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WHY EPON?

Par Franck Bertuzzi et Gérard Dupin 2006

STATE OF THE ACCESS NETWORK

PROVEN, PERSISTENT DEMAND

Persistent demand for affordable broadband is real, with service orders for new Ethernet connections or E1 lines increasing 40% year over year. The massive supply of broadband content available on the web stimulates a continuously escalating Demand / Supply / Demand spiral that is more than doubling Internet usage every year. A three-year build-out of new metro / long haul fibre transports has brought fibre broadband to within a mile of most business users. Yet the last mile has seen no fundamental infrastructure upgrade in the last 50 years, but this situation is changing rapidly. The announcement in the United States of the FCC triennial plan and the RFP for Fibre to the Premises solutions issued jointly by Verizon, BellSouth and SBC, the largest business BPON deployment in the world performed in the city of Moscow by COMCOR (9.000 nodes installed and still growing), France Telecom’s first GPON pilot in Paris or the recent involvement of British Telecom into its 21st Century network based on GPON products show the interest to upgrade the performance of the access loop and bring broadband access to the residential market all over the world.

PROVISIONING THE LAST MILE… FIRST

Thus the bandwidth delivery challenge now focuses on the “last mile” access problem. Over the last few years, the Internet has not only become part of our daily lives, but it has woven itself into the essential fabric of both local and worldwide enterprise transactions. Such business-to-business demand cannot tolerate a last-mile bottleneck separating them from broadband access. Competition from wireless, cable, and satellite technologies will satisfy this demand, leaving traditional carriers out of the Broadband Market.


UNIQUE SOLUTIONS FOR THE FIRST MILE

The purpose of PON is to improve the carriers’ ability to exploit new broadband markets using a new technology approach that replaces the aging copper network. As a distinct technology option, PON offers five unique advantages:

1) Provide a fundamental advance in distribution media – delivering advanced reliability and bandwidth capacity to replace the constrained and high-maintenance copper distribution system. Eliminate active electronics, their power supplies, and their maintenance cost from the outside plant.

2) Provide a new network deployment paradigm that lets network topologies more closely mirror the geographic demand characteristics of the subscriber base – thus enabling radically more efficient routes that cut the cost and time to construct networks.

3) Deliver a ubiquitous, carrier-grade platform that eliminates complex overlays and partial bandwidth solutions. Furnish a fully-integrated voice, video and data platform with low first-in cost. Enable an on-demand service mix supporting incremental subscriber demands on a pay-as-you-grow basis.

4) Incorporate scalability that accommodates long-term growth in raw bandwidth, evolution of service mix, quantity of individual subscribers, and subscriber churn. Deliver profitability & competitiveness for the carrier both initially and long-term.

5) Assure advanced revenue opportunities in both gross receipts from expanded subscriber base and from higher margins enabled through premium services.

PON’s forward-thinking technology is designed to affordably eliminate the access bottleneck with:

- A complete carrier-class network bridging the CO to the customer premises, using only one fibre to serve up to hundreds of IP and/or E1 ports - on a single 622Mb/s BPON system, extending to 2.5 Gb/s with GPON.

- Unparalleled affordability in fibre-based bandwidth for the subscriber, enabling massive new-market penetration for the carrier

- Full customization of any desired service mix using standardized service modules plus full grooming at the CO / POP for IP, TDM, Frame Relay and ATM

- On-demand bandwidth scalability for the subscriber plus long-term network scalability for the carrier to future-proof against forklift upgrades

- Optimal bandwidth management employing hybrid IP / ATM traffic shaping that provides higher profit margins for the carrier plus ideal service level contracts for the subscriber

This System Overview will provide a broad description of the network components used in a PON solution, and the networking advantages this system can deliver to improve the way bandwidth is distributed in the Access Network. While imbedded copper access has provided symmetric E1 service and continuously improved bandwidth capacity via Digital Subscriber Line (DSL) and Inverse Mux Technologies, it is believed that 1) its usefulness for data cannot live up to escalating subscriber demand, and 2) its profitability is severely limited due to the high maintenance costs incurred from copper. While non-copper technologies like Gigabit Ethernet, wireless, and satellite are coming online in an attempt to serve this bandwidth need, each fails to provide the carrier with a comprehensive access solution. Thus, an end-to-end, highly affordable approach specifically designed to solve each of today’s bandwidth delivery challenges using a single, integrated platform is required.

TURNKEY, CARRIER GRADE TECHNOLOGY

The PON technology addresses each of the fundamental categories required for delivering a comprehensive access solution like no other available option. Figure #1 itemizes the shortcomings of various broadband options in comparison to PON. Note the Opportunistic column in the subscriber category that indicates whether the technology facilitates new-customer prospecting.

