Analysis of RIP Protocol

Today, we will mainly introduce the RIP Protocol, which we first came into contact with when learning the routing protocol. What are the main characteristics of this protocol? Next we will introduce this protocol in detail. An important feature of the RIP Protocol is that it can tell you about the target network from other routers. You may have heard of this type of routing protocol called "rumor routing by rumor. It works by adding the value of the metric field to a router before broadcasting the RIP data packet. For example, if vroa A tells you that you can pass through two hops to vrob B, then you will know that vroa A and vrob B can directly talk to each other, because the distance between them is only one hop point. Therefore, vroa A has A link in the same broadcast domain like vrob B. However, you do not.

When the scale or number of hops reaches 16, it means you have encountered a problem. 16 this number means infinity in the RIP Protocol. An infinite number equal to 16 is a mechanism used to stop the infinite increase of measurement values. This design is based on the working principle of "rumor routing. This issue is a bit complicated. However, please take a look at the example of the three routers below the router:

Vroa A knows that it can reach vroc C within 2 hops through vrob B. The picture in your mind can be A straight line. Router B is in the middle, and router A and router C are at both ends. Now, because router B is directly connected to router C, it will know when router C fails.

However, when router B has the opportunity to tell router A about the fault of router C, router A sends A RIP update message. This information includes "I can reach vroc C within 2 hops ". Of course, vrob B will trust vroa A, which means that vrob B believes that vroa A can reach vroc C. Of course, router A cannot reach router C because its path must pass through router B.

However, router B does not know this situation, because the only information in the RIP Protocol is the next hop address, that is, router. Finally, when router B sends its next update, it will include the route to router C, which is now 3 hops. Router A believes in Router B, because router B is the only channel to router C after all. This kind of thing often happens, and our number of hops reaches 16. This route will be abandoned and will not continue forever.

How can this problem be solved? There is no way to use the distance vector protocol. When we tell our neighbors about the world, we don't provide detailed information about every network, so that just now the kind of infinite computing will happen. The Link Status Protocol provides the entire network to all routers, so this problem can be avoided. Horizontal segmentation is another way to help avoid this problem. However, this method also has flaws.

Split-horizon means that we need to track the port sent by the update information, and pay attention to the update information sent from other routers that may conflict with it. In other words, the router records the interface used when a route information is sent out. When the router receives the route update information to the same target from this interface, it will understand that this is the information that has just been sent back by other routers, to avoid problems from a certain program, but when more routers are involved, the above information will still exist. This example will become more complex. However, if you are interested in the RIP Protocol, you can try to design an environment in which a vro with the Split-horizon function still calculates infinite numbers.

The last "problem" of the RIP Protocol is the slow aggregation speed. This is true, mainly because of the 30-second wait time for each update interval. However, in small organizations, this does not matter. R12002 can run on almost all hardware, even on a cheap "Home Router" that you bought to support broadband network connections. Even if you do not use the RIP Protocol as an IGP protocol, it is still useful to understand this protocol, because the host can also use this protocol as an alternative to manually setting a default gateway. Finally, even if your organization is small, it is enough to use all static routes. r12002 will bring you more convenience.

The RIP Protocol is a distance vector Internal Gateway Routing Protocol. It uses the number of hops and the next hop router to describe the routes.

R12001 is used for broadcast, but does not support CIDR address resolution. R12002 is a classless Inter-Domain Routing and uses Multicast technology.

Although the convergence speed of this protocol is slow and there are some flaws, RIP is very suitable for small and medium-sized enterprises.