GPON-Fundamentals_Huawei.pdf

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HUAWEI TECHNOLOGIES Co., Ltd. Huawei Confidential
Security Level:
OBA000100 GPON
Fundamentals

Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 2
References
ITU-T 984.1
ITU-T 984.2
ITU-T 984.3
ITU-T 984.4

Objectives
Upon completion of this course, you will be able to:
Describe GPON Network Architecture
Outline GPON Basic Concepts
Outline GPON Applications

Contents
1. Overview of Optical Access Network
2. Basic Concepts of PON
3. GPON Frame Structure
4. GPON Key Technologies
5. GPON Management and Service Provisioning
6. Basic Services over GPON Network

Contents

CO
Curb
Customer
Premise
BA
FTTC
FTTB
OLT
OLT
Architecture of Optical Access
Network
DSLAM
250-700m
Urban Coverage
3.5-5km
Remote Business
xDSL 2~20Mbps
OLT
FTTH
ODN
MDU
ONT
ONU
Optical Line Termination Optical Networks Termination
Optical Networks Unit
Multi-Dwelling Unit
2.5Gbps Down /1.25Gbps Up

From the architecture diagram, the optical access network comprises the following
scenarios:
1. FTTB scenario
SBU : Single business unit ; providing a comparatively small number of ports such as
10/100/1000BASE-T, RF, and DS1/T1/E1 ports
MTU :Business Multi-tenant unit ; providing a comparatively larger number of ports,
including 10/100/1000BASE-T, RF and DS1/T1/E1 ports., VDSL2, and so on.
2. FTTC FTTCab scenario
MDU : Multi-dwelling unit ;providing a comparatively larger number of ports, including
10/100/1000BASE-T, RF, VDSL2, and so on.
3. FTTH scenario
SFU : Single family unit , providing a comparatively small number of ports, including
following types: POTS, 10/100/1000BASE-T, and RF.
What is Optical Access
Network?

Contents

What is PON?
Passive Optical Network
OLT
ONU
Optical Line Terminal
Optical Network Unit
Passive Optical
Splitter
PSTN
Internet
IPTV
ONU
ONU
PON is a kind of passive optical network featuring one-to-multiple-point architecture;
PON is short for Passive Optical Network ;
PON consists of Optical Line Terminal (OLT), Optical Network Unit (ONU) and Optical
Distribution Network(ODN).
Passive Optical
Splitter

Why GPON?
GPON（
（
（
（Gigabit-capable Passive Optical Networks）
）
）
）
GPON supports :
Triple－play service
high-bandwidth
long-reach (up to 20 km)
GPON is the choice of large carriers in the international market.
1Mbps 3M 8M 25M 2.5G
ADSL/ADSL2+
Copper Based
VDSL / ADSL2+
Copper Based
PON
Fiber Based
2002 2003 2006 2010
Time
Internet
Video conferencing
Remote control
Access
Technology
Service
requirements
VoD
HDTV
Game
Live TV
VoD
HDTV
3km 2km 1km ~20km
Coverage
diameter

GPON Principle----Data
Multiplexing
GPON adopts Wavelength Division Multiplexing (WDM) technology,
facilitating bi-direction communication over a single fiber.
To separate upstream/downstream signals of multiple users over a single
fiber, GPON adopts two multiplexing mechanisms:
In downstream direction, data packets are transmitted in a broadcast manner;
In upstream direction, data packets are transmitted in a TDMA manner.
1490nm
1310nm

GPON Principle----Downstream Data
Broadcast mode

GPON Principle----Upstream Data
TDMA mode

ITU-T G.984.3
• Specifications of TC layer in the GPON system
• GTC multiplexing architecture and protocol
stack
• GTC frame
• ONU registration and activation
• DBA specifications
• Alarms and performance
ITU-T G-984.1/2/3/4
Simple development process
Powerful compatibility
ITU-T G.984.1
• Parameter description of GPON network
• Requirements of protection switch-over
networking
GPON Standards
GPON Standards
ITU-T G.984.4
• OMCI message format
• OMCI device management frame
• OMCI working principle
ITU-T G.984.2
• Specifications of ODN parameters
• Specifications of 2.488Gbps downstream optical port
• Specifications of 1.244Gbps upstream optical port
• Overhead allocation at physical layer

