May 2000

OKI Technical Review 182

Vol. 67

Special Issue on TELECOM99: UDC [621.395.74 : 681.7.068.2] : 681.324 (100)

ATM-PON
Kiyoshi YOKOTA*, Kazuho KAWAGUCHI*, Shinya IKO**, Noboru YAMAMICHI**, Ryuji TANAKA** Abstract We developed an ATM-PON (Passive Optical Network) system that complies with new international standards such as ITU-T/FSAN and can develop globally. The ATM-PON system is an optical access system that can provide to the user flexible service such as everything from low-speed to high-speed access and various QoS guarantees at low cost.

1.

Introduction

2.

System Overview

As Internet usage such as sending/receiving electronic mail and browsing home pages progresses, data communications are no longer limited to business applications and quickly expand into the home as well. On the other hand, the access lines that provide users with a method of accessing services has been diversifying recently. Highspeed data communications service by ADSL (Asymmetric Digital Subscriber Line) that uses metal wires, voice/data communications services that use CATV networks, and Internet access services that use wireless devices such as portable telephones have given users a wider range of choices to meet their needs. Employing PON (Passive Optical Network) technology in FTTH (Fiber to the Home), which is representative of the optical fiber service that is used in the above access systems, makes quality, high-speed broadband communications possible and also makes it possible to reduce costs. Using ATM (Asynchronous Transfer Mode) technology as well makes it possible to flexibly provide service such as various access rates from low-speed to high-speed, and a variety of QoS (Quality of Service) guarantees in order to meet the users needs. Access systems that utilize this ATM-PON technology, which combines ATM and PON technologies, will make it possible to provide faster service at lower cost in the near future. 1 Up until now, we have been developing an access system that uses this ATM-PON technology. 2 This system is compliant with FSAN (Full Service Access Network)/ITU-T, which is a world standard ATM access system technology, and can be globally developed. Adopting the newest traffic technology makes it possible for this system to provide an abundant service menu to the user. 3 In this article, we would like to describe the configuration and features of the ATM-OLT (Optical Line Terminal), ATM-ONT (Optical Network Terminal) , and NE-OpS (Network Element Operation System) that comprise the ATM-PON system.
* ** Team Leader, Multimedia Systems Department, 2nd Basic Network Division, Network System Business Group. Team Leader, Software Center, Network System Business Group.

2.1 Overview Figure 1 illustrates an overview of the ATM-PON system. The ATM-PON system consists of ATM-ONT, ATMOLT, and NE-OpS. 2.2 Support of international standards ATM-PON is based on the following standards. 1. ATM-PON realizes more economical access lines by employing an interface that is compliant with G.983.1 and G.983.2. 2. It also employs an interface that is compliant with G.967.1 and G.967.2 in the SNI (Service Node Interface) prescribed between the SNs (Service Nodes) and AN (Access Network). This makes it possible to efficiently distribute resources to the transfer lines shared with the SNs in real-time when SVC (Switched Virtual Channel) service is requested via UNI (User Network Interface). 3. It also employs a TMN standard Q3 interface as the upper-order OpS interface.

3.

ATM-PON System Configuration

3.1 ATM-OLT configuration and features ATM-OLT is an ATM access node device that accommodates a maximum of 32 highways (HW) for various inter-

