Ip Video to the Home Using an Ethernet Passive Optical Network T

IP VIDEO TO THE HOME USING AN ETHERNET PASSIVE OPTICAL NETWORK T. Neel, Alloptic

One of the key challenges to Internet discusses the benefits, features, and protocol (IP) video in the past has been technological foundation of EPON, in the large amount of bandwidth needed to comparison with APON, as the best deploy it. Optical fiber is recognized as alternative end-to-end architecture for the most effective means for transporting IP video. voice, video, and data traffic; however, it is expensive to deploy and manage The Case for IP Video Services point-to-point (PP) fiber connections between every subscriber location and Video Delivery Options the central office. Ethernet passive Over the past few years, digital-cable optical network (EPON) is an emerging and digital broadcast satellites (DBS) broadband fiber infrastructure that have created a new business revenue addresses the high cost of PP fiber model for the television (TV) industry. solutions. Gigabit EPONs were also Similarly, IP multicast has the ability to developed to address the shortcomings generate new revenue models for the of asynchronous transfer mode passive Internet. There are many ways to deliver optical networks (APON), which are video to the home. Video delivery inappropriate for the local loop as they options to the home include the are complex and expensive and lack following: cable TV (CATV) over sufficient video capabilities and hybrid fiber/coax (HFC), DBS, digital bandwidth capacity. EPONs provide cable over HFC with a set-top box, greater service capabilities and higher multi-channel multipoint distribution bandwidth at reduced costs. Though service (MMDS), IP video over digital EPONs are in the early stages of subscriber line (DSL), analog video development, they figure to become the overlay over fiber, and IP video over primary means for delivering converged optical EPONs. Despite this plethora of video, voice, and data over a single choices, the trend is toward convergence optical access system. This paper on two different layers (see Figure 1).

Figure 1: Convergence of all Services over One Network

In the first layer of convergence, three IP, there is convergence to a single networks are converged into a single infrastructure on a single protocol. IP is optical-fiber network. The second layer thus the ubiquitous protocol for network of convergence occurs in the IP layer. convergence (see Figure 2). With the introduction of new services to

The optical last data IP Traffic mile network IP data needs to carry this IP video IP voice

Optical Access deployments need to be Source: www.caida.org optimized for today IP delivery

voice

Figure 2: IP Traffic Will Dominate the Last Mile

Because of the increase in IP traffic on definition TV (HDTV). New services in networks, service providers must be able the buffered video space include to offer different types of services, such personal videocassette recorders (VCR), as video, data, or voice. Optical access time-shifted TV, and full-screen deployments need to be optimized for IP streaming video. Viewers can now enjoy delivery, and Ethernet is just that—a interactive features of video, Web-based packet-based network, optimized to video, and services that allow them to carry IP traffic. watch programs at their convenience. The market for personal VCRs is growing at the moment because of TiVo Services Enabled by IP Video boxes, which act locally or remotely in IP video enables a growing number of an IP video head-end. As this technology services. Existing services for real-time matures, more enablers will become video include broadcast and pay-per- available. Service providers benefit from view TV, and streaming video is an IP video services, as it is easier to example of buffered video on the manage a converged single network for Internet. The simple act of adding voice, data, and video. IP video services bandwidth enables new video services. create multiple revenue streams, New services for real-time video include improved competitiveness, and a interactive TV, on-demand TV, simplified network at reduced cost that is videoconference, integrated Web easy to manage, administer, and content, digital TV (DTV), and high- customize. IP video is in the process of

becoming an incremental investment services for the end user include more over data and voice, which are already in video services, better picture quality, IP format, and it allows service providers bundled service packages, Web-enabled to amortize the cost of broadband services, and ultra-fast Internet access. In buildout over multiple services. IP video addition, end users can choose from a reduces provisioning costs for the large team of service providers to service provider, as interactive media provide any service at any time. allows the subscriber to perform self- provisioning relatively easily. Converged EPON Primer networks minimize equipment and network management costs and There are three primary ways to run fiber eliminate the need to train a large to a home. The first option is to establish number of technicians to maintain the PP links (see Figure 3). network. The benefits of IP video 32 homes

