What’s a CDN and how does it relate to the Internet? A content delivery network works with the Internet, not as a replacement. The public does not connect directly to a CDN. These are privately run networks designed to provide high bandwidth combined with low latency, jitter and packet loss. They are designed for capacity and quality to support content producers and distributors. Thus, the name Content Delivery Network. They are designed to deliver content, most often in IP video format, from point to point or point to multipoint.
What CDNs do in take a load off the Internet and ensure quality of transmission for most of the distance traversed. Say a customer wants access to an HD video download or stream. You can try to jam that through the Internet and take your chances with traffic congestion and other quality degradations. Or, the provider can send the program over a CDN directly to the Internet Service Provider. The ISP, say a cable company, then gives access to the CDN delivered content to their customer. In this case, it could be through the Cable broadband service or the content could be used to feed a separate cable channel.
Sure, content can still be degraded between the ISP head end and the customer, but at least the service providers have control of that portion of the network. They can choose how to manage the bandwidth shared by their customers to ensure satisfactory video quality.
The media shift now in progress is gravitating toward most consumers getting their video services via cable or satellite rather than through over the air broadcast channels. That’s why you haven’t heard much screaming over the replacement of analog transmission by digital. It's not that those converter boxes are so wonderful. It's that the satellite and cable set top boxes that feed TV sets are capable of providing a variety of compatible analog, digital, SD and HD television signals. Old TVs as well as new are supported.
Digital HDTV was just one phase of the transformation. What’s happening now is that more and more set top boxes and television receivers themselves come with Ethernet ports for IP content. Plug these ports into an Internet router and the TV set becomes capable of displaying video content that never leaves the Net. Netflix is an example of a content provider that uses the Internet. So is YouTube. Even the broadcast networks are providing archives of already aired shows on their Internet sites.
This move from airwaves to broadband will likely result in more and more spectrum repurposed to wireless Internet service. At the same time, IP video content will increase and require a robust delivery mechanism. This is why CDNs are growing and will continue to for the foreseeable future. Level 3, one of the world’s largest IP backbones for content delivery, recently added 1.65 Tbps of global capacity and added Toronto, Montreal, Brussels, Munich and Hamburg to its CDN. Video content delivery is now worldwide.
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