NW-OpS Q3 NE-OpS Q3 UNI ONT OLT SNI SN

Figure 1: Configuration of ATM

ATM-PON

faces and a VP/VC (Virtual Path/Virtual Channel) connection process bandwidth of 4.8 Gbit/s with a single unit. The ATM-OLT hardware consists of an ATM core switch, a multiplex and demultiplex section, an interface section, a clock section, and a supervisory control section. The main signal section (ATM core switch, multiplex and demultiplex section, interface section) and common section (clock section, supervisory control section) are duplicated to enable highly reliable operation. Table 1 indicates the ATM-OLT specifications, and Figure 2 illustrates an overview of the ATM-OLT configuration. 1. ATM core switch section The ATM core switch is an output buffer type large capacity switch. Since it has sufficient capacity with respect to the ATM-OLT system capacity, cell transfer can be performed under favorable conditions even for operation that has a high burst traffic load rate. 2. Multiplex and Demultiplex Section The multiplex and demultiplex section flexibly accommodates the various types of interfaces that ATM-OLT supports, and converts (multiplexing/demultiplexing) to core switch connections format. It also has a buffer (queue) for various types of traffic control, and controls cell flow based on the ATC/QoS (ATM Transfer Capability/Quality of Service) of the connection. There are two types of traffic control buffers. First is the class queue, which controls the traffic of each class according to the ATC/QoS supported by ATM-OLT. The class queue gathers and accommodates connections of the same ATC/QoS class, then realizes quality of each ATC/QoS by outputting according to the bandwidth setting and priority which corresponds to that class. ATM-OLT has five class queue and since each one is equipped with sufficient buffer capacity for the estimated traffic, it is possible to securely support 5 types of ATC/QoS simultaneously. The other type of traffic control buffer is the VC queue, which is used to support GFR traffic. In the case of ATM-OLT, each GFR connection is accommodated in the VC queue, and GFR support is realized by reflecting the band usage status then reading each VC queue. 3. Interface section The interface section terminates transmission interfaces such as ATM-PON, SDH (Synchronous Digital Hierarchy), PDH (Plesiochronous Digital Hierarchy), performs the conversion into intra-device cell format, and performs ATM layer cell processing which are the OAM (Operation Administration and Maintenance) and UPC (Usage Parameter Control). By converting these interfaces into common intra-device interfaces, it is possible to accommodate each type of interface in any location. 4. Supervisory control section The supervisory control section consists of a processor section, a SIG (Signaling section), and a remote reset section. The processor section is a self-developed highspeed communications processor which manages de10

Items

Interface

ATM-PON Bandwidth ATC/QoS Equipment Practice

Specifications Interface Access lines: ATM-PON (FSAN/ITU-T G.983.1/G.983.2)/ Single-Star: (155.52 Mbit/s) Transfer lines: SDH (51.84/155.52/622.08 Mbit/s) PDH Number of accommodations: max. 32 Max. number of connections: 32ONT/Max. distance: 20 km 4.8 Gbit/s DBR[class1], DBR[class2], SBR, GFR, DBR[Uclass] Optical metric equipment practice. All optical connections are accessible from the front of the equipment. Table 1: Specifications of ATM-OLT

ATM-OLT ATMONT PON-IF ATM Core SW SDH IF Transfer line (50 M/ 150 M/ 600 M) Transfer line (45 M)
Cell demultiplexer Cell demultiplexer

ATM -NT

SS-IF SS-IF SS-IF

PDH IF

Clock section

Supervisory control section NE-OpS IF

CLK IF

Figure 2: Block diagram of ATM-OLT

vices, manages connections, and controls all ATM-OLT functions including NE-OpS interface. The SIG section terminates ATM cell communications (control sectionIF section communications, SNI communications, NEOpS communications) that are performed both intradevices and outside the devices. Using SNI functionality to realize SVC service and applying ATM cell communications for controlling devices are two features of ATMOLT. 5. Equipment Practice ATM-OLT is mounted in cabinets and units that apply the optical metric equipment practice 4. Taking economy and workability into account, a method was adopted in which optical fiber operation is accessed from the front panel of the cabinet. Photo 1 shows the appearance of the ATM-OLT device. 3.2 ATM-ONT configuration and features ATM-ONT is a device which accommodates two Line Cards for connecting user devices, accommodates one ATMPON access line, and connects user terminal equipment and ATM-OLT together. ATM-ONT consists of the core section, which performs ATM-PON interface processing and multiplex and demultiplex processing, the line card section, and the power supply section.

