Operation and Configuration Guide 3.14
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depot environment and aggressively (e.g. every 2 seconds) when operating in
metropolitan networks.
•
Signal Strength Average Length
: this value specifies the number of
background scan samples that are integrated in order to evaluate alternative
APs. The default value of 10 readings is recommended for environments
where there is only one access point with the appropriate credentials. For
metropolitan networks, where the vehicle is expected to roam from access
point to access point this value should be set to 1.
•
Minimum Dwelling Period
: the minimum amount of time (in milliseconds) to
wait for a response on a channel after sending a probe message to check for
a new access point.
•
Maximum Dwelling Period
: the maximum amount of time (in milliseconds)
to wait after having received a response to a probe message while scanning
for a new access point on a channel, to check for additional responses.
•
Time Off-Channel During Scan
: the total time (in milliseconds) to scan for
access points and wait for responses across channels, before reverting a
previous access point.
•
Roaming Squelch
: this setting instructs the oMG to remain associated (i.e.
do not roam) with an AP unless the current AP is disqualified by the quality
settings discussed below. This is typically desirable in a depot situation. This
should be disabled in a metropolitan network where fast roaming is required.
•
Satisfactory Quality of Signal
: once an oMG has associated with an AP, it
will remain associated unless the SNR drops below the value specified for
this field (provided that Roaming Squelch is enabled).
•
Minimum Quality of Signal
: the oMG will not associate to an AP unless its
signal quality meets or exceeds the value specified for this field. The value (in
dB), specifies the SNR (signal to noise) not absolute signal level. A low SNR
usually implies a low signal.
•
Minimum Quality of Signal Differential
: when the WiFi interface is consid-
ering a switch to a new access point, the difference in signal SNR between
the current access point and the new one must be greater or equal to this
value.
•
Permanent Blacklist
: this is a list of BSSIDs that the WiFi interface should
never connect to.
•
Enable WMM
: enables WiFi Multimedia QoS. The default for all WiFi cards is
disabled.
A.3.3 Ethernet Link Configuration Settings
•
High Cost Link
: defines this link as High Cost, limiting the frequency and
amount of management data sent over the link. Ethernet links are rarely high
cost.
•
Change Default MTU Size
: when enabled, allows the MTU size to be
changed from its default of 1500.
•
MTU Size
: the new MTU size to use.
•
Auto Local IP
: enables DHCP for this interface. The IP address will be
assigned by a DHCP server connected to the access network.