ADC CRA-C User manual

Megabit Modem CRA-C

User Manual

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Manual Number: 425-613-150-02

ii Megabit Modem CRA-C User Manual

Megabit Modem CRA-C User Manual

P/N 425-613-150-02

Revision 02

May 1998

This document contains proprietary information which is protected by

copyright.

Information contained in this document is company private to PairGain

Technologies, Inc. and shall not be modified, used, copied, reproduced or

disclosed in whole or in part without the written consent of PairGain.

PairGain is a registered trademark, and Megabit Modem is a trademark of

PairGain Technologies, Inc.

Other product names mentioned in this manual are used for identification

purposes only and may be trademarks and/or registered trademarks of their

respective companies.

The information in this publication is believed to be accurate in all respects.

However, PairGain Technologies cannot assume responsibility for any

consequences resulting from the use thereof. The information contained herein

is subject to change. Revision to this publication or new additions to it may be

issued to incorporate such changes.

Megabit Modem CRA-C User Manual iii

FCC NOTICE

This equipment has been tested and found to comply with the limits for a

Class B digital device, pursuant to Part 15 of the FCC Rules. These limits are

designed to provide reasonable protection against harmful interference when

the equipment is operated in a commercial environment. This equipment

generates, uses, and can radiate radio frequency energy and, if not installed and

used in accordance with this instruction manual, may cause harmful

interference to radio communication.

However, there is no guarantee that interference will not occur in a particular

installation. If this equipment does cause harmful interference to radio or

television reception, which can be determined by turning the equipment off

and on, the user is encouraged to try to correct the interference by one or more

of the following measures:

•

Reorient or relocate the receiving antenna.

•

Increase the separation between the equipment and receiver.

•

Connect the equipment into an outlet on a circuit different from that

to which the receiver is connected.

•

Consult the dealer or an experienced radio/TV technician for help.

Any changes or modifications not expressly

approved by the grantee of this device voids

the user’s authority to operate the equipment.

iv Megabit Modem CRA-C User Manual

DECLARATION OF CONFORMITY

Manufacturer’s name

PairGain Technologies, Inc.

and address:

14402 Franklin Ave

Tustin, CA 92780-7013

U.S.A.

declares that

Product name:

Megabit Modem CRA-C

conforms to the following

Standards:

EN55022 (1987), EN50082-1 (1992),

EN60950 (1994)

Application of Council Directives:

89/336/EEC, 73/23/EEC

I, the undersigned, hereby declare that the equipment specfied above conforms

to the above directives and standards.

Signature:

Roy Stephens,

Director of Quality Assurance

Place:

Tustin, CA, U.S.A.

Date:

March 16, 1998

Megabit Modem CRA-C User Manual v

USING THIS MANUAL

This manual helps you:

•

understand the features of the PairGain

®

Megabit Modem™ CRA-C

and how the unit operates as a component within a network

•

install the Megabit Modem CRA-C

•

configure your unit to operate within the network

•

contact PairGain if you need additional help

Three types of messages with icons appear in the text:

Notes inform you of special circumstances.

Cautions indicate the possibility of damage to equipment.

Warnings indicate the possibility of personal injury.

Using This Manual

vi Megabit Modem CRA-C User Manual

Megabit Modem CRA-C User Manual vii

CONTENTS

ABOUT THE MEGABIT MODEM CRA-C __________________ 1

About Rate Adaptive Transmission.....................................2

Rate Adaptation.............................................................. 2

Reach, Data Rate, SNR Margin,

and Noise Environment............................................ 4

INSTALL THE MEGABIT MODEM CRA-C_________________ 7

Unpack and Inspect the Shipment.......................................7

Identify LEDs and Connectors............................................ 9

Front Panel..................................................................... 9

Rear Panel.................................................................... 11

Install the Megabit Modem CRA-C ..................................12

Connect to the ADSL Line ...........................................12

Connect to the Data Network........................................ 13

Power Up and Check LEDs ..............................................16

CONFIGURE AND VIEW STATUS________________________ 17

Connect to an ASCII Terminal.......................................... 17

How to Log On and Navigate the Menus .......................... 19

How to Configure a Remote Unit...................................... 23

Configure System Settings................................................ 24

Configure ADSL Transceiver ...........................................26

Configuration ...............................................................26

Reset ADSL Transceiver .............................................. 29

Configure the Bridge/Router............................................. 30

Configure as a Bridge................................................... 31

Configure as a Router................................................... 34

Configure SNMP.......................................................... 38

Reset the Ethernet Bridge............................................. 40

View Status ......................................................................41