Basic Performance Parameters
2.48832
2.48832
2.48832
1.24416
2.48832
0.62208
2.48832
0.15552
1.24416
1.24416
1.24416
0.62208
1.24416
0.15552
Downstream
Rate(Gbps)
Upstream
Rate(Gbps)
1.24416 Gbit/s up, 2.48832 Gbit/s
down is the mainstream speed
combination supported at current
time.

Basic Performance Parameters
1：64/up to1：128
Split ratio
20 km
Maximum differential fibre
distance
20 km
Maximum physical reach
60 km
Maximum logical reach
The distance
between nearest
and farthest
ONTs

Contents

GPON Network Model Reference
GPON Network Model Reference
WDM
ONU/ONT
NE
WDM
OLT
NE
Service node
Optical
splitter
T reference point
V reference point
R/S S/R
ODN
UNI SNI
IFpon IFpon
ONU Optical Network Unit
ONT Optical Network Terminal
ODN Optical Distribution Network
OLT Optical Line Terminal
WDM Wavelength Division Multiplex Module
NE Network Element
SNI Service Node Interface
UNI User Network Interface

GPON Multiplexing Architecture
IFpon
O
N
U
O
N
U
O
N
U
T-CONT Port
T-CONT
Port
Port
T-CONT
T-CONT
Port
Port
Port
Port
Port
ONU-ID
identifies
ONUs
Alloc-IDs
identifies T-
CONTs
Port-ID
identifies GEM
ports
GEM Port: the minimum unit for carrying
services.
T-CONT: Transmission Containers is a kind of
buffer that carries services. It is mainly used to
transmit upstream data units. T-CONT is
introduced to realize the dynamic bandwidth
assignment of the upstream bandwidth, so as
to enhance the utilization of the line.
IF pon: GPON interface.
Based on the mapping scheme, service traffic
is carried to different GEM ports and then to
different T-CONTs. The mapping between the
GEM port and the T-CONT is flexible. A GEM
port can correspond to a T-CONT; or multiple
GEM Ports can correspond to the same T-
CONT.
A GPON interface of an ONU contains one or
multiple T-CONTs.

OLT ONT
T-CONT
T-CONT
GEM Port GEM Port

Physical Control Block
Downstream (PCBd)
Payload
AllocID Start End AllocID Start End
1 100 200 2 300 500
T-CONT1
(ONT 1)
T-CONT 2
(ONT 2)
Slot
100
Slot
200
Slot
300
Slot
500
PLOu PLOAMu PLSu DBRu X Payload x DBRu Y Payload y
Upstream
Bandwidth Map
125us
Downstream Framing
Upstream Framing
GPON Frame Structure
GPON Frame Structure
OLT
ONT 1
ONT 64

PLOu PLOAMu PLSu DBRu x Payload x DBRu y Payload y PLOu DBRu z Payload z
Preamble
A bytes
Delimiter
B bytes
BIP
1 bytes
ONU-ID
1 bytes
Ind
1 bytes
ONU ID
Msg ID
1 bytes
Message
10 bytes
CRC
1 bytes
DBA
1,2,4bytes
CRC
1byte
DBA Report Pad if needed
GEM
header
Frame
fragment
GEM
header
Full
frame
GEM
header
Frame
fragment
PLI Port ID PTI HEC
ONT A ONT B
Upstream Framing
GPON Upstream Frame Structure
GPON Upstream Frame Structure