64 transceivers 64 trunk fibers

66 transceivers 2 trunk fibers

33 transceivers 1 trunk fiber

Figure 3: PONa Natural Step in Access Evolution

In Figure 3, each of the 32 homes uses that they require power, which creates a two fibers, which correspond to 64 separate network with power needs. transceivers and 64 trunk fibers. Using a curb switch reduces the number Convergence to a single fiber reduces the of trunk fibers; however, the number of number of fibers and transceivers to 32 optical transceivers is not diminished. and 64 respectively. Because it is a fiber- The cost of curbside switch boxes is rich infrastructure, companies have dominated by the cost of the optical begun to install curb switches, such as transceivers. Therefore, the most logical Ethernet switches, in the network. A solution would be to replace this box potential problem with these switches is with an optical splitter to serve as a

passive directional coupler. The optical between metro-network capacity and the splitter reduces the number of end user’s needs, separated by this last- transceivers needed by nearly 50 percent mile bottleneck. PONs respond to this and conserves fiber in the trunk, on the last mile of the communications order of 1 to 64. PON is therefore a infrastructure between the service- natural step in access evolution, as it provider central office, head-end, and simplifies the infrastructure and requires customer locations. PONs are point-to- little maintenance. multi-point (PMP) networks, which have the capacity to downstream broadcast PON Architectures media to residential homes. The Bandwidth is increasing on long-haul following figure illustrates PON networks through wavelength division architecture (see Figure 4). multiplexing (WDM) and other technologies. However, there is a gap

Figure 4: PON Architecture

There are some benefits to using PONs conversion is required for Ethernet. for video overlay. Although there is a APON has been the traditional choice, cost to install an amplifier, which is especially the optical carrier (OC)−3, shared by multiple locations, PONs are which has a bandwidth of 155 megabits passive and eliminate all power in the per second (Mbps). In APONs, data is field. The two primary types of PON transmitted in fixed-length, 53-byte cells technology are APON and EPON. with a 48-byte payload. At the time that APON was developed, ATM was APON considered best suited for multiple APONs were developed in the mid- protocols, and PON appeared to be the 1990s through the work of the full- most economical broadband optical service access network (FSAN) initiative solution. in the interest of extending high-speed services, such as IP data, video, and EPON Ethernet over fiber, to homes and EPON was developed in 2000 and 2001 businesses. In APONs, protocol through the Ethernet in the First Mile

(EFM) initiative, the standardization number of lasers required at the central effort of the Institute of Electrical and office. Unlike PP fiber-optic technology Electronics Engineers (IEEE). EPON optimized for metro and long-haul was developed because the APON applications, EPONs respond to the standard proved to be an inadequate needs of the access network in a simpler solution for the local loop. EPON has a and more cost-effective manner. EPONs gigabit-per-second (Gbps) bandwidth allow service providers to run fiber into and yields eight times more bandwidth the last mile at lower cost in order to than APON. While EPON offers greater provide an efficient, highly scalable, bandwidth and broader service end-to-end fiber-optic network that is capabilities at reduced costs than APON, easy to manage. Ethernet has evolved it has a similar fiber infrastructure. It is significantly in the past 15 years, and most effective to transport data, video, everything about it has changed except and voice traffic via fiber. However, the frame. Figure 5 illustrates how EPON has a point-to-multipoint (PMP) Ethernet has evolved for metropolitan- architecture, which eliminates the need area-network (MAN) and wide-area- for regenerators, amplifiers, and lasers network (WAN) applications. from an outside plant and minimizes the

Figure 5: Ethernet Has Evolved for MAN and WAN Applications

In EPONs, data is transmitted in conversion. An important industry variable-length packets of up to 1,522 objective is full-service fiber to the home bytes per packet in a 1,500-byte payload (FTTH) for delivering data, video, and (according to the IEEE 802.3 protocol voice over a single platform. The first for Ethernet), distinguishing it from instances of broadband in the home APONs. Ten-gigabit Ethernet (10 GbE) appeared with the advent of DSL and products had begun to appear in the cable modems. Ethernet acts as an end market before standards. Ethernet has user for these boxes. The paradigm shift evolved into a different medium as a in the industry has occurred with the use dedicated PP, full-duplex-type lens and of Ethernet as the ubiquitous broadband is beginning to challenge metro networks port with a registered jack (RJ) 45 and local area networks (LAN) quite connector (see Figure 6). rapidly. Ethernet also eliminates protocol

