Fttx Guide

7/31/2019 Fttx Guide

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FTTx/PON Resources GuideDeploying and Maintaining Reliable, Low Cost Network Services


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Introduction

Table of Contents

Abstract.....................................................................................................................................................

References.................................................................................................................................................

Advantages of FTTx and PON.....................................................................................................................................

Components of a PON System....................................................................................................................................

PON Installation...................................................................................................................................................

PON Specifications............................................................................................................................................

PON Measurement Parameters...................................................................................................................................

PON Troubleshooting..................................................................................................................................................

Selecting the Right Testing Instrument........................................................................................................................

Conclusion...................................................................................................................................................................

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Abstract

Testing fiber-to-the-X (FTTx) networks that include passive optical network (PON) architectures presents unique challenges to

service providers. During installation, the network must meet certain standards parameters. Once the FTTx network is

deployed, each subscriber connection requires additional tests to ensure service quality. Maintaining the operation of the PON

network and troubleshooting potential problems also requires specialized testing procedures and equipment. Anritsu offers a

complete line of FTTx and PON test equipment to ensure your networks will perform at their highest levels. The MT9083 Series

OTDRs are high performance, all-in-one testing tools to ensure the quality of your optical fibers including PONs featuring up

to a 1x128 split. The MT9090A with MU909011A Fault Locator module is the first tester

designed specifically for short fiber such as drop cables.


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Mobile/WirelessReferences

B-PON

For more information on ongoing PON Recommendation activities, including Gigabit-PON (G-PON), please check the ITU-T

Study Group 15 website at: www.itu.int/ITU-T/com15

G.983.1 Broadband optical access systems based on Passive Optical Networks

Specifies an optical access system with symmetrical line rates of 155.520 or 622.080 Mbit/s and asymmetrical line rates of155.520Mbit/s upstream and 622.080 Mbit/s downstream.

G.983.2 ONT management and control interface specification for B-PON

Specifies requirements for the OMCI, managed entities of a protocol-independent Management Information Base and

protocol/detailed messages for the ONT management and control channel.

G.983.3 A broadband optical access system with increased service capability by wavelength allocation

Adds an additional wavelength band to a G.983.1 B-PON to enable the distribution of unidirectional or bidirectional video

broadcast or data services.

G.983.4 A broadband optical access system with increased service capability using dynamic bandwidth assignment

Specifies the enhancements to a G.983.1 B-PON to allow the use of dynamic bandwidth assignment.

G.983.5 A broadband optical access system with enhanced survivability

Specifies protection features for a G.983.1 B-PON.

G.983.6 ONT management and control interface specifications for B-PON system with protection features

Specifies the OMCI for a B-PON system with protection features.

G.983.7 ONT management and control interface specification for dynamic bandwidth assignment (DBA) B-PON

system

Specifies the OMCI for a B-PON system using dynamic bandwidth assignment.

G-PON

For more information on ongoing G-PON Recommendation activities, please check the ITU-T Study Group 15 website at:www.itu.int/ITU-T/com15

G.984.1, Gigabit-capable Passive Optical Networks (G-PON): General characteristics

This Recommendation provides examples of services, User Network Interfaces (UNI) and Service Node Interfaces (SNI) that

are required by network operators. In addition, it shows the principal deployment configuration. Wherever possible, this

Recommendation maintains characteristics from the ITU-T G.982 and G.983.x series Recommendations in order to promote

backward compatibility with existing Optical Distribution Networks (ODN) that comply with these Recommendations.

G.984.2, Gigabit-capable Passive Optical Networks (G-PON): Physical Media Dependent (PMD) layer specification

This Recommendation specifies the physical layer requirements and specifications for the Physical Media Dependent (PMD)

layer. It covers systems with nominal line rates of 1244.160 Mbit/s and 2488.320 Mbit/s in the downstream direction and

155.520 Mbit/s, 622.080 Mbit/s, 1244.160 Mbit/s and 2488.320 Mbit/s in the upstream direction. Both symmetrical andasymmetrical (upstream / downstream) Gigabit-capable Passive Optical Network (G-PON) systems are described.

