Jsliang Job Series – 25 – Computer Networking Basics

Another three years of sewing, testing what to add what, scattered knowledge points.

Now this scattered knowledge point is a little bit less, but still write, after cross domain what will use point.

There are three types of computer network architecture:

• OSI architecture
• TCP/IP architecture
• A five-tier architecture

The details will not say, this should be expanded, the length can be written into a book.

The university time learns this, be rao gets the head big by the professor, afraid afraid.

I am a user. I cannot access a web site, but I can access a proxy server.

What about this proxy server, it can access the site that I can’t access, so I connect to the proxy server, tell it that I need the content of the site that I can’t access, and the proxy server goes and gets it back to me.

In a nutshell:

In forward proxy, the user knows the IP address of the server, but cannot access it by himself.

User 1 \ user - agent -> server/user 3Copy the code

Features:

1. Through some software (proxy server)
2. Access to resources that would otherwise be inaccessible (wall climbing)
3. The proxy server can hide user information (manage Internet access records).

Reverse proxy means that a proxy server is pushed between the client and the server, and all requests are managed through the proxy server.

For example: Taobao has a master server, server inside a lot of small servers. When users visit, they access the master server’s address (public IP), and the master server assigns specific small servers (private IP) to handle your request.

In a nutshell:

In a reverse proxy, the user does not know the IP address of the requested server.

User 1 server 1 \ / User 2 -> Master server -> Server 2 / user 3 Server 3Copy the code

Features:

1. Ensure safety. The client accesses the public IP address, and the reverse proxy server accesses the Web server on the Intranet.
2. Load balancing. The reverse proxy server performs polling to select the Intranet server to access.

CDN stands for Content Delivery Network.

The basic idea is to avoid the bottlenecks and links that may affect the speed and stability of data transmission on the Internet as far as possible, so that the content transmission is faster and more stable.

• Do not use the CDN

Jsliang, a user in Guangzhou, is requesting an IP address in Beijing.

It might go something like this:

Guangzhou user -> Guangzhou server -> Hunan server -> Hubei server -> Beijing server

It takes a lot of time to search one by one.

• Use the CDN

Beijing server specified a CDN service provider, and then this service provider has a Guangzhou server to do deployment, we can directly visit the Guangzhou server to find the information.

• Simple to understand

Dong goes shopping, buys a shampoo, a foreign brand, and sends it directly from her guangzhou warehouse.

If the user is from Beijing, send it from the warehouse in Beijing.

And that’s what our CDN service providers do.

• For example,

We refer to jQuery in the page. If the resource is placed on the home server, it will increase the pressure on the home server. If you ask for the jQuery official website address, it may be too far. Therefore, CDN is used to allow CDN service providers to judge which resource library is closest to the user’s example and provide which address to the user.

• applicable

1. A static resource that does not update frequently
2. The home server has fewer resources

• Forward proxy and Reverse Proxy【 Reading Suggestions: 10min】
• Learn about CDN in five minutes【 Reading Suggestions: 10min】
• Ramble: how to explain to girlfriend what is CDN?【 Reading Suggestions: 20min】
• On THE CDN, back to the source and other issues【 Reading Suggestions: 10min】
• What is CDN? What are the advantages of using CDN?【 Reading Suggestions: 10min】

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