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IPTV calls for content-aware network edge devices

Posted: 01 Apr 2008 ?? ?Print Version ?Bookmark and Share

Keywords:IPTV network? packet processing? IP network design? passive optical network?

There is a rapidly growing momentum behind worldwide broadband deployment and the emerging "triple-play" convergence of voice, video and data services. This momentum is offering network carriers a promising answer to shrinking revenue from traditional landline voice customers.

By bundling voice, video and data services in unique and creative ways, carriers hope to differentiate themselves from both traditional and new-entrant competitors. Of particular interest is the move to an all-IP network and the deployment of IPTV, which is expected to enable operators to offer a wide range of exciting new services and generate incremental revenue streams.

New demands
It is important to note, however, that IPTV is very different from traditional cable/satellite TV services and will place significant new demands on telecom network infrastructure. In a cable/satellite-based system, for example, viewers can only watch those channels offered by the service provider. With IPTV, however, users have a much wider channel selection and they can also view what they want when they want it.

Built around the same transport mechanism subscribers already use for Internet browsing, instant messaging, e-mail and other communications functions, IPTV allows carriers to offer a truly interactive environment for the first time. This interactive environment combines HDTV, video on demand (VoD), network private video recorder, video telephony, Internet access and other multiple functions. For the current "lean-forward" generation accustomed to extreme multitasking, the ability to simultaneously text message friends via TV while watching is a powerful draw that neither "PC-over-broadband" nor cable/satellite TV can match.

The greatest obstacle that service providers face in the successful implementation of IPTV is the state of the transport network.

QoE factors
As currently constructed, the transport network supports Internet traffic, VoIP and video over the Internet, but the quality-of-experience (QoE) for each of these services is limited.

Two factors are important in users' QoE: the bandwidth offered by the access network and the mechanisms available to manage traffic at the edge of the network. In particular, any implementation of IPTV today would be forced to share the same IP network with unmanaged traffic. Inevitably, this network architecture would lead to bandwidth contention and bottlenecks.

For IPTV to succeed, carriers and service providers must offer a QoE equal to or better than that offered by today's cable/satellite TV. The key to achieving this goal will be the development of "content-aware," network edge devices that are capable of tracking, managing and prioritizing the multiple signal streams flowing through the edge of the network.

Required platform
A second major obstacle to the implementation of IPTV is the development of a common platform to roll out IPTV services. This platform must offer low operating costs, excellent scalability, simple maintenance, guaranteed compatibility with existing infrastructure and a rapid ramp up to volume production. Since IPTV networks must offer a wide range of constantly evolving features and functions, the platform must also be highly modular in form to ensure operators that their significant capital investment will be "future-proof."

IPTV edge devices must also support multicast streams for regular broadcast channels and unicast streams for VoD content. Multicast capabilities will require dedicating resources. For special broadcast channels, IPTV multicast streams may use pre-reserved resources from head-end to the IP edge. At the IP edge, dynamic resources will be required to broadcast these special channels to the digital subscriber line access multiplexers (DSLAMs) and/or the passive optical network (PON) aggregators responsible for sending IPTV streams into subscribers' homes.

The key to managing this increased bandwidth and guaranteeing QoS will be the development of network edge devices capable of extremely rapid packet processing for deep-packet inspection (DPI) at up to 10Gbit line rates. These capabilities will allow service providers to filter bandwidth-intensive applications (e.g. P2P file sharing and encapsulated traffic). Moreover, they will also play a key role in prioritizing bandwidth associated with premium content (i.e. VoD, HD channels and sporting events).

IP edge devices in the IPTV network will be responsible for aggregation, channel changing, edge routing, congestion management and traffic shaping to provide QoE to IPTV subscribers. These new edge devices must be bandwidth-efficient and able to simultaneously manage both broadcast video (multicast streams) and VoD content (unicast streams). They must also offer faster channel change by giving preference to requests from the access network (via DPI) of the IGMP messages and prioritizing them for processing at the edge device.

One of the distinguishing features of IPTV will be "time-shift" viewing, which allows the viewer to "shift" the timing of the broadcast of an entire channel lineup. This will give service providers an opportunity to insert time-sensitive and content-relevant advertisements into a broadcast. Furthermore, operators will be able to offer both demographic-specific and variable-length advertising based on users' preferences. This functionality will be implemented using content-insertion software, based on DPI functionality embedded in IP edge devices, where local broadcast channels and advertisements are fed into the IPTV network.

ATCA blades scale nodes as subscriber base grows. Pre-integrated platforms shorten development.

Distributing content
Telecommunications companies have not yet determined how they will handle clients and suppliers of content such as P2P video traffic, which will require a different strategy that can apply to a business environment and to recreational consumption. Service providers will need to use DPI to determine what content is flowing across their IP network. They can then use that information to modify their delivery strategy and potentially create new revenue streams from P2P TV. IP edge devices need to have highly flexible and scalable storage capabilities to address changing user tastes and fluctuations in content popularity.

Frequently used features such as an electronic programming guide, digital rights management servers and subscriber e-mails will also be kept at the edge of the network. To deliver these services, operators will need to integrate application servers, which will be upgraded into the IP edge platform.

Additionally, to support the coming convergence of IP multimedia subsystem services into the IPTV network, telcos will need IP edge platforms with enough scalability to adapt to advancements in hardware and software. Service providers will probably need IP edge devices built into a field-proven, standardized hardware architecture such as advanced telecommunication computing architecture (ATCA), which is widely regarded as the next-generation carrier-grade, standards-based telecommunications infrastructure.

To reach broadcast-TV-quality levels, these IP edge devices must also offer bandwidth-prioritization capabilities for providing guaranteed QoS. HD VoD servers will require multiple high-capacity unicast streams to DSLAMs. To deliver this level of service, the edge device will need to combine the general processing power found today in an ATCA multiprocessor computing blade, with the high-speed packet processing power available in an ATCA packet-processor blade. By basing their platforms on the ATCA standard, IPTV providers can scale their nodes with plug-and-play, ATCA-compliant blades as their subscriber base grows. Pre-integrated platforms will help service providers meet demand for increasingly complex systems in short development windows and will reduce integration and compliance risk.

Managing security
Network security will also be a major concern for IPTV operators. Intruders can use unprotected nodes to spoof or masquerade data in various ways. In an IPTV network, providers will need equipment capable of performing 10Gbit/s line rate DPI at Layers 4 through 7 to analyze complex patterns for threat signatures. Over time, these complex patterns will also likely evolve. The only way to combat these threats will be through network edge platforms that can combine hardware- and software-based DPI at line rates to block distributed denial-of-service attacks, and quarantine and block the latest worms and viruses at the edge of the network. The ideal solution is to combine a high-speed packet-processing blade with traffic-engineering capabilities on an ATCA-based platform.

To support several channels using SDV technology, IPTV networks will require high-speed switching in the range of 10Gbit/s to support a fast, satisfactory channel-change experience. To connect the high-speed core network to DSLAMs/PONs in the access network, service providers will need Ethernet-switching capability at the edge; an ATCA-based 10GbE switch can meet this switching requirement.

Software requirements for IPTV edge devices will be critical as well. These nodes will require unicast stream handling, multicast stream handling, SLA-based QoS and subscriber-management capabilities. Ideally, these applications should be hosted on flexible, open standards-based platforms to simplify functional integration and drive down costs.

- By Nitin Tomar
Technical Marketing Engineer
Continuous Computing Corp.

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