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Past, Present, and Future

发布时间:2013-11-19 13:02:21  

ITU PON –Past, Present, and Future

A Review of ITU-T PON Activities

Telcordia Contact:

Rob Bond

Senior System Engineer

Network Services and Assurance/Access Technology


+1 732.699.3445

Prepared For:

FTTH Council WebinarJuly 30, 2008

Copyright 2008 Telcordia


?Brief Introduction to Passive Optical Networks


?History of PON Development

?Recent G-PON related activities in the ITU-T?A Look Ahead

–Next Generation PON Activities


Copyright 2008 Telcordia

Passive Optical Network (PON) System Characteristics

?Fiber Optic Media

–All PON systems are based a point-to-multipoint physical topology where a single feeder fiber from the local exchange office is shared by a group of subscriber optical terminals (typically 32 or more)

–A passive optical splitting device (i.e., power splitter or WDM splitter) is used to couple the optical signals from the shared feeder fiber to the individual subscriber (distribution) fibers, and vice-a-versa.

?Active Electronics

–A single optical transceiver in the exchange is shared by a group of subscriber optical terminals (typically 32 or more)

–For a fiber-to-the-premises (FTTP) systems, there is generally no active electronics in the outside plant.

–The various PON technologies make use of different multiplexing techniques to allow shared access to the fiber media

?TDM-based PONs and WDM-based PONs are two broad categories

?TDM-based PONs are by far the most commonly deployed

–The various PON technologies also differ in available digital capacity, how they dynamically allocate upstream bandwidth to subscribers (for efficient PON bandwidth utilization), and embedded operations capabilities (just to mention a few examples)


Copyright 2008 Telcordia

TDM PON Example



TDM transmission with multiple “listeners” (encryption to insure


?Upstream–TDMA transmission with upstream transmissions (bursts) scheduled to prevent overlap

OLTONT Optical Line TerminationOptical Network Termination

(* with G.984.6 Reach Extender)

PONs are (in some sense) like HFC systems –shared medium


Copyright 2008 Telcordia

Example of WDM-PONwavelength Hybrid WDM-PON Fixed* or


opticsWavelength selection heresplitter* “Fixed” optics might be a cost reduced

version of convention DWDM long-haul optics Most believe adaptable optics will be required for a practical WDM-PON system

Copyright 2008 TelcordiaColorless ONTs:Transmitter and Receiver front-end filter characteristics are wavelength adaptable5

Today’s PON Systems

?TDM-PONs Rule: The vast majority of PON systems deployed today are TDM-based PON systems(i.e., B-PON, E-PON, and G-PON)

–They almost exclusively operate on a single fiber, with WDM used to provide bi-directional transmission

–A third wavelength in the downstream is sometimes used for broadcast video services (e.g., Verizon FiOS)

?WDM-PON: Very limited deploys, mainly in Korea

–Costs of WDM-PON in delivering mass market dedicated wavelength services are still higher high relative to TDM-PON–WDM and hybrid WDM-PONs are expected to play a greater role in Next Generation (NG) PON systems (e.g., 5+ years) than today


Copyright 2008 Telcordia

TDM PON Architecture and Technologies

Network optical transceiver (TXR) shared by “N” subscribers

OLT implementations may not necessarily support all PON technologies indicated


Copyright 2008 Telcordia

x-PON Technology Time Line

FSAN GPON 7thGPON Interop Event



OMCI 802.3ah (G.984.4) (EPON) publishedpublished

G.984.2 amd2, G.984.6 published

BPON Completed:April 2000BPON 1st Interop Event:March 2004

GPON Completed:June 2004GPON 1st Interop Event:Jan 2006

BPON 1stwide-scale deployment:May 2004GPON 1st wide-scale deployment:4Q 2007

GPON Specs focused & enhanced:3Q07-1Q08


Copyright 2008 Telcordia


Recent Activities

9Copyright 2008 Telcordia

Overview of Recent ITU PON Activities?Efforts to focus, clarify, and reduce options within the recommendations

?New Feature and Functions

–New Optical Layer Supervision Functionality –G-PON Reach Extension

Fully –Enhancement Band RecommendationService and


RichNetwork Operator



Copyright 2008 TelcordiaHighly Interoperable

Focus/Clarification Update Examples?The operational rates focused on 2488/1244 Mbps (down/up), with other rate combinations depreciated (made obsolete) [G.984.1, G.984.3]?G-PON Protection types (a) and (d) were deprecated [G.984.1]

?New G.984.1 Appendix that [G.984.1]

–provides examples of practical G-PON system

architectures, typical services and external interfaces–provides various protocol stack associated with services and architectures