PCBd
n
Payload
n
PCBd
n + 1
Payload
n
Psync
4 bytes
Ident
4 bytes
PLOAM
13 bytes
BIP
1 bytes
Plend
4 bytes
Plend
4 bytes
US BW Map
N*8 bytes
FEC Ind
1 bit
Reserved
1 bit
Super-frame
Counter 30 bits
Blen BW Map
Length 12 bits
Alen ATM Partition
Length 12 bits
CRC
8 bits
Access 1
8 bytes
Access 2
8 bytes
…..
Access n
8 bytes
Alloc ID
12 bits
Flags
12 bits
SStart
2 bytes
SStop
2 bytes
CRC
1 byte
Send PLS
1 bit
Send PLOAMn
1 bit
Use FEC
1 bit
Send DBRu
2 bits
Reserved
7 bits
125us
Coverage of this BIP Coverage of next BIP
Downstream Framing
GPON Downstream Frame
Structure
GPON Downstream Frame
Structure

TDM
TDM data Payload
TDM fragment
HEC
PTI
Port ID
PLI
GEM Frame
Ingress buffer
TDM Buffer
Mapping of TDM Service in GPON
Mapping of TDM Service in GPON
TDM frames are buffered and queued as they arrive, then TDM data is multiplexed
in to fixed-length GEM frames for transmission.
This scheme does not vary TDM services but transmit TDM services transparently.
Featuring fixed length, GEM frames benefits the transmission of TDM services .

GEM
Payload
CRC
PTI
Port ID
PLI
GEM Frame
Ethernet Packet
DA
SFD
Preamble
Inter packet gap
SA
LengthType
MAC client data
FEC
EOF
5 bytes
Mapping of Ethernet Service in GPON
Mapping of Ethernet Service in GPON
GPON system resolves Ethernet frames and then directly maps the data of frames
into the GEM Payload.
GEM frames automatically encapsulate header information.
Mapping format is clear and it is easy for devices to support this mapping. It also
boasts good compatibility.

Contents

GPON Key Technologies-
Ranging
DBA
T-CONT
AES
Attenuation

Ranging
OLT obtains the Round Trip Delay (RTD) through ranging process, then
specifies suitable Equalization Delay (EqD) so as to avoid occurrence of
collision on optical splitters.
To acquire the serial number and ranging, OLT needs open a window, that is,
Quiet Zone, and pauses upstream transmitting channels on other ONUs.
ONU3
ONU2
ONU1
OLT

DBA
What is DBA?
DBA, Dynamic Bandwidth Assignment
Why DBA?
It enhances the uplink bandwidth utilization of PON ports.
More users can be added on a PON port.
Users can enjoy higher-bandwidth services, especially those requiring
comparatively greater change in terms of the bandwidth.
DBA operation modes
SR-DBA: status report-DBA
NSR-DBA: non status report-DBA

SR-DBA Operation
DBA block in the OLT constantly collects information from DBA reports, and sends the algorithm
result in the form of BW Map to ONUs .
Based on the BW Map, each ONU sends upstream burst data on time slots specified to
themselves and utilizes the upstream bandwidth.
DBA algorithm
logic
DBA report
BW Map
Time slot
T-CONT
T-CONT
T-CONT
Scheduler
ONU
OLT
Control
platform
Data
platform

SR-DBA Operation
Payload
US BW
Map
Data Report
PCBd
D/S Direction
U/S Direction
OLT ONT
①
①
①
①
②
②
②
②
③
③
③
③
④
④
④
④
Based on the algorithm result of
last time, OLT delivers BW
Maps in the header of
downstream frames.
Based on the bandwidth allocation
information, ONU sends the status
report of data currently waiting in
T-CONTs in the specified time
slots.
OLT receives the status report
from the ONU, updates BW Map
through DBA algorithm and then
delivers the new BW Map in the
next frame.
ONU receives the BW Map from
the OLT and sends data in the
specified time slots.