Figure 6: Ethernet to the Homethe Only Choice

With regard to these FTTH networks, transmitting data downstream from the there must be some consideration for the optical line terminal (OLT) to multiple cost and size of these units. These boxes optical network units (ONU) is different can be decoupled, leaving a simple box from transmitting data upstream from outside and another inside the home. multiple ONUs to the OLT. EPON broadcasts data downstream to all EPON Downstream ONUs, which use media access control APON can only carry IP traffic by (MAC) addresses to extract designated breaking packets into 48-byte segments, packets. Figure 7 illustrates the which is a time-consuming, complicated, techniques used to manage downstream and expensive task. EPON can carry IP traffic in an EPON. traffic more effectively without overhead costs. In EPON the process of

Figure 7: Ethernet PON Downstream

Data is broadcast downstream from the the traffic into three separate signals, OLT to multiple ONUs, and each packet each one transporting ONU−specific is able to designate the data to the packets. The ONU accepts only those appropriate ONU. The splitter divides packets that are intended for it and

leaves the other packets for other ONUs. difference: ONUs transmit data upstream The process for EPON downstream is to the OLT in Ethernet frames with the same as it is for any shared-medium ONU−specific time slots to avoid Ethernet LAN. transmission clashes. Statistical multiplexing is achieved by adjusting the EPON Upstream size of a time slot to the amount of The transmission of data upstream over available data (see Figure 8). an EPON is largely the same as downstream transmission, with one key

Figure 8: Ethernet PON Upstream

The time slots are synchronized to mode (ATM), and token ring. Ethernet is prevent upstream packets from a universal standard, with no variations. interfering with one another once the Another advantage of EPON for IP video data are joined to a common fiber. Each is that it is scalable from LANs to MANs ONU has a separate time slot, the to WANs. Traffic is IP. Byte life begins upstream traffic is divided into frames, and ends as IP and Ethernet, and cable and each frame is then separated into and DSL modems have Ethernet ONU−specific time slots. interfaces. New competitive local- exchange carriers (CLEC), enterprise Advantages of EPON for IP Video local exchange carriers (ELEC), and data EPON provides an Ethernet pipe that local-exchange carriers (DLEC) can start transports IP more effectively and at the with IP−centric networks. EPON is a lowest cost. It leverages off-the-shelf IP plug-and-play environment with fewer and Ethernet component solutions and a arcane parameters. It is a reliable system steep component cost curve. Ethernet is with structured wiring and an optical the most widely deployed network, with plant that has management and approximately 300 million ports troubleshooting tools. As equipment worldwide; 80 percent of all networks in costs are decreasing, workforce costs are the world are Ethernet. LANs are not coming down. EPON for IP video approximately 95 percent Ethernet today, serves as a workforce solution, and many and have virtually eliminated all other LAN technicians already understand and networks including fiber distributed data know how to work with Ethernet. interfaces (FDDI), asynchronous transfer

Quality of Service techniques that allow EPONs to offer the There are cost and performance same reliability, security, and quality of advantages to EPON as well, which service (QoS) as more expensive allow service providers to deliver synchronous optical network (SONET) profitable service over an economical and ATM solutions (see Figure 9). platform. There are a number of