FIGURE 1 – COMPARISON OF ACCESS TECHNOLOGIES


SYSTEM ARCHITECTURE

The high-value design factors integrated into BPON and GPON solutions include:

- Converged Voice, Video, and Data services with native IP, TDM, and ATM at the premises

- Support for Voice over ATM (AAL1 & 2) and Voice over IP (H.248 or mostly SIP based)

- Small footprint with high port density and low unit cost for small first-in cost

- Fibre and passive optical splitter networks for lowest-cost network maintenance

- Extensive scalability in both bandwidth, port density, and network nodes to future-proof the network

- Modularity enabling the flexibility to both customize and cost-optimize varying subscriber applications using standardized blades

- Single-fibre economy with Point-to-Multipoint connectivity

- Multiple protection options

- Web-enabled EMS with OSS compatibility and service management connectivity

- Custom ASIC technology to lower system costs while increasing traffic performance

- Automated Network Planning tools to simplify and accelerate design of new fibre networks

- Complete EF&I support to speed system deployment

WHAT IS A PON?

“PASSIVE”

Standard passive optical network solutions have a reach in excess of the typical 20 km of many PONs. This fact enables us to deliver repeater-less networks over a 400 km² area. Neither the fibre itself nor the optical splitters require any active components to enable a distributed network. Splitters allow any desired topology – star, tree, or bus – by simply fractioning the light to separate fibres. Commonly available splitters come in several options ranging from 1x2 to 1x32. Each time the light is split, there is a power loss of optical power, and so optical budgets are carefully analyzed when planning a PON. Finally, splitters can be either “even” splits of the input power or “fractional” splits where a percentage of the power is tapped at each split. Fractional splitters allow efficient power distribution for “drop & insert” and bus applications. In all cases, the fibre and splitter require no power supply, no adjustments, and no preventive maintenance – making them truly passive. Splitter applications have evolved to the point that network deployment devices are readily available. While a splitter cassette may reside in unprotected areas, carriers typically want a secure enclosure to manage both craft access and cable routing.

“OPTICAL”

Optical transmissions through glass are environmentally isolated so that no outside interference is possible. Neither power induction, radiation, RFI, or magnetic effects can impact the signal, introduce noise, or disrupt traffic. Additionally, fibre offers outstanding resistance to lightning. Thus, combined with passive splitters, a Passive Optical transport assures unsurpassed reliability, with drastically reduced maintenance costs, and flexibility to deploy anywhere without regard to power availability or environmental ambience like heat, humidity or RF.

“NETWORK”

The network can be designed with any desired topology by placing the optical splitters in convenient locations without dependence upon power availability or remote cabinets. This networking flexibility results in ease of deployment unmatched by any electronic technology. Networks can be easily tailored to economically match service area densities. Since broadband markets are free from mandated service

1 by 1 splitter Fiber splitter cabinet


constraints, PONs can be optimally designed to serve only high traffic areas. As service areas grow, or new bandwidth demand arises, passive splitters again provide the answer. By pre-installing splitters with high splitting ratios (i.e.8x, 12x, or 16x) with ports left unused, new service is simply a matter of attaching subscriber fibre to open taps. While Repeater PON allows future expansion of PON, DWDM provides increased capacity over a given service area with no additional fibre, making the network truly future-proof.

NETWORKS CLOSELY ADAPTED TO GEO-MARKETS

When laying a traditional, regulated telephone network, ubiquitous service delivery is mandated. New broadband markets are unregulated, allowing networks to be more efficiently built to serve only high-demand areas. These specific opportunistic markets are characterized by varying geographies, and have unique deployment characteristics – giving rise to the term “Geo-Markets”. PON is ideally suited for letting network planners closely tailor fibre routes that reach these Geo-Markets with an efficiency not possible with regulated telephony plants.

PON is uniquely adaptable to exploit geo-market opportunities due to its:

1) Low cost of the customer-premises termination elements

2) Freedom from powered network elements,

3) High bandwidth capacity through thin, flexible fibre elements,

4) Quickly-deployable, highly-tailored topologies using only low-cost splitters,

5) Adaptability to unique geographic requirements like campus and hi-rise markets.

BUSINESS AS USUAL

Of most importance to the service provider, PON networks enable a “Business as Usual” approach to planning and deployment. As an integrated service platform, PON can provide both advanced bandwidth services as well as traditional telephony. It provides smooth integration with traditional TDM, ATM, Frame Relay, and IP public networks at the CO or POP, and can support aggregation and backhaul of ATM and DSL services

Location of PON in the access network

Fibre paths can be installed by selecting from a wide menu of options including:

- Dark Fibre – simply lighting existing fibre

- Metro Access Networks – extending MAN fibre to the premises using only feeder spans


- Strung Fibre using pole right-of-ways.

- Trenched Fibre

- Pulled Fibre using new high-speed conveyors to lay fibre inside any existing conduit like pipelines, utility tunnels, even sewers

Finally, integration at the CO follows normal network practices. Installation of the electrical head-end unit provides standard switch interfaces. Provisioning of the network termination devices at the customer premises is then performed using an OSS-compatible Element Management System.

PON ACTIVE COMPONENTS

Think of a PON as a distributed switch, with the CO access provided through the Optical Line Terminal (OLT) and the subscriber premises access delivered via the Optical Network Terminal (ONT). In between these two active components lies nothing but passive glass fibres and optical splitters. These passive components act like a distributed backplane linking the active components.