G.984.3, Gigabit-capable Passive Optical Networks (G-PON): Transmission Convergence Layer Specification

This Recommendation specifies the frame format, media access control method, ranging method, OAM functionality and

security in GPON networks.


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Advantages

| FTTx/PON Resource Guide

Advantage of FTTx and PON

Service providers are running optical fiber much deeper into the access network in order to deliver higher bandwidth that

makes it possible to offer multiple high performance voice, video and data services to customers. The diffusion of fiber into

the access network is often called the Fiber-to-the-X (FTTx) network. There are two basic types of FTTx architectures. In a

point to point (P2P) network, laser transmitters in the central office (CO) are dedicated to individual users. A more popularalternative, because of its high performance to price ratio, is a passive optical network (PON) in which the transmitters are

shared among multiple users.

FTTx and PON

FTTx networks are designed to deliver high performance Triple Play services to users by bringing fiber directly to or near the

customer premises.

FTTx Acronyms

FTTH - fiber to the home

FTTP - fiber to the premise

FTTU - fiber to the user

FTTC - fiber to the curb/cabinet

FTTB - fiber to the business

FTTN - fiber to the node

The PON architecture is commonly used for FTTx networks because it employs optical splitters to deliver signals to multiple

users without conversion or intervention. Unlike traditional networks where services are direct point-to-point links between

customer and provider, PONs share a common distribution segment before being split to several users, therefore reducing

installation costs. FTTx networks feature active and passive components. The OLT and ONT segments are active while the

PON, as the name states, is passive.

PONs enable service providers to provide virtually unlimited bandwidth for applications such as high definition television

(HDTV), video on demand (VOD), streaming video, gaming and peer-to-peer (P2P) file sharing that require large amounts of

bandwidth. PON equipment costs have dropped to the point where they are competitive with copper networks and new

products such as bend-resistant fibers and easier-to-use cable management systems have simplified PON installation. With

each 1080 pixel HDTV channel requiring up to 6 megabytes, triple play services typically require about 20 MB per home, just

about the limit of what can be provided with copper but well within fiber's capabilities.

Figure 1: Types of FTTx


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Components

The termination equipment for a PON system in the central office (CO) is called the Optical Line Termination (OLT) which

multiplexes voice and video for downstream transmission to the splitter. The OLT uses a traditional card and chassis

architecture, housing the laser transmitters that are shared among the users. The OLT combines the signals into a single fiber

at the CO using WDM techniques. A fiber distribution frame (FDF) at the CO integrates a number of OLTs together with splicing

trays and connectors that connect the OLT to the backbone network.

Components of a PON System

The distribution cable terminates at the OLT and runs to the pad or pole mounted fiber distribution hub (FDH) which houses

the optical splitter. The splitter is a passive component that requires no maintenance and no power but has a high relatively

high insertion loss, typically 15 dB for 32 port splitter. The FDH typically accommodates up to 10 splitters each of which typically

has up to 32 branches.

Applications where the fiber runs all the way to the customer premise normally use a distribution cable running from the FDH

to the Fiber Distribution Pedestal (FDP) which serves as a splice or connection point close to the customer premises and

contains fiber management. A drop cable with a typical length of several hundred feet runs from the FDP to the ONT in the

customer premises.

The ONT splits the signal into the voice, video and data services used by the customer. The ONT uses various interfaces

including RJ-11 twisted pair jacks for voice service, RJ-45 Ethernet jacks for high speed data and 75 ohm coaxial ports for video

service.

In applications in which the fiber terminates prior to the CP and then converts to some other transmission medium, the

distribution cable runs from the FDH and terminates at an Optical Network Unit (ONU) located at the curb (Fiber to the Curb

(FTTC)) or cabinet (Fiber-to-the-Cabinet or FTTCab). In some cases, the distribution cable is deployed to the customerpremises. In other cases, the drop cable runs all the way from the FDH to the customer premises.