May 2000

OKI Technical Review 182

Vol. 67

Register/Eliminate devices (OLT, ONT), register/eliminate packages, forced switching, retrieve mounting status Set/Cancel Intra-office/Inter-office sections, forced switching, retrieve section configuration information and history information Set/Cancel PON sections, change ONT assignment band, retrieve PON section configuration information and history information Set/Cancel VP, switching VP, change route, set/change UPC/NPC parameters, retrieve VP configuration information and history information Set/Cancel VC, set/change UPC/NPC parameters, retrieve VC configuration information and history information

Configuration management

Section

PDS

Photo 1: Appearance of ATM-OLT

VP

VC

Table 2: Specifications of ATM-ONT

The core section has the following functions: ATMPON interface termination, cell multiplexing and demultiplexing, and two-class priority control. There are various Line Cards have multiple line cards that support UNI, so it is possible to choose the suitable one to use with the particular user equipment interface. Table 2 indicates the ATM-ONT specifications. 3.3 NE-OpS 1. NE-OpS configuration NE-OpS accommodates multiple ATM-OLT devices and ATM-ONT devices. It consists of a server for executing each managed function, an operation screen for maintenance personnel, an HMI (Human Machine Interface) terminal that provides notification display functionality, and information transfer networks (DCN: Data Communication Network) that connect servers and HMI terminals together. The DCN between NE-OpS and ATMOLT can make connections either using ATM in-channels or via an ISDN network. Usage of ATM in-channels is usually given priority, but by switching to ISDN network usage when there is a failure, it is possible to realize a DCN that is economical and highly reliable at the same time. 2. Operation functions From the viewpoint of management functions, operation functions are classified as configuration management functions, fault management functions, performance management functions, and system management functions. Table 3 indicates an overview of the NE-OpS management functions. OpS has HMI functionality for providing these functions to the operation. 3. Software architecture The operation functions prescribe specifications as operations (Create, Delete, Get, Set, Action) performed on modeled managed resources (devices, packages, sections, VP, VC, etc.) as managed objects (MO). It is therefore possible to realize processing using these combinations even for complex operations. Figure 3 illustrates the NE-

Alarm Inhibit/Cancel event notification at each supervising conditions supervision unit

Failure management

Failure switching Database matching Alarm matching

Report the automatic switching results Compare MIB contents between OPS/NE, forcibly release MIB contents between OPS/NE Cancel inconsistencies in the alarm status between OPS/NE

Test, VP/VC conduction test, VP/VC loopback test, OAM function VP/VC continuity test

Performance management

Performance Collect/Accumulate performance information, information retrieve performance information management

System Security DCN management, remotely transfer System managed management program files, back up database

Table 3: Managed functions

OpS software architecture in the system. NE-OpS realizes scenarios that are executed as sequential control of MOs analyzes requests made to the MOs, and realizes operation function by way of NE-agents that realize the behavior of each MO and NE resource management that controls resources inside the NE. 4. HMI The HMI terminal realizes graphic user interface operation screens to facilitate smooth maintenance work. These operation screens provide operators with unified operability in accordance to the MO level the operations are to be performed on.

4.

Conclusion

In this article, we described the ATM-PON system we developed. This system is compliant with the newest international standards and is expected to be widely applied both in Japan and abroad. It is also possible that other systems may be developed based on this system by expanding its functionality.
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ATM-PON

5.
1.

References
GUI terminal

2.

3. 4.

Ueda, Maekawa: Development of ATM Subscriber Accommodation System (Model C), NTT R&D, 48, 5, (1911): 22~27. Yokota, Yokochi, Kawaguchi, Yamamichi: ATM Optical Access System, Oki Denki Kenkyu Kaihatsu 179, 65, 3,(1998): 49~52. ITU-T Rec. G.983.1: Broadband optical access systems based on passive optical networks (PON), (1998). Tokunaga, et al: Development of Optically Metric Mounted Communications Devices, Oki Denki Kenkyu Kaihatsu Issue, 179, 65, 3,(1998): 203~206.

Screen process #1

Screen control

Screen process #n

Map management

OpS server Scenario group Scenario #1 Event management Scenario #n History information management MIB management

Q3 communications control NE(OLT) NE-agent MO MO MO MO

NE resource management

Figure 3: Software architecture of NE-OpS

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