Copyright 2008 Telcordia

Focus/Clarification Update Examples (2 of 2)?Clarifications to dynamic bandwidth assignment (DBA) operation and removal of miscellaneous ambiguities


?Improved alignment of G-PON specifications with DSL Forum Ethernet Aggregation Network Architecture requirements, per TR-101/WT-156 [ongoing G.984.4]–G-PON configuration info in support of TR-101 architectures–Improved G-PON traffic management support (marking, shaping, policing, drop precedence support, etc)

?Clarification and selection of preferred implementations of G-PON management functions [ongoing G.984.4 Implementers’ Guide]

–For example, preferred G-PON implementations in support of likely Ethernet flow handling scenarios


Copyright 2008 Telcordia

New Features/Functions:

Optical Layer Supervision (OLS)

?Additional “hooks” added to recommendations to utilize optical transceiver measurement information inherent in most optical transceiver devices (per SFF-8472 ), plus misc OLS improvements

–New OLS appendix added that describes the measurement and monitoring optical transceiver related parameters, including (Temperature, Voltage, Bias Current, TX/RX Power) [G.984.2]–Addition of FEC performance monitoring and fiber distance estimation techniques [G.984.3, G.984.4]

–New management functionality for reporting ONT OLS data



Copyright 2008 Telcordia

New Features/Functions:

ONU Registration Process Updates

?A new “Registration ID” based process is being specified that allows an ONT join a PON and be authenticated (i.e., associated with a valid customer) without requiring the use of the hardware serial number (SN) of the ONT. [ongoing in G.984.3, G.984.4]

–Makes use of the existing ONT password PLOAM message to report a Registration ID to the OLT.

–The Registration ID is associated with a specific customer and is entered into the ONT (by an unspecified method) by the Telco

equipment installer at the time of ONT installation.

–The OLT uses the received Registration ID to validate that the ONT requesting to join the PON is associated with a valid customer.

–This is an alternative to the classic SN-based authentication, which requires the installer to associate a very specific ONT (one with

service order’s specified SN) with a customer installation.

–With a Registration-ID approach, the installer only needs to enter the service order’s specified Registration ID into an arbitrarily chosen ONT.


Copyright 2008 Telcordia

New Features/Functions:

Reach Extension (RE)

?Class “C+” Single Sided Reach Extension [G.984.2]:

–New class of OLT optics that supports up to 32 dB of ODN loss (compared to today’s 28 dB, Class B+, systems)

–Up to 40 km reach @ 1x32 split

–ONT continues to use existing Class B+ optics, but must utilize FEC.

?Mid-Span Reach Extension [G.984.6, G.984.4]

–New Recommendation (G.984.6) that specifies a physical layer reach extension device (Regenerator or Optical Amplifier) in the fiber link between the OLT and ONT.

?The maximum reach is up to 60km

?Loss budgets of in excess of 27.5 dB in both spans

–New requirements in support of mid-span RE management

[ongoing G.984.4]


Copyright 2008 Telcordia

G-PON (Mid-Span) Reach Extension

Motivations: Serving Distant Housing Cluster

?Classic application to extend the geographical reach of a Class B+

G-PON system by locating a RE at a remote site, outside the CO–While a Class B+ 20 km reach is good, there are still a significant number of customers beyond this reach in some Operator’s networks


Copyright 2008 Telcordia

G-PON (Mid-Span) Reach Extension

Motivations: CO Consolidation

?This application may involve both larger reach and larger split ratios,

placing. OLTs in a more centralized location (i.e., deeper in the network) with the RE placed in the local exchange office where an OLT would


Copyright 2008 Telcordia

New Features/Functions:

Enhancement Band

?New Recommendation published (G.984.5) that:

–Defines wavelength ranges reserved for additional service signals overlaid via WDM on an operating G-PON system–Effectively specifies the wavelength blocking filter needed on today’s G-PON ONTs to be compatible with (i.e., blind to) next generation (NG) PON systems overlaid on the same optical distribution network (ODN) as the G-PON system

–Lays the ground work for specifying NG-PON systems that allow Operators to gradually migrate (i.e., on an individual customer basis) customers from a working G-PON ONT to a NG-PON ONT without disrupting existing (non-migrated) customers


Copyright 2008 Telcordia

New Features/Functions:

Enhancement Band –G.984.5 Wavelength PlanG.984.2

G.984.5Regular (FP)

NG-PON (G.9xx)


BCD* Requires the use of reduce water peak fiber (G.652.C/D)

