Itu Pon Past Present Future

Copyright 2008 Telcordia

ITU PON – Past, Present, and Future

A Review of ITU-T PON Activities

Telcordia Contact:Rob BondSenior System EngineerNetwork Services and Assurance/Access [email protected]+1 732.699.3445

Prepared For:FTTH Council WebinarJuly 30, 2008


2

Overview

Brief Introduction to Passive Optical Networks (PONs)

History of PON Development Recent G-PON related activities in the ITU-T A Look Ahead

– Next Generation PON Activities


3

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)


4

TDM PON Example Downstream – TDM transmission with multiple “listeners” (encryption to insure

privacy) Upstream – TDMA transmission with upstream transmissions (bursts) scheduled

to prevent overlap

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

Downstream (single -fiber systems): 1490 nm Upstream: 1310 nm RF video (if present) 1555 nm

TDM Time Division Multiplex TDMA Time Division Multiple Access CC Cross Connect NB Narrow Band BB Broadband OLT Optical Line Termination ONT Optical Network Termination

TDM

ONT2

ONT32

1:32 Optical splitter (or 1:64 for shorter reaches or

with Reach Extender)

OLT

Access Node

NB

BB

CC Video

Data

E1/T1/ Telephony

Data

E1/DS1

GbE STMn/OCn

ONT1

E1/DS1/ Telephony

POTS

VOIP

(and/or)

TDMA

Up to 60 km* physical reach

(* with G.984.6 Reach Extender)


5

Example of WDM-PON

Access node

OLT

SNI

wavelength splitter

1 to N s on single fiber

Wavelength selection here

dedicated pair

dedicated pair

ONTBitrate 1

ONTBitrate 2

Feeder Fiber

Colorless ONTs: Transmitter and Receiver front-end filter characteristics are wavelength adaptable

Fixed* or adaptable optics

power splitter

TDMAONT

(Fixed Optics)

TDMAONT

(Fixed Optics)

power splitter

Hybrid WDM-PON example

* “Fixed” optics might be a cost reduced version of convention DWDM long-haul optics NOTE: Most believe adaptable optics will be required for a practical WDM-PON system


6

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


7

TDM PON Architecture and Technologies

OLT

FiberBP

ON

GP

ON

Max 32 way split (may be cascaded)

OLT implementations may not necessarily support all PON technologies indicated

•Typically: 622 Mbps/155 Mbps (down/up)

•ATM-based transport

LU #1

LU #N, N ≤32

Fiber

Max 64 way split [constrained by PMD attenuation limits]

• Typically: 2488/1244 Mbps

• GFP-like transports (Ethernet, and/or TDM)

LU #1

LU #N, N ≤64

EP

ON

Fiber

• 1250 Mbps/1250 Mbps [~850 Mbps effective payload rate])

• Ethernet-based transport

LU #1

LU #N, N ≤32

20 km Maximum Reach

20 km ONU differential range

B-PON

G-PON

E-PON

Max 32 way split (16-way specified in standard)

splitter

splitter

splitter

ITU-T G.983.x

ITU-T G.984.x

1000BASE-PX20 per IEEE 802.3ah

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

TXR

TXR

TXRLU #N, N ≤32

ONT

ONT

ONT


8

G.984.5 published

G.984.1, G.984.3G.984.4 Rev2 published

G.984.2 amd2, G.984.6 published

GPON Specs focused & enhanced: 3Q07-1Q08

x-PON Technology Time Line

1995 2000

FSANfounded

‘98 ‘99 ‘02 ‘04 ‘05 ‘06‘01

BPON (ITU G.983.1)

