The answer will depend on who you ask and how technically savvy they are.

Non-professionals often think of IPTV as the same thing as Internet video. Ask them about IPTV and they’ll respond YouTube, Facebook or user-generated content. The typical Internet user may include news clips from sites like CNN, FOX and others as examples of IPTV. However, let us be clear. Those are NOT examples of IPTV. Those are examples of Internet video and there is a huge difference between the two.

Professionals realize that IPTV is anything but the latest YouTube clip. Experts recognize that IPTV represents high-quality entertainment, one viewed over a closed system providing a controlled user experience. Think high definition cable, PPV, VOD, HD DVRs. Think cable.

A true IPTV network has two unchangeable characteristics; it is a closed network and it provides a specified minimum quality of experience. Let’s examine these characteristics more closely.

IPTV is…

First, an IPTV system operates over “closed” networks. This means a network that is built by a service provider to deliver IP-encapsulated content. This content is delivered from a central location to tens or hundreds of thousands of locations (homes). Viewers pay the service provider to be connected to this IPTV network. You don’t pay, you don’t get connected—just like cable TV.

Second, IPTV networks provide and maintain a minimum Quality of Service, QoS. Both service provider and viewer expect that the content will be supplied in a high quality form—all the time. For the provider, maintaining this high QoS is key to survival and success against the competition--cable TV.

Now, we’ve properly defined IPTV. It is a closed network. One that’s owned, controlled and maintained by a service provider. And, the network provides a minimum quality of service. IPTV is NOT the latest Internet video.

Now let’s look closer at some of the underlying technologies that separate IPTV from Internet video.

A common language

The source of confusion about the difference between IPTV and Internet video lies in the name “Internet Protocol, IP”. Internet Protocol is simply a common language used to send data between two or more computers. This language is ubiquitous and its meaning will be perceived the same by an Apple computer running OS X, an IBM server running Linux or a Microsoft application. Internet Protocol is a universal language that is understood by a wide variety of platforms and applications.

Sending data between two computers on a network starts by breaking the data into packets. Each packet has two IP addresses in its header; the address of the source computer and the address of the destination computer. With these addresses, the data can move from transmitter to receiver.

IP defines two common protocols for sending messages within IP packets; Transmission Control Protocol (TCP) and User Datagram Protocol (UDP). TCP is a reliable, connection-oriented protocol that guarantees reception and in-order delivery of data from sender to receiver. If a packet doesn’t arrive in time and is presumed lost, the receiver sends a request for retransmission of that packet.

UDP, on the other hand, is a connectionless protocol that provides a “best effort” to getting the data from point A to point B. However unlike TCP, UDP does not guarantee perfect transport of the data. If a data packet gets lost along the way, the destination application will simply never get that data.

Traffic cop

In a private network, the traffic is controlled by the network’s owner, say an IPTV service provider. Nothing gets on that network without permission of the owner. This service provider can control the content and amount of traffic.

A service provider would not expect to deliver the latest hit HD movie on a VOD basis to your home over the public Internet. Why? One reason would be the Internet’s non-real-time performance. It could take hours for the content to finally reach your STB. Even then the feed would likely contain errors, which would impair the picture/audio quality.

A typical Internet connection may experience various types of delays and interruptions. All these are bad when your business is based on providing a high quality experience. So, let’s look at one type of network performance measurement a service provider might monitor. Its called IP loss ratio or IPLR. This is the ratio of delivered packet to lost packets.

A typical Internet connection may experience an IPLR of 1x10-3. The loss ratio on a private network using dark fiber can approach 1x10-14 or better. The smaller the number, the better. IPLR is a key network performance marker and one that network engineers have to consider when designing systems.

In addition to the LPLR, it’s important to know the characteristics of network losses. It is one thing to design a network to recover from random errors that happen occasionally and in no particular order. A whole different set of design requirements come into play if the errors occur infrequently, but last for several seconds at a time. Clearly, the continually-changing loss profile of the Internet is vastly different from the loss profile of a closed private network. And, in part because it cannot be controlled, a superior QoS cannot be guaranteed over the public Internet.

Next time we’ll discuss more key network protocols and how they are used by IPTV networks to provide superior service.