Foreword
Bowen interpretation of the evolution of large sites Talking about his family moved to the CDN static files Bowen are involved CDN, this time we have to explain in detail under CDN architecture
Brief introduction
CDN content distribution network is built on top of the network, relying deployed around the edge server, load balancing through the center of the platform, content distribution, scheduling and other functional modules, allowing users to obtain the required content of the nearest , reduce network congestion and improve user access response speed and hit rate. The key technology of CDN main content storage and distribution technologies.
The basic principle is widely used in a variety of CDN cache server , the cache server distributed to these regions with relatively dense user access or network when the user accesses the site, the user's access technology utilizing the global load will point to the nearest working properly cache on the server, the cache server in response to direct user requests
benefit
To enhance the speed of access to resources, to provide users with a better user experience , such as access to a picture, if available from the original source station may need to 30s, but may require only 1 ~ 5 s after use cdn, cdn is because from the closest to the user server resources to obtain pictures
Suitable
Static resources, such as js, css, image resources, videos, music resources, software resources, etc.
CDN architecture
Example: a user access to image resources (eg cdn.pic1.54php.cn/test.jpg)
By dns browser parses the cdn.pic1.54php.cn CNAME server to the CDN
CDN internal server through the storage engine to see whether the file on the CDN storage server
If the picture is directly returned to the user
If not, CDN storage server starts from the original site and then download the pictures stored in the picture returned to the user
Key analysis
We also use the following two points CDN service vendors must configure two
Operation cname: cdn.pic1.54php cname specified by the manufacturer to a CDN name (especially step a)
Configure the source station address: cdn server can not find the picture will download the resource (especially Step Four) from the source station site
CDN resources so every item will need to configure two domain names, such as my blog resource image configuration is as follows
cname操作：cdn.pic1.54php.cn cname 7xo9jr.v1.com.z0.glb.qiniudns.com.
源站域名配置：pic1.54php.cn A xxx.xxx.xxx.xxx (博客服务器ip)
Westward CDN Technology
Front of the main talking point of view users, in order to provide technical accumulation CDN service needs of our study together again
DNS intelligent analytic
Caching technology such as varnish, squid, etc.
Load balancing technology such as nginx
DNS intelligent analytic
Why do we need intelligent parsing?
That can get resources from the nearest server to ensure that users in different regions to achieve the role of speed.
So what is the smart resolve?
For example, user John Doe is Shanghai users, user John Doe is Beijing, then by regional policy, Mr Tan is to get resources to obtain pictures from Shanghai server, John Doe is obtained from a server Beijing
Caching
The pursuit of faster, although access to resources from the nearest server fast enough, but it can also be faster by caching technology, I work there is a nice varnish and squid in contact with both technologies. You can view the presentation on squid Squid operating practices
Load Balancing
As the name suggests is used to distribute tasks, if our server is a group of more than one, then it would have to balance the load-balancing software to distribute tasks
to sum up
We hope that through the perspective of users and service providers point of view to explain, we have a certain understanding of CDN
Original Address: CDN services technology architecture diagram
Tags: CDN CNAME speed optimization Squid Varnish
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Reproduced in: https: //my.oschina.net/54php/blog/799100