Knowledge about three common protocols of IP routing: RIP, OSPF, and OSPF

The main node device of the Internet network is a router, which forwards received data through the route table. The forwarding policy can be manually specified through static routing, Policy Routing, and other methods ). In a small-scale network, manually specifying a forwarding policy is fine. However, in a large-scale network, such as a multinational enterprise network or ISP network), If you manually specify a forwarding policy, it will bring a huge workload to the network administrator, it also becomes very difficult to manage and maintain route tables. To solve this problem, the dynamic routing protocol came into being. The dynamic routing protocol allows the router to automatically learn the networks of other routers, and automatically update the route table after the network topology changes. The Network Administrator only needs to configure the dynamic routing protocol, which greatly reduces the workload compared to manually specified forwarding policies. Finding the optimal data transmission path is a meaningful but complex task.

Major deciding factors:

The optimal path may depend on the number of forwarding times between nodes, the current network running status, data transmission rate, and topology.

To find the optimal path, Each router needs to communicate with each other through the routing protocol. The routing protocol is only used to collect data about the current status of the network and find the optimal transmission path. Based on the data, the router can create a route table for future packet forwarding. In addition to the ability to find the optimal path, the routing protocol can also be characterized by the convergence time-the time it takes for the router to find the optimal transmission path when the network is changed or disconnected. Bandwidth overhead-the bandwidth required by the running network to support the routing protocol. Learn more about the most common routing protocols: RIP, OSPF, VPN, and BGP.

1. RIP Routing Information Protocol): Routing Information Protocol

RIP is a distance vector routing protocol and the earliest routing protocol, but it is still widely used in R, because it only considers the number of hops between nodes when selecting the optimal path between two points. It does not consider network congestion and connection rate. Protocols are usually used in small network environments with simple network architecture.

Currently, RIP has three versions: r00001, r00002, and RIPng.

Working principle: the RIP Router broadcasts its route table to other routers every 30 seconds.

This type of broadcast can cause a large amount of data transmission, especially when a large number of routers exist in the network. If the route table changes, it may take several minutes for new information to be transmitted to a remote location in the network. Therefore, the RIP convergence time is very long.

In addition, the maximum number of RIP hops is 15 hops. If data is to be retransmitted for more than 15 hops, it cannot be transmitted. In addition, RIP is slower than other types of routing protocols,

RIP version 1 does not support variable-length Subnet Mask (VLSM) and non-consecutive subnets. In the same network, the number of all sub-networks is the same, and authentication of the routing process is not supported, this makes r12001 vulnerable to attacks.

RIP version 2 supports VLSM and discontinuous subnets, and uses multicast addresses to send pavement update information. It is safer to add the MD5 algorithm!

RIPng is mainly used for ipv6.

Ps: the number of relay or hop is the same concept. It is calculated by transmission.

2. OSPF shortest path First): open shortest path firs

OSPF introduces the concept of "region area)". All routers in each region maintain a database LSDB with the same link status ). The region is further divided into the backbone region where the number must be 0) and the non-backbone region where the number is not 0). If a network running OSPF only exists in a single region, this area can be a backbone area or a non-backbone area. If the network has multiple regions, there must be backbone areas, and all non-backbone areas must be directly connected to the backbone areas. OSPF uses the maintained link status database and the shortest path Priority Algorithm SPF to calculate the route table. OSPF converges quickly. Due to its unique openness and excellent scalability, the OSPF protocol is widely deployed in various networks..

This Routing Protocol makes up for some defects of RIP and can coexist with RIP in the same network. OSPF uses a more flexible algorithm when selecting the optimal path. Optimal Path refers to the path with the highest efficiency from one node to another. In an ideal network environment, the optimal path between two points is to directly connect two points. If the amount of data to be transmitted is too large or the loss of data during transmission is too large, the data cannot be transmitted along the most direct path, the router needs to select another path with the highest efficiency through other routers. This solution requires the vro to have more memory and a more powerful central processor. In this way, the user will not feel that the occupied bandwidth has been reduced to a minimum, but the convergence time is very short. OSPF is the second protocol used most After RIP.
3. VPN (Enhanced Internal Gateway Routing Protocol): Cisco private Protocol

This routing protocol was developed by Cisco In The Middle Of 1980s. It has fast convergence time and low network overhead. It is easier to configure and require less CPU than OSPF. OSPF. It also supports multiple protocols and limits excess network traffic between routers.

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