THE OLT

The OLT has usually a large number of PON interfaces (minimum 4, up to 32). One individual PON can feed up to 32 ONTs with each ONT capable of delivering multiple IP ports, E1 ports, or a combination of both. Furthermore, since each traffic port is completely isolated and secure over the PON, an individual ONT can serve several different simultaneous subscribers – distributing each ONT cost over as many as 20 separate customers. Using an average of 11 subscribers per ONT, and 128 ONTs per OLT, a single system can serve as many as 1350 different subscribers. Finally, BPON runs at a symmetrical bandwidth of 622 Mb/s (2.5 Gb/s downstream and 1.25 Gb/s upstream for the GPON) which gives the system the necessary bandwidth to simultaneously fulfil the needs of all customers served by the same OLT.

BANDWIDTH DISTRIBUTION VIA PON

BANDWIDTH DISTRIBUTION

A BPON solution delivers 622Mb/s service bi-directionally and supports up to 32 ONTs.

A GPON solution delivers 2.5Gb/s downstream and 1.25Gb/s upstream service and supports up 64 ONTs (128 ONTs in the future).

Since subscribers are widely divergent in bandwidth usage, each subscriber on an ONT can be sold a service contract specifying the bandwidth they will have available to them. Any granularity of service is possible in Nx64K steps. Hundreds of 4, 8, or 12Mb/s users can be served - or an entire PON can be dedicated to a few customers, each needing 200 to 400 Mb/s. This flexibility allows unlimited “granularity


of service”, overcoming one of the major limitations of SDH. Full-rate E1 service can provide 300 active ports per OLT, and fine service granularity is provisioned using the IP ports in 64K increments. These distribution scenarios assume the PON bandwidth is being permanently divided among the users. But the limitations of this “channelized” or nailed-up approach have been overcome with “Dynamic Bandwidth Allocation” (described below) – enabling an actual subscription rate to far exceed the rated capacity of the PON backplane.

BANDWIDTH UTILIZATION

First-generation PON systems simply allocate a fixed segment of the PON capacity to each subscriber according to their bandwidth contract. This fixed allocation “nails up” the available bandwidth per subscriber contract – whether or not the subscriber is using bandwidth at any given moment. However, since data traffic is highly bursty, a nailed-up channel will go underutilized for the vast majority of the time – and will be available to no one else on the PON. Thus, up to 90% of a traditional PON’s total bandwidth will go unused, and the PON can quickly become saturated with a relatively few users.

User traffic channelized or “nailed up” over the transport

In contrast, recent PON systems are designed using second-generation technology embedded in patented ASICs. Instead of nailing-up transport across the PON, PON systems use Dynamic Bandwidth Allocations (DBA) to efficiently aggregate all traffic to achieve maximum bandwidth utilization. By avoiding nailed-up channels, it can transport up to 20 times the user traffic compared to a static PON or IP network running at the same bandwidth. Most importantly, by avoiding nailed-up and unused channels, DBA assures that 100% of the system capacity is billable.

User traffic aggregated for efficient transport


DYNAMIC BANDWIDTH ALLOCATION

PON systems constantly monitor the real-time status of traffic flow throughout the network. By knowing the current user load, it can then allocate additional access to marginal subscribers, and higher-rate usage to premium subscribers – in real time as demand fluctuates.

This real-time management of bandwidth allocation offers important advantages in three key areas:

1) Subscriber-side improvements in broadband service

2) Switch (or CO) side improvements in load balancing to optimize switch utilization and prevent PON congestion

3) Higher overall system capacity for both the amount of active bandwidth and the number of subscribers supported.

DYNAMIC ALLOCATION OF SUBSCRIBER ACCESS

The next chart is an actual record of bandwidth usage for a hi-tech manufacturer with 200 employees. Note that a high data rate is occasionally important to support peak usage, but also observe that a low data rate predominates much of the time. Taking advantage of this bursty nature of data traffic, DBA uses the quiet time of one subscriber to send data from a busy subscriber. Since the peak loads from several subscribers rarely coincide, DBA can be used to increase system capacity up to ten fold.

TYPICAL DATA TRAFFIC

SERVICE LEVEL AGREEMENTS & QOS

PON systems assure QoS by supporting extensive SLA categories, and by defining the priority for specific connections. Low-end or “best effort” contracts deliver traffic throughput only as competing traffic allows, yet provides significant capacity gains. On the other end of the scale, premium level contracts assure priority access, but begin to nail up bandwidth across the transport as the QoS guarantee approaches 100%.

In between can fall a range of service levels as dictated by the carrier. The broader the range of service offering, the easier it becomes to sell services across a wide broadband market – essentially letting the carrier tailor service to exact customer needs.