System Information ...................................................... 41

ADSL Transceiver Status.............................................. 42

Ethernet Bridge Statistics.............................................. 48

Log Out............................................................................ 49

Contents

viii Megabit Modem CRA-C User Manual

NETWORK AND MANAGEMENT OVERVIEW____________ 51

MAC Layer Bridging and Spanning Tree Protocol............51

Static IP Routing...............................................................53

Megabit Modem CRA-C IP Addresses..........................59

Management Protocols......................................................61

SNMP...........................................................................61

Megabit Modem CRA-C SNMP Agent .........................62

MIB and Trap Support..................................................63

Network Configuration and Image Code Download ..........64

BOOTP.........................................................................64

TFTP ............................................................................66

Encapsulation Protocols....................................................66

TECHNICAL SPECIFICATIONS _________________________ 67

TECHNICAL ASSISTANCE______________________________ 69

World-Wide Web..............................................................69

FTP ..............................................................................69

LIMITED WARRANTY _________________________________ 71

GLOSSARY____________________________________________ 73

Megabit Modem CRA-C User Manual 1

ABOUT THE MEGABIT MODEM CRA-C

The PairGain

®

Megabit Modem™ CRA-C uses Asymmetric Digital

Subscriber Line (ADSL) technology to provide, on a single pair telephone line,

a multi-megabit Ethernet connection between the subscriber and the service

provider. The Megabit Modem CRA-C transmits data up to 3.16 Mbps from a

service provider and receives data up to 1.08 Mbps from a subscriber. The

Megabit Modem CRA-C is rate adaptive; its speed is adjusted to the maximum

attainable data rate depending on distance and line condition. Additionally,

ADSL technology allows ordinary telephone service to coexist with the

high-speed data service on the same wire pair.

The rate-adaptive Megabit Modem allows the service provider to deliver the

best possible data rate for any subscriber. Typically, a subscriber closest to the

provider receives the highest data rate available, while subscribers farther

away receive data at a lower transmission rate.

The Megabit Modem CRA-C has field-proven Carrierless

Amplitude-modulation and Phase-modulation (CAP) line coding.

The 2-dimensional, 8-state Trellis coding with Viterbi decoding and

the Reed-Solomon forward-error-correction provide robust transmission

in harsh environments.

Use the Megabit Modem CRA-C for application solutions, particularly those

requiring high-speed transmission to the subscriber, such as:

Internet access

remote Local Area Network (LAN) access

telecommuting

•

small office or home office

Other features of the Megabit Modem CRA-C include:

embedded Simple Network Management Protocol (SNMP) agent

IEEE 802.1d transparent MAC level bridging with Spanning Tree

protocol support

static IP routing to provide secure access to the Internet

BOOTP and TFTP to download software

10BASE-T Ethernet port for connection to an Ethernet LAN

line port for Rate-adaptive ADSL single-pair connection

•

console port for maintenance and management

About the Megabit Modem CRA-C

2 Megabit Modem CRA-C User Manual

Use the Megabit Modem CRA-C with these other PairGain products:

•

Megabit Modem CRA (at subscriber site)

•

S1 Network Interface Device (network interface at subscriber site)

About Rate Adaptive Transmission

The following definitions are useful for understanding the operation of the

Megabit Modem:

•

Bit Error Rate (BER) is the ratio of received bits that are in error

relative to the total number of bits received, measured over time.

For example, 10

-7

BER means that on average one error occurs per

10

7

bits received.

•

Signal to Noise Ratio (SNR) is the ratio (typically expressed in dB) of

the received signal power to the received noise power. It is a measure

of the quality of the transmission. The theoretically achievable BER

can be extrapolated from the measured SNR.

•

Margin (SNR margin) is the amount of degradation in SNR that the

system can tolerate under the current conditions and still achieve a

10

-7

BER. A margin of 6 dB, for example, would mean that the SNR

can degrade by 6 dB and still provide a performance of 10

-7

BER. The

PairGain Megabit Modem CRA-C has a margin configuration option

that defaults to 6 dB, but may be set anywhere between -3 dB to 9 dB.

•

Reach is the longest loop length that the system can support with

a given margin and a BER of less than 10

-7

at the given data rate.

