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IPTV AND BROADBAND INFRASTRUCTURE USING OPTICAL ETHERNET NETWORKS
 

IPTV AND BROADBAND INFRASTRUCTURE USING OPTICAL ETHERNET NETWORKS

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    IPTV AND BROADBAND INFRASTRUCTURE USING OPTICAL ETHERNET NETWORKS IPTV AND BROADBAND INFRASTRUCTURE USING OPTICAL ETHERNET NETWORKS Document Transcript

    • IPTV AND BROADBAND INFRASTRUCTURE June 2007 USING OPTICAL+ETHERNET NETWORKS The strong worldwide demand for next-generation broadband services is driving service providers to invest heavily in first- mile access technologies such as DSL, HFC and FTTH. Now, end-user bandwidth is set to rise dramatically as new IPTV video service bundles are offered. To remain competitive and profitable, providers need cost-efficient, scalable second-mile solutions that provide affordable backhaul to their service nodes. The deployment of high-capacity Internet Protocol TV (IPTV), video, data and triple play services presents service providers with many challenges. The tremendous increase in service bandwidth combined with unpredictable service adoption, leads to uncertainty in traffic patterns and required capacity. The Fiber Service Platform (FSP) is a So backhaul networks that provide very high scalability and family of innovative products that flexibility for future traffic demands must be planned and provide comprehensive Optical+Ethernet deployed. The over-riding imperative is to do so at the lowest networking solutions for access, metro cost, both initial and ongoing. core and regional networks. ADVA Optical+Ethernet transport solutions provide the answer, Optical Networking is focused on the thanks to the enormous bandwidth scalability of optical needs of enterprise and service provider transport and the widespread adoption of Ethernet as the customers deploying data, storage, voice low-cost transport protocol for these new services. This white and video applications. paper examines how scalable, low-cost Ethernet over Coarse Wavelength Division Multiplexing (CWDM) provides carriers with a reliable and economic method to support new services and future capacity growth. Optical networking plus Ethernet provides the ideal Fibre-to-the-Node (FTTN) infrastructure for ADVA Optical Networking Inc. new IP-DSL Access Multiplexers (DSLAMs) and also today’s © 2007. All rights reserved. ATM-based DSLAMs and legacy SONET/SDH services. LEGAL DISCLAIMER: The information provided in this document is distributed Table of contents: “as is” without any warranty, either express or limited. Next-generation services: from one-play to bundles 2 Flexible Optical+Ethernet network infrastructure 3 Evolution of broadband technology to Ethernet/IP 4 Requirements in the second-mile: access backhaul 5 Architectural choices and goals 6 Optical backhaul for cost-optimized multi-services 7 Future evolution: the right technology 9 Author: Stephan Rettenberger, ADVA Optical Networking
    • Next-generation services: from one-play to bundles High-speed Internet access, peer-to-peer video gaming and multimedia download have driven residential customer demand for high-speed connectivity. The Windsor Oaks Group estimates more than 271 million fixed broadband subscribers worldwide at the end of 2006, with a CAGR of 12% to 533 million at the end of 2012. Yet customers demand more. Video services (increasingly offered using IPTV) are recognized as the key to higher ARPU and bundled services that include data, voice and video – triple play – are being launched. DSL accounts for the majority of broadband connections in Europe and more than 64% of the worldwide broadband market. It retains its stranglehold versus Hybrid Fiber Coax (HFC) and other high-speed offerings such as Fiber-to-the-Home (FTTH). DSL is the key first-mile technology for both residential users and the fast-growing small-office/home-office (SOHO) market. The future of the market will be driven by personalized multimedia; for example, video offerings such as childrens’ TV, TV replay, music videos and 2-way video calling have proven successful for FastWeb in Italy. What seems to be needed is a “one-play” focused video service. Whether one-play or triple play, different operators invest in different growth strategies, but they all recognize an exploding bandwidth demand – perhaps even an order of magnitude increase in the next 5 years – which must be met by the network. The different services in the triple play package have different characteristics and requirements regarding bandwidth and network performance1: :: IPTV (broadcast) – uni-directional service, normally multi-casted, 4-6Mbit/s peak bandwidth per channel and medium requirements on jitter and delay performance – perhaps rising to 10-20Mbit/s for HD video services; :: Video-on-Demand (VoD) – uni-directional unicast service, 4-6Mbit/s peak bandwidth per movie and medium requirements on jitter and delay performance; :: Voice-over-IP (VoIP) – bi-directional service, 40kbit/s