Broad range of QoS options increases subscriber base

OVERSUBSCRIPTION OF DATA SERVICE

Additionally, “over subscription” is possible. With SLAs assuring throughput of priority traffic, PON can be

“overbooked” to sell services that travel the network during other subscribers’ “downtime”. Thus, in contrast to a traditional PON processing only 1/10 of its backplane capacity, PON’s over subscription lets carriers bill up to 10 times the backplane’s data rate.


Type of QoS options available

SUSTAINED CELL RATE (SCR), PEAK CELL RATE (PCR), AND OVERSUBSCRIPTION RATIO

One QoS parameter available with BPON is the Sustained Cell Rate (SCR). The Connection Admission Control (CAC) function in the Management System ensures that the aggregate of the bandwidth required for CBR connections summed with the aggregate of the SCRs for the variable bit rate connections does not exceed a particular level. That level is equal to the capacity of the PON multiplied by the oversubscription rate, a parameter that is provisioned on a per system basis. Another important connection parameter is the Peak Cell Rate (PCR), applicable only to variable bit rate connections. With PCR set to a value greater than the SCR, the system will use DBA to allocate bandwidth between the two values (even if the over-subscription ratio is set to unity.) This scenario enables the carrier to sell more capacity (the amount between the SCR and PCR) while still insuring that each connection’s SCR is not violated. The carrier may also adjust the over-subscription rate above unity, further increasing the system capacity.

TRAFFIC SHAPING

The PON honours two sets of traffic contracts simultaneously. One contract is set at the CO interface to control traffic rates to and from the public switch. The other is the Service Level Agreement sold to each subscriber. Our PON constantly monitors the ONT demand for traffic and controls or “shapes” the user traffic to match the traffic contract at the CO. Using this parameter, PON then buffers user traffic until throughput at the switch is assured. Total user traffic is never allowed to exceed the switch handoff rate, and thus congestion over the PON towards the CO is prevented.

Detail of min/max settings possible with VBR SLA

Several advantages then result from this traffic shaping process:

- Prevents swamping the ATM or IP switches

- Optimizes packet loads to improve efficiency of switch utilization

- Prevents packet congestion on the PON

- Prevents re-sent packet duplication, increasing traffic capacity on the PON

- Assures subscriber traffic is delivered with optimal service quality


Benefits of traffic shapping

SUMMARY ADVANTAGES OF DYNAMIC BANDWIDTH MANAGEMENT

The technical aspects of DBA can seem complex, however the benefits of this approach versus a channelized, or “nailed-up” system are of major significance to the capacity – and thus profitability of the system.

Congestion-Proof Backplane with More Efficient Switch Port Utilization

The percentage of the backplane’s capacity that can be actually billed at any given moment is paramount. If that backplane is busy re-sending dropped packets, that delay is lost revenue. The Traffic Shaping feature of DBA assures that congestion and resulting packet loss does not occur within a PON backplane, making 100% of the system cycles productive cycles.

Ten Times the Paying Traffic Per System Megabyte

On a channelized system, if a subscriber is not using the full bandwidth for which he subscribed, that capacity remains unusable and unbillable to any other client. Typically, up to 90% of a channelized system is not being utilized at any one moment. But with DBA, PON dynamically slots paying users into that unused bandwidth. Thus, the system can accommodate up to ten times the traffic over the same system bandwidth. This “multiplier” effect means 10 paying customers can be served over the same bandwidth used to serve one subscriber on a channelized system. Since nailed-up networks supports fewer clients, simple amortization means subscriber rates must increase to compensate. These higher rates then make that system’s service uncompetitively priced.

Optionally, channelized systems can obtain the same throughput as PON, but only by over-provisioning their transport at added cost. Thus a Gigabyte/second nailed-up network will offer the same throughput as a Megabyte/second network running DBA. The choice to oversubscribe or overprovision a network is diagrammed below.

Overbooking The Backplane

A channelized network can never be oversubscribed. But with DBA, one subscriber’s downtime is allocated to another waiting subscriber. Essentially, DBA lets the carrier overbook the system – but without the negative consequences experienced on an airline. Since overbooking occurs in nanosecond time frames, few users notice a delay. The other customer-protection feature making overbooking feasible is the Service Level Agreement (SLA) whereby each customer pays for his prioritization of access on a sliding scale. High-priority SLAs then command a premium price.

Broader Market Penetration plus High-Margin Revenues

In a channelized system, all subscribers are serviced on an equal footing – essentially paying the premium rate for high-priority service, whether they need it or not. PON enables a tiered service level, making “best effort” service more affordable – and thus competitively priced for broader market acceptance. Premium rates can then be charged for those subscribers who appreciate and need the priority access – thus yielding higher margins.

The following chart illustrates statistically how DBA exploits the downtime of one user to support higher system throughputs.


Comparison of overprovisionded 15 MEG pipe with nailed-up traffic versus 10 MEG pipe using DBA

The graphs are accurate in their relative sizes, showing how three users on a 15Mb/s pipe can actually be served using only ½ of a 10 Mb/s pipe – effectively diagramming a 3:1 gain in system throughput. Three-to-one was used for visual clarity, while 10, even 20:1 has been used successfully in actual field deployment. Clearly the cost of over-provisioning a network with excessive bandwidth to compensate for the limitations of static, channelized bandwidth is too costly.

