SDN中基于图分割的自适应带内网络遥测探测路径配置

软件定义网络（SDN）是一种将控制与转发平面分离的新型网络架构，可以基于全局信息进行网络资源的调度和优化，而精确的调度需要对全网信息（包括网络中所有交换设备状态及拓扑中所有链路信息）进行准确的测量.带内网络遥测可以在转发数据包的同时实现相关信息的采集，其中配置全网覆盖的探测路径是带内网络遥测需要解决的关键问题之一.但现有SDN网络中全网覆盖的带内网络遥测路径配置方案存在以下问题：（1）需要提前部署大量探测节点导致维护开销增大；（2）探测路径过长导致探测分组长度超过网络中的MTU值；（3）冗余的探测路径导致测量引入的流量负荷在网络整体流量中占比过大；（4）动态变化拓扑下探测路径调整恢复时间长等.为解决上述问题，提出了SDN中基于图分割的自适应带内网络遥测探测路径配置（ACGS）方法，其基本思想是：利用图分割对网络拓扑图进行划分，通过控制拓扑规模来限制探测路径长度；在分割后的子图中求解欧拉回路得到只遍历子图中有向边一次的探测路径，以避免探测节点数量过多、探测路径冗余度高的问题；并利用局部调整与整体调整相结合的方式解决拓扑动态变化时探测路径恢复时间长的问题.实验结果证明ACGS方法能够在SDN网络环境下，实现探测路径长度适中、探测节点数量较少、探测路径冗余程度更低的全网覆盖带内网络遥测探测路径配置，并实现其在拓扑动态变化后更快速的调整.

Adaptive Detection Path Configuration for In-band Network Telemetry in SDN Based on Graph Segmentation

Software-defined network (SDN) is a new network architecture that separates the control and forwarding planes. It can schedule and optimize network resources based on global information. Nevertheless, precise scheduling requires accurate measurement of information on the entire network (including the status of all switching devices in the network and all link information in the topology). In-band network telemetry (INT) can realize the collection of relevant information while forwarding data packets, and configuration of detection paths which cover the entire network is one of the key issues to be solved for INT. However, existing detection path configuration methods for INT have the following problems. (1) The deployment of a large number of detection nodes is required in advance, which leads to increased maintenance overhead. (2) The detection path is too long, which results in the length of detection packet exceeding the MTU value in the network. (3) The redundant detection paths cause the traffic load introduced by the measurement to account for too much of the overall network traffic. (4) The recovery time of the detection path adjustment under the dynamically changing topology is too long. In order to solve the above problems, an adaptive detection path configuration method for in-band network telemetry in SDN based on graph segmentation (ACGS) is proposed. The basic idea is to divide the network topology with the graph segmentation to restrict the length of detection path by controlling the topology scale, solve the Euler circuit in the divided subgraph to obtain a detection path that only traverses the directed edges in the subgraph once, to avoid the problems of too many detection nodes and high detection path redundancy; and use the combination of local adjustment and global adjustment to solve the problem of long recovery time of the detection path when the topology changes dynamically. The experimental results prove that the ACGS method can realize the INT detection path configuration in SDN with moderate detection path length, fewer detection nodes, lower detection path redundancy, and faster adjustment under the dynamically changing topology.