Cross-layer optimization in TCP/IP networks
Cross-layer optimization in TCP/IP networks
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DOI：
10.1109/tnet.2005.850219
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发表时间：
2005-06
期刊：
影响因子：
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通讯作者：
Jiantao Wang;Lun Li;S. Low;J. Doyle
中科院分区：
文献类型：
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作者：
Jiantao Wang;Lun Li;S. Low;J. Doyle
TCP-AQM 可以解释为分布式原对偶算法，以最大化源速率的总效用。我们表明，如果将拥塞价格用作链路成本，则 TCP/IP 的均衡（如果存在）可以最大化源速率和路由的总效用。当且仅当该效用最大化问题及其拉格朗日对偶不存在对偶间隙时，均衡才存在。在这种情况下，TCP/IP 不会因为不将流量分割到多个路径而产生任何损失。然而，这种平衡可能不稳定。它可以通过在链路成本中添加静态组件来稳定，但代价是平衡效用降低。然而，如果链路容量得到最佳配置，则必然稳定的纯静态路由足以实现效用最大化。此外，单路径路由再次在最优状态下实现了与多路径路由相同的效用。
TCP-AQM can be interpreted as distributed primal-dual algorithms to maximize aggregate utility over source rates. We show that an equilibrium of TCP/IP, if exists, maximizes aggregate utility over both source rates and routes, provided congestion prices are used as link costs. An equilibrium exists if and only if this utility maximization problem and its Lagrangian dual have no duality gap. In this case, TCP/IP incurs no penalty in not splitting traffic across multiple paths. Such an equilibrium, however, can be unstable. It can be stabilized by adding a static component to link cost, but at the expense of a reduced utility in equilibrium. If link capacities are optimally provisioned, however, pure static routing, which is necessarily stable, is sufficient to maximize utility. Moreover single-path routing again achieves the same utility as multipath routing at optimality.