3Com 520 - Manual (Page 18)

1-4 C H A P T E R 1: G E T T I N G S T A R T E D
Using ISDN to Support Leased Line WAN
Circuits
ISDN provides an ideal service to connect remote
LANs. To be effective, the connecting bandwidth
needed is at least 64 Kbps to achieve a realistic
throughput. Slower speed links can be used but
usually only when usage is low and infrequent, or if
higher speed circuits cannot be provided.
Leased digital point-to-point circuits can still be cost
effective if usage spans many hours per day.
However as ISDN tariffs reduce, this balance also
changes. ISDN can be used to provide effective
backup of these point-to-point WAN circuits in two
ways.
■ Firstly, if the point-to-point circuit fails, an ISDN
channel can be dialled-up automatically and quickly,
to provide an alternative path to the remote unit.
■ Secondly, if the leased circuit becomes heavily loaded
due to peaks in the traffic between remote bridges or
routers, additional bandwidth can be automatically
dialled-up to supplement the bandwidth of the
leased circuit. The interconnected bridges would then
treat the leased line and ISDN channel as parallel links,
sharing the load across the two.
Pack Contents Checklist
Before you install your OfficeConnect Remote, check
the contents of the box against the pack contents
checklist below. If any of the items have been
damaged in transit or are missing, then contact the
3Com dealer from whom the equipment was
purchased.
■ 1 x OfficeConnect Remote unit.
■ 1 x power adapter fitted with an appropriate plug for
your national power supply.
■ 1 x 1.5 meter RJ45 to RJ45 male plug ISDN 2
connecting cable.
■ 1 x 1.5 meter DB9 to DB9 serial manager port cable.
■ 1 x British Telecom to RJ11 convertor (UK models of
OfficeConnect Remote 520 and 530 only).
■ 1 x OfficeConnect Remote User Guide .
■ 1 x OfficeConnect Remote Software Reference guide.
■ 1 x Warranty Registration Card.
It is important that you save the unit’s box and
protective packing material in case you need to
store, or transport it in the future.
Rc.bk : RC01.FRM Page 4 Thursday, July 10, 1997 9:53 AM