The document describes a case study of China's CNC Yangzhou using GPON (Gigabit PON) technology to build a broadband access network serving 21 towns. CNC selected FlexLight's Optimate GPON solution which uses an Optical Line Terminal (OLT) located at CNC's central offices and Optical Network Terminals (ONTs) located in customer premises in each town. The GPON network provides voice, data, and video services over a single fiber, lowering costs compared to deploying new fibers. After successful testing, CNC commercially deployed the FlexLight GPON system to provide services to 15 towns, with potential for future expansion. The modular GPON equipment met CNC's requirements for

1. Using GPON to Build A Broadband Access network
As Case Study from One of China’s Leading Service Providers
Rong Han, Vice President, CNC Yangzhou
Jianfei Ye, Manager of Network Department, CNC Yangzhou

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TABLE OF CONTENTS
1. BACKGROUND............................................................................................................. 3
2. EXISTING FIBER NETWORK AND DEMAND FOR TOWN ACCESS NETWORK ................ 3
3. PERFECT TECHNOLOGY TO ACCESS THE TOWNS — GPON .......................................... 4
4. VENDOR SELECTION – FLEXLIGHT’S OPTIMATE GPON SOLUTION ............................. 5
5. “REAL WORLD” LESSONS LEARNED FROM DEPLOYING GPON.................................... 8
6. CURRENT STATUS AND SUMMARY.............................................................................. 9

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Using GPON to Build A Broadband Access network.
As Case Study from One of China’s Leading Service Providers
Rong Han, Vice President, CNC Yangzhou
Jianfei Ye, Manager of Network Department, CNC Yangzhou
1. Background
Yangzhou CNC Broadband Networks Company is a next-generation service provider based
in Yangzhou, China, and is part of CNC China, the country’s second largest service provider.
CNC provides a full array of services to its customers through the provisioning of Fast
Broadband Internet Access, Professional Enterprise Telecom Services and Voice.
More and more end-users in China are demanding broadband access to the Internet with
demands on service quality. CNC Yangzhou competes with several service providers in the
area including China Telecom, and generally has less network infrastructure and fibers
deployed than this larger carrier. It therefore needs to provide cost-effective technologies
which can be deployed rapidly and reliably in order to win new business from competing
providers.
In CNC Yangzhou’s territory, there are many villages and towns served by the Yangzhou
municipal government. In each town, CNC wishes to build access networks to administrative
departments, schools, tax bureaus, tobacco bureaus and some business buildings.
In this case study, CNC outlines their requirements for a 21-town access network, and
their experience deploying a Gigabit PON (GPON) solution.
2. Existing Fiber network and demand for Town Access Network
The company’s network is based on a high-capacity, highly-reliable fiber Wide Area
Network (WAN) and broadband Metropolitan Area Network (MAN), with typically 355Mbps
international interfaces and a 40G backbone. Through this backbone infrastructure, CNC can
perfectly deal with the enormous information demands from its customers. To build their
access networks, CNC Yangzhou has traditionally deployed fiber and LAN technologies.
There are three main nodes in CNC Yangzou’s MAN, each using a CISCO 6500 series
router as the Internet convergence device. In addition, there is a CISCO 12000 series router
on the core node as the interface to the main CNC Internet backbone, CNCnet.
Among all the villages and towns in the area, 21 towns urgently need broadband access.
These towns are distributed largely in three different geographic directions with fibers from

