High availability IEEE 1588 nodes over IEEE 802.1aq Shortest Path Bridging networks

The modern industrial and substation automation Ethernet networks have demanding requirements about high availability. Recently, the IEEE 802.1 WG proposes the IEEE 802.1aq, also known as Shortest Path Bridging, to manage Ethernet redundant networks. The IEEE 1588 protocol can exploit the SPB capabilities to manage multiple paths in order to improve synchronization availability. In the paper, the possibility to send copies of IEEE 1588 messages over multiple paths has been analyzed. In particular, the attention has been focused on the combining algorithms in the slaves, which is used to recover the time from multiple sources. In details, some specific fault tolerant combining algorithms, based on synchronization quality estimation have been proposed. The considered solutions are compared to traditional approaches under fault conditions by means of a specifically developed simulation environment.