The impact of IPTV and other broadband multimedia services on service provider backbones will be enormous, with some of the greatest impact being felt by the metro optical transport network.
The sheer volume of users and services, and increases in bandwidth dictate a new approach to network planning. Support for emerging consumer broadband services, combined with high speed business interconnection services, will require an incredibly flexible infrastructure--particularly since the rate of service penetration and market adoption is unpredictable. Service providers need an optical infrastructure that enables them to adapt to demand as it emerges, and to add new services and increase bandwidth to existing services without impacting the ongoing operations of the network. They must be able to add nodes, or modify services and technologies on existing nodes, to reach new customers and roll out services quickly--again, without impacting ongoing network services.
Driven by changes in consumer viewing practices, even the very nature of the traffic will change over time. Initially, the traffic may be generated by broadcast and multicast services (such as IPTV or pay per view), but TV viewing behavior is shifting away from Broadcast TV towards deferred viewing (store for play). In a 2003 report, Kagan World Media projected that North American cable operators would install 1.3 cable-DVR boxes in 2003, 3.6 million in 2004, 6.7 million in 2005, 9.9 million in 2006 and 12.5 million in 2007. In Europe, IMS Research estimates that by the end of 2005, over 2.6 million households in Europe were using a DVR -- by 2010 it believes this figure will be 41 million.
Increasingly, traffic will be dominated by interactive services, such as video on demand (VoD), gaming, and high definition personal video conferencing. More flexibility in how and when consumers experience content will drive increasing demand for consumer-based storage devices such as media center PCs, PVRs, iPods and even cellular phones. VoD services will be delivered to consumers in either a streaming, buffered or downloaded service model tailored to a combination of the consumer service request, and the terminal and/or storage device capabilities. At the same time, legacy services must be accommodated on the new infrastructure, to maintain existing customers and revenues.
To be ready for all these changes, service providers need to have an extremely flexible infrastructure in place. They need to implement an infrastructure now that will serve broadband market needs over the next ten to fifteen years. This infrastructure shouldn't force the provider to commit to a single technology or single topology--the market is far too dynamic for that. The ideal infrastructure is one that has been designed from day one for maximum flexibility, growth and reliability. For that you need an agile, service-transparent infrastructure that can be fully managed end to end. For that, you need wavelength networking.
Planning for
Uncertainty
The future is uncertain, but it is possible to plan for it. The new broadband multimedia infrastructure must enable service providers to:
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Add bandwidth to existing services and add new services without impacting existing services
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Rapidly add new service distribution elements, without impacting existing services
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Scale the network in all directions: the number of customers and services, as well as the bandwidth required per customer or service
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Deliver all services reliably and quickly, day in and day out, so customers have no reason to look elsewhere
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Manage the network end to end, to ensure all resources are being used to maximum efficiency
To satisfy all these requirements, service providers need a scalable, flexible wavelength transport infrastructure such as the one shown in Figure 1.
Figure 1 -- Optical Layer Evolution
Metro Access
The first thing to consider in the metro access network is the customer end. The network must be "access agnostic." It must accept input from any source: DSLAM, MSAN, FTTx, PON, MSPP, WiMAX or any other type of access device. The customer end is also a key contributor to scalability issues. The number of end points accessing the network and the bandwidth required to service those end points is going to grow enormously with increasing demand for broadband multimedia services.
Consider what is required to support broadcast TV services. In the past, networks were planned around the assumption that each user experienced a certain amount of downtime within any block of time. With broadcast services, the entire customer population can be plugged in at the same time, expecting non-stop service. Interactive services, such as VoD, gaming, and high definition personal video conferencing tend to place different service delivery requirements on the network infrastructure. Here, the sheer number of simultaneous consumer interactive sessions could become an issue in its own right.
Attempting to deliver this level of service with a traditional network would be cost prohibitive--if it were possible at all. Instead, service providers must look for a solution that has been purpose-built for this environment.
The solution chosen must be open and flexible, supporting all technologies, not just Ethernet. While Ethernet is undoubtedly emerging as the main traffic type now, other technologies could easily evolve in response to new and currently unknown requirements. Service providers need to ensure that their new infrastructure has the flexibility to adapt to whatever the future has in store. It should also support legacy technologies such as ESCON, FICON, Fibre Channel, SONET and SDH.
Support for multiple topologies is essential for deep penetration of fiber into the access network, which in turn enables service delivery close to the subscriber. Not only must the network support all topology options (mesh, ring, linear), it must be possible to change and adapt topologies, as need dictates.
A wavelength-based infrastructure can meet all the access requirements. It provides the optical layer resiliency necessary to deliver non-stop services. By supporting Ethernet (GigE)-based wavelength networking, the service provider can avoid unnecessary complexity and overhead. The wavelength infrastructure can handle the scalability requirements, even as growth goes from 1 to 2.5 Gbps per access point to 10 Gbps. A carrier-grade wavelength infrastructure enables the service provider to monitor the network end to end, quickly deploy new service end points, and optically switch and optically replicate wavelengths from a central management point. Ideally, network planning tools will be available to help the service provider keep one step ahead as new services roll out and new markets develop.
