36 S&C Instruction Sheet 1074-530
SpeedNet Client Tool
•
Hello Interval
—The
Hello
interval setting determines how frequently the Speed-
Net ME Radio broadcasts a neighbor beacon message (hello message). Smaller
Hello
interval values increase the wireless network’s responsiveness to routing changes but
do so at the expense of creating additional network communication overhead. Larger
Hello
interval values decrease the wireless network’s responsiveness to routing
changes but reduce excessive wireless traffic in the process. This value is measured in
seconds and the recommended value is 30 seconds.
•
Allowed Hello Loss
—The
Allowed Hello Loss
value determines the number of
consecutive Hello messages that, when missed, constitutes a link failure that will lead
to a new route request for routes incorporating the link that failed. Setting this value
too low can cause unnecessary route generation when a Hello message was lost be-
cause of a temporary circumstance (e.g. a burst of interference or a packet collision).
Setting this value too high can cause excessive data loss in a route that is no longer
viable because of the persistent failure of a link in the route. The recommended value
is 6.
•
Net Diameter
—The Net Diameter parameter determines the maximum of number of
wireless hops between the source and destination nodes, specifically, the maximum
number of hops that a route request message can travel. The Net Diameter should be
set to at least the maximum number of hops expected for application traffic. If the Net
Diameter is set too low, then route creation may fail because of route requests never
reaching the desired endpoint. If the Net Diameter is set marginally too low, then
primary route creation may succeed but creation of a secondary route may not
succeed in the case of a link failure along the primary route. If the Net Diameter is set
too high, then route requests may propagate needlessly to too many radios generating
excessive overhead. Setting the Net Diameter too high is a more critical issue in high
density connected mesh deployments than in linear deployments. In mesh deploy-
ments, the overhead incurred by the Net Diameter can increase as the square of the
diameter. Do not set this value to the number of radios in the mesh. Set it to the lowest
possible value that allows for redundancy. The recommended value is 10 hops.
•
Node Traversal Time
—The
Node Traversal Time
value provides an estimate of the
time required for a packet to traverse one wireless hop. This value affects how long
a SpeedNet ME Radio waits before resending a route request packet. This value is
measured in milliseconds and the recommended value is 150 msec.
•
ARQ Retry Tolerance
—The ARQ Retry Tolerance parameter allows a configurable
number of successive, unique packet delivery retries before terminating a route. When
this number of successive retries is reached, a radio node is able to know more quick-
ly that its next hop radio neighbor is no longer available to route packets, and a route
will be built around that unavailable neighbor if there is another valid neighbor.
This configuration parameter is useful to balance the identification of an unavail-
able neighbor with packet delivery success rates so more expedient routing may be
performed around an unavailable node. The recommended value is 3.
•
Link Threshold
—SpeedNet ME Radio only considers a neighboring radio node
valid if its signal strength is above a configured threshold, called the grayzone
threshold.
A radio neighbor with signal strength above the grayzone threshold is considered
viable to build routes through, and a neighbor below this threshold will not be used
for routing from that specific radio.
The grayzone threshold removes excessive neighbors from a SpeedNet net-
work. The recommended number of neighbors is between 2 and 25. If more than
25 neighbors are visible, setting the “grayzone threshold” to a stronger signal strength
value reduces the number of neighbors and their routing protocol maintenance traffic.
Excessive neighbors can lead to network congestion. The grayzone threshold configu-
ration parameter name is Link Threshold
.