Components of a PON System

Figure 2: Possible PON Architectures


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Components


Figure 3; Typical PON Layout with a Video Overlay

PON Installation

Typically PONs are installed in two segments by two different groups with different testing requirements. The first phase is the

installation of the feeder cable from the CO to the FDH or FDP and the distribution cable to the FDP. This segment is typically

installed by a contractor and is certified after installation by measuring the total loss and evaluating splices and connectors. This

segment requires a PON capable optical time domain reflectometers (OTDR) with high dynamic range and the ability to test

multiple wavelengths and provide detailed reporting needed for certification.

The second last mile segment runs from the FDH or FDP to the ONT. Testing during installation and maintenance typically

requires a fault location, connectivity check and isolation. The highly capable instruments used to certify the feeder cable arenot required for testing this segment and so it is possible to use a less expensive and more user-friendly drop cable fault locator.

Figure 4: Possible PON Architecture


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Specifications

The International Telecommunications Union Standardization Sector (ITU-T) has created several standards for optical access

systems based on the PON architecture. Broadband PON (BPON) uses Asynchronous Transfer Mode (ATM) cells for

transmission to a maximum of 32 customers and has a maximum access speed of 155 Mbps upstream and 622 Mb/sdownstream. Gigabit PON (GPON) was later developed to increase access speed to 1.2 Gbps downstream and 622 Mbps

upstream, making it possible to serve a maximum of 128 customers. The Ethernet PON (EPON) standard uses standard 802.3

frames with symmetric 1 Gbps upstream and downstream rates. Since EPON is active Ethernet based it uses a powered switch

in the outside plant and dedicated switches and fiber runs. Advantages of EPON include the fact that no encryption is needed

since lines aren't shared and that bandwidth can be easily changed. On the other hand, EPON is more expensive due to switch

power costs and dedicated fibers. DPON is a DOCSIS standard based for multiple system operators (MSOs) that allows use of

the current head-end and customer premises equipment.

The Typical Network Planning Specifications for a PON System

Video transmission downstream from the CO OLT to the premise ONT is 1550nm at 622Mbits/sec (BPON) or 1.2Gbits/sec

(GPON).

Voice/data and IP Video (if used) transmission downstream from the CO OLT to the premise is 1490nm at 622Mbits/sec

(BPON) or 1.2Gbits/sec (GPON).

Transmission upstream from the premise ONT to the CO OLT is 1310nm at 155Mbits/sec (BPON) or 622Mbits/sec (GPON).

Most PONs today are using an ATM protocol with access to bandwidth using time division multiple access (TDMA) upstream

and, TDM downstream. IP and Gigabit Ethernet based PON systems are also beginning to see widespread deployment.

Total End-to-End Optical Budget

25 dB for a Class B PON Network

30 dB for a Class C PON Network

PONs present major testing challenges, largely because the presence of the relatively high-loss optical splitter means that

testing from the CO does not provide a dedicated optical path as with traditional point-to-point fiber networks. The PON is

shared by multiple customers so the situation frequently exists where one or a few customers are down while the rest are still

operating. This makes troubleshooting more difficult to perform because it must be done without disrupting service to the

customers that are up and running. Another complicating factor is that 1490 nm and 1550 nm transmissions are both possiblein the downstream transmission while 1310 nm upstream transmissions are not present unless the downstream transmission is

there to stimulate it.

PON Specifications

Figure 5: PON Architecture (BPON)

Maximum End-to-End Length

20 km determined by the 1310 nm optical budget

25 dB - 12 dB splitter = 13 dB

13 dB - 6 dB (connector and splice loss) = 7 dB

7 dB / 0.35 dB/km (1310 nm fiber loss) = 20 km

7 dB / 0.20 dB/km (1550 nm fiber loss) = 35 km


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PON Measurements Parameters

Optical return loss (ORL) should be measured between the termination fibers located at the customer premise (ONT or ONU)

and the CO (OLT) after the entire network is completed from end to end but before connection to any termination equipment.

Typical ORL specifications values are +30 dB to +35 dB.

