连接缓冲管理和行程安排 forDifferentiated 服务.pdf

JoBS: Joint Buffer Management and Scheduling for
Differentiated Services ?
Liebeherr and Nicolas Christin
Computer Science Department, University of Virginia, Charlottesville, VA 22904, USA
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Abstract. A novel algorithm for buffer management and packet scheduling is
presented for providing loss and delay differentiation for traffic classes at -
work router. The algorithm, called JoBS (Joint Buffer Management and Schedul-
ing), provides delay and loss differentiation independently at each node, without
assuming admission control or policing. The novel capabilities of the proposed
algorithm are that (1) scheduling and buffer management decisions are performed
in a single step, and (2) both relative and (whenever possible) absolute QoS re-
quirements of classes are supported. Numerical simulation examples, including
results for a heuristic approximation, are presented to illustrate the effectiveness
of the approach and pare the new algorithm to existing methods for loss
and delay differentiation.
1 Introduction
Quality-of-Service (QoS) guarantees in works are often classified according
to two criteria. The first criterion is whether guarantees are expressed for individual
end-to-end traffic flows (per-flow QoS) or for groups of flows with the same QoS re-
quirements (per-class QoS). The second criterion is whether guarantees are expressed
with reference to guarantees given to other flows/flow classes (relative QoS), or whether
guarantees are expressed as absolute bounds (absolute QoS).
Efforts to provision for QoS in the in the early and mid-1990s, which re-
sulted in the Integrated Services (IntServ) service model [3], focused on per-flow ab-
solute QoS guarantees. However, due to scalability issues and a lagging demand for
per-flow absolute QoS, the interest in QoS eventually shifted to relative per-
class guarantees. Since late 1997, the Differentiated Services (DiffServ) [2] working
group has di