per voice channel and stringent requirements on jitter and delay performance; :: Internet access – asymmetric service, uplink 5kbit/s and downlink 50kbit/s average per user during peak hours and loose requirements on jitter and delay performance. The challenge? Service provider revenue is growing only slightly in value, yet the volume of traffic and users continues to increase, both in industrialized and developing countries. Infonetics Research estimates IPTV subscribers grew by 166% during 2006 to reach 7.2million worldwide and this is just the beginning of the next phase in broadband growth. In the big picture, control of cost is thus essential, and it is obvious that network infrastructure has a decisive role in cost-effectively accommodating such rising bandwidth demand. 1 Values are based on a generic model. Actual numbers may vary. 2
    • Flexible Optical+Ethernet network infrastructure DSL access is capable of supporting today’s varied service requirements. Yet next- generation broadband services require higher capacity, driving an increased penetration of Fiber to the Node (FTTN) with Very-high-rate DSL (VDSL)/VDSL2 drops to the end- customer. Cable TV systems, using coax feeds to the end-customer, are more than capable of supporting the varied service requirements, yet they too require an increasing capacity. Even as extreme competition drives prices downwards, service providers need to offer higher Quality of Service (QoS) to ensure viewers maintain their Quality of Experience (QoE). They need to offer high availability services and still higher capacity to the end-user. Looking ahead, FTTH ONT and OLT growth is forecasted at 50% (Dittberner Associates) and is widely expected to be the engine of broadband growth in many countries. And with the transition to HDTV video services, it’s clear that capacity demand will not reduce in the foreseeable future. IP backbone Broadcast Video on Demand server server BSR Ethernet transport TV/Video 1…n Set-top Internet Box (STP) Voice Figure 1: Triple play next-generation access scenario New second-mile network technologies such as Carrier Ethernet and CWDM transport have proven less costly than legacy SONET/SDH and ATM architectures and enable carriers to cost-effectively manage the large amounts of bandwidth required. By using Optical+Ethernet transport to process multi-Gigabit/s of Ethernet traffic onto protected optical fiber, service providers enjoy uncompromised availability and scalability coupled with dramatic improvements to operational efficiency and future flexibility (Figure 1). As a result, CWDM optical technology is accepted as an essential part of next-generation broadband, whether it is based on DSL or based on alternative technology such as HFC. The integration of Ethernet packet technology brings advantages in terms of network utilisation and link efficiency, as packet data traffic grows to rapidly eclipse TDM traffic types. 3
    • Evolution of broadband technology to Ethernet/IP The Windsor Oaks Group reports that (Figure 2): “DSL will remain the dominant broadband technology, with 64% of total fixed broadband subscribers. FTTH will offer the strongest growth opportunity with 29% CAGR, while cable will be the lowest at 9%.”2. Global Broadband Subscribers by Type, 2004-2012 DSL Cable Modem FTTH Other 600.000 500.000 Subscribers (000) 400.000 300.000 200.000 100.000 0 2004 2005 2006 2007 2008 2009 2010 2011 2012 Source: broadbandtrends.com Figure 2: Global broadband subscribers, forecast by technology Following the commercial introduction of DSL, the technology has undergone substantial innovations to increase supportable bandwidth/distance. Today, Asymmetric DSL2 (ADSL2) and ADSL2+ are available. These International Telecommunication Union (ITU-T) standards deliver 12Mbit/s and more than 25Mbit/s maximum capacity downstream, respectively. Further increase in capacity is provided by VDSL2 (ITU-T G.993.2) to provide 100Mbit/s symmetrical up and downstream over short loop lengths. Older generation DSLAMs use ATM as the underlying aggregation mechanism for connecting to the carrier network. Backhaul to the metro core is based on SONET/SDH, typically at OC3/STM-1, 155Mbit/s. However, as bandwidth needs increase and the service mix changes, this first-generation architecture is no longer adequate and is being supplanted. The latest DSLAM technology uses Ethernet and IP with Gigabit Ethernet (GbE) uplinks. Related DSL network technology, such as the Broadband Services Router (BSR), which typically sits at the metro core and manages traffic flow, follows this trend. As illustrated in Figure 1, Ethernet is emerging as the next-generation IPTV transport mechanism all the way to the customer premise, where the set-top box signals channel changing. Internet Group Management Protocol (IGMP) supports multicast applications. In such a network architecture, the fine granularity of SONET/SDH transport becomes an expensive liability. In this case it is far more cost-effective to use CWDM and manage high- capacity GbE connectivity and processing at the wavelength level instead. 2 Courtesy The Windsor Oaks Group, May 2007 4