published BPON OMCI

(G.983.2) published

IEEEEPONbegins

FSAN begins GPON

‘03

BPON OMCI

(G.983.2) Revised

GPON OMCI (G.984.4) published

GPON TC (G.984.3) published

IEEE 802.3ah (EPON) published

1st GPON Interop Event

FSAN begins NG-PON

FSAN GPON CTS

BPON Completed: April 2000

BPON 1st Interop Event: March 2004

BPON 1st wide-scale deployment: May 2004

GPON Completed: June 2004

GPON 1st Interop Event: Jan 2006

GPON 1st wide-scale deployment: 4Q 2007

‘07

IEEE begins 10GEPON

‘08

7th GPON Interop Event

‘09


9

ITU PON

Recent Activities


10

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

– Enhancement Band Recommendation

ITU G.984G-PON

Solutions

Fully Standardiz

e

Service and

Feature Rich

Network Operator Friendly

Highly Interoperabl

e


11

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


12

Focus/Clarification Update Examples (2 of 2)

Clarifications to dynamic bandwidth assignment (DBA) operation and removal of miscellaneous ambiguities [G.984.3]

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


13

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 [G.984.4]


14

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.


15

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]


16

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– As an alternative to a field-located OLT

splitter

ONT

ONT

ONT

1x32

Local Exchange Office

OLT

RE

Remote Site

Class B+ (e.g., 40 km) Class B+ (e.g., 20 km)


17

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 traditionally reside.

splitter

ONT

ONT

ONT

1x32

Hand-off to Communications Service Providers or LEC Core network

OLT1x4

RE

splitter

1x32

splitter

1x32

1x32Local Exchange Office

Class B+ (e.g., 40 km)

Class B+

Operators hoping for reductions in CO (1) powering, (2) real estate, and (3) maintenance costs


18

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


19

New Features/Functions: Enhancement Band – G.984.5 Wavelength Plan

1260 1280 1300 1320 1340 1360 1380 1400 1420 1460 1480 1500 1520 1540 1560 1580 1600 1620 1640 16601440 1680

O-band E-band S-band C-band L-band U-band

G.984.2

Legend: GPON Up

GPON Dn

RF Overlay Present

Future

* 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

G.984.5

or

or

NG-PON

Regular (FP)

Reduce (DFB)

Narrow (CWDM)

NG-PON (G.9xx)

A BNG-PON Option 1 *

CNG-PON Option 2**

D


20

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”


21

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”


22

ITU PON

What Might the Future Hold?


23

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?


24

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 systems are 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)


25

Coexistence: Use of G.984.5 Wavelength Plan

1260 1280 1300 1320 1340 1360 1380 1400 1420 1460 1480 1500 1520 1540 1560 1580 1600 1620 1640 16601440 1680

O-band E-band S-band C-band L-band U-band

G.984.2

Legend: GPON Up

GPON Dn

RF Overlay Present

Future

* 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

G.984.5

or

or

NG-PON

Regular (FP)

Reduce (DFB)

Narrow (CWDM)

NG-PON (G.9xx)

A BNG-PON Option 1 *

CNG-PON Option 2**

D

Seems unlikely


26

NG-PON via Overlay G-PON: Stacked More G-PON Systems on the same ODN

splitter

1x32

G-PONOLT

WDM

G-PONOLT

15xx/15yy nm(G.984.5)

1490/1310 nm

1490nm/1310 nm GPON

Overlay GPON (15xx/15yy nm )

G-PONOLT

G-PONOLT

32-way split GPON gives each customer sustained bandwidth 80/40 Mbps

Upgrade 4 customers to overlay GPON gives them 622/311 Mbps sustained bandwidth each


27

NG-PON: 10G PON with Serial 10G Upstream

1:32

2G-Rx1G-Tx

Vid.Rx

CO

G.984.5 Compatible

1550 nm(or below)