Rate Adaptation

With PairGain's rate adaptive technology, the Megabit Modem CRA-C

can automatically adjust to the fastest speed possible, given the transmission

distance and line conditions. Alternatively, the provider can manually set

the modem to a specific rate. The available data rates are:

•

downstream (transmit) rates: 3.168 Mbps, 2.528 Mbps, 2.208 Mbps,

1.888 Mbps, 1.568 Mbps, 1.248 Mbps, 928 Kbps, 608 Kbps

•

upstream (receive) rates: 1.080 Mbps, 944 Kbps, 808 Kbps, 672 Kbps,

536 Kbps, 400 Kbps, 264 Kbps, 82.66 Kbps

About the Megabit Modem CRA-C

Megabit Modem CRA-C User Manual 3

The Megabit Modem CRA-C can be set to any one of three modes that

determine how the data rate is selected. It is important to note that rate

adaptation occurs only during startup. The Megabit Modem CRA-C will

not change its data rate while the link is up. The three startup modes are:

•

Full startup always:

In the full startup mode, the system figures out

the highest upstream and downstream data rates it can support under

the current line conditions, with a margin greater than or equal to the

configured margin. This is done during every ADSL startup attempt.

The system will always attempt a full startup where it will set a

transmission rate up to the maximum specified. It determines this rate

by assessing the signal quality data (line length and noise conditions,

for example) and the margin configuration setting. It then comes up

in the highest available rate based on this information.

•

Session startup:

In session startup mode, the system uses the data

rates set during a previous full startup, rather than re-assessing the

signal quality data. In this mode the system performs a full startup

upon every powerup or reset and would also revert back to a full

startup attempt when a session startup is not successful for 30 seconds.

•

Fixed data rate:

In a fixed-rate mode (fixed data rate), the user

programs both the upstream and the downstream data rates using the

Transceiver Configuration Menu. The user can select from available

data rates shown above. Another configuration parameter is the

startup SNR margin that is also configurable using the Transceiver

Configuration Menu. The system will attempt to come up to the

programmed data rates with a margin greater than or equal to the

configured margin. Failure to complete startup with the desired

margin results in repeated attempts to accomplish it.

When a connection is lost in any mode (the cable disconnected, for example),

the system attempts reconnection as if it has been reset.

About the Megabit Modem CRA-C

4 Megabit Modem CRA-C User Manual

Reach, Data Rate, SNR Margin, and Noise Environment

The maximum transmission rate of the Megabit Modem CRA-C is determined

by distance, SNR margin, and the condition of the line (wire gauge, condition

noise environment). Figure 1 shows the relationship between reach and data

rate for a given set of conditions. The plots can be used to determine the

achievable reach at a given data rate, or they may be used to determined the

achievable data rates at a given distance. In all of the cases except the no

noise case, a margin of 6 dB was allocated above the SNR that provides a Bit

Error Rate (BER) of 10

-7

.

These line conditions fall within the range of the plots shown in Figure 1:

•

no noise (0 dB margin)

•

low noise (−140 dBm-Hz Additive White Gaussian Noise (AWGN))

•

24 ISDN lines in the same binder group

•

24 HDSL lines in the same binder group

•

24 ADSL lines in the same binder group

•

10 T1 lines in an adjacent binder group

•

one T1 line in the same binder group

The performance shown is "typical" for PairGain Megabit

Modem CRA products. Due to variations in environment and

test setup, PairGain does not guarantee performance to the

figures shown.

One of the configuration options in the Megabit Modem CRA-C is the

startup margin setting. This setting defaults to 6 dB but may be set from

-3 dB to 9 dB. The modems will attempt to come up at the programmed

margin setting. Setting the margin high allows for a cushion against changing

line conditions and impulse noise. Setting the margin low provides less

protection but allows the modems to come up at a higher data rate (if in the

rate-adaptive modes) or at a longer loop length (if in the fixed data rate mode).

The default setting of 6 dB is recommended and provides an overall BER

better than 10

-10

. Reducing the setting to 0 dB will only provide a BER of

less than 10

-7

and is not recommended.

About the Megabit Modem CRA-C

Megabit Modem CRA-C User Manual 5

Figure 1.

Reach for a Rate Adaptive ADSL Megabit Modem

About the Megabit Modem CRA-C

6 Megabit Modem CRA-C User Manual

Megabit Modem CRA-C User Manual 7

INSTALL THE MEGABIT MODEM CRA-C

Install the Megabit Modem CRA-C using these sections:

For information about this topic Go to page

Unpack and inspect the shipment 7

Identify LEDs and connectors 9

Install the Megabit Modem CRA-C 12

Power up and check LEDs 16

Unpack and Inspect the Shipment

Upon receipt of the equipment:

1 Unpack each container and visually inspect it for signs of

damage. If the equipment has been damaged in transit,

immediately report the extent of damage to the transportation

company and to your sales representative. Order replacement

equipment if necessary.

2 Check the contents to the packing list to ensure complete and

accurate shipment. If the shipment is short or irregular, contact

your sales representative. If you must store the equipment for a

prolonged period, store the equipment in its original container.

