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In the coming years, more and more telephone companies will begin offering IP-based television service, or IPTV, to round out their triple play offering. There are several theories as to how successful this will be. Some believe it will be a huge money pit that wont turn a profit; others feel the technology has such an advantage over the cable MSOs platform that success is a slam-dunk. In reality, several independent telephone companies and municipalities have already proven that it is possible to operate a profitable IPTV/Triple Play franchise.
Certainly, it is not just a matter of if you build it, they will come. There is no service functionality associated with IPTV that the MSOs cant provide. It may be more efficient to send everything via IP to the home and may, therefore, be a logical architecture for a greenfield deployment. When and if the efficiency gain is called for, cable can start sending video over the DOCSIS (Data Over Cable Service Interface Specification)-based IP pipe alongside VoIP and data and the game is essentially even. So, it comes as no surprise that the levers are revenue, CAPEX, and OPEX.
On the revenue front, given the fact that the platform is based on IP, the potential application set is limitless with the ability to integrate telephony, chat, polling, click-to-purchase, and a wealth of other interactive functions into the TV experience. The ultimate keys to revenue generation, besides the economy, will be the level of creativity and the relative brand strength as evidenced, for example, by the success that Google is experiencing.
In polls taken over the past few years, telephone companies have been cited as the preferred provider for a bundle of services that includes video. For the telcos to be successful, theyll need to be mindful of several network-related considerations in order to maintain their brand, contain costs, and consistently generate revenue. These include scalability, reliability, service quality, and openness.
Today, most people watching TV are tuned into a broadcast channel either watching the program live or having it captured to their recording device. Using IP-layer multicast as well as physical layer broadcast, a video stream appears at most only once on any network segment from the point of origination to anywhere in the network even if it is viewed or recorded by many subscribers. Video on Demand (VoD) requires a unique video stream for each subscriber watching a particular program. Until recently, this consisted of movies, a set of programs from premium channels, and some free niche programming content. This resulted in a peak simultaneous usage of about 15 percent. In the future, it is expected that almost all of the most popular channels and programs will be available on demand. As they are broadcast, they will be ingested into a server and ready for on demand viewing within five seconds and stored for, perhaps, one to two weeks. Simultaneous usage could grow to 50 percent or more.
For bandwidth scalability, the transport network should be based on 40-wavelength DWDM with reconfigurability at the wavelength and subwavelength level to rapidly add capacity in 1 Gbps or 10 Gbps increments to the central office and remote terminal locations where it is needed. For service scalability, the access node should perform IP forwarding. This serves to hide all the Ethernet MAC addresses of all the subtending subscriber devices from the rest of the network. Instead of the aggregation switches and routers needing to know and store the 2502,000 or so MAC addresses per access node, they only need to know the MAC address of the access node itself. This avoids having to partition the network and allows it to scale almost indefinitely.
While there are no E911-type regulatory requirements for video, some might consider its full time availability to be a life or death matter. Nobody has ever died because the TV went out, but Id run for cover if it happened during the fourth quarter of the Super Bowl or the decisive final episode of American Idol.
To ensure that video is always available, the operator should employ fault-tolerant servers and redundant broadcast feeds, as well as a robust distribution architecture between the service edge router (SER) or broadband remote access server (B-RAS) at the video serving office and the access node at the wire center or remote terminal. Per-user/service packet treatment should be employed at the SER/B-RAS as well as the access node. This will ensure that each subscriber and application receives the contracted quality of service without adversely impacting any other subscriber.
Transport should be based on carrier-grade Ethernet aggregation configured in a logical hub-and-spoke design over a physical ring. At layer 2, the end-to-end system only requires class-based queuing, but must support at least two strict priority packet queues, so that both VoIP and video have their own, and are transmitted immediately. Other data services should have separate queues to ensure an appropriate quality of service without impacting the more sensitive VoIP and video traffic. In conjunction with VoIP and video being managed by a connection admission control function, so as to avoid oversubscription, this will ensure that those packets arent dropped or delayed.
By utilizing transport nodes with integrated Ethernet switching arranged in a logical hub-and-spoke over physical ring architecture, the aggregation network is drastically simplified as compared to routers or MPLS/VPLS switches interconnected in a Layer 2 or 3 ring. It enables protection at Layer 1 with restoration in less than 15 milliseconds compared to several seconds when done at higher layers. This design also enables Layer 1 drop-and-continue of the broadcast traffic to all nodes on the ring. Carrier-grade Ethernet leverages the ITU-T Optical Transport Network standards to provide the robustness of SONET on the cost-curve of Ethernet.
To minimize capital expense and maximize service flexibility, the network must be built using open standards. It may seem expedient to choose a single supplier to provide an integrated solution when first deploying IPTV, but that comes a degree of risk. Cable operators have been locked into a duopoly of suppliers for the video head end to set-top box due to proprietary systems. Again, it has been demonstrated by several independent telcos that it is possible to build a network using best-of-breed components from several vendors. At a minimum, a service provider should test that a second vendor can plug into every portion of the network to ensure the system is based on open standards. This will result in price-value competition and unrestrained innovation.
As telephone companies deploy video, it is apparent that they are at the very beginning of what is sure to be a continually evolving triple play network. As such, it is imperative that the network be simple to scale and operate, uncomplicated so as to ensure robustness and service quality, and open to change. IT
Mitch Auster is senior director of product marketing at Ciena Corporation. For more information, please visit the company online at www.ciena.com (news - alerts).
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