PON TECHNICAL SPECIFICATIONS

SUPPORT FOR 622MBPS SYMMETRICAL OPERATION (BPON)

The need for symmetrical 622 Mbps operation has been recognized for higher-density business deployments and is also supported by our BPON platform. The 622 Mbps bandwidth is divided between many subscribers on the same single-fibre strand. The optical line terminal (OLT) broadcasts data downstream at 1,490 nm and the ONTs burst data upstream at 1,310 nm in their assigned time slots.

Upstream transmission (from the ONT to the OLT) uses a Time Division Multiple Access (TDMA) protocol, and the OLT has a burst mode receiver. Upstream cell transmissions from the ONTs are synchronized, via a high-speed scheduling algorithm running within the OLT, such that cells from one ONT do not collide with cells from other ONTs. The OLT performs concentration and statistical multiplexing of user data from multiple PONs. The OLT then delivers the combined data, via standards-based interfaces (e.g. E1/E3, or SDH) to other network elements.

Upstream and downstream optical paths

COMMON ATM PLATFORM

BPON addresses two types of traffic on a common ATM platform (this is not supported by GPON as it is rather targeting residential applications). Synchronous TDM transport of E1 services is accomplished through CES on the PON. For northbound connectivity out of the OLT (towards the network), the CES stream can be propagated over an ATM network interface module (NIM) or reconstituted into a TDM signal mapped via M13 functionality into a E3 TDM card, or as a VT1.5 tributary into an STM-1 TDM NIM. A Gigabit Ethernet northbound interface is available whenever it is necessary to have northbound connectivity to core IP networks.


For packet traffic, BPON provides 10/100 auto-sensing Ethernet ports on service interface modules. The LAN PDUs are mapped into ATM AAL5 PDUs and then segmented into ATM cells. Depending on the mapping, the resulting ATM cells are queued into separate buffers, and await transmission upstream on the PON. PON can be viewed as a distributed ATM switch, with centralized scheduling and distributed buffering. The centralized scheduling at the OLT and transfer of scheduling decisions to the ONT results in “dynamic bandwidth allocation”. The centralized scheduler can arrange the information for all queues on all ONTs in hierarchically arranged lists; this enables priority-based scheduling. The queues can be arranged into many priority levels; the system currently maps the queues into ATM service categories, and a few levels specific to LAN traffic. Each ONT can have up to 256 queues. Traffic flows are typically mapped into virtual circuits, and the system is designed to allocate each VC with its own queue. PON uses FSAN compliant ATM transport on the PON. This enables the use of time proven ATM functionality and QoS features.

RANGING

In order to establish synchronized time slots, or grants, for upstream burst-mode traffic from the ONTs, the OLT measures the light-speed delay time, or range, to each ONT.

After range calculations are made by the OLT, timing delay correction factors are sent to each ONT on the PON. The correction factors make the round trip delay for each ONT the same, as seen by the OLT. This delay is part of the process of synchronizing upstream traffic, and is approximately 250 microseconds, corresponding to one optical round-trip on a typical PON. Ranging is performed frequently (at intervals on the order of seconds) to maintain PON synchronization. Grants refer to the process whereby the OLT gives, or grants, permission to each ONT (by sending downstream PLOAM cells) to send burst-mode upstream traffic in a synchronized manner.

QOS AND GRANT SCHEDULING

The OLT and ONT follow a strict master-slave model. The OLT is aware of the transmission needs of all queues at each ONT. Using this information, it arrives at scheduling decisions (cell transmission opportunities) for each queue on the PON. These decisions are then conveyed to the ONTs in the downstream physical layer OAM cells (PLOAM cells). This communication of the scheduling decision is referred to as allocating a “grant” to a queue. It specifies exactly the upstream time slots the ONT should use for a transmission.

The upstream transport of cells queued at the ONT is accomplished via two grant types. The first is applicable to transport of periodic cell streams when the needs of the connection are known in advance. This is true for AAL1 constant-bit-rate (CBR) streams for Circuit Emulated Service (CES) TDM transport, as well as other CBR streams. At the highest priority, the OLT schedules “unsolicited grants” for all CBR streams.

To accommodate fluctuating bandwidth needs of bursty data traffic, PON uses “solicited grants.” Traffic that typically is handled using solicited grants includes LAN traffic, ATM VBR, UBR and other variable traffic. The queue for these traffic types are linked into lower priority levels by the OLT. The queue length is reported to the OLT with a snapshot of the state of all queues on the PON. Finally, in order to ensure that the traffic exiting the PON and transported to the northbound cards meets the traffic contracts, the OLT performs reverse dual-leaky-bucket shaping to generate transmit opportunities for the ONT queues. Based on queue state information, as well as the negotiated traffic contract for the various circuits, the OLT performs scheduling. Thus, any upstream traffic that is allowed onto the PON is assured of being shaped when it exits from a network card. This also ensures that all buffering is pushed to the periphery of the PON thereby enabling low initial first cost.


