Core-stateless Fair Bandwidth Allocation for Guaranteed Services, Part I: End-to-end Precise Basic Bandwidth Guarantees

The core-stateless packet scheduling scheme has both scalability and the ability of fine granularity QoS guarantees. However, maintaining scheduling parameters only in the packet header make it difficult for core-stateless networks to provide deterministic (zero loss) fair bandwidth allocation to each flow. To address this problem, we conceptually separate bandwidth allocation into two steps: the allocation of the basic bandwidth that equals to the reserved rate of the flow and the allocation of extra bandwidth. In this paper, we propose a novel virtual delay vector based core-stateless packet scheduling algorithm, called VCSGR (vector-based core-stateless guaranteed rate). We show that a network of servers running such algorithms provides the same end-to-end delay guarantee as a network of corresponding GR servers. Furthermore, VCSGR uses virtual delay vector technique to achieve accurate basic bandwidth guarantee, which is an essential step toward deterministic fair core-stateless packet scheduling algorithms