Hello everyone, I am Mr. Xu.
Routing protocol , friends who often read my articles know that I have told you many times.
This is a very important concept in the network world. Generally speaking, it is responsible for delivering data packets from source nodes to destination nodes.
Recently, many newcomers have paid attention to it. After thinking about it, I decided to reorganize the routing protocol from the perspective of Xiaobai.
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01 One sentence can explain clearly, what is the routing protocol
Routing protocol, the official explanation is that it is an online protocol that specifies the data packet forwarding method.
From Xiaobai's point of view:
This is like when you send a letter, you need to go through the post office to send the letter from the sender to the recipient.
In the network world, the routing protocol is the post office system of the network.
It specifies how to communicate and transfer data packets between different routers to ensure that data packets can be accurately and efficiently transmitted from address A to address B.
Imagine that when you send a letter, you definitely need to know the correct mailing rules and delivery methods to ensure that your letter can reach the other party according to the correct path, right?
In networking, routing protocols provide similar rules and guidance for packets.
It determines which routers the data packets should pass through in the network, and how to choose the best path for transmission, so as to ensure that the data packets can reach the destination quickly and reliably.
02 "Fool" interpretation, two types of routing protocols
In the networking world, there are many different routing protocols to choose from, just like there are many different methods of postal delivery.
The same is true for routing protocols, which can be divided into many types, and can also be classified according to different standards , both horizontal and vertical.
You can see this picture for details, and list them all for you.
Here I will tell you about the difference between static routing and dynamic routing according to the routing table update method.
01 Static routing protocol, Xiao Ming will teach you how to go
Summer vacation is here, and you decide to go to your good friend Xiao Ming's house to play.
At this time, Xiao Ming gave you a whole map, and what he gave was a specific route map on how to get to his house.
"Turn right from this street, then left, then go straight".
Follow this line strictly.
This is the case with static routing protocols. You manually set up the routing table and clearly specify which path the data packet should take.
But if traffic conditions change, you have to update the map (routing table) manually.
This protocol is suitable for simple networks or situations where precise control over routing is required.
02Dynamic routing protocol, I only rely on navigation
You can go to his house by yourself without relying on Xiao Ming's map.
You decide to drive from home, then you open the navigation, enter the destination, and then ask the navigation to plan the best route for you.
Now, this navigation is the dynamic routing protocol.
It will dynamically choose an optimal route for you according to traffic conditions and road conditions.
If you are on your way and there is a traffic accident one kilometer ahead, the navigation will automatically adjust the route for you and help you choose a faster road to reach your destination.
The same is true of dynamic routing protocols, which dynamically select the best path to transmit data according to changes and failures in the network.
03 These five commonly used dynamic routing protocols are actually very easy to distinguish
From the above description, it can be clearly seen that the static routing system does not seem to be very smart.
This is only suitable for simple networks, or situations that require precise routing control.
Under normal circumstances, everyone still uses dynamic routing , basically the following five categories.
For specific knowledge, you can refer to the five-minute-a-day series posted earlier.
The link is arranged for you:
"Basics of Network Routing (1) RIP Principle and Configuration"
"Basics of Network Routing (2) EIGRP Protocol"
"Networking Routing Basics (3) OSPF Protocol"
"Networking Routing Basics (4) ISIS Protocol"
"Networking Routing Basics (5) BGP Protocol"
Of course, you can also listen to me continue to tell you.
01 RIP, simple guide
RIP is like a simple guide , it just tells the router how many steps it takes to get to the destination.
Ideal for small networks as it is easy to configure.
However, it has a limitation: it can only tell you the distance, but not much about the network.
02 OSPF, detailed map
OSPF is like a very detailed map used to help routers find the shortest path in a large network .
It tells the neighboring routers around each router about the network, allowing each router to calculate the fastest path.
This is very useful for large networks because of its fast and accurate routing capabilities .