Metro Core
Initially, due to the uncertainty of where services will be needed and which services will be in demand, service providers will likely opt for a centralized service delivery model in which the metro core acts as the sole service delivery point. This will enable providers to control costs by limiting capital expenditures while service demand is building. However, the infrastructure must be adaptable and allow service providers to move from a centralized model into a distributed network of service delivery points as demand grows. Any adaptation of the network including topology changes, and additions or deletions of nodes, services and/or technologies must be possible without disrupting existing services.
The bulk of traffic handled in the core network will likely be Ethernet. However, like the access network, the core must be able to handle traffic from legacy systems. To enable the service provider to operate a single, unified infrastructure, the metro core network should also support the interconnection of large data centers and SANs.
The ideal metro core network is based on flexible wavelength distribution, and supports:
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10 Gbps-based wavelength services today, with planned migration to 40 Gbps
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N x 10 Gbps wavelengths
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Multiplexing of 1 x GigE channels onto a single 10 Gbps wavelength
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Deployment of new service points, reconfiguring and addition to existing end points in line with service demand
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Optical resilience, including the ability to manage the entire service delivery architecture end to end, with features such as auto power balancing
Metro Switching
The most cost-effective way to get huge amounts of traffic from the access to the core is through switching. The best approach here is to deploy a next generation optical node that is capable of optical wavelength switching, to function as a metro services switching point. The metro services switching point ensures service resiliency: a must for video (and voice) services. The switching point must implement switching on an "as required" basis; service processing should only be undertaken when it provides value. Otherwise, the traffic simply passes through the switch. The switch must also offer CWDM and DWDM termination. Optical layer media replication supports cost-effective distribution of broadcast multimedia content to multiple simultaneous end points, all with optical resiliency and speed.
To support broadband multimedia service delivery, multiservice aggregation and switching is required for:
Wavelengths,
supporting
Ethernet, supporting
SONET/SDH, to groom legacy traffic for local service delivery platforms
Short haul data services, to provide managed networking for legacy services and eliminate the need for overlay networks
With a unified service delivery infrastructure, service providers can transport services from the access point through the core of the network, aggregating as appropriate to ensure optimal utilization of the underlying fiber infrastructure. They can also plan and manage the network from end to end. With the metro services switching point, providers can switch traffic, which enables them to put optical services deeper into the network (i.e., closer to the customer).
Flexible Access Options
Each optical access point should support both CWDM and DWDM, to ensure service providers have the flexibility to implement the appropriate solution for their evolving needs. In addition, the network must have the necessary scalability to support traffic at 1 and 2.5 Gbps now, with planned evolution to 10 Gbps.
Service providers need to invest in equipment that allows them to adapt the topology of their network over time. They must have the flexibility to network wavelengths as necessary to support an ever increasing number of multimedia services.
Cost benefits can be achieved by terminating multiple WDM chains on one metro node. Driving WDM deeper into the network also means that service providers can use WDM to support services from other network layers, including multiservice access networks, IP-based DSLAMs, FTTx and cable head ends.
Maintaining the status quo is not an option. Service providers must implement an extremely flexible infrastructure than enables them to leverage optical scalability, resilience and service assurance. They need to deploy optical wavelength networking deep into the access network, and only undertake service layer processing when it adds value. Above all they need to be able to manage the network from end to end.
A unified service delivery architecture will enable providers to leverage optical wavelength transparency and switching to support a range of services, including broadcast and interactive broadband multimedia services. It is the only infrastructure that has the flexibility and growth potential to enable service providers to meet the broadband revolution head-on.
About
the Author
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With 20 years of experience in the telecommunications industry, Nick Cadwgan brings a proven combination of product management, product marketing, sales support and business management expertise to his position at Meriton Networks. With global responsibility for the product marketing of the Meriton Networks Agile Optical Networking portfolio, Mr. Cadwgan draws upon his keen knowledge of optical networking, SONET/SDH, Carrier Ethernet and Carrier Interworking (IP) architectures, infrastructure, protocols and services. Prior to Meriton Networks, Mr. Cadwgan held the position of Director of Product Line Management at leading companies such as Critical Telecom (developer of broadband enabling platforms for new generation access networks), Tatara Systems (a leader in mobile services convergence), Nortel Networks' Optical Data Network Business Unit and Carrier Router Business Unit, and Newbridge Networks' Internetworking Group.
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About Meriton
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Meriton
Networks Inc. has developed the industry's first unified end-to-end Agile Optical Networking (AON) architecture, a crucial element for carrier and enterprise migration to next-generation IP services networks. A flexible, scalable, futureproof infrastructure capable of multi-mission, multi-topology support, the Meriton AON architecture equips telecommunications networks with the capabilities needed for the Broadband Revolution, including rapid service deployment with one-time node engineering and zero-touch, automated provisioning under a unified control plane. With metro access, metro core and regional extension products, all fully managed by a best-in-class suite of network planning and management tools, Meriton Networks gives network operators a single source for the rapid, cost-effective delivery of high-speed services.
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