7.5.1.2 Mechanisms

JoBS performs scheduling and buffer management in a single pass. JoBS dynamically allocates service rates to classes in order to satisfy the delay constraints. The service rates needed for enforcing absolute delay constraints are allocated upon each packet arrival, while service rates derived from relative delay constraints are computed only every $N$ packet arrivals. If no feasible service rate allocation exists^7.1, or if the packet buffer overflows, packets are dropped according to the loss constraints.

The service rates are translated into packet scheduling decisions by an algorithm resembling Deficit Round Robin. That is, the scheduler tries to achieve the desired service rates by keeping track of the difference between the actual transmission rate for each class and the desired service rate for each class. Scheduling in JoBS is work-conserving.