The first case to consider here is the 'too-much' case. We need to decide, when it is worth to renegotiate a connection in order to save bandwidth. This is at least the case, when corresponding bandwidth savings on all existing connections would free resources for a new connection. Therefore we relate the required action value with average active connections and usually requested resources by a connection in this link:
To determine the time a connection is allowed to exceed the maximum difference between
allocated and used bandwidth, we must consider tolerated idle times and
fluctuations. Thus it is reasonable to define the value 
in terms of the usual duration of connections on this link:
where 
is a constant depending on personal requirements regarding
bandwidth savings. 
has to be greater, if call blocking occurs often and
vice-versa. A value of '2' seems a good approximation as starting point.
The 'too-little' case on contrary should set the maximum amount of discarded cells on a connection in relation to usually transported cells on connections of this link.
Again an initial value would be chosen for 
(e.g. 10) and has
to be adapted by the control part of our model, i.e. the user
calling us because he has problems.