    • Requirements in the second-mile: access backhaul Successful rollout programs for next-generation bundled services require more than powerful first-mile access technologies, however. The second-mile of the access network can easily become the bottleneck, thus carriers also need a scalable FTTN transport solution. Protected, low-cost backhaul of aggregated DSLAM traffic to the metro/core is key for long-term service success and profitability. CWDM provides an excellent solution, in combination with Ethernet. Further, the transition to FTTN/VDSL2 and FTTH architectures using various types of PON or other technologies requires careful planning, to ensure that future flexibility is not compromised. Any second-mile solution must offer high scalability for the future but also deliver low first-in costs today. What are some of the key requirements to consider? CAPACITY AND TOPOLOGY We take a simple example of a DSLAM supporting up to 500 subscribers in a geographical serving area. A triple play service model in today’s market, such as that described previously, might create the following bandwidth requirements per DSLAM: :: 400Mbit/s for 80 active TV broadcast channels at 5Mbit/s each; :: 125Mbit/s for 500 VoD subscribers (5% activity rate) at 5Mbit/s each; :: 25Mbit/s for 500 Internet subscribers, at an average of 50kbit/s, and :: 4Mbit/s for 500 voice subscribers (20% activity rate) at 40kbit/s. The total aggregated bandwidth per DSLAM, then, is 554Mbit/s (400+125+25+4) – so that providing 1Gbit/s per DSLAM for backhaul to the metro core is sufficient in this simple case. Note however, that using VDSL to enable multiple video stream delivery could increase bandwidth demand still further, as could a higher service activity rate, or indeed, use of high-capacity uplinks for peer-to-peer applications. A jump to HD video might drive capacity to 2Gbit/s, depending on the usable compression. Scalability is key and a backhaul capacity rising to several Gbit/s might eventually be required. For most service providers, fiber cost plays a significant role. Availability of dark fiber may be limited or even non-existent, requiring costly lease arrangements with another carrier. It is, therefore, critical to choose a topology and technology that supports efficient use of fiber infrastructure – no matter whether it is owned or leased. Ring topologies have proven to be the best choice for any type of network scenario in which traffic must be backhauled from multiple locations to a central point. Initial investment and ongoing operational costs are relatively attractive. The physical ring requires only one fiber pair, allows efficient protection mechanisms and is easy to operate. Logical traffic patterns between DSLAMs and the BSR are hub and spoke and match this model perfectly. Typically, three to five DSLAM access nodes are connected to one hub node and can be easily supported using CWDM access rings with growth headroom. 5
    • Architectural choices and goals Recalling the big picture imperatives discussed earlier, in order to drive cost out of an IPTV network infrastructure, operators need to pay attention to several priorities (Figure 3): :: Eliminate network layers by integrating optical and Ethernet technology; :: Increase network efficiency by circuit multiplexing and packet aggregation; :: Deploy operationally simple technology; :: Automate using provisioning, management and OAM facilities; :: Flexible node processing: pass-thru, add/drop, drop & continue BSR Video Ethernet layer server ISP Intelligence Metro hub node Virtual connectivity Packet efficiency Optical layer Scalability Protection Fibre efficiency PON-ONT Optical+Ethernet IP-DSLAM transport node Figure 3: Metro access generic network layer architecture Considering that there is often a shortage of fibre in metro and access areas, that GbE and legacy services must be supported from OC3/STM-1 to 10Gbit/s and that reliable and robust protection schemes are needed, optical networking is a clear-cut solution. With a judicious integration of Ethernet, traffic efficiency can be greatly increased whilst low costs are maintained since the complexity of a full L2 Ethernet network is avoided. Thus, this approach tends to provide the lowest cost per bit in a wavelength – the bottom line. OPERATIONAL EXPENSE It may seem trite to state that network characteristics have a high impact on operational expense, but that is precisely the case. Opex is notoriously difficult to quantify, but several Optical+Ethernet attributes provide confidence that opex can be controlled. For example, transport-centric networks are intrinsically simpler than switch-centric networks. Carrier Ethernet is still developing as a mainstream approach and an optical layer OAM provides proactive alarms, clean fault diagnosis and fast troubleshooting. Service management is simpler (point-to-point vs multipoint) and since there are fewer and less complex parameters, configuration is simpler as well. Finally, the well-known rapid and reliable protection mechanisms of an optical layer ensure high availability and support low costs. 6
