CDN website accelerates, not only big website can have

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CDN

CDN, many entry-level webmaster may be unfamiliar with this term, CDN is the abbreviation of contentdeliverynetwork, we can be called "Content distribution Network", it is built and overwritten on the existing Internet base, A virtual network consisting of node server clusters distributed across regions. The goal is to add a new layer of network architecture to the existing Internet, publish the content of the Web site to the nearest user's network "edge", so that users can get the required content, solve the Internet congestion situation, improve user access to the site response speed. It solves the problem that the network bandwidth is small, the user's traffic is big, and the dot distribution is unequal. CDN and the core idea is to route the user to the nearest service point in response to the user request.

The traditional CDN service, because of the huge investment of the cache node, makes the CDN service expensive, such as ChinaCache. Due to the free mode of internet development in China, most of the websites have not yet realized profit, in this case can only be exclaiming in front of the expensive CDN acceleration service. However, the use of idle server and bandwidth resources can bypass the cache node investment huge this clearance, with more advanced node detection mechanism can provide users with a stable CDN accelerated service, while greatly reducing the cost of CDN services, Will originally only a few large websites can enjoy the CDN accelerated service to drive down the altar, become small and medium-sized website can also enjoy the mass products.

Current application of CDN Market

The technology, first proposed by MIT's graduate students in 1998, was initially used by Akamai to provide a professional CDN service. Today, the United States already has 70%~80% website to consider using CDN service. In the aftermath of the US incident, MSNBC.com, one of America's biggest portals, surged, and more than 90% of its traffic was shared by CDN, including 30 million minutes of 13 million streaming videos. A survey shows that 2003 CDN service expenditure will increase from 2000 to 97 million U.S. dollars to 2003 of 2 billion U.S. dollars. China's CDN market is still in the reclamation stage, but the development potential is enormous. Founded more than two years of ChinaCache has been established in the country 43 nodes covering the national network, for telecommunications "internet Star", Sina, Sohu, TOM, Ogilvy Interactive, ebay, Coca-Cola, Sony and other companies to provide CDN services.

3. CDN changes to the original website access mode

Traditional Web Access procedures

(1) Users will submit HTTP requests to the www.xxx.com domain name to browser software like IE

(2) After IE receives the domain name request, to the local DNS request to the domain name www.xxx.com resolution.

(3) Local DNS sends a request to a DNS server that is authorized by the Web site to authorize the DNS server to send the IP address of the Web site to local DNS.

(4) After IE gets the HTTP server IP address, sends the HTTP request to the server.

(5) When an HTTP server responds to an HTTP request, IE is responsible for displaying the response content.

The problem with the traditional Web access process is that the DNS parsing process converts the host domain name of a Web site to an IP address, and does not determine whether the server can respond properly to a user's request, even if the server is down or the user request is slow, and the request is sent to the server.

After the introduction of CDN, users will be required to cache the content of the access to the nearest cache node, users directly from the cache node to obtain content, so that also avoid the intermediary to go too many switches, routers brought by the delay. This mainly to the host domain name resolution of the steps to do the transformation, DNS query is not to return to the server source station IP address, but to return to the user's nearest reliable cache server node.

Two. Does the existing CDN technology meet the requirements of the public?

If I want to enter CDN This market, become CDN operator, for other website users to provide CDN acceleration service, I should have what conditions?

1. Hardware

First deploy the cache node, the deployment node to consider the user's geographical location, the diversity of different operators. Here the cache node coverage of the geographical range, the more extensive the operator effect the better. Of course the deployment of cache nodes also takes up most of the cost of CDN operations. At the beginning of CDN operation, each operator should have a node in a large area, such as telecom in South China, northeast, east, northwest and southwest.

2. Software aspects

With so many cache nodes, how do these cache nodes respond to user Web requests? How to monitor and manage so many cache nodes? That's what the software does. I sum up, CDN operating system software is divided into three large

A. High performance HTTP proxy server, which is deployed on the cache node to respond to the user's HTTP request with high performance.

B. Cache node monitoring platform, the software can monitor the working status of all cache nodes in time, and can respond to the change of nodes in time.

C. A high-performance DNS server, which can select the nearest stable cache node of the requesting user to respond to the user's request in real time.

For CDN operators, the largest chunk of investment should be in the cache node layout of this piece, with the increase in the number of nodes, the investment will rise in a straight line, ideally in each visitor's home to put a node, and as the network operators, the first area visitors to the door to put multiple nodes. ChinaCache, for example, has deployed more than 500 nodes across the country, but even so, because of the breadth of the visitor's source, it cannot be met.

In fact, we are going into the mistaken idea that the road to Rome is only one, but it is not, there are more convenient, economical way to reach the destination. There are a lot of servers on the Internet, only a handful of these servers are in a state where the load is basically saturated, most of the servers are in a state of not eating, and even the servers with higher resource utilization have different workloads at different times of the day, such as game servers that are busier at night and more idle during the day, Some Web servers on the contrary, in the IDC room there is still a large number of unsold, unused servers and bandwidth resources, then these now idle computing and bandwidth resources not only can not produce any value, but also to waste electricity, not with our construction to solve the social goals of the incompatible! How do you make use of these unused resources? Don't forget, the above we build CDN services just need a lot of cache node resources, if you can use these idle servers and bandwidth for users need to provide CDN services, not the best of both worlds!