In deploying new connections to a live PON system, verify optical power at 1550 and 1490 nm and splice the assigned drop

cables to their respective coupler outputs. At the customer premises, test for live PON receiver power with an optical power

meter at the 1550 nm setting with a 1550 nm pass filter. If the optical power meets the approved -28 dBm level, connect the

ONT. A green light will confirm OLT and ONT communication and equipment operation can be verified.


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Troubleshooting


PON Troubleshooting

If all customers connected to a PON system are out of service, testing can proceed at the CO without danger of interfering

with existing service. System diagnostics will usually detect a problem with the OLT and the solution is normally a line-card

replacement. The OLT manager will usually identify a broken fiber on the main leg as all branches associated with the OLT will

become nonresponsive. Troubleshooting can then proceed with an OTDR or a simpler break indicator.

Figure 6 outlines a methodology for troubleshooting PON networks in the more difficult situation where one or some

customers connected to the PON are out of service. When a fault occurs in the subscriber's FTTH service, if other subscribers

sharing the OLT are not experiencing the same fault, then the problem is either in the drop cable between the FDH and the

ONU/ONT, in the ONU/ONT or in the subscriber's home network. The technician should begin by disconnecting the optical

fiber from the ONU/ONT and checking the optical signal level with a power meter.

If no power is measured on the drop cable, the chances are that the problem is either a break in the fiber or a high loss event

such as a bad splice. Since no power is being received at this ONT location, there is no danger of interfering with traffic on

the PON when testing the fiber using an OTDR. But to be safe it's a good idea to troubleshoot with an OTDR using the 1650

nm wavelength to avoid interfering with the ONT in the event of a mistake.

If the optical power level is lower than the specification, there is a good chance that there is a break or damage in the drop

cable. Maintenance of a PON drop cable requires care when the rest of the network is still in service. One approach is to isolate

the drop cable under test from the rest of the network but this is not easy because the connections are often high on utility

poles and wires, and disconnecting fiber splices is difficult. The solution is to use a short wavelength OTDR such as the Anritsu

MT9090A or MT9083 series with test pulses at a wavelength of 780 nm. Testing from the subscriber's side at 780 nm has no

effect at all on the in-service customers. The dynamic range at 780 nm is 8 dB so faults in a 2 km or shorter drop cable can be

accurately pinpointed.

If the power is OK, then test down the stream from the coupler with an OTDR and bare fiber adapter to pinpoint the

attenuation.

Figure 6: PON Troubleshooting Overview


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Selection

Selecting the Right Testing Instruments

An OTDR is the universal tool used to pinpoint faults and certify the workmanship in a fiber installation. OTDRs find and char-acterize both reflective and nonreflective events in optical fiber runs by sending laser pulses of different widths. There are two

main parameters that measure the performance of an OTDR. The dynamic range determines the length of fiber link that theOTDR can test - higher values enable testing longer lengths. The event dead zone is the minimum distance of separation be-tween two different optical reflective events that the OTDR can resolve - shorter values enable resolving more closely spacedevents. Dynamic range and event dead zone both increase with longer pulse widths so tuning the OTDR normally requires atradeoff between these two parameters.

Not all OTDRs are capable of testing splitter based PONs. To perform well in measuring and certifying PONs, OTDRs need a

small dead zone to allow measurement of near end connectors within the CO in riser cables and at the customer premises.

They also need a high dynamic range in order to measure the high losses that are typically involved in PONs. Figure 7 compares

the measurements provided by a conventional OTDR (blue) and the Anritsu MT9083, a PON capable OTDR (red). The splitter

is easily identified by the large losses at 2.5 km and 2.7 km. The conventional OTDR lacks dynamic range, resulting in a large

amount of noise at distances greater than the splitter and making it impossible to accurately test through the splitter. On the

other hand, the MT9083 OTDR has no difficulty in testing through the splitter.

After initial construction of a PON system it is necessary to accurately and completely characterize the fiber link from the OLT

to the FDH and, most important, to measure loss and ORL. A PON-capable OTDR such as the MT9083 makes this task easier

through its ability to distinguish between the loss properties of the individual PON branches, making it possible to test the

feeder cable from the ONT end.