** the upper-limit value is determined as an operator choice from 1580 to 1625 nm


Copyright 2008 Telcordia

ITU G-PON Specifications

?G.984.1, March 2008, Jan 2003, "General

characteristics for Gigabit-Capable Passive Optical Networks (G-PON)”

?G.984.2, Jan 2003, “Gigabit-capable Passive Optical Networks (G-PON) : Physical media dependent (PMD) layer specification”, plus Amd. 1, (2/06), Amd. 2, (3/08)

?G.984.3, March 2008, Oct 2003, “Gigabit-Capable Passive Optical Networks (G-PON): Transmission Convergence Layer”

?G.984.4, February 2008, April 2004 , “Gigabit-capable Passive Optical Networks (GPON): ONT Management and Control Interface specification”


Copyright 2008 Telcordia

New Additions -ITU G-PON Specifications?G.984.5, Sept 2007, "Enhancement band for gigabit capable optical access networks”?G.984.6,March 2008, “Gigabit-capable Passive Optical Networks (G-PON): Reach extension”


Copyright 2008 Telcordia

ITU PONWhat Might the Future Hold?

22Copyright 2008 Telcordia

NG-PON Directions

?ITU-T Study Period 2009-2012:

–New study period begins in less than 6 months–It is expected to include work on access systems that will replace or augment today’s G-PON systems

?What are the likely technology directions and system attributes to be considered?


Copyright 2008 Telcordia

NG-PON: Likely Attributes

?A number of large network Operators have expressed preliminary thinking on what they would like to see in a Next Generation (NG) PON

–Coexistence:NG-PON systems need to coexist on the same fiber with today’s giga-bit PON

?Allows existing G-PON subscribers to be individually migrated to NG-PON on an as-needed basis without disrupting other users on the PON

?Relies on the deployment of G.984.5 compliant ONTs today and NG-PON systems using G.984.5 enhancement band wavelengths

–Digital Capacity: At a minimum NG-PON systemsare generally viewed as 10 Gbps downstream and 2.5 Gbps upstream, or a system that overlays multiple G-PON systems on the same ODN.

–Loss Budget:At a minimum, NG-PON are expected to operate over “Class C” ODNs (30 dB loss). Class C++ (>32 dB) operation with optical pre/post optical amplification

–Split Ratio:At a minimum at 64-way split should be supported, but for some applications (e.g., office consolidation) a 256-way (or higher) split may be need (would require optical amplification)

–Reach:At a 20 km physical reach is required and at least a 60 km logical reach (reaches greater than 20 km may require optical amplification)


Copyright 2008 Telcordia


Use ofG.984.5 Wavelength PlanG.984.2

G.984.5Regular (FP)

NG-PON (G.9xx)

* Requires the use of reduce water peak fiber (G.652.C/D)

** the upper-limit value is determined as an operator choice from 1580 to 1625 nm


Copyright 2008 Telcordia

NG-PON via Overlay G-PON:

Stacked More G-PON Systems on the same ODN26Copyright 2008 Telcordia

NG-PON: 10G PON with Serial 10G UpstreamOverlay new 10G/10G NG-PON system27Copyright 2008 Telcordia

10G NG-PON with Parallel 5G Upstream

2 WDM Upstream @ 1.3mm, 1 Downstream @ 1.5mm

Copyright 2008 Telcordia


NG-PON: Likely Directions (1 of 2)?IEEE 802.3av Alignment:

–There seems to be significant industry support for aligning the 10G optics (PMD) of an ITU NG-PON system (to the greatest extent possible) with the optical layer specification of the emerging IEEE 10GEPON (802.3av) Task Force

?A near-final 802.av draft is expected by the time the ITU-T SG15 NG-PON work begins in 2009.

?Optical layer specifications now being use by IEEE are in alignment with ITU optical budget rules (was not always the case)

?Would allow ITU NG-PON systems to leverage volumes of 10GEPON optics (cost benefits)

–There are other voices, however, proposing alternative PMDs for NG-PON (e.g., DWDM-based channelization)

?G-PON Reuse:The transmission convergence (TC) sublayer [framing, media access control, PON activation, PON encryption, etc] and higher layer functionality (i.e., OMCI) will likely be based on the reuse of significant portions of G-PON


Copyright 2008 Telcordia

NG-PON: Likely Directions (2 of 2)?Non-Coexistence NG-PON:

–NG-PON work may also consider the specification of a system that does not need to coexist on the same ODN as G-PON (e.g., for “Greenfield”). Such NG-PON systems are not restricted ?To G.984.5 enhancement band operation

?By optical characteristics (e.g., loss, reflections) of embedded ODN components (e.g., fibers and splitters)