    • Optical backhaul for cost-optimized multi-services Optical networks have a long history of success. High capacity Dense WDM (DWDM) systems are the foundation of today’s backbone networks. Scalable multi-service rings connect central offices around metropolitan areas and expand into regional networks, while dedicated implementations support mission-critical applications for large corporations. The value proposition of WDM is clear: lowest-cost-per-bit transport, support of any protocol and bit-rate, high scalability and future-proofed for network growth. Carrier-class CWDM systems expand the application of the technology still further. Utilizing wider wavelength spacing than DWDM, CWDM uses low-cost components to deliver up to 10Gbit/s per wavelength. Such systems are extremely attractive in price; they are a perfect fit for FTTN backhaul requirements in an access network, where cost sensitivity is very high. Logical connection WiMAX FTTH PON ADSL / ADSL2+ FTTC (VDSL, HFC) L2 card GbE-ADM Framer VDSL 1 ..... 20 GbE-ADM Integrated L2 functionality Lowest-cost transport for GbE pipes: Lowest-cost transport for very high GbE count, Pass-thru only partially filled (statistical gain): Add/Drop L2 based aggregation into 10G Drop&Continue (broadcast) Multicast support Figure 4: Broadband backhaul via CWDM rings CWDM rings with a Gigabit-Ethernet-Add-Drop Multiplexer (GbE-ADM) function provide very adaptable, flexible configurations. For example, multiple DSLAMs can be connected to the service node at a metro core hub using a single wavelength (illustrated in Figure 4). Or different networks, for example the PON network, can be deployed on a separate wavelength. This has obvious advantages for future scaling and network isolation. Use of separate wavelengths also opens the door to access unbundling and wholesale service offerings. WDM also allows easy integration of DSLAM-based broadband networks using SONET/SDH or ATM interfaces. In some cases, the mobile network can be converged onto the same access infrastructure in order to take advantage of common backhaul. 7
    • GBE-ADM: COST-EFFECTIVE ETHERNET TRANSPORT The GbE-ADM function is a new capability introduced by ADVA Optical Networking, which provides flexible pass-thru, add/drop and drop&continue functionality of four GbE channels at a particular node. The GbE channels are multiplexed onto a 4Gbit/s wavelength channel for transmission around the ring. Different approaches exist when it comes to protecting services against various network and equipment failures. Cost sensitivity is high in access networks, and protection against fiber cuts is the main concern. The best strategy is to perform protection at the lowest network layer possible, in this case the optical layer. The ring architecture here allows an easy 1+1 full optical line protection capability, by sending the 4Gbit/s aggregate wavelength channels both ways around the ring, clockwise and anti-clockwise. Switchover in the rare event of failure should be extremely fast, less than 50ms, and is performed by the receiving transponders at the head-end. This architecture also supports a nodal drop & continue functionality. This has proven invaluable in easily provisioning and delivering TV broadcast services, at maximum network efficiency. Nodes simply access the required GbE stream while the stream is in transit at the node. Other operating configurations include pass-through and add/drop mux. CWDM rings with GbE-ADM function offer a compelling set of advantages: :: highest data transport capacity for lowest operational cost; :: wire-speed Gigabit Ethernet with node pass-thru, add/drop or drop&continue; :: low latency, high QoS and no packet loss; :: easy network overlays for different services or different operators; :: simple and transparent managed FTTN infrastructure; :: SONET/SDH-like simplicity, with no need for optical link engineering, optical amplifiers or power balancing (less operational complexity); :: fast and automatic optical-layer protection mechanisms with client OAM; :: easy combination of legacy services such as ATM on a single fiber, and :: efficient backhaul of multiple DSLAMs per node through the use of Time Division Multiplexing (TDM) to a 4Gbit/s wavelength. In summary, the use of technology such as GbE-ADM increases the efficiency of the system. MPEG video compression technology squeezes video into a lower bandwidth – while GbE-ADM and CWDM squeezes those channels onto a transport network at lower cost. 8
