Effective switch memory management in OpenFlow networks
Effective switch memory management in OpenFlow networks
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DOI：
10.1145/2611286.2611301
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发表时间：
2014-05
影响因子：
2.3
通讯作者：
Anilkumar Vishnoi;Rishabh Poddar;V. Mann;Suparna Bhattacharya
中科院分区：
文献类型：
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作者：
Anilkumar Vishnoi;Rishabh Poddar;V. Mann;Suparna Bhattacharya
OpenFlow网络需要从逻辑集中控制器在有限容量的交换存储器(特别是三值内容可寻址存储器或TCAM)中安装流规则。控制器可以通过交换机以离散时间间隔生成的事件来管理OpenFlow网络中的交换机内存。最近的研究表明，目前数据中心的每个服务器机架每秒可以有多达10,000个网络流量。增加TCAM大小以适应这些大量的流规则不是一个可行的解决方案，因为TCAM成本高昂且耗电。当前的OpenFlow控制器通过安装具有默认空闲超时的流规则来处理此问题，在默认空闲超时之后，交换机会自动将规则从其TCAM中逐出。当超时过高时，这会导致对短期流的交换机内存使用效率低下，而当超时过低时，会导致频繁流的控制器工作负载增加。在此背景下，我们提出了SmartTime-一个OpenFlow控制器系统，它结合了自适应超时启发式算法来计算有效的空闲超时和流规则的主动回收，从而在确保TCAM未命中(或控制器负载)不增加的同时，有效地利用了TCAM空间。据我们所知，SmartTime是第一个在OpenFlow控制器中真正实现智能流量管理策略的产品，可以部署在当前的OpenFlow网络中。在我们使用多个真实数据中心数据包跟踪和缓存大小的实验中，SmartTime自适应策略在总成本方面始终比性能最好的静态空闲超时策略或随机驱逐策略高出58%。
OpenFlow networks require installation of flow rules in a limited capacity switch memory (Ternary Content Addressable Memory or TCAMs, in particular) from a logically centralized controller. A controller can manage the switch memory in an OpenFlow network through events that are generated by the switch at discrete time intervals. Recent studies have shown that data centers can have up to 10,000 network flows per second per server rack today. Increasing the TCAM size to accommodate these large number of flow rules is not a viable solution since TCAM is costly and power hungry. Current OpenFlow controllers handle this issue by installing flow rules with a default idle timeout after which the switch automatically evicts the rule from its TCAM. This results in inefficient usage of switch memory for short lived flows when the timeout is too high and in increased controller workload for frequent flows when the timeout is too low. In this context, we present SmartTime - an OpenFlow controller system that combines an adaptive timeout heuristic to compute efficient idle timeouts with proactive eviction of flow rules, which results in effective utilization of TCAM space while ensuring that TCAM misses (or controller load) does not increase. To the best of our knowledge, SmartTime is the first real implementation of an intelligent flow management strategy in an OpenFlow controller that can be deployed in current OpenFlow networks. In our experiments using multiple real data center packet traces and cache sizes, SmartTime adaptive policy consistently outperformed the best performing static idle timeout policy or random eviction policy by up to 58% in terms of total cost.