We consider the tradeoff between resource efficiency and performance isolation that emerges when multiplexing the resource demands of Network Slices (NSs). On the one hand, multiplexing allows the use of idle resources, which increases resource efficiency. On the other hand, the performance of each NS becomes susceptible to traffic surges in other NSs, which degrades performance isolation. The analysis of this tradeoff enables network operators to determine the effect of performance isolation on the operating cost of each NS. To study the tradeoff, we solve an optimization problem where we find the multiplexing policy that requires the least provisioned resources to honor the Service Level Agreements (SLAs) of all NSs. The SLA of each NS i states that its resource demand should be met for $P^H_i$ fraction of time, and for $P^L_i \leq P^H_i$ fraction of time, it should be met regardless of the demands of other NSs. For resource demands that follow ergodic Markov chains, we show that the well-known Max-Weight scheduler is an optimal multiplexing policy. Since the Max-Weight scheduler does not require any knowledge of the statistics of the resource demands, we also propose its use in non-markovian settings. For resource demands obtained in the LTE module of ns-3, we show that the Max-Weight scheduler reduces the provisioned bandwidth by 36.2% when no performance isolation is required. Lastly, for these non-markovian resource demands, the Max-Weight scheduler maintains its optimality since it requires as much provisioned bandwidth as the best non-causal scheduler.

翻译：本文研究了网络切片（NSs）资源需求复用过程中出现的资源效率与性能隔离之间的权衡问题。一方面，资源复用允许利用空闲资源，从而提升资源效率；另一方面，每个切片的性能易受其他切片流量突发的影响，导致性能隔离下降。对该权衡的分析使网络运营商能够确定性能隔离对各切片运营成本的影响。为研究这一权衡，我们求解了一个优化问题，旨在找到满足所有切片服务等级协议（SLAs）所需的最小预置资源对应的复用策略。每个切片i的SLA要求：在$P^H_i$比例的时间内满足其资源需求，且在$P^L_i \leq P^H_i$比例的时间内，无论其他切片的资源需求如何，其资源需求均应得到满足。对于遵循遍历马尔可夫链的资源需求，我们证明了著名的最大权重调度器（Max-Weight scheduler）是最优的复用策略。由于最大权重调度器无需了解资源需求的统计特性，我们亦建议将其应用于非马尔可夫场景。针对ns-3 LTE模块中获取的资源需求，我们证明当无需性能隔离时，最大权重调度器将预置带宽降低36.2%。最后，对于这些非马尔可夫资源需求，最大权重调度器仍保持最优性，因其所需的预置带宽与最佳非因果调度器相当。