonomous System). Each AS is considered AS a self-managed Interconnect Network, an autonomous system uses the same routing policies and algorithms internally. 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, in addition, it does not share the internal route selection information with the Internet Router. The routing 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, in addition, you can freely switch routing information. The Internal Gateway Routing Protocols include r12001, r00002, IGRP, VPN, OSPF, and IS ｡

Some dynamic routing protocols are also developed to connect to autonomous systems in a large interconnected network. They are called EGP-Exterior Gateway Protocls) external gateway protocols are called Inter-Domain protocols because they work across 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 to information. External Gateway routing protocols include EGP and BGP4 (Border Gateway protocol 4 )｡

Summary

In summary, the dynamic routing protocol is a dynamic algorithm and Method for Finding routes in router forwarding groups of L3 network devices. A good dynamic routing algorithm can not only increase the available bandwidth of the network, but also reduce 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 ｡