Repeater
Because using the bridge mode makes the network transparent, the use of repeaters has certain limit-
ations. To keep matters simple we recommend using a single repeater. However, if certain rules are
observed, using multiple repeaters in the same network is possible.
The total number of repeaters in the network is configured for every unit individually under Bridge mode
parameters. This information is contained in every packet sent. All units that receive such packet will
resume transmission only after sufficient time has been allowed for the packet to be repeated. The
packets received from user ports remain buffered and are sent after the appropriate time passes. This
prevents collisions between remote radio modems. There can be no repeater collisions if only one re-
peater is used.
Where two or more repeaters are used, collisions resulting from simultaneous reception of a repeated
packet must be eliminated. Collisions happen because repeaters repeat packets immediately after re-
ception, i.e. if two repeaters receive a packet from the centre, they both relay it at the same time. If
there is a radiomodem which is within the range of both repeaters, it receives both repeated packets
at the same time rendering them unreadable.
Examples:
1. Repeaters connected serially
A packet is transmitted and repeated
in steps 1, 2, 3.
Centre
RPT1
RPT2 Remote
1
2
3
In improperly designed networks collisions happen
if a remote radio modem lies in the range of two
X
COLLISION!
1
1
2
2
WRONG
CEN RPT1
RPT2 REM
repeaters (see the image): the packet sent from
the centre (1) is received by both repeaters. It is
repeated by them both (2) causing a collision at
the remote. In other words – there should not be
more than one repeater where the centre and re-
motes' coverage areas overlap.
Solution 1.
Adjust signal coverage so that RPT2 is out of range
of the centre and RPT1 is out of the range of the
GOOD
Coverage area
1
2
3
CEN RPT1
RPT2 REM
remote radio modem. This can be achieved for
example by reducing the output power or using a
unidirectional antenna.
RipEX Radio modem & Router – © RACOM s.r.o.
18
RipEX in detail
Summary of Contents for RipEX 1.6.0
Page 2: ......
