User's Manual

34 Document Number: 0100SM1401 Issue: 12-16
Network Address Translation (NAT)
Network Address Translation (NAT) provides a radio in IP routing mode, the ability to perform local port forwarding. Port
forwarding can be beneficial in a network where:
- An IP network has run out of available IP addresses.
- Multiple devices co-exist on a single IP network while sharing the same IP address.
In a standard IP routing radio network, each radio behaves as a network gateway to each of the local subnets. This type of
network consists of:
- A number of LANs: These are the subnetworks residing on the local side of each radio gateway. To subnet these
networks, each LAN requires a uniquely allocated IP range.
- A single Radio WAN: Each radio gateway is configured with a unique WAN address. This creates a subnetwork for the
radio channel.
NAT port forwarding can eliminate the requirement for unique addressing within the LAN subnets by translating the source
address of message sent from a device residing on the LAN with the address allocated to the radio router’s WAN network.
Devices residing on a local subnet will no longer be addressed by their unique IP address, rather, the IP address of the radio
gateway along with a unique port number.
When port forwarding is being configured, each IP device within a local network is allocated one port number on the radio
gateway and a port forwarding rule is entered into the gateway to define:
Gateway Listening Port - The port number which has been allocated to a single device on the radio gateways LAN.
When a message addresses this port number and forwarded to the radio gateway, the corresponding port forwarding rule will
be executed.
IP address and port number of the allocated device - When the Gateway Listening Port is addressed, the corresponding
rule is executed, where the message address will be translated to the IP address and port number defined in these rule
parameters.
Virtual LAN (VLAN)
VLAN can help provide isolation between separate entities who share a single network.
For example, Department A may require access to radio configuration/Diagnostics, while Department B may only requires
access to SCADA information. By implementing VLAN, a virtual network segregation can be implemented to help isolate each
of the departments from one another.
The following diagram shows managed switches placing separate hosts onto unique VLANs. Each remote has been
configured to use VLAN 1 on the ETH1 interface, which provides access to radio services, and VLAN 2 for the ETH2 interface
for SCADA control access.
Part D – Feature Detail
[VLAN 1] Network Management
[VLAN 2] SCADA Control
Un-Tagged packets
ETH1
Network
Management
SCADA
Control
ETH2
ETH2
Ethernet
Switch
WAN
Ethernet
Switch
ETH1
Optional connection for
radio system diagnostics