Figure 9: Quality of Service

The techniques include guaranteed QoS prioritization and bandwidth reservation using type of service (ToS) field and and management, is another key element differentiated services (DiffServ). Port- for successful IP video delivery. Another aware bandwidth reservation, queuing important factor is IP video processing, techniques, and traffic shaping are also which includes video coding and necessary to guarantee QoS. Redundancy compression, such as that defined by the and security are other important aspects moving pictures experts group MPEG−2 of QoS. Full system redundancy standard. A related video-processing provides high availability and reliability. standard, MPEG−4, provides features Diverse-ring architecture with full that are similar to those found in redundancy and path protection is personal computer (PC) TV. A standard- another available element of EPON. definition quality TV (SDTV) will run at Another important aspect of QoS is 2 to 12 Mbps in comparison, and a high- multi-layered security, such as virtual definition TV (HDTV) will run at 10−60 local-area network (VLAN) closed-user Mbps in compression. Another element groups and support for virtual private of IP video processing is TV conversion, network (VPN), Internet protocol such as IP set-tops, home gateways and security (IPSec), and tunneling. personal computers with traditional analog video output. How IP Video Works IP Multicast A key element for successful IP video IP multicast provides efficient delivery delivery is a high-bandwidth access of selective broadcast IP TV by sending network, such as GbE PON. High a single data stream (IP video channel) bandwidth is required to support high to multiple users simultaneously. IP quality and also multiple channels being multicast is more efficient than unicast delivered to televisions in a household or as a protocol because it conserves a multi-dwelling unit. QoS, such as bandwidth on the network. It sends only

one copy of a channel regardless of the requests. IP multicast leverages number of requests, and channels are broadcast features of PON (see Figure forwarded only according to customer 10).

Router packet PoP replication 80 30

Headend 150

300 Television 80

Video Server

multicast and unicast IP video

Figure 10: IP Multicast

For example, traffic, such as real-time End-to-End Architecture for IP Video video, comes in over broadcast satellite, and it might already be MPGEG-2 Customers are also interested in video on encoded or come in as off-air content. It demand, which comes from stored video. passes through an encoder, which Upon request, video servers send IP performs multiplexing and wraps it in IP unicast traffic out to end user packets. A stream flow of IP multicast is subscribers. A converged switch then then released from the IP headend boxes. processes multicast and unicast traffic. An example of end-to-end IP video- network architecture is shown in Figure 11.

Carrier Video Headend Central Office GigaForceªedgeGEARª Chassis Video Server 1.25 Gb/s Video Archive symmetric Voice, Data,GigE Video PON Content Video Pump Files Stream IP ePON Service OVS real-time IPIP Router Router Switch Tag Files feed service FTTHONU ONU Broadband Network Switch and Transport IPOA VideoVideo Networking Networking POS SystemSystem ware Suppliers:

Time-shifted MPEG-2 Video Real-time MPEG-2 video Tag Information Baseband video MPEG-2 MPTS Satellite Local Baseband Content

Figure 11: End-to-End IP Video Network Architecture

The Internet TV (ITV) manager is an IP Video Head-End Equipment important component, as it sends the IP video head-end equipment converts menu and other elements to the set-top video content to packets and prepares it, box. It interfaces with billing and adjusting bit rates for distribution across orchestrates the workings of the IP head- an IP video network. IP video head-end end. architecture is illustrated in Figure 12.

Video Video Server Archive Time-shifted MPEG-2 Content Video Pump Stored Files Stream Service Tag Info Video OVS Tag real-time Files feed service MPEG-2 Video Middleware

Broadband Network Switch/Router

Off-Air Content GEMS

MPEG-2 MPTS Real-time MPEG-2 Real-Time Video

Baseband Digital Turnaround or Baseband Encoders Satellite Video Content

Figure 12: IP Video Head-End Architecture

IP video head-end equipment provides IP multicast and unicast delivery. IP video content injection with real-time IP head-end culminates in the access encoders and video servers, delivering network, which is a Gigabit Ethernet satellite and off-air content to baseband PON. IP multicast is a point-to- encoders or digital turnaround. The multipoint (PMP) network, which uses video signals are then converted into EPONs to deliver IP video. One key individual MPEG packets, and video function of EPON is as a central office servers play out unicast video on request. chassis that has a multi-service interface Head-end equipment associates streams to the core WAN. It has a GbE interface with unique IP multicast addresses. It to the PON with Layer-2 and Layer-3 also provides video content management switching and routing, and it handles through IP video middleware platforms QoS issues, service-level agreements and video customer premises equipment (SLA), and traffic aggregation. Acting as (CPE), which allows it to interface with a point to multipoint network, EPON video servers and billing systems. Head- splits optical signals traveling across a end equipment authenticates and single fiber onto multiple fibers. It is a authorizes access to video content, and cost effective means of distributing high- manages set-top boxes. Another bandwidth data, video, and voice traffic important function of head-end across the last mile of the network to equipment is its ability to provide video customer-located ONUs (see Figure 13). content distribution via core and metro