The shipping carton contains, in addition to the Megabit Modem CRA-C and

this manual, the cables described in Table 1.

Install the Megabit Modem CRA-C

8 Megabit Modem CRA-C User Manual

Table 1.

Cables for

Megabit Modem CRA-C

Item Description Function

Straight-through

Category 3 cable

Black unshielded

twisted-pair (UTP)

cables terminated with

RJ-45 connectors.

Connects the Megabit Modem

CRA-C Ethernet MDI-X port

to a network device with an

MDI port.

Cross-over

Category 5 cable

Yellow UTP cable

terminated with RJ-45

connectors.

Connects the Megabit Modem

CRA-C Ethernet MDI-X port

to a network device with an

MDI-X port.

ADSL cable Gray UTP cable

terminated with RJ-11

and RJ-45 connectors.

Connects the Megabit Modem

CRA-C to the ADSL line.

Console cable Flat, silver, eight-wire

cable with RJ-45

connectors at each end.

Plugs into the Console port to

connect the Megabit Modem

CRA-C to an ASCII terminal.

Do not use as a 10BASE-T

Ethernet cable.

Console adapter A rectangular DB-9 (F)

to RJ-48 adapter with

two captive mounting

screws.

Optional. Connects the

Megabit Modem CRA-C to an

ASCII terminal for

configuration and viewing

status.

Power supply An AC to DC power

supply that plugs into

the power outlet.

Provides primary power to the

Megabit Modem CRA-C and

establishes a safety ground.

Do not tamper with the power supply safety

prong. It is a critical element for the secondary

lightning protection provided within the Megabit

Modem CRA-C. If you tamper with the safety

prong, you risk serious injury.

Install the Megabit Modem CRA-C

Megabit Modem CRA-C User Manual 9

Identify LEDs and Connectors

The Megabit Modem CRA-C front panel has LEDs that show status for power

and data transmission. The rear panel has external interface connectors and a

power switch.

Front Panel

Figure 2 and Table 2 describe the LEDs on the Megabit Modem CRA-C

front panel.

Figure 2. Megabit Modem CRA-C Front Panel

Install the Megabit Modem CRA-C

10 Megabit Modem CRA-C User Manual

Table 2.

Front Panel LEDs

LED Mode Description

Power Green Indicates power is on.

10BASE-T

LINK Green

Off

Ethernet connection up.

Ethernet connection down.

TX Green

Off

Transmit activity at port.

No transmit activity at port.

COL Green

Off

Collisions occurring on the port.

No collisions occurring on the port.

ADSL

SYNC Solid green

Flashing green

Off

Normal operation.

Training in progress.

Megabit Modem CRA not synchronized with

Megabit Modem CRA-C.

STAT Solid green

Flashing green

Normal operation.

Test/Alarm condition exists.

MAR Solid green

Flashing green

Margin is above threshold.

Margin is below threshold.

Install the Megabit Modem CRA-C

Megabit Modem CRA-C User Manual 11

Rear Panel

Figure 3 and Table 3 describe the Megabit Modem CRA-C rear panel features.

Figure 3.

Megabit Modem CRA-C Rear Panel

Table 3.

Rear Panel Components

Name Function

POWER connector 6-pin mini-DIN type port that supplies power to Megabit

Modem CRA-C.

Do not connect any other wall-plug supply to the

Megabit Modem CRA-C unit, otherwise, you can

permanently damage the unit.

ON/OFF switch Toggle switch used to turn modem ON and OFF.

CONSOLE port RJ-45 connector (RS-232 compatible) used to connect an

ASCII terminal for configuring the Megabit Modem(s).

10BASE-T

MDI-X port

RJ-45 MDI-X (cross-over) port used to connect the Megabit

Modem CRA-C to a 10BASE-T port of a data network device.

ADSL port RJ-48 port used to connect the Megabit Modem CRA-C to the

ADSL transmission line.

Install the Megabit Modem CRA-C

12 Megabit Modem CRA-C User Manual

Install the Megabit Modem CRA-C

Complete the steps in the order listed to install the Megabit Modem CRA-C:

•

connect to the ADSL line

•

connect to the data network

Connect to the ADSL Line

The Megabit Modem CRA-C requires a single pair of telephone wires to

connect the subscriber to the service provider. One wire is the Tip

and the other is the Ring. See Table 4 for pinouts. Connect the Tip and Ring

wires to your Megabit Modem CRA-C:

1 Plug the RJ-45 connector of the ADSL cable (gray) into the

ADSL port on the Megabit Modem CRA-C rear panel (Figure 4).

2 Connect the RJ-11 connector to the ADSL line.

Figure 4.

Connecting to the ADSL Line

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