10.10.10.50/24
192.168.50.2/24
Routing table RipEX50:
192.168.1.0/24
10.10.10.1
192.168.2.0/24
10.10.10.1
192.168.3.0/24
10.10.10.3
Default GW
192.168.50.2
è
è
è
192.168.2.2/24
Routing table
:
192.168.1.0/24
10.10.10.1
RipEX2
192.168.50.0/24
10.10.10.1
192.168.3.0/24
10.10.10.1
è
è
è
10.10.10.3/24
192.168.3.2/24
Routing table RipEX3:
192.168.50.0/24
10.10.10.50
192.168.1.0/24
10.10.10.50
192.168.2.0/24
10.10.10.50
è
è
è
10.10.10.1/24
192.168.1.1/24
192.168.1.2/24
Routing table
:
192.168.2.0/24
10.10.10.2
RipEX1
192.168.50.0/24
10.10.10.50
192.168.3.0/24
10.10.10.50
è
è
è
192.168.3.1/24
3
50
FEP
1
192.168.50.1/24
Radio IP
ETH IP
FEP IP
10.10.10.2/24
2
192.168.2.1/24
Fig. 2.2: Addressing
Formal consistency between the last byte of the radio IP address and the penultimate byte of the eth-
ernet address is not necessary but simplifies orientation. The “Addressing” image shows a routing table
next to every RipEX. The routing table defines the next gateway for each IP destination. In radio
transmission, the radio IP of the next radio-connected RipEX serves as the gateway.
Example of a route from FEP (RipEX 50) to RTU 2:
•
The destination address is 192.168.2.2
•
The routing table of the RipEX 50 contains this record:
Destination 192.168.2.0/24 Gateway 10.10.10.1
•
Based on this record, all packets with addresses in the range from 192.168.2.1 to 192.168.2.254
are routed to 10.10.10.1
•
Because RipEX 50’s radio IP is 10.10.10.50/24, the router can tell that the IP 10.10.10.1 belongs
to the radio channel and sends the packet to that address over the radio channel
•
The packet is received by RipEX 1 with the address 10.10.10.1 where it enters the router
•
The routing table of RipEX 1 contains the record:
Destination 192.168.2.0/24 Gateway 10.10.10.2
based on which the packet is routed to 10.10.10.2 over the radio channel
•
The packet is received by RipEX 2
•
The router compares the destination IP 192.168.2.2 with its own ethernet address 192.168.2.1/24
and determines that the packet’s destination is within its ETH network and sends the packet over
the ethernet interface – eventually, the packet is received by RTU 2.
RipEX Radio modem & Router – © RACOM s.r.o.
20
RipEX in detail