edgeGEAR Central Office Chassis bizGEAR 1u bizGEAR 24 Port MDU Layer 2 transport, Layer 3 enabled Ethernet EMS POTS Ethernet 16 x 1G PONs in 10u DS1 POTS Carrier class, NEBS compliant DS1, DS3 4096 ONUs in 7ft.rack Qos, DiffServ, and ToS IP CATV Network Video Headend

ATM homeGEAR 1000 IP Data IP Router Ethernet Network Optical Splitter POTS Video (RF/IP) EPON Voice, Data MPEG2/IP Video Network TDM Voice 1.25 Gbps symmetrical and Data Voice, Data, Video Video 1510 nm downstream Network 1310 nm upstream 15xx nm, DWDM, RF Video Central Office

Leased Line Private DWDM

Figure 13: Access Network and EPON Architecture

Business and curb applications are and it is possible to have up to 64 users possible with these types of networks, on a single EPON fiber.

CPE single TV. In a sense, the IP set-top box CPE includes ONUs, and a set-top box acts like an Ethernet port, translating TV or a residential gateway. Traffic is into a suitable format. A user can have a received by the ONU, which acts as an separate set-top box per TV or install a interface between the EPON and a residential gateway that will connect to customer’s data, video, and telephony multiple TVs. The residential gateway equipment. It receives traffic in optical decodes MPEG−2 streams for multiple format and converts it to the customer’s TV sets and may offer value-added desired format. For example, an EPON services (VAS). If a user receives 100 ONU may have RJ11 POTs ports for multicast streams, the ONU will only let voice, and RJ45 100 Mbps Ethernet one signal through to the TV, or up to ports for Internet access and IP video. four signals in the case of residential The set-top box receives IP packets gateways (see Figure 14). through a standard 10/100 Base T port and decodes the MPEG−2 stream for a STB decodes one MPEG-2 stream for a single TV

ONU

10/100BaseT Set Top Box Coax TV

POTS

Passive Optical Network PC Telephone Residential Gateway decodes multiple MPEG-2 streams for multiple TV sets and may offer VAS

Residential Ethernet TV Gateway Coax 10/100BaseT POTS ONU

Telephone Figure 14: IP Video CPE

The end user’s experience is similar to into a unified, single-network solution, watching CATV, as the IP streams, at though it requires significant bandwidth around 4 Mbps, are indistinguishable and QoS techniques. IP video enables from analog video. integrated and interactive Web applications. EPON is an IP−based Summary Ethernet broadband network, which delivers 1,000 times the speed of DSL or IP format treats video as data and cable modems. EPON is available at a supports any type of TV service. It fits low infrastructure maintenance cost. It is

scalable and designed to be a plug-and- video demonstration to further illustrate play network. Figure 15 provides an IP the equipment being used.

IP Set Top

ONU Ethernet IP Video Manager edgeGEARª Central Office Chassis Oracle Video Server

Splitter Gigabit Ethernet PON IP Voice, Data, Video IP Encoder

Gigabit Ethernet Aggregation Switch

Figure 15: IP Video over EPON Lab Demo

The equipment includes IP set-top boxes, the ONU, and a box that sits in the local exchange. Servers store video, and encoders take real-time traffic and code it as IP. The aggregation switch gathers it together into a single GbE port and delivers it over the metro access. EPONs systems are in deployment/trials; a significant number of the trials underway will quickly migrate into full deployment. Many companies view this optical IP Ethernet architecture as the most effective means for transporting voice, data, and IP video services over a single network.