A hands-on assessment of transport protocols with lower than best effort priority
A hands-on assessment of transport protocols with lower than best effort priority
复制标题
对低于尽力优先优先级的传输协议进行实际评估
DOI：
--
复制
发表时间：
2010
期刊：
影响因子：
--
通讯作者：
C. Testa
中科院分区：
文献类型：
--
作者：
G. Carofiglio;L. Muscariello;D. Rossi;C. Testa
去年，官方的BitTorrent客户端切换到LEDBAT，这是一种新的拥塞控制算法，目标是低于“最佳努力”的传输服务。在本文中，我们通过包级模拟来研究这个新协议，特别关注与其他低于最佳努力协议（如TCP-LP和TCP-NICE）的性能比较：我们的目标确实是量化和相对加权这些协议提供的低优先级级别。我们的结果表明，LEDBAT传输通常可以达到最低的优先级，TCP-NICE和TCP-LP的默认配置代表了越来越高的攻击级别。此外，我们通过在协议间（针对TCP）和协议内（针对LEDBAT本身）场景中调整其主要参数，对LEDBAT性能进行了仔细的敏感性分析。在协议间的情况下，即使在配置错误的情况下，LEDBAT也会像TCP一样激烈地竞争，但我们表明，仅仅通过调整其参数来实现任意级别的低优先级是不可能的。在协议内部的情况下，我们展示了具有稍微不同设置的遗留流的共存，或者经历不同的网络条件，可能导致严重的不公平。
Last year, the official BitTorrent client switched to LEDBAT, a new congestion control algorithm targeting a lower-than Best Effort transport service. In this paper, we study this new protocol through packet-level simulations, with a special focus on a performance comparison with other lower-than Best Effort protocols such as TCP-LP and TCP-NICE: our aim is indeed to quantify and relatively weight the level of Low-priority provided by such protocols. Our results show that LEDBAT transport generally achieves the lowest possible level of priority, with the default configurations of TCP-NICE and TCP-LP representing increasing levels of aggressiveness. In addition, we perform a careful sensitivity analysis of LEDBAT performance, by tuning its main parameters in both an inter-protocol (against TCP) and intra-protocol (against LEDBAT itself) scenarios. In the inter-protocol case, even in case of misconfiguration LEDBAT competes as aggressively as TCP, but we show that it is not possible to achieve an arbitrary level of low-priority by merely tuning its parameters. In the intra-protocol case, we show that coexistence of legacy flows with slightly dissimilar settings, or experiencing different network conditions, can result in significant unfairness.