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the core node. In the first stage of the project to provide network access to these towns,
CNC designed a network to provide coverage and also meet their service requirements.
3. Perfect technology to access the towns ———— GPON
CNC had two main choices in designing this new town access network for Yangzhou:
deploy more fibers, or find a new technology, which can transport the three types of services
with less fibers.
Since deploying new fibers requires additional capital investment and time, CNC
explored innovative ways to better utilize the existing fiber infrastructure while also reliably
providing services. During the equipment selection, CNC established the following guidelines
for technology and vendor selection:
Reliable and flexible network infrastructure
Be able to provision of a full breadth of present and future services. All
the requirements for services should be considered from the beginning, avoiding
repeated investment future services.
All the services should be provided with minimal initial investment.
Profitable service provisioning
Fully provide all kinds of CNC service, including traditional voice, value-added
services and intelligent services on the same access network.
Support new services in the future as required.
Cost performance
The design should consider OPEX costs, and not just CAPEX costs, in order to
reduce network maintenance cost year after year.
High Return on Capital Employed (ROCE) and a short ROI cycle is desirable.
Attention to future development
The solution should have good compliance with future technology.
All the devices should be modularized in the network, and easy to upgrade.
Stability and high performance
The networks should be stable with high performance.
All devices should be stable with very low failure rates

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4. Vendor Selection – FlexLight’s Optimate GPON Solution
After thorough testing of several equipment providers’ solutions, CNC selected the Gigabit
PON (ITU-T G.984.x) GPON Optimate platform from FlexLight Networks, Inc
(www.flexlight-networks.com ). Optimate is FlexLight’s economical Gigabit PON (GPON)
solution, which readily addresses CNC’s need for economical and reliable voice, data and video
access over a single fiber access facility. It offers the benefits of high-speed data over PON,
while guaranteeing the E1 Quality-of-Service CNC’s voice customers expect from TDM
services and private line tariffs.
CNC began testing FlexLight’s Optimate GPON solution in October 2003. In the testing,
CNC used Optimate to provision all network services in 2 towns and the system proved very
stable. Figure 1 is a typical topology of FlexLight’s GPON solution.
Figure 1: GPON Topology
The FlexLight Optimate platform provides a solution for connecting CNC’s Central Offices
(CO) with Customer Premises Equipment (CPE) located in residential and business buildings.
FlexLight’s Optimate system consists of the following main entities:
Optical Line Terminal (OLT) The OLT is located at the Central
Office(CO), interfacing CNC’s metropolitan access network’s (MAN)
broadband services. The main functionality of the OLT is to adapt the
incoming traffic (Voice and Data) from the metropolitan rings into
FlexLight’s GPON transport layer.
Optical Network Terminal (ONT) The ONT is located at the
customer premises. The main task of the ONT is to interface the
customer enterprise services (Legacy TDM services such as E1/T1 as

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well as data services such as Ethernet) and transport them over the
GPON optical network toward the OLT.
Management (FlexManage) FlexManage is the network
management system used to provision and manage the FlexLight GPON
network.
In February, 2004, CNC began to commercially deploy FlexLight’s GPON system to build
the town access network. CNC designed a network covering 21 towns, and in the first
implementation stage, installed a 15-town network. After two weeks of hard work by both
FlexLight and CNC engineers, CNC successfully provisioned all services provided to these 15
towns using FlexLight’s GPON access technology. Figure 2 depicts the topology of the full
service GPON access network provided by FlexLight Networks.
Figure 2 Full service access by GPON
FlexLight’s Optimate platform is modularized in its design, so CNC deployed all the
equipment in their minimal configuration to lower the initial capital costs of deployment. The
network can be upgraded as user-demand increases by adding additional ports / service cards
at nominal costs. In each town, CNC deployed an Optimate 1000NT (ONT) with 4 Fast
Ethernet (FE) ports and 4 E1 ports. In 2 of the main MAN nodes, CNC deployed an Optimate
2500LT (OLT) with 1 Gigabit Ethernet (GbE) interface module and 1 STM-1 module.

