2. Parallel repeaters
Improperly designed network:
Centre
Repeater1
Remote1
1
2
1
2
Remote2
Repeater2
X
COLLISION!
GOOD
WRONG
1
2
1
2
CEN
CEN
RPT1
RPT1
REM1
REM1
1
2
1
2
REM2
REM2
RPT2
RPT2
2
- RipEX REM1 is within the range
of two repeaters (RPT1 and RPT2).
The repeaters receive a packet (1)
from the centre (CEN) and repeat
it at the same time (2) causing a
collision at REM1.
Well-designed network:
- A remote is only in the range of a
single
repeater
(REM1-RPT1,
REM2-RPT2).
There is always only one repeater
where the centre and remote cov-
erage areas overlap.
2.3. Router mode
RipEX works as a standard IP router with two interfaces (radio and ethernet) and two COM port devices.
There is a sophisticated anti-collision protocol on the radio channel, which checks and verifies every
single packet. Being an IP router, each unit can simultaneously work as a store-and-forward repeater
and deliver packets to the connected equipment.
The router mode is suitable for all uses. In contrast to the bridge mode, a packet reception is confirmed
over the radio channel even in very simple polling type applications, and if necessary the packet is re-
transmitted.
2.3.1. Detailed Description
Router mode is suitable for multipoint networks, where multi-master applications with any combination
of polling and/or spontaneous data protocols can be used. The proprietary link-layer protocol on the
radio channel is very sophisticated, it can transmit both unicast and broadcast frames, it has collision
avoidance capability, it uses frame acknowledgement, retransmissions and CRC checks to guarantee
data delivery and integrity even under harsh interference conditions on the radio channel.
RipEX works as a standard IP router with 2 independent interfaces: radio and ETH. Each interface has
its own MAC address, IP address and mask.
IP packets are processed according the routing table rules. You can also set the router’s default gateway
(applies to both interfaces) in the routing table.
The COM ports are treated as standard host devices, messages can be delivered to them as UDP
datagrams to selected port numbers. The destination IP address of a COM port is either the IP of ETH
or the IP of a radio interface. The source IP address of outgoing packets from COM ports is always the
IP of the ETH interface.
17
© RACOM s.r.o. – RipEX Radio modem & Router
RipEX in detail