1310 nmwindow

1490 nm

Legacy user

Vid Tx

2G-Tx1G-Rx

Triplexer

OLT

G-PON

Existing G-PON User

Overlay new 10G/10G NG-PON system

New triplexerNew triplexer

10G-RxVid.Rx

ONT, 1.3m window up

10G-Tx

NG-PON User

10G-RxVid.Rx

ONT, 1.3m window up

10G-Tx

NG-PON User

New filter

Above1550 nm

NG-PON OLT

10G-Tx10G-Rx

There are cost concerns with 10 Gbps serial

upstream ONTs, hence …


28

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

1:32

2G-Rx1G-Tx

Vid.Rx

CO

G.984.5 Compatible

1550 nm(or below)

1490 nm

Legacy G-PON user

10G-RxVid.Rx

ONTa, 1270 nm up

5 G-Tx

New triplexer

Vid Tx

2G-Tx1G-RxOLT

10G-RxVid.Rx

ONTb, 1350 nm up

5 G-Tx

New triplexer

10G NG-PON with Parallel 5G Upstream

Triplexer

1310 nmwindow

10G-Tx

5 G-Rx New NG-PON OLT

5 G-Rx

Above1550 nm

New filter

1310 nmwindow


29

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


30

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)


31

Hybrid WDM-PON w/ Extended Reach

Metro Office

OLT

SNI

wavelength splitter

1 to N s on single fiber

Wavelength selection here

dedicated pair

dedicated pair

NG ONTBitrate 1

NG ONTBitrate 2

power splitter

TDMA

TDMA

power splitter

RE

Remote Office

NG ONTBitrate 1

NG ONTBitrate 2

Reach ≥ 60 km

Optical Trunk Line

Optical Feeder


32

NG-PON with Reach Extension Example #2: NG-PON Multiplexer

splitter

ONT

ONT

ONT

1x32

Local Exchange Office

OLT

Remote Site

60 km Class B+ (e.g., 20 km)

RE with 1:4 TDM multiplexing

1x32

1x32

40 Gbps

Four TDM NG-PON Systems

1x32

Four (1x32) 10G NG-PON Systems

NG-PON Media Access Control/DBA functionality remains here


33

Summary

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


34

About Telcordia Provider of network software and services

to 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 instandards bodies and industryforums

Deep expertise in next-generationnetworks, operations, and services


35

PON Interoperability

Acronyms


36

Acronyms AN: Access Node

ATM: Asynchronous Transfer Mode

B-PON: Broadband PON

CDM: Code Division MultiplexingCO: 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


37

Acronyms - 2

DWDM: Dense Wavelength Division Multiplexing

EFM: Ethernet in the First Mile (IEEE 802.3ah)

EMI: Electromagnetic Interference

EMS: Element Management System

EOC: Embedded Operations Channel

E-PON: Ethernet PON

FDF: Fiber Distribution Frame

FDH: Fiber Distribution Hub

FDI: Feeder-Distribution Interface


38

Acronyms - 3

FEC: Forward Error Correction

FITL: Fiber In The Loop

FOT: Fiber Optic Terminal

FSAN: Full Service Access Network

FTTB: Fiber-to-the-Business

FTTCab: Fiber-to-the-Cabinet

FTTC: Fiber-to-the-Curb

FTTH: Fiber-to-the-Home

FTTN: Fiber-to-the-Node (or Neighborhood)

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


39

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


40

Acronyms - 5

OAM: Operations, Administration and Maintenance

ODN: Optical Distribution Network

OLT: Optical Line Termination

OMCC: ONT Management and Control Channel

OMCI: ONT Management and Control Interface

ONT: Optical Network Termination

ONU: Optical Network Unit

OSP: Outside Plant

OSS: Operations Support System


41

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


42

Acronyms - 7

SAC: Serving Area Concept

SAI: Serving Area Interface

SONET: Synchronous Optical Network

STB: Set-Top Box

TA: Terminal Adapter

TDM: Time Division Multiplexing

TDMA: Time Division Multiple Access

TE: Terminal Equipment

TX: Transmitter

TXR: Transceiver (Transmitter and Receiver)


43

Acronyms - 8

VF: Voice Frequency

VoIP: Voice over IP

WDM: Wavelength Division Multiplexing

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