Port Sharing With Multiple Hosts - GE MDS SD Series Technical Manual

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The type of network shown in Figure 7 can also be used for general
Ethernet bridging as supported by the over-the-air bandwidth of the
system. Bridge filters in the radio may be set to reduce Ethernet traffic
over the RF channel, and improve performance.

Port Sharing with Multiple Hosts

The transceiver allows for several external data networks to use the
same RF network without confusing the data streams. In such a system,
multiple host computers at the Master Unit poll their respective RTUs,
which may be alone or co-located at the Remote sites. Figure 8 shows
an example of such a system. In this case, two host computers (Host A
and Host B) are connected to the Master Unit via the applicable data
ports.
At the Remote sites, serial and Ethernet-based RTUs are employed, and
responding to a specific host computer. In the case of the Remote shown
on the lower right side of the figure, two RTUs are co-located, but
responding to different host computers and handling entirely different
data streams.
The radio eliminates the need for an external adapter or special external
configuration and handshaking when multiple host systems are con-
nected to the network. The radio automatically controls access to the RF
channel by multiple hosts when Packet w/MAC is activated. Virtual
Radio Channels (VRCs) are used to separate serial data streams on
COM2, COM1, or IP payload ports. Packet w/MAC operation provides
Media Access Control. It is the recommended method of operation for
port sharing systems. See "Understanding VRC's" on Page 60.
NOTE: An option exists to operate in Packet mode without MAC.
However, this Packet mode option should only be used for
systems that use legacy methods of collision avoidance
including Multihost and Listen Before Transmit (LBT). The
mode Packet w/MAC provides superior performance and
better network reliability, collision avoidance and better
overall throughput.
SD Series Technical Manual MDS 05-4846A01, Rev. H