This parameter can be used to optimize the performance of the
Routing Calculator in the situation where updates that are
pending to the Link State Database concern intra-area routes.
In this case, the Routing Table can be updated either by one
full recalculation, or by multiple incremental SPF
recalculations.
This parameter is used to configure the threshold value for
which recalculation by multiple incremental SPF updates is no
longer quicker than a single full recalculation.
-1 Indicates that this threshold is infinite, and incremental
SPF recalculations are always done in preference to a full
recalculation.
0 Indicates that incremental SPF updates will never be used.
1..2147483647 (n)
Indicates that a full recalculation will be performed
whenever there are more than 'n' updates to make to
intra-area routes.