NSR-DBA Operation
NSR-DBA
NSR is an algorithm scheme that realizes DBA. It helps to predict the
bandwidth allocated to each ONU based on the traffic from ONUs.
Procedure:
Step1: Monitor the number of data packets received by OLT within the
specified interval.
Step2: Use the result of real time monitoring in step 1 to calculate the
utilization rate.
Step3: Recognize the congestion status by comparing the utilization
rate with the specified limits.

DBA Working Principle
Based on service priorities, the system sets SLA for each ONU, restricting service bandwidth.
The maximum bandwidth and the minimum bandwidth pose limits to the bandwidth of each ONU, ensuring
various bandwidth for services of different priorities. In general, voice service enjoys the highest, then video
service and data service the lowest in terms of service priority.
OLT grants bandwidth based on services, SLA and the actual condition of the ONU. Services of higher priority
enjoy higher bandwidth.

T-CONT Bandwidth Terms
Transmission Containers (T-CONTs): it dynamically receives grants
delivered by OLT. T-CONTs are used for the management of upstream
bandwidth allocation in the PON section of the Transmission
Convergence layer. T-CONTs are primarily used to improve the upstream
bandwidth use on the PON.
T-CONT BW type falls into FB, AB, NAB, and BE.
Five T-CONT types: Type1, Type2, Type3, Type4, and Type5.

T-CONT Type and Bandwidth Type
Type1 T-CONT is of the fixed bandwidth type and mainly used for services sensitive to delay and services of
higher priorities, such as voice services.
Type2 and type3 T-CONT is of the guaranteed bandwidth type and mainly used for video services and data
services of higher priorities.
Type4 is of the best-effort type and mainly used for data services (such as Internet and email), and services of
lower priorities. These services do not require high bandwidth.
Type5 is of the mixed T-CONT type, involving all bandwidth types and bearing all services.

QoS Mechanism of ONU in GPON
GPON
VOIP
VOD
DATA
TDM
Traffic-flow
Scheduling
And buffer
control
Service
differentia
based on
802.1p
GPON
VOIP
VOD
TDM
Traffic-flow
Scheduling
And buffer
control
Service
differentia
based on
802.1p
OLT
Splitter
Service traffic based on
GEM Port-id
Traffic classification of services based on LAN/802.1p.
Service scheduling based on the combination of strict priority (SP) and Weighted Round Robin
(WRR) algorithms.
Service transmission based on service mapping with different T-CONTs, enhancing line utilization
and reliability.

QoS Mechanism of OLT in GPON
VOIP
BTV
DATA
TDM
GPON
GPON
GE/10GE
Upstream service
traffic based on
different VLANs
Ethernet
bridging
Non-
blocking
switching
802.1p
COS
Queuing
scheduling
DBA
TDM Gateway
PSTN
BSR
OLT
Traffic classification based on VLAN/802.1p.
Service scheduling based on combination of strict priority (SP) and Weighted
Round Robin (WRR) algorithms.
DBA algorithm, enhancing uplink bandwidth utilization.
Access control list (ACL)-based access control on layers above layer-2.

AES Encryption in GPON
End User
1
End User
End User
1
1
End User
3
End User
End User
3
3
ONT
End User
2
End User
End User
2
2
3
3 3
3
1
1
3
3
3
3
2
2
1
1
1
1
1
1 1
1
2
2
ONT
ONT
1
1
3
3
3
3
2
2
1
1
1
1
1
1 3
3 3
3
2
2 1
1 1
1
OLT
Encryption
Decryption
Decryption
Decryption
1
1
1
1 3
3 3
3
2
2 1
1 1
1
OLT applies Advanced Encryption Standard (AES) 128 encryption.
GPON supports encrypted transmission in downstream direction, such as AES128 encryption.
In the case of GEM fragments, only the payload will be encrypted.
GPON system initiates AES key exchange and switch-over periodically, improving the reliability
of the line.
AES: Advanced Encrypt Standard
A globally-used encryption algorithm