Figure 7: Traces from traditional PON capable OTDRs

Figure 8: MT9083 offers excellent resolution


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Selection

12 | FTTx/PON Resource Guide

Selecting the right testing instruments

A dual mode design enables the MT9083 OTDR series to offer excellent dynamic range and dead zone resolution. The user

can simply select high resolution or enhanced range mode based on the task at hand. When HR mode is selected, the

MT9083 series provides good measurement range with an industry leading deadzone of less than 1 meter. When ER mode is

selected, the MT9083 provides unparalleled performance for measurement distance, measurement speed and deadzone. The

MT9083B and MT9083C provide up to 45 dB dynamic range, providing a measurement range of over 200 km and making it

possible to test a 100 km fiber in less than 10 seconds. The combination of a high dynamic range with a short pulse makes it

possible to test the entire fiber path through the splitter. Splitters up to a single 1x128 or closely spaced, cascaded splitters are

completely and accurately measured with industry leading resolution. The MT9083 series also offers a full SCPI command

support for remote operations or automated testing. Traditional tools have not provided the right solution for the technicianscharged with maintaining and troubleshooting local access networks. Handheld OTDRs and Fault Locators lack the resolution

needed for short drop cable spans while mini-OTDRs were too large, too expensive and too complicated. The new MT9090A

from Anritsu finally addresses this need by providing all of the features and performance required for installation and

maintenance of short fibers in a compact, modular test set. Realizing that short fiber premise applications such as FTTx drop

cables, intra-building riser cables and cell towers have different testing requirements, Anritsu designed the MT9090A from the

ground up. It features 5 cm resolution for accurate mapping of events, deadzones of less than 1 meter (3 feet) and a built-in

10 m (30 ft) launch fiber to ensure everything is evaluated. Since multiple users share the common feed fiber, FTTx maintenance

becomes difficult when only one or two users are down. To address this need, Anritsu also offers a 780 nm Fault Locator module

that can be used to troubleshoot in-service FTTx networks without costly filters and without disruption to other customers.

MT9083 Series MT9090A/MU909011A Fault Locator


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Conclusion

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FTTx networks with PON architectures provide the opportunity to deliver dramatic increases in bandwidth. Service providers

are using this bandwidth to deliver new value-added services such as HDTV, VOD and gaming to customers. But the

deployment and maintenance of PON architectures presents some significant challenges to service providers. For example, the

presence of the splitter complicates testing because there is no longer a dedicated optical path from CO to the customer.

Installation of a PON requires carefully measuring key performance parameters against network specifications. Once the FTTP

network is deployed, each subscriber connection requires additional tests to ensure service quality. Overcoming testing

challenges is critical to delivering high-performance and reliable service to customers at a low cost. The correct test equipment

and knowledge can quickly result in a trouble-free FTTx network. Anritsu offers the expertise and the optimized FTTx test

equipment to meet these challenges.


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Anritsu Corporation5-1-1 Onna, Atsugi-shi, Kanagawa, 243-8555 JapanPhone: +81- 46-223- 1111Fax: +81-46-296-1238

U.S.A.

Anritsu Company1155 East Collins Blvd., Suite 100, Richardson,TX 75081, U.S.A.Toll Free: 1-800-267-4878Phone: +1-972-644-1777Fax: +1-972-671-1877

CanadaAnritsu Electronics Ltd.700 Silver Seven Road, Suite 120, Kanata,Ontario K2V 1C3, CanadaPhone: +1-613-591-2003Fax: +1-613-591-1006

BrazilAnritsu Eletrnica Ltda.Praca Amadeu Amaral, 27 - 1 Andar01327-010-Paraiso-So Paulo-BrazilPhone: +55-11-3283-2511Fax: +55-11-3288-6940

Mexico

Anritsu Company, S.A. de C.V.Av. Ejrcit o Nacional No. 579 Piso 9, Col . Granada11520 Mxico, D.F., MxicoPhone: +52-55-1101-2370Fax: +52-55-5254-3147

