Operators Increasingly Turn to Switched Video Transport

By Linda Faust

Network operators and MSOs are dealing with a rapid rise in both streamed and on-demand video content within their networks. As these operators support video services and move to high definition and 3D services, bandwidth demands increase enormously while service revenues do not. Streamed multicast IPTV traffic creates even harsher challenges. To address these challenges, network operators are working to figure out how to optimize this traffic to simplify network operations — and at the same time reduce costs. However, network upgrades and related investments can grow faster than related revenue, impacting future margins. Some of the key challenges that these operators need to consider include:

• Consumer Expectations:  User expectation for high-quality content is a given, irrespective of the nature and capability of the communication network.
• Capacity and Performance Constraints: Handling performance issues such as jitter, bandwidth and latency based on the nature of network traffic becomes extremely crucial. While content transmitted is impacted by network issues such as packet loss and transmission delay, distribution mechanisms such as multicasting possess certain inherent limitations. In addition, flooding of data across all existing networks irrespective of their requirements creates bottlenecks and disrupts network performance.
• Content Delivery:  Operators must offer new or differentiated services to retain existing customers and expand their customer base. Network operators feel the need to radically lower the cost of their transport networks if they are to be profitable in the future, and that requires optimizing the costs without compromising on scalability, efficiency, or manageability.
• Cost of Ownership: Network operators incorporating high resolution and high performance technologies used for transmitting data intense content incur heavy capital investments with the purchase of high-performance routers, switching devices and other hardware. Power consumption, repair and other maintenance also account for higher operational expenses.
• Environmental Considerations: There has been an increase in demand to minimize energy consumption and lower carbon footprint. Power-efficient and low-power consuming solutions provide an immediate and long-time benefit.

Many larger operators are now depending on Ethernet-based networks to meet this demand. There are a plethora of technology possibilities available and changing requirements can make these choices very challenging. 

One route to reduce the costs while increasing bandwidth availability is to simplify the network infrastructure and allow for the use of simpler, lower cost approaches like Switched Video Transport. Video distribution networks often are router-based. Router-based networks are costly and technologically challenging, with expensive equipment costs and demands for less available, more senior technical resources to build-out and ongoing operation, administration and maintenance (OAM). Today’s transport networks are evolving into packet optical networks, which combine packet and transport technologies and offer the performance, reliability and cost savings needed by network operators.

Building on a packet optical infrastructure, Switched Video Transport can further increase capacity while reducing costs and complexity by integrating video distribution into the transport network itself. Some packet-optical devices combine optical transport and packet switching features that can use current standards, specifically IGMPv3 and Source Specific Multicast, to listen to router traffic flows, decide what actions to take and to perform packet-switch function for the broadcast traffic. This enables the traffic to be optimized as required, but it also provides improved latency and jitter characteristics over the traditional router-based approach. In addition, integrating these capabilities into the transport network without adding a separate layer provides simpler management, operational simplicity and lower costs.

Swiss cable TV operator upc cablecom chose to use this approach for its new network. The new network is based on four interlocking rings, covering all regions of Switzerland. It serves a minimum of 2.1 million households, as well as approximately 240 smaller broadband cable operators. The network is based on an underlying ROADM-based optical layer, which supports a wide range of capabilities including broadcast and broadband services.

Alexander Lorenz, upc cablecom's vice president, network services, has said that before choosing this solution, the company considered an alternative network model based on distributed IP routers. However, they realized this would mean higher costs and complexity as well as higher latency and jitter, which would be undesirable for TV transmissions.

This approach enables operators to cost-effectively scale video distribution networks and to optimize the multicast traffic as they move from standard definition TV to high definition TV and ultimately 3D TV.  A common transport platform can support optimized multicast traffic and unicast traffic (either via Layer 1 WDM or via standard Layer 2 Ethernet). It can also support wholesale services such as mobile backhaul and broadband backhaul all at the per-wavelength level over the same infrastructure and under the same management platform. With a highly simplified network operation, the operator merely enables the feature within the necessary nodes and it will then automatically listen to traffic and  optimize the network accordingly without any complex procedures. This is very important as IP functionality is being used in a transport platform that is typically managed by a transport team within the operator, at a lower cost. Finally, in locations where multiple languages are used and in some regions that require additional local language channels, these can be added locally without the need for distribution across the whole network.

So in summary, by simplifying the network and taking advantage of evolving network technology, Switched Video Transport can meet the operator’s challenges, delivering higher performance and lower costs.

Linda Faust is director, product marketing, at Transmode, and has 20 years experience in networking and storage networking industries .