Fibre Attenuation and Power Budget
Fibre attenuation relates to the fibre length
The attenuation of fibre splicing point is
generally less than 0.2dB
Other factors may cause attenuation, such
as fibre bending
About 0.35 dB per km
for 1310,1490nm
30 dB
15 dB
Class C
NOTE – The requirements of a particular class may be more
stringent for one system type than for another, e.g. the class C
attenuation range is inherently more stringent for TCM systems
due to the use of a 1:2 splitter/combiner at each side of the
ODN, each having a loss of about 3 dB.
28 dB
25 dB
20 dB
Maximum loss
13 dB
10 dB
5 dB
Minimum loss
Class
B＋
＋
＋
＋
Class B
Class A
Table G.984.2 – Classes for optical path loss
Huawei’s OLT and ONU
28 dB (Class B+)

-8
dBm
Minimum overload
-27
dBm
Minimum sensitivity
+5
dBm
Mean launched power MAX
0.5
dBm
Mean launched power MIN
ONU
ONU:
-8
dBm
Minimum overload
-28
dBm
Minimum sensitivity
+5
dBm
Mean launched power MAX
+1.5
dBm
Mean launched power MIN
OLT
OLT:
Single fibre
Unit
Items
Parameters of GPON (Class B+)

Contents

Control and Management Plane
M u l t i p l e x i n g b a s e d o n f r a m e l o c a t i o n
P L O A M
p a r t i t i o n
A T M p a r t i t i o n G E M p a r t i t i o n
F r a m e
h e a d e r
A l l o c - I D
f i l t e r
A l l o c -I D
f i l t e r
E m b e d d e d
O A M
A T M T C a d a p t e r G E M T C a d a p t e r
V P I / V C I
f i l t e r
P o r t - I D
f i l t e r
O M C I a d a p t e r
O M C I
P L O A M
G T C F r a m i n g s u b - l a y e r
T C A d a p t a t i o n s u b - l a y e r
- B W G r a n t i n g
- K e y S w i t c h i n g
- D B A

GPON Management
OAM message at the physical layer falls into three types:
embedded OAM, PLOAM and OMCI .
The embedded OAM and PLOAM channels manage the functions of the
PMD and the GTC layers. The OMCI provides a uniform system of
managing higher (service defining) layers.
The embedded OAM channel is provided by field-formatted information
(such as BW Map，DBRu) in the header of the GTC frame. The functions
that use this channel include: bandwidth granting, Dynamic Bandwidth
Assignment signalling and so on.
The OMCI channel is used to manage the service defining layers that lay
above the GTC.

GPON Service Provisioning
Carriers’ nightmare
Application scenario
Service Provisioning
NMS 2000
Access Network
Billing
1 Subscribe for services
2 Configure service network
3
Order Management
Start up ONT and make registration with serial number
ONT
ONT
ONT
ONT
CRM
User
Send terminals to users
1
2
Finish the auto-configuration of OLT
Initial configurations (such as service system information
configuration, data configuration) are required on
terminals and then they can be put into use. To finish
these configurations, it is not cost-effective to carriers.
GPON supports zero configuration on
terminals and plug-and-play of terminals,
which is cost-effective.
Flexible Configuration plan of GPON
STB
3
Use OMCI to finishing data
configuration on ONT

Contents
3. Analysis of GPON Standards

BRAS
AAA Server
IP Core
ASP/ISP
CPE
MSE
Ethernet
OLT
Softswitch
Internet
VoD Server
Middle
ware
NMS
TL1/CORBA
/API
BB service platform
Carrier’s OSS
Notification
Triple Play Solution in GPON
IPTV
Phone
PC
SFU
Phone
PC
SBU
CPE
MDU
VDSL
NSP
IP
Voice
CBU
E1
FE
ODN
Splitter
Base station

Questions
GPON network architecture?
Describe DBA operation mode?
Describe GPON service provisioning?

Summary
In this presentation, we introduced GPON basic
concept ,architecture ,and principle.
We also discussed about GPON service provisioning and
application.

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