基于分域分层BIER的SDN组播

Multicast in SDN based on Hierarchical Domain BIER

【目的】针对基于位索引显示复制(BIER)的大规模软件定义网络(SDN)组播中,可能存在特定长度的比特串(BitString)无法表示所有BIER转发路由器(BFRs)的问题,文章设计了一种分域分层(HD)-BIER模型,并设计了其构建算法。【方法】HD-BIER模型是由多个小规模子域(SD)组成的多层BIER网络,使BIER在大规模网络中能够支持超过BitString表示容量的设备数量。文章提出的HD-BIER构建算法综合考虑了BitString长度(BSL)限制、节点之间的链路长度与网络的连通性,并基于社区划分算法的思想,引入基于节点相似度的模块度函数作为BIER SD划分结果的评价指标,采用自底向上方式动态构建HD-BIER网络。【结果】仿真实验表明,在节点数量超出BSL的简单和复杂网络中,HD-BIER构建算法均能有效构建突破BSL限制的HD-BIER网络,且所构建的HD-BIER模型在BitString逐层封装和解封的方式下不仅能够保证组播业务数据流的正常传输,还能在此过程中不影响SDN组播通信性能。【结论】仿真结果证明,所提HD-BIER模型为更大规模的网络提供了有效的组播业务支持方案。

【Objective】Aiming at the problem that BitString can not represent all Bit-Forwarding Routers(BFRs)in large-scale Software Defined Networking(SDN)multicast based on Bit Index Explicit Replication(BIER)due to the limited length,this study designs a Hierarchical Domain(HD)-BIER model and devises its construction algorithm.【Methods】The HD-BIER model is a multi-layer BIER network composed of multiple small-scale Sub Domains(SD),which enables BIER to support a number of devices exceeding the capacity of the BitString representation in large-scale networks.The proposed HD-BIER construction algorithm takes into account the BitString Length(BSL)limitation,link lengths between nodes,and network connectivity.It leverages the concept of community partition algorithms and introduces a modularity function based on node similarity as an evaluation metric for BIER SD partitioning.The construction follows a bottom-up approach to dynamically build the HD-BIER network.【Results】The simulation results show that the HD-BIER construction algorithm can effectively construct HD-BIER networks that exceed the BSL limit in either simple networks or the complex networks with a large number of nodes.Additionally,the resulting HD-BIER model not only ensures normal transmission of multicast service data flows through the gradual encapsulation and decapsulation of BitString layers but also maintains SDN multicast communication performance throughout this process.【Conclusion】The simulation results validate that the proposed HD-BIER model presents an effective multicast service support solution for even larger-scale networks.