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3 C

O M

M P A C T

3Com Impact External Digital Modems and Adapters

Give You Speed and Reliability

Basic ISDN Advantages

ISDN service —offered by major

telephone companies around the

world— offers many advantages

over analog telephone connections.

Performance and Economy

ISDN is fast. Using a single tele-

phone connection, Basic Rate ISDN

provides two B channels for digital

calls, each carrying up to 64 Kbps

of data or voice communication.

Combining the two channels via

Multilink PPP creates a 128 Kbps

data pipe between two sites.

For Internet users and teleworkers,

ISDN speeds the process of locat-

ing data resources and download-

ing files. ISDN saves money, too,

by reducing telephone line usage

time and associated charges. A

data file that takes four minutes to

transmit with the fastest analog

modem (28.8 Kbps) takes less than

one minute with an ISDN external

digital modem or ISA adapter

using Multilink PPP.

With ISDN, calls connect in a mat-

ter of seconds. Analog modems

must negotiate the speed that the

telephone line will support, which

can take up to 30 seconds to set up

a connection.

Analog Modems

2400 bps

14.4 Kbps

ISDN digital modems and adapters are four times as fast as the fastest analog modems —

and nearly 50 times as fast as many analog devices.

I S D N A

Digital Reliability

ISDN is a digital technology, trans-

mitting 0s and 1s over the tele-

phone line instead of modem tones.

As a result it is inherently very reli-

able, like an audio CD or a CD-

ROM. By contrast, analog phone

lines pick up noise from their sur-

roundings, which can block connec-

tions, slow transmission, and cor-

rupt data.

Digital

Modems

and

Adapters

One

ISDN

Channel

28.8 Kbps

64 Kbps

D A P T E R S

A N D

Multilink PPP—Getting the

most out of ISDN

To give you the highest possible

transmission speed over an ISDN BRI

connection, all 3Com Impact adapters

and digital modems support the

Multilink PPP (Point-to-Point Protocol)

and IETF Internet Standard. With

Multilink PPP on both ends of a BRI

connection, two 64 Kbps ISDN chan-

nels are combined into one 128 Kbps

data pipe, without additional hard-

ware or lines from your ISDN

provider.

Multilink PPP, combined with 3Com's

bandwidth on-demand technology,

lets you utilize your ISDN resources

Two

how and when you need them. In

ISDN

cooperation with 3Com's

Channels

(Multilink

AccessBuilder 4000-ISDN, your 3Com

PPP)

ISDN ISA adapter can automatically

open a second B channel to handle a

sudden transmission load, then trans-

parently close the second connection

when network requests are satisfied.

Just as easily, a Multilink PPP session

makes room for an outgoing voice call

or fax transmission starting over the

3Com Impact external modem's

Phone Out port, then resumes full

bandwidth when the call or fax ends.

Compared with other ISDN multiplex-

ing schemes, the Multilink PPP stan-

dard offers superior flexibility and

interoperability, giving you transpar-

ent channel aggregation—simply and

inexpensively. And with 3Com's con-

128 Kbps

tinuing support for Multilink PPP you

can count on interoperability for all

your ISDN networking, now and in the

future.

O D E M S