DEPLOYING PON

The OLT typically resides at a hubbing point such as a Central Office (CO) or building Point Of Presence (POP), and provides the point-to-multipoint connectivity to multiple ONTs. The ONTs provide the communications drop interfaces to corporate subscribers. The ONTs are installed on or near the

subscriber’s premises in the telecom equipment closet or with LAN servers. Full 622Mb/s symmetric BPON service or 2.5 Gb/s downstream - 1.25 Gb/s upstream GPON traffic can be deployed using only a single fibre to make PON feasible in fibre-lean environments. By lighting dark fibre in conduits or in risers, carriers can add subscribers block by block or floor by floor.

ECONOMIC IMPACT AND RESULTING OPPORTUNITY

When all of the active electronics are removed from the outside plant, maintenance costs plummet. Low-cost, multi-service ONTs reduce first-in expense. Taken together these advances in access architecture will revolutionize broadband delivery, making subscriber services affordable, reliable, and flexible like never before. The lower cost of PONs can then exponentially expand the broadband subscriber base while its higher reliability reduces subscriber churn. Finally, as described below, PON also enables premium service delivery to produce high-margin subscribers.

FSAN STANDARDIZATION

The importance of FSAN's role in BPON and GPON technologies should not be overlooked. FSAN is an international body of Telecom volunteers who have formed a consortium of vendors and carriers. Over the last two years this working body has met monthly to define the global standards for PON. As a standards-setting group FSAN is building the consensus for PON standardization to ensure PON becomes a well-standardized technology worldwide. Such standardization will then assure telecom operators that PON will provide the crucial capabilities and interoperability required for system reliability.

FSAN regularly contributes its findings and recommendations to the various standards bodies shown here, which ultimately result in certification by the ITU-T.

APPLICATIONS SUPPORTED

For the carrier struggling to maintain E1 for data and 64k for voice using separate copper drops, PON provides the simple alternative: an economical platform that delivers private line E1 plus native 10/100baseT LAN service using a single access device.

SERVICE ADAPTABILITY

PON is a service-agnostic platform, designed to deliver the flexibility crucial for generating maximum service revenues from a single, integrated platform. The ability to rapidly tailor both initial and subsequent subscriber demands accelerates broadband sales. As subscriber churn or growth occurs, this adaptability economically accommodates change to preserve subscriber satisfaction using low-cost swap outs of plug-and-play SIMS.

As an agnostic platform, PON will continue to leverage its adaptability to stay abreast of bandwidth service demands. This service-agnostic approach delivers the reliable purchase assurance that PON can be the long-term investment offering optimal return for next-generation broadband needs.

SUPPORT FOR MULTIPLE BROADBAND MARKETS

In addition to service adaptability, PON also provides fundamental network choices enabling the

carrier to economically serve divergent market segment. For those subscriber areas needing

access to the Public Switched Network, all necessary carrier-class functionality for TDM, IP, and

ATM are integrated. However, many broadband markets need only local, campus networking for

data-centric applications, whether provided via a carrier directly to the end user.

Carrier participation in FSAN standard bodies


Supports multiple segments of the broadband market

Government and institutional WANs, educational campuses, and corporate parks can all benefit from PON as a low-cost, hi-speed voice, video, and data voice network. This non-public network uses a hair pinned application and is described below.

Hair pinned Networks

Standalone networks can be implemented by use of hair pinning without the need for network side connections. Also, hybrid networks can be achieved by provisioning local (hair pinned) connections

internally to the system and public network connections outside of the system. Ideal for Greenfield or fibre-ready “smart-buildings”, campuses, and hi-rises, PON offers a rapid, economical choice for lighting these facilities. Native Ethernet ports eliminate the need for additional routers while 64k ports can directly feed local PBXs to achieve a low-cost fibre network of unsurpassed reliability. PON’s unique Dynamic Bandwidth Allocation assures congestion-free performance for high-capacity cell and packet data, even when full-motion video is required.

Every ONT can be centrally provisioned to simplify point-to-multipoint connectivity using the integral element management system. Software-controlled, point and click connections between any ONT can be instantly assigned for circuit emulation and VLAN provisioning with a graphical layout of all connections.

Hair pinned applications for campus networks

Public Networks

Using STM-1 network card, singly or in multiples, PON is capable of large bandwidth service aggregation and backhaul. Carriers find this useful for aggregating DSL traffic from DSLAMS in MDU and office building locations, employing BPON as a low-cost 622 Mb/s backhaul to their CO/POP. Similarly, wireless operators can apply this low-cost backhaul with its highly flexible topology options for reaching wireless BTS sites.

With carrier-grade reliability, PON is the logical choice for ILECs wanting to aggressively join the race for broadband revenues. Carriers are assured low first-in cost, pay-as-you-grow expandability, negligible maintenance, rapid provisioning, and high service capacity. Consequently they will realize superior profitability with near-limitless scalability (see DWDM below.) Whether terminated in a CO or a POP, PON’s carrier class design assures seamless interoperability with public networks.