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Optimate 2500LT
The Optical Line Termination (OLT) located
at CNC’s Central Office is used to interface
with CNC’s metropolitan network broadband
services through the GbE and STM1 standard
interfaces. The OLT adapts the incoming
services from the metropolitan SDH and
Ethernet rings (both data and TDM) into the GPON-compliant transport layer for
transporting services to each town’s ONT.
The OLT performs the following downstream functions:
Adaptation of the incoming metropolitan-layer (METRO) services into GPON
encapsulated channels.
Transporting G.984 (GPON) mapped services toward the ONTs over the GPON fiber
network.
Execution of GPON transmission convergence functions such as framing, media
access control, and OAM.
And the following upstream functions:
Interface of the GPON optical distribution network
Recovery of customer services encapsulated using the G.984 protocol
Grooming and aggregation of customers services into SONET/SDH and GbE
interfaces output to the METRO network.
Optimate1000NT
The Optimate 1000-NT (ONT) is an
optical customer premise equipment
(CPE) platform, with a gigabit capacity,
which supports the transport of various
customer services, such as Ethernet (10/100 BaseT) and TDM (Native E1/T1) over a
passive optical network. The 1000-NT is a 1U device that has three user selectable
service slots. It converts the GPON protocol back to standard interface services, while
providing scalability and flexibility in terms of bandwidth and service types.
The ONT performs the following downstream functions:

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Interfacing the GPON fiber network at 2.488 Gb/s.
Extraction of customer services from the incoming GPON signal.
Driving the customer’s Data and TDM interfaces on their CPE.
And the following upstream functions:
Adaptation of the user services into the GPON transport protocol.
Generation of bursty, 1.244 Gb/s, optical signal toward the OLT, based on media
access control commands from the OLT.
5. “Real World” Lessons Learned From Deploying GPON
During several months’ of “real-world” deployment of GPON, CNC further validated that
GPON is the best solution for access network. Compared to other technologies readily
available in the market,, it has absolute advantages:
GPON can bring all types of services from the end users to the MAN.
CNC therefore does not need to buy different dedicated equipment for voice, data
and even for video. GPON can provision all services in their native formats
from customer premise to MAN.
GPON is cost-effective (CAPEX and OPEX) due to its effective fiber usage.
GPON is a point to multi-point topology, with stronger access capability than
competing point-to-point topologies, which saves CNC a large amount of
fibers. In CNC’s solution, FlexLight’s GPON only uses 1 fiber to each of the 3
geographic directions from the CO to the various towns. For example, the town
Shatou is located at the center of 5 other towns. With FlexLight’s GPON solution,
CNC used only a single 20km fiber from the Cental Office (CO) to Shatou, and
deployed a passive fiber splitter at Shatou to run short fibers from that split point
to these 5 towns. This saved on the upfront capital costs by allowing the existing
fiber infrastructure to be used to service five additional customers instead of CNC
needing to deploy additional fiber at additional capital and time costs. It further
will save CNC ongoing Operational costs due to the fact that GPON’s passive
network requires no outside plant power or ongoing maintenance versus
competing “active” technologies.
Running a single GPON system is easier and more cost-effective for CNC
than running three different networks for voice, data and video. GPON
makes it possible to have all services managed in one network management
system with one core group of OAM&P methodologies. Having a single network

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platform for all services, instead of having a dedicated and discrete voice platform,
data platform, etc., reduces the maintenance effort and costs for CNC by having
one platform to support and maintain.
The network can be built with minimal up-front capital investment and
be expanded for future services as needed. FlexLight’s GPON can be built
step-by-step in a “pay-as-build” mode. In this starting stage, CNC received all the
services provided with the minimal investment, while guaranteeing an upgrade
path.
6. Current status and summary
As soon as the GPON town network was completed, CNC began to provide various
services on it, including legacy voice, NGN voice, DDN line and Ethernet. CNC’s users on this
network today include the Cable TV department, town government, schools, tobacco bureau,
tax bureau, banks and other business organizations in every town.
The current network topology, showing all towns, fiber runs and GPON splitter locations is
shown in figure 3.
Figure 3 CNC Yangzhou Current Deployment
FlexLight’s Optimate GPON solution provided CNC a full solution to carry the array of
network services provided by CNC Yangzhou, and allowed CNC to stay in front of the
competition by reliably and economically providing services to their customers.