Connectivity is the basic stuff from which the Internet is made. We define several such metrics, some of which serve mainly as building blocks for the others. This metric is probably not directly useful, because it is instantaneous and unidirectional.
Most applications also require connectivity over an interval.
Finally, one might not have instantaneous connectivity due to a transient event such as a full queue at a router, even if at nearby instants in time one does have connectivity. These points are addressed below, with this metric serving as a building block. This means that most packets will have nowhere near the 255 second lifetime. In principle, however, it is also possible that packets might survive longer than 255 seconds. Consideration of packet lifetimes must be taken into account in attempts to measure the value of this metric.