03 EIGRP, a combination of the first two
EIGRP combines the advantages of OSPF and RIP.
It can provide more information about the network and can choose the best path based on several factors.
It is suitable for medium-sized networks and has the ability of fast convergence.
04 IS-IS, less used but more advanced
IS-IS is a protocol similar to OSPF and is used in large networks.
Its working principle is similar to OSPF, but it is relatively rare in practical applications.
You can think of it as a more advanced and complex routing protocol similar to OSPF.
05 BGP, which can realize cross-border communication
BGP is a protocol used between internetworks . It helps exchange information between different Internet networks and choose the best path to forward data.
BGP is the foundation of the global Internet, which facilitates communication between Internet networks across national borders.
These five routing protocols just cover the distance vector routing protocol and link state routing protocol I mentioned earlier.
I'll take one out of each and tell you about it.
04 So vivid? Interesting talk about RIP and OSPF
RIP is a distance vector protocol . In general, in some small networks or simple network environments, RIP is still an optional choice because it is relatively simple and easy to configure and deploy.
But with the development of modern networks, more complex and powerful routing protocols such as OSPF have gained wider application.
OSPF is a link state routing protocol, which provides more precise routing and fast convergence capabilities, and is suitable for medium and large enterprise networks and Internet service providers.
This time, let me explain these two things to you in a different scene.
01 RIP, a walking machine without a soul
If you have just joined a company and are not familiar with the surrounding area, you want to go to a shopping mall near the company to eat, but you don't know how to get there.
You first asked your colleague Xiao Ming, and he said that you should go straight ahead from here to find Xiao Wang.
You found Xiao Wang, he said turn left into the first alley and look for Xiao Ma.
Then you find Pony, he said just turn right ahead and you will be there.
Finally, you made it to the mall you wanted to go.
In this case, the RIP protocol is like how you ask your colleagues.
As a beginner, you don't know anything about the geographical layout of the neighborhood.
Although your colleagues only know where you are and the places that are close to you, you still rely on your colleagues for guidance.
The shortest path they tell you is based on their own knowledge .
After you gather this information, choose the shortest path to reach your destination.
The same is true for the RIP protocol, which only knows the information between adjacent routers. It uses this information to select paths, but it has limited knowledge of the topology of the entire network.
02 OSPF, go to destination with soul
Still this example, if you have just joined a company, you are not familiar with the surrounding area, and want to go to a shopping mall near the company to eat, but you don't know how to get there.
You turn on the mobile phone navigation, there are three routes for you to choose:
1. Go straight, cross the zebra crossing and turn right.
Second, turn right first to a certain building, then go straight, then turn around and come back.
3. Turn left, go straight through a bridge, and turn right.
You also asked two colleagues and they gave you two more options:
Fourth, Xiao Ming said, you can pass through an alley, so you don't have to wait for the traffic lights.
Fifth, Xiao Wang said, you can go straight ahead and go through the underground passage outside the company.
Now, you have five options.
You have mastered the information, went through it in your mind, now is the rush hour for off-duty, and it is very sunny. After summing up, you decide to combine plan 1 + plan 5, and then walk to the shopping mall in the most efficient way.
In this case, OSPF is like this. It can adjust the path according to the real-time traffic information and the communication between routers to provide the best route selection .
It realizes the optimal path selection and fast data transmission in the network by calculating and updating the routing table.
How about it, did you realize it after seeing this?
In the online world, there are always a lot of dry and difficult content, but as long as we change our thinking and learn to convert it into our own cases, it will become your knowledge .
If you still don’t understand the network knowledge and want to study systematically, you can also private message me and send the password "learning" , hoping to give you some effective suggestions.
When you don’t understand what you have learned, ask yourself, if I were to explain this thing to a layman, what should I say.
Slowly, you will fully understand this knowledge point.
Original: Xu Gongzi丨10 years of senior network engineer, more network workers to improve dry goods, please pay attention to the official account: Network Engineer Club