An efficient method of reselecting Grand Master in IEEE 802.1AS

Abstract

Recently, IEEE 802.3 Ethernet network is not limited to be used as the sub-network of a vehicle but also can be used as backbone network of a vehicle. Audio/Video Bridge (AVB) standard is about the Ethernet technology that can be used as a backbone network in a vehicle. AVB provides time-synchronized low latency streaming service through the Ethernet. 802.1 AS protocol in AVB can synchronize the time between different nodes through Grand Master (GM) which is selected by the Best Master Clock Algorithm (BMCA). If the synchronization message of GM is not received by another node within timeout interval, the protocol selects a new GM in the network through BMCA. This method can occur the bunching error because of consecutive exchange of messages. This paper proposes an efficient method to re-synchronize GM's time. This proposed method is to use a table which indicates a pre-defined sequence of GM to reconfigure GM. As a result, the reconfiguration procedure of GM with the sequence table can decrease generated traffic and a time when operating an existing BMCA procedure. In addition, this proposed method reduces the residence time of the bridge to prevent bunching of consecutive messages. Therefore, this paper proposes more efficient method of reselecting the GM than the BMCA.