Content Delivery Network – is the system which serves content to the user. Service provider, providing CDN services offers to transport static content and streaming video as quickly as possible to the consumer. For the distribution of content on the server system the company uses its own dedicated network or the Internet, and the distribution of content on the CDN servers is also optimized. Switches are used though, which operate not only on the 2nd channel level, but also at higher, connecting separate cash server’s virtual network.
Special algorithms are developing to determine the responsible server, based on the task – to minimize traffic on the network (selection the nearest server), minimizing the cost, minimizing the time. Optimization of algorithms is complex and varied.
CDN are different in scale – some work for smaller clients and their regional audience, for example, for only one country, others are oriented by the major broadcasters distribute content and have their servers in almost all countries of the world.
CDN helps deliver content to the end user, but they cooperate with content providers on one side, and internet service providers on the other hand, that is a B2B business, unlike most peer solutions (P2P).
One of the most popular search requests according to the Content Delivery Network is how to choose the best CDN technical requirements, security, analytics, etc.
First of all it is important to understand which content distribution you deal with.
Content Delivery Network services most often used with 3 types of content distribution:
1) Downloading – downloading large files, such as distributing software. CDN in this case is used to provide secure access to the service and fast download from http\ https
2) Progressive downloading – the file starts playing almost immediately – after a short buffering. The user thus does not have to wait for a complete download file to start watching, so this format is used actively feeding, for example, companies are trying to post your videos on websites, or large text that site visitors can immediately begin to browse.
3) Streaming. The file is not stored on the user’s computer except a small buffer, compensating for unevenness of the IP-packet arrival.
Differences:
If everything is clear with Content Delivery Network, how about their suppliers? There are a lot of companies, and they are differ in price, service and quality.
Here are the main factors to determine when choosing a supplier:
- Point of Presence
The more points, the better, but, why do you need a point of presence in China, if you have English-language website? When you compare the CDNs you should take into account the number of points of presence in the countries and regions of your interest. Points of presence also are not equivalent – connectivity and peering agreements with local providers are very important though.
- Value added services
CDN can provide additional services. For example (partial list):
• Real-time information to the refusal of separate units
• Analytics
• Integration with CMS
• DRM for content
• Ready html / flash video player for video-enabled features of CDN
• Policy Management cache
It is important to pay attention to necessary protocols and files. Find out whether your provider offers streaming and flash media (RTMP, RTSP), if you are planning to deliver this type of the content.
Perhaps, the provider is very good in everything else, but if it does not have necessary services for you, you will not be satisfied.
- Technical nuances:
Redirect technology: It’s either any-cast on the DNS level, or forwarding through redirects. Anycast, for obvious reasons, is faster
Accuracy of forwarding: unfortunately, provider is not able to evaluate this index objectively, although just this index is very important – which part of the target audience gets to the closest server.
- Accounting
How does the supplier take the money? For megabytes or megabits per second? Is there a minimum contract period? Is there any contract (between the site owner and CDN provider), or is it an automatic self-serving on-demand provisioning, i.e., “I threw the money into the account and received the control panel”?
Starting from which traffic it makes sense to think about a CDN?
To repeat a thought: if you need to serve customers quickly, the traffic volume is no longer important –the most important is the closes point (server) to the target audience.
If, there is, no necessity for considerable latency, Content Delivery Network is used to relieve the load to the server, start thinking about CDN – when the traffic is TB per month.
And finally, our friendly advice:
Do not chase the cheapest one, do focus on quality!