PTP网络非对称时延抖动修正算法设计与分析

Design and Analysis of Delay Asymmetry Jitter Correction Algorithm for PTP Network

为了改进PTPV2时间同步网络非对称时延抖动对主从时钟同步精度的影响,设计了传输报文的非对称时延抖动修正算法;基本思路是在主从时钟交换报文信息中,找出最佳报文用于从时钟的调整;采用两级过滤先进增强时间恢复算法,即使发生网络传输阻塞,也能筛选出未受阻塞的幸运报文用于时钟偏差估计;新算法能够很容易集成到PTPV2协议中,而不会影响基本的报文信息交换;实际测试结果表明,新设计的时间恢复算法,在普通交换机网络中,可有效抑制非对称时延抖动,主从时钟同步精度也可优于100ns。

In order to improve the slave synchronization accuracy with respect to the master clock for asymmetric communication links,a delay asymmetry correction algorithm is designed.The key ideal is filter clock updates devived from the master-slave message exchange,using ony good sampes for slave updates.The advanced enhanced time recovery algorithm which two consecutive filtering was proposed,make sure that only good samples are used to update the slave clock correctly under heavy traffic load in the network.The proposed algorithm can easily be integrated into PTPV2 protocols,and not influences the basic message exchange.The test results show that the new algorithm can effectively mitigation delay asymmetry jitter in the presence of various bursty bi-directional traffic loads and network conditions,the synchronization accuracy between master and slave clocks is batter than 100 ns.