PON traffic groomed to public switches for multi-point applications

SUPPORT FOR NETWORK TERMINALS

While PON excels with cost-saving delivery of native IP and TDM requiring no additional routers or NT gear, it also provides compatibility for network termination devices like IADs and Service Access Muxes. This capability enables the use of various NT devices for extended services like derived voice and voice over IP. Additionally these NT devices can function as service aggregators to further extend the virtual port density of the ONT.

Compatibility with other network terminal devices

BROAD SCOPE OF APPLICATIONS

A short list of the broadband applications that PON will support includes:

- Leased-line (TDM) transport for voice

- Multipoint VPN / VLAN

- LAN / WAN – 10/100bT and GigE

- Storage Area Networks

- Broadcast Television transport and video production suite networking

- Videoconferencing

- Voice over IP / ATM

- Campus Networking

- Co-Location Bandwidth Exchange

- Aggregation and Distribution Networks: - DSLAMs - IADs - Wireless - CATV

SCALABILITY – FUTURE PROOFING

Intended as the cost-effective solution for the next generation of broadband access, PON vendors address the scalability question head-on. Once a carrier deploys a PON network, it can accommodate both service and bandwidth growth for the foreseeable future, without needing forklift upgrades. It has engineered pay-as-you-grow scalability into our product on several levels:

Flexible architecture assures incremental expandability of

- The number of ONTs on a PON

- The number of PONs per OLT

Expansion of transport capacity over an existing fibre trunk using DWDM


Expansion of geographic reach using Repeater PON

ELEMENT MANAGER SYSTEM - EMS

The EMS is a set of software applications which support the Operations, Administration, Maintenance, & Provisioning (OAM&P) activities of the Service Provider. The EMS manages the elements of the BPON and GPON sub-network, in a scalable, reliable, component based system.

OSS control of the PON via CORBA- compatible TMS

CONFIGURATION MANAGEMENT

EMS provides quick and reliably configuration of the network equipment for service, the features include:

- Physical Interface Configuration

- Remote testing/diagnostics

- Network synchronization Tools

- Automatic notification of State Change

- Auto-discovery

- Graphical front panel view

PAN provides remote provisioning of the entire PON

CIRCUIT PROVISIONING

EMS provides a simple, graphical user interface to facilitate service, the features include:

- Point and click connections from Network Interface Module to Service Interface Module


- Point and click connections from SIM to SIM (hairpinning)

- TDM, circuit emulation and VLAN provisioning

- Graphical layout of all connections

EMS screen for remotely provisioning the OLT

FAULT MANAGEMENT

Sophisticated Fault Management is provided to allow the rapid diagnosis of problems:

- Collects and lists all current alarms

- Alarm correlation/alarm reduction

- Automatic/manual clearing of alarms

- SNMP/TL1/CORBA alarms generated to NMS

- Alarm Logging

- Flexible Alarm Filtering

- Alarm propagation

Alarm history report

PERFORMANCE MANAGEMENT

EMS provides pro-active network management:

- Extensive list of performance parameters are monitored and collected

- User definable thresholds

- Threshold crossing alerts (TCA) generated

- TCAs logged in archive

Software download is provided to allow simple and safe distribution of software. The TMS maintains all the versions of software for all the cards supported on the OLTs and the ONTs. Software can rapidly be distributed to either a specific card on an NE, all cards on an NE, all collection of PONs associated with an OLT). The download is written to a 'holding area' and then validated for both the integrity of the download and the compatibility of the version with the hardware. The software can then be activated, again at either the card level, PON level or system level. A facility is also provided to immediately revert back to a previous version in the event of a problem.


EMS is usually written completely in Java and runs from any client equipped with a standard browser, eliminating the need to install specific application software on the client. This greatly simplifies software distribution and upgrades. Java is extremely portable, allowing multiple platforms to easily be supported. NT and Solaris are the first target platforms.

Interoperating with existing OSS application is a key concern for the TMS. Thus, SNMP and TL1 are supported to integrate into legacy systems and network management platforms. CORBA is supported as to provide the utmost ability to integrate into an OSS environment.

Performance statistics screen


A PROPOS DES AUTEURS

Ingénieur Télécom depuis 1991, Franck Bertuzzi a occupé dans le domaine des transmissions optiques des fonctions opérationnelles (déploiement du réseau télécom d'Eurotunnel), de développement commercial et marketing (promotion du GPON de Terawave) et d'avant vente (équipements DWDM et Ethernet de Tellabs puis Ciena). Depuis 2007, il est manager d'une équipe d'ingénieurs sur la France, l'Afrique et Israel au sein de la société Ciena. Ingénieur Télécom ENSERB de formation, il a de plus obtenu un Executive MBA en 2005 à l'ESC Lille et l'Université de Technologie de Sydney, Australie.

