User's Manual

Chapter 10: Mesh Radio Configuration
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devices in a mesh to reduce the likelihood of asymmetric links. The default transmit power is
21 dBm.
If the transmit power is set to a value in excess of what can be supported by
the mesh radio, the actual radio output power will be the highest power
supported by the mesh radio.
CLI
The example below shows how to set the mesh radio’s transmit power cap with the ‘txpower’
parameter in the ‘mesh0’ interface. The txpower parameter is specified in dBm, with a
minimum granularity of 0.5 dBm.
> use mesh0
mesh0> set txpower=20
Web GUI
The mesh radio’s transmit power cap can be set via the web interface using the “Mesh” tab on
the “Wireless Interfaces” page (see Figure 39). The “+” and “-“ buttons can be used to increase
or decrease the power cap setting in 0.5 dBm steps, or a value can be entered in the text box.
10.5 RSSI Threshold Levels
The mesh networking algorithm evaluates link qualities to neighboring mesh devices and only
considers links with a received signal strength indicator (RSSI) value equal to or greater than
the ‘RSSI Join’ value specified to be usable. The ‘RSSI Join’ value is set to 27 by default. This
value reflects the lowest RSSI that will allow the mesh radio to operate reliably at its highest
data rate. It is possible to achieve longer link ranges, at the cost of reduced throughput, by
reducing the ‘RSSI Join’ value.
In combination with the ‘RSSI Join’ value, the ‘RSSI Margin’ value is used to set the RSSI level
at which links are dropped. A link will be considered broken when its RSSI drops below the
‘RSSI Join’ level by the amount specified with ‘RSSI Margin’. For example, with an ‘RSSI Join’
value of 27 and an ‘RSSI Margin’ value of 3, the link will be dropped if the RSSI goes below
24. The ‘RSSI Margin’ protects the links from the fluctuation in link strengths due to fading.
Based on empirical testing of the EnRoute500, a value of 3-5 is recommended for outdoor
deployments of the EnRoute500.
CLI
The example below shows how to set the mesh radio’s RSSI thresholds with the
‘fabric.rssi.join’ and ‘fabric.rssi.margin’ parameters in the ‘mesh0’ interface .