Software‐defined networking (SDN) is a network concept that brings significant benefits for the mobile cellular operators. In an SDN‐based core network, the average service time of an OpenFlow switch is highly influenced by the total capacity and type of the output buffer, which is used for temporary storage of the incoming packets. In this work, the main goal is to model the handover delay due to the exchange of OpenFlow‐related messages in mobile SDN networks. The handover delay is defined as the overall delay experienced by the mobile node within the handover procedure, when reestablishing an ongoing session from the switch in the source eNodeB to the switch in the destination eNodeB. We propose a new analytical model, and we compare two systems with different SDN switch designs that model a continuous time Markov process by using quasi‐birth–death processes: (1) single shared buffer without priority (model SFB), used for all output ports for both control and user traffic, and (2) two isolated buffers with priority (model priority finite buffering [PFB]), one for control and the other for user plane traffic, where the control traffic is always prioritized. The two proposed systems are compared in terms of total handover delay and minimal buffer capacity needed to satisfy a certain packet error ratio imposed by the link. The mathematical modeling is verified via extensive simulations. In terms of handover delay, the results show that the model PFB outperforms the model SFB, especially for networks with high number of users and high probability of packet‐in messages. As for the buffer dimensioning analysis, for lower arrival rates, low number of users, and low probability of packet‐in messages, the model SFB has the advantage of requiring a smaller buffer size.

中文翻译：

---

基于移动OpenFlow的网络中切换延迟和缓冲区容量的性能分析

软件定义网络（SDN）是一种网络概念，可为移动蜂窝运营商带来巨大收益。在基于SDN的核心网络中，OpenFlow交换机的平均服务时间在很大程度上受到输出缓冲区的总容量和类型的影响，该缓冲区用于临时存储传入的数据包。在这项工作中，主要目标是对由于移动SDN网络中与OpenFlow相关的消息交换而导致的切换延迟进行建模。当从源eNodeB中的交换机到目标eNodeB中的交换机重新建立正在进行的会话时，移交延迟定义为移动节点在移交过程中所经历的总延迟。我们提出了一个新的分析模型，我们比较了两种具有不同SDN交换机设计的系统，它们使用准生死过程对连续时间马尔可夫过程进行建模：（1）无优先级的单个共享缓冲区（模型SFB），用于所有输出端口，用于控制和用户流量和（2）两个具有优先级的隔离缓冲区（模型优先级有限缓冲[PFB]），一个用于控制，另一个用于用户平面流量，在此始终将控制流量放在优先位置。比较两个提议的系统的总切换延迟和满足链路施加的特定分组错误率所需的最小缓冲区容量。通过广泛的仿真验证了数学建模。在切换延迟方面，结果表明，模型PFB优于模型SFB，特别是对于具有大量用户和分组消息可能性较高的网络。对于缓冲区大小分析，对于较低的到达速率，较低的用户数量和较低的入包消息概率，SFB模型具有需要较小缓冲区大小的优势。