–May be focused on a slightly longer deployment horizon and hence consider the use of technologies currently viewed as “emerging” (e.g., colorless WDM-PON, 40 Gbps TDM) and that are capable of supporting 1 Gbps per subscriber

–Depending on the market success of standalone G.984.6 reach extenders, NG-PON work may also include the integration of long-reach optics in the system specifications (see the next two slides)


Copyright 2008 Telcordia

Hybrid WDM-PON w/ Extended Reach


Metro Office

Remote Office

Wavelength selection heresplitterReach ≥ 60 km


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NG-PON with Reach Extension

Example #2: NG-PON Multiplexer

Four (1x32) 10G NG-PON Systems



Copyright 2008 Telcordia


?ITU PON systems continue to evolve to meet Operator needs worldwide while maintaining a stable, backwards compatible, specification

?Work on defining NG-PON recommendations is expected to begin with the new ITU study period in January

–Systems based on TDM/TDMA technology providing coexistence on the same fiber with today’s G.984.5-compliant G-PON systems seems likely

–Consideration of other technologies is possible (WDM-PON, Code Division Multiplex), especially in the context of NG-PON for

greenfield (non-coexistence) applications


Copyright 2008 Telcordia

About Telcordia

?Provider of network software and servicesto the global telecom market

?Proud Bell System history

?Leader in service fulfillment

?Leader in number portability solutions?Leader in MVNO service delivery

?Over 880 patents issued, delivering industryleading technologies

?Leadership positions in

standards bodies and industry


?Deep expertise in next-generationnetworks, operations, and services


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PON InteroperabilityAcronyms

35Copyright 2008 Telcordia


AN: Access Node

ATM: Asynchronous Transfer Mode

B-PON:Broadband PON

CDM: Code Division Multiplexing

CO: Central Office

COT: Central Office Terminal

CPE: Customer Premises Equipment

CTS: Common Technical Specification

CSA: Carrier Serving Area

DBA:Dynamic Bandwidth Assignment

DSL: Digital Subscriber Line

DSLAM: Digital Subscriber Line Access Multiplexer


Copyright 2008 Telcordia

Acronyms -2

Dense Wavelength Division MultiplexingEthernet in the First Mile (IEEE 802.3ah)Electromagnetic InterferenceElement Management SystemEmbedded Operations ChannelEthernet PON

Fiber Distribution FrameFiber Distribution Hub

Feeder-Distribution Interface


Copyright 2008 TelcordiaDWDM: EFM: EMI: EMS: EOC: E-PON:FDF: FDH: FDI:

Acronyms -3

Forward Error Correction

Fiber In The Loop

Fiber Optic Terminal

Full Service Access Network





Fiber-to-the-Node (or Neighborhood)

Fiber-to-the-Premises (includes FTTH and FTTB)


Copyright 2008 TelcordiaFEC: FITL: FOT: FSAN: FTTB: FTTCab: FTTC: FTTH: FTTN: FTTP:

Acronyms -4

GEM: G-PON Encapsulation ModeGFP: Generic Framing ProcedureG-PON: Giga-bit PON (G.984.x series)GE-PON: a commercialized E-PONILEC: Incumbent Local Exchange CarrierLU: Living Unit

MAC:Media Access ControlMDF:Main Distribution FrameMOCA:Multimedia Over CoaxNID:Network Interface Device NT:Network Termination


Copyright 2008 Telcordia

Acronyms -5

OAM: Operations, Administration and MaintenanceODN: Optical Distribution Network

OLT: Optical Line Termination

OMCC: ONT Management and Control ChannelOMCI: ONT Management and Control InterfaceONT: Optical Network TerminationONU: Optical Network Unit

OSP: Outside Plant

OSS: Operations Support System


Copyright 2008 Telcordia

Acronyms -6

P2P: Point to Point

P2MP: Point to Multi-Point

PFOC: Passive Fiber Optic Component

PLOAM: Physical Layer Operations, Administration, and Maintenance

PMD: Polarization Mode Dispersion

PON: Passive Optical Network

POTS: Plain Old Telephone Service

QoS: Quality of Service

RX: Receiver


Copyright 2008 Telcordia

Acronyms -7

SAC: Serving Area ConceptSAI: Serving Area Interface

SONET: Synchronous Optical NetworkSTB: Set-Top Box

TA: Terminal Adapter

TDM: Time Division MultiplexingTDMA: Time Division Multiple AccessTE: Terminal Equipment

TX: Transmitter

TXR: Transceiver (Transmitter and Receiver)


Copyright 2008 Telcordia

Acronyms -8

VF: Voice Frequency

VoIP: Voice over IP

WDM: Wavelength Division Multiplexing


Copyright 2008 Telcordia

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