The objective of the JoBS algorithm is to provide absolute and
relative (proportional) loss and delay differentiation independently
at each node for classes of traffic. JoBS therefore provides
service guarantees on a per-hop basis. The set of performance
requirements are specified to the algorithm as a set of per-class
Qualtiy of Service (QoS) constraints. As an example, for three
classes, the QoS constraints could be of the form:
Here, the first two constraints are relative constraints and the last
one is an absolute constraint. The set of constraints can be
any mix of relative and absolute constraints.
More specifically, JoBS supports the five following types of constraints:
JoBS does not rely on admission control or traffic policing, nor does it
make any assumption on traffic arrivals.
Therefore, a system of constraints may become infeasible, and
some constraints may need to be relaxed.
QoS constraints are prioritized in the following order.
That is, if JoBS is unable to satisfy both absolute and relative constraints,
it will give preference to the absolute constraints.