公用IPv6网络承载服务SLA监测研究

Research on QoS Monitoring for Public IPv6 Network Bearer Service SLA

分析了NGI中网络承载服务SLA(NSLA)的应用需求,针对NSLA可能的应用场合及IPv6特点定义了适用于NSLA的QoS参数:IP分组传送延迟(IPTD)、IP分组延迟变化(IPDV)、IP分组传送失败率(IPFR)和IP分组吞吐能力(IPTC),其中IPTC能有效刻画公用IP网段集维持业务流量模式的能力。分组识别和时钟同步是IPv6网络NSLA监测的两个关键问题。文中给出了分组识别的解决思路;为降低对同步的要求、支持较低成本的NSLA监测,除IPTD外其余参数均可容忍出入测量点之间存在有限的时钟不同步。此外,综合应用特点、用户感知、IPv6协议等因素,讨论了面向应用NSLA的QoS参数设定。最后设计了一个包括采集器、前端机、分析机、原始数据库和结果库等部件的NSLA监测系统,采用ON-OFF系统抽样方式被动监听自然流量,在各部件的协作下可实现各QoS参数的测量。

After the demands for network bearer service SLA （NSLA） in NGI are analyzed,taking possible application scenarios of NSLA as well as new features of IPv6 into account,this paper defines four QoS parameters for IPv6 NSLA：IP packet transfer delay （IPTD）, IP packet delay variation （IPDV）, IP packet fail ratio （IPFR） and IP packet throughput capability （IPTC）,where IPTC is suitable for characterizing the ability of IP network section ensemble to sustain a given traffic pattern. Packet recognition and clock synchronization are two key issues for IPv6 NSLA monito- ring. In this paper an approach to packet recognition is proposed, and to weaken synchronization demands and allow NSLA monitoring at lower cost,all QoS parameters but IPTD are rendered to be tolerant to limited unsynchronization between clocks of an ingress measurement point （MP） and its corresponding egress ones. Moreover we discuss the selec- tion of QoS parameters for application-oriented NSLA based on factors of application features, user perception and IPv6 protocol. Finally,a NSLA monitoring system consisting in meters, front processors, analyzers, raw data databases and result databases is designed. It adopts ON-OFF systematic sampling method to monitor natural traffic passively, and measure QoS parameters timely under the collaboration of all components of the system.