En 2006, dans le cadre de travaux en coopération avec l'ARCEP, il a rédigé la partie

technique du livre blanc introduisant le PON. [email protected]

Gérard Dupin, diplômé de l’École Nationale Supérieure des Télécommunications (ENST) a plus de 30 ans d’expérience dans le secteur des télécommunications. Il a successivement occupé divers postes de responsabilité au sein de France Télécom,

notamment à la Direction des Télécommunications Sous-Marines de FTLD, où il a été responsable du Département Ingénierie, et impliqué pendant près de dix ans dans l’ingénierie, le design et le déploiement de très nombreux projets sous-marins de France Télécom

Il a ensuite rejoint Global Crossing en tant que responsable de la filiale française, où il a assuré la mise en place de la structure et de l’organisation, les déploiements réseau et où il a également assuré le déploiement des câbles sous-marins du réseau PEC.

Il fournit depuis 2002 des prestations de conseil en télécommunications dans les domaines des projets d'infrastructures - réseaux sous-marins, backbones internationaux, datacenters, réseaux wireless ou d'accès optiques - pour des opérateurs ou des gouvernements, ainsi que du conseil en stratégie et business développement pour diverses sociétés du secteur TIC. Gérard Dupin est également très actif dans la commercialisation de produits IT de plusieurs sociétés françaises ou étrangères.

Gérard Dupin est administrateur de Forum Atena.

[email protected]


Table des matières

WHY EPON? .................................................................................................. 1

STATE OF THE ACCESS NETWORK ................................................................. 1 PROVEN, PERSISTENT DEMAND........................................................................................................... 1 PROVISIONING THE LAST MILE… FIRST ............................................................................................... 1 UNIQUE SOLUTIONS FOR THE FIRST MILE ............................................................................................. 2 TURNKEY, CARRIER GRADE TECHNOLOGY .............................................................................................. 2 SYSTEM ARCHITECTURE .................................................................................................................... 3

WHAT IS A PON? .......................................................................................... 3 “PASSIVE” .................................................................................................................................... 3 “OPTICAL” .................................................................................................................................... 3 “NETWORK” .................................................................................................................................. 3

Networks Closely Adapted To Geo-Markets ............................................................................................... 4 Business as Usual ........................................................................................................................................ 4

PON ACTIVE COMPONENTS ............................................................................................................... 5 THE OLT ....................................................................................................................................... 5

BANDWIDTH DISTRIBUTION VIA PON.......................................................... 5 BANDWIDTH DISTRIBUTION .............................................................................................................. 5 BANDWIDTH UTILIZATION ................................................................................................................ 6

DYNAMIC BANDWIDTH ALLOCATION ........................................................... 7 DYNAMIC ALLOCATION OF SUBSCRIBER ACCESS ..................................................................................... 7

Service Level Agreements & QoS ................................................................................................................ 7 Oversubscription of Data Service ............................................................................................................... 7 Sustained Cell Rate (SCR), Peak Cell Rate (PCR), and Oversubscription Ratio ............................................ 8

TRAFFIC SHAPING ........................................................................................................................... 8 SUMMARY ADVANTAGES OF DYNAMIC BANDWIDTH MANAGEMENT ............................................................... 9

PON TECHNICAL SPECIFICATIONS ............................................................. 10 SUPPORT FOR 622MBPS SYMMETRICAL OPERATION (BPON) ................................................................ 10 COMMON ATM PLATFORM ............................................................................................................... 10 RANGING .................................................................................................................................... 11 QOS AND GRANT SCHEDULING ......................................................................................................... 11 DEPLOYING PON .......................................................................................................................... 12

Economic Impact and Resulting Opportunity ........................................................................................... 12 FSAN Standardization ............................................................................................................................... 12

APPLICATIONS SUPPORTED ............................................................................................................. 12 Service adaptability .................................................................................................................................. 12 Support for multiple broadband markets ................................................................................................. 12 Support for network terminals ................................................................................................................. 14 Broad scope of applications ...................................................................................................................... 14

SCALABILITY – FUTURE PROOFING ............................................................ 14

ELEMENT MANAGER SYSTEM - EMS ............................................................. 15 CONFIGURATION MANAGEMENT ........................................................................................................ 15 CIRCUIT PROVISIONING ................................................................................................................. 15 FAULT MANAGEMENT ...................................................................................................................... 16 PERFORMANCE MANAGEMENT ........................................................................................................... 16

A PROPOS DES AUTEURS ............................................................................ 18


Les idées émises dans ce livre blanc n’engagent que la responsabilité de leurs auteurs et pas celle de Forum ATENA.

La reproduction et/ou la représentation sur tous supports de cet ouvrage, intégralement ou partiellement est autorisée à la condition d'en citer la source comme suit :

© Forum ATENA 2006 – Why Pon?

Licence Creative Commons

- Paternité

- Pas d’utilisation commerciale

- Pas de modifications


L'utilisation à but lucratif ou commercial, la traduction et l'adaptation sous quelque support que ce soit sont interdites

sans la permission écrite de Forum ATENA.

why epon? - forum atenamoscow by comcor (9.000 nodes installed and still growing), france...

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