U.K.Anritsu EMEA Ltd.200 Capability Green, Luton, Bedfordshire, LU1 3LU, U.K.Phone: +44-1582-433200Fax: +44-1582-731303

FranceAnritsu S.A.16/18 avenue du Qubec-SILIC 72091961 COURTABOEUF CEDEX, FrancePhone: +33-1- 60-92-15-50Fax: +33-1-64-46-10-65

GermanyAnritsu GmbH

Nemetschek Haus, Konrad-Zuse-Platz 181829 Mnchen, GermanyPhone: +49-89-442308-0Fax: +49-89-442308-55

ItalyAnritsu S.p.A.Via Elio Vittorini 129, 00144 Roma, ItalyPhone: +39-6-509-9711Fax: +39-6-502-2425

Sweden

Anritsu ABBorgafjordsgatan 13, 164 40 KISTA, SwedenPhone: +46-8-534-707-00Fax: +46-8-534-707-30

FinlandAnritsu ABTeknobulevardi 3-5, FI-01530 VANTAA, FinlandPhone: +358-20-741-8100Fax: +358- 20-741-8111

DenmarkAnritsu A/SKirkebjerg All 90, DK-2605 Brndby, DenmarkPhone: +45- 72112200Fax: +45- 72112210

SpainAnritsu EMEA Ltd.Oficina de Representacin en EspaaEdificio Veganova

Avda de la Vega, n 1 (edf 8, pl 1, of 8)28108 ALCOBENDAS - Madrid, SpainPhone: +34-914905761Fax: +34-914905762

RussiaAnritsu EMEA Ltd.Representation Office in RussiaTverskaya str. 16/2, bld. 1, 7th floor.Russia, 125009, MoscowPhone: +7-495-363-1694Fax: +7-495-935-8962

United Arab EmiratesAnritsu EMEA Ltd.Dubai Liaison OfficeP O Box 500413 - Dubai Internet City

Al Thuraya Building, Tower 1, Suit 701, 7th FloorDubai, United Arab EmiratesPhone: +971-4-3670352Fax: +971-4-3688460

SingaporeAnritsu Pte. Ltd.60 Alexandra Terrace, #02-08, The Comtech (Lobby A)Singapore 118502Phone: +65-6282-2400Fax: +65-6282-2533

IndiaAnritsu Pte. Ltd.

India Branch Office3rd Floor, Shri Lakshminarayan Niwas, #2726, 80 ft Road,HAL 3rd Stage, Bangalore - 560 075, IndiaPhone: +91-80-4058-1300Fax: +91-80-4058-1301

P.R. China (Hong Kong)Anritsu Company Ltd.Units 4 & 5, 28th Floor, Greenfield Tower, Concordia Plaza,No. 1 Science Museum Road, Tsim Sha Tsui East,Kowloon, Hong KongPhone: +852-2301-4980Fax: +852-2301-3545

P.R. China (Beijing)Anritsu Company Ltd.Beijing Representative OfficeRoom 2008, Beijing Fortune Building,No. 5, Dong-San-Huan Bei Road,

Chao-Yang District, Beijing 100004, P.R. ChinaPhone: +86-10-6590-9230Fax: +86-10-6590-9235

KoreaAnritsu Corporation, Ltd.8F Hyunjuk Building, 832-41, Yeoksam Dong,Kangnam-ku, Seoul, 135-080, KoreaPhone: +82-2-553-6603Fax: +82-2-553-6604

AustraliaAnritsu Pty. Ltd.Unit 21/270 Ferntree Gully Road, Notting Hill,Victoria 3168, AustraliaPhone: +61-3-9558-8177Fax: +61-3-9558-8255

TaiwanAnritsu Company Inc.7F, No. 316, Sec. 1, Neihu Rd., Taipei 114, Taiwan

Phone: +886-2-8751-1816Fax: +886-2-8751-1817

Specifications are subject to change without notice.

Rev 1 0609

Please Contact:

Anritsu All trademarks are registered trademarks of their respective companies.Data subject to change without notice.For the latest specifications and products visit www.anritsu.com

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