This attribute indicates whether a route should be selected on the
basis of minimizing the route cost or the route delay. Each trunk has
a cost and a delay metric associated with it. The cost of a route is
the sum of the trunk cost metrics for all trunks included in the route.
The delay of a route is the sum of the trunk delay metrics for all
trunks included in the route. The delay metric of a trunk is equal to
half the measuredRoundTripDelay operational attribute of the
trunk.