    • THE IMPLICATIONS OF VDSL The commercial availability of VDSL2 technology enables service providers today to deliver up to 100Mbit/s over a pair of twisted copper cable. IPTV offerings in High Definition TV (HDTV) quality combined with a strong Video on Demand (VoD) component clearly benefit from this technology. On the downside, however, the distance capability of VDSL is reduced versus ADSL, and the DSLAM needs to move closer to the end-user – in many cases within the range of less than one kilometer. The resulting Fiber-To-The-Curb (FTTC) architecture implies that typically the number of subscribers per DSLAM is significantly lower than in the ADSL case. The number of GbE ports back at the mini Pop, on the other hand, increases, since there are in average more VDSL-based DSLAMs at the curb than ADSL-based DSLAMs at the node. Figure 4 shows the architectural difference. The higher number of GbE ports in the VDSL scenario drives also a higher amount of total bandwidth in the second mile although the individual GbE ports may only be partially filled. In that case network efficiency and costs of the backhaul architecture can be further improved by using a 10Gbit/s aggregate channel with increased Ethernet processing. This architecture scales well to meet future demand, without costs spiraling out of control. Future evolution: the right technology Carriers around the globe are preparing to launch high-capacity next-generation broadband and video services to their residential and SOHO customers DSL plays a key role in enabling IPTV, video and triple play services to end-users over first- mile copper networks. In the second-mile of the access network, optical transport solutions are ideally suited to provide cost-efficient backhaul of growing traffic volumes to the metro core. CWDM rings, in particular, have the right cost points and functionality to secure fast return on investment and ensure long-term scalability and efficiency for FTTN/VDSL2 architectures. The optimal use of Optical+Ethernet transport technology can ensure maximum bandwidth efficiency for both circuit and packet distribution and backhaul in high capacity applications. The integration of L1 and L2 network layers provides simpler operations and lowest cost- per-bit transport. GbE-optimized muxponder and ADM cards deliver the lowest latency and jitter and zero packet loss. As packet traffic comes to dominate, further efficiencies are possible by integrating additional L2 packet processing into the optical layer. The promise of video services and IPTV technology is driving huge changes in the first- and second-mile backhaul networks. A flexible approach is required to support diverse services such as xDSL and PON with unpredictable demand – without making expensive up-front commitments. Optical+Ethernet networks allow service providers a freedom with low first- in cost and massive scalability plus increasing efficiency via TDM and packet grooming/multiplexing. ADVA Optical Networking delivers the integrated Optical+Ethernet difference: Operational simplicity, more revenue and lower cost. 9
    • The right technology ADVA Optical Networking has a long history of providing application-focused fiber-optic solutions that add value to, and ADVA AG Optical Networking remove cost from, carrier networks. With a comprehensive Campus Martinsried portfolio of innovative Optical+Ethernet networking solutions, Fraunhoferstrasse 9a 82152 Martinsried/Munich ADVA Optical Networking is an ideal partner for service Germany providers seeking to roll out differentiated portfolios of high- t +49 89 89 06 65 0 f +49 89 89 06 65 199 speed services. Regardless of which type of service the service info@advaoptical.com provider decides to offer, ADVA Optical Networking has the right solution to affordably backhaul the traffic to the metro ADVA Optical Networking Inc. core and beyond. One International Blvd. Suite 705 Mahwah, NJ 07495 USA t +1 201 258 8300 f +1 201 684 9200 info@advaoptical.com ADVA Optical Networking Ltd. Clifton Technology Centre Clifton Moor York YO30 4GU United Kingdom t +44 1904 692 700 f +44 1904 692 097 info@advaoptical.com ADVA Optical Networking Corp. Ibasen Bldg. 7F Nihonbashi-kobunacho 4-1 Chuo-ku, Tokyo 103-0024 Japan t +81 3 6667 5830 f +81 3 6667 5839 info-asiapacific@advaoptical.com ADVA AG Optical Networking About ADVA Optical Networking Hightec 6, bât. A, 1er étage 9 Avenue du Canada, Les Ulis 91966 Courtaboeuf Cedex ADVA Optical Networking (FSE: ADV) is at the forefront of France t +33 1 64 86 46 04 providing Optical+Ethernet solutions that advance next- f +33 1 69 07 87 19 generation networks for data, storage, voice and video info@advaoptical.com services. ADVA Optical Networking’s strength comes from passionate and dedicated employees, all sharing a common www.advaoptical.com vision: a fast, customized response to customers’ ever- changing needs. Our innovative Fiber Service Platform (FSP) and strong customer focus provide carriers and enterprises the ability to scale their networks and deliver intelligent, competitive new services. ADVA Optical Networking’s solutions have been deployed at more than 200 carriers and 10,000 enterprises in more than 40 countries worldwide. For further information: www.advaoptical.com. 10