RDRN System Emulation
Emulating the Rapidly Deployable Radio Network (RDRN) environment enables the RDRN
software developers to test and evaluate large RDRN configurations in the laboratory
under controlled and repeatable conditions. The Emulation Manager (EM) emulates and
displays the environment that the RDRN computers use in determining network topology
and routing. The laboratory RDRN emulation system consists of:
The portion of the system that the emulation manager emulates consists of:
- Multiple rack mounted IBM compatible computers running the RedHat 4.X/5.X
operating system configured as MN and MAP RDRN nodes
- A single EM IBM compatible computer running the RedHat 5.X operating system.
- One or more ATM switches
- Ethernet LAN connecting testbed computers, EM computer and the ATM switch(s)
- ATM connections connecting the testbed computers to the ATM switch(s).
In an emulation the EM acts as the GPS receiver for each RDRN node and propagation
medium for the Orderwire packet radio transceiver and the high bandwidth radio links.
Establishment of high bandwidth (HBW) radio links between nodes is also emulated by the
EM and ATM switch(s). Loss of signal between nodes due to range for Orderwire and HBW
and terrain blockage for HBW communications is emulated by the EM.
- Node location (lat/lon), speed, direction and elevation
- Topography of the terrain in the emulated radio network area
- Orderwire and High Bandwidth radio messages between nodes
- Loss of radio messages due to terrain or range between nodes.
During an emulation the EM displays node position and HBW connection status between
nodes using a graphical display.
In the real world RDRN nodes move about over terrain and use GPS to determine their
position on the terrain. They receive NMEA 0183 format GPS messages containing the
current time, their latitude/longitude location, speed, direction and height from a GPS
receiver over a serial link. In the emulation environment RDRN nodes receive GPS messages
in the same format with the same information from the EM over a UDP socket. The information
to put into the GPS messages for each node in an emulation is determined by the EM using
a predefined node movement scenario file and digital elevation maps.
Orderwire messages in the real environment are transmitted and received via packet
radio transceiver connected to an RDRN over a serial link. In the emulation environment
Orderwire messages are transmitted and received by the nodes via the EM over UDP sockets.
Propagation of the Orderwire packets is emulated by the EM by broadcasting an Orderwire
packet datagram sent to the EM by a node to all other nodes within an emulated range limit
(~90 km) of the transmitting node. The EM does not require any knowledge of the structure
of the Orderwire packets in the UDP datagrams.
In the real environment two neighboring RDRN nodes electronically steer HBW radio
beams at each other to establish an ATM connection over the radio link. For the emulation
case two neighboring nodes send a request to the EM to establish a physical ATM connection
between them through the ATM switch(s). This emulates the radio connection between the
nodes. The nodes then establish a 'virtual' ATM connection over the physical ATM connection.
The establishment of the 'virtual' ATM connection is equivalent to the establishment of the
ATM connection in the real environment. The nodes can also request that the EM delete
physical ATM connections.
The RDRN nodes send the requests to the EM for physical ATM connections utilizing UDP
sockets and a emulation management request protocol developed for this project. The EM
controls and statuses the ATM switch(s) through SNMP commands over Ethernet.
The EM monitors the range between nodes as the emulation runs. When two nodes request
a physical ATM connection the EM creates the connection if the nodes are within the HBW
range (~ 9km) and the terrain does not block line of sight (LOS). If two connected nodes
exceed the HBW range or loose LOS the EM deletes the physical ATM connection to emulate
the loss of LOS or exceeded range.
As the emulation manager runs it displays the positions of the RDRN nodes on a 2D
display of the terrain covered in the emulation scenario. MN nodes are displayed as
filled circles while the MAP nodes are displayed as squares. Each node is displayed in
a unique color. As the emulation progresses the displayed symbols of the nodes are moved
on the 2D display to represent the movement of the nodes in the emulated environment.
The user may enable display of the past path of the nodes. The node paths are displayed
as solid grey poly lines.
When any two nodes are connected with a physical ATM connection the EM displays the
connection with a solid black line between the nodes. As the nodes move the connection
moves with the nodes. The user may enable display of past ATM connections. They are
displayed with a dotted grey line.
The emulation runs in real time. The user is able to pause and continue the emulation.
Pausing the emulation prevents the EM from sending GPS messages to the nodes. When the
user continues the emulation the EM restarts sending GPS messages where it left off.
An auxiliary window may be created by the user to display statistics about the nodes.
The node symbol used in the 2D display is shown and matched with its scenario name, type
(MN/MEP), speed, direction, height, latitude/longitude and range to other nodes.
An auxiliary window may be created by the user to display current connection status.
For each node the connection status to other nodes is displayed. The status consists of
the PVC of the physical connection, name of connected node, number of cells sent and
number of cells dropped.
This page is under construction/rennovation.
Last Update: October 25, 1999 02:00pm (GMT-0600)