In network calculus, a fundamental result is the classical delay bound given by the horizontal deviation between the arrival and service curves. While widely used, the classical bound is derived from the notion of virtual delay. In this work, we first show that the maximum packet delay is always upper-bounded by the maximum virtual delay, revealing inherent conservatism when applying the virtual-delay-based bound to packet delay. Motivated by this insight, we revisit packet delay analysis and derive a new packet delay bound that requires no assumptions beyond the arrival and service curves. Specializing the new bound to a system with leaky-bucket arrival curve and rate-latency service curve shows strict improvement over the classical bound, which is further demonstrated through a case study in time-sensitive networking (TSN).

翻译：在网络演算中，一个基础性结论是由到达曲线与服务曲线之间的水平偏差给出的经典延迟界。尽管该经典界被广泛使用，但其推导基于虚拟延迟的概念。本文首先证明数据包最大延迟始终受虚拟最大延迟的上界约束，揭示了将基于虚拟延迟的界应用于数据包延迟时固有的保守性。受此启发，我们重新审视数据包延迟分析，推导出新的数据包延迟界，该界无需在到达曲线与服务曲线之外引入任何额外假设。将新界特化至具有漏桶到达曲线和速率-延迟服务曲线的系统时，其严格优于经典界，并通过时间敏感网络（TSN）的案例研究进一步验证了该改进。