Sierra Wireless oMG series, Operation And Configuration Manual, Page: 24 / 101

Operation and Configuration Guide 3.14
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There are actually two sets of settings on the Dynamic Priority Policy
configuration screen:
Figure 5-9: Settings on the Dynamic Priority Screen
The first set allows for the enabling and setting of a Priority Score on a link. The
priority score is added to a base score of 1000 which is assigned by the system.
This combined score then indicates the priority (preference) of the link which the
system determines by comparing against the scores from other links. Note that
equal values can be specified when enabling the policy on different links to
indicate that those links are equally preferable.
It's important to note that although this setting appears on the configuration
screen of the Dynamic Priority Policy, it's actually not specific to that policy and
can be set and used in conjunction with any policy.
The second category of settings are for the Dynamic Priority policy itself and
include the ability to enable and specify a
Link Down Penalty value which can
reduce a link's score when some condition is not being met (e.g. a link has not
been able to establish a connection for some time). The other value that can be
defined is the Recovery Period which specifies the amount of time that a link's
score will be incremented again by the system. A link "proves" itself when its
score increments back to its original combined score over this period, at which
point the system may reselect it as the active link.
Consider the following example where there is a WiFi device and two cellular
devices (C1 and C2) installed on an oMG. The WiFi device is the most preferred
device while C1 is preferred over C2. To model this in the Dynamic Priority policy
the following settings were used:
The graph in Figure 5-10 on page 25 shows a simple time line in which a vehicle
is outside of a depot, C1 is the current WAN link, but the connection is eventually
lost. As a result C1's overall score is re calculated using its current score minus its
assigned penalty (1200-300) to give a new score of 900. Since this is lower than
C2's current score of 1100, C2 takes over.
Table 5-1: Example of Dynamic Priority Settings
WiFi C1 C2
Base Score 1000 1000 1000
Priority Score 300 200 100
Link Down Penalty Not Enabled 300 300
Recover Period Not Enabled 120 120