Laurent Montini

Synchronous ethernet: a method to transport synchronization

This article discusses the evolving transport architecture, covering some of the synchronization distribution problems to many endpoints where mobile backhaul and TDM emulation occur. It shows how synchronous Ethernet fits into both the Ethernet and synchronization architectures, and discusses how this helped development in standardization bodies. Standardization allows the key building blocks of Ethernet silicon and specific timing devices to be developed, which allows a robust system implementation to be constructed while allowing interworking with and migration from existing SONET/SDH-based transport infrastructure. Finally, results are shown that indicate a very high level of performance is achievable with Synchronous Ethernet not subject to the normal packet delay variation and traffic load conditions that can occur in packet based networks.

Development of the first IEEE 1588 telecom profile to address mobile backhaul needs

This article describes the work performed by ITU-T SG15Q13 for defining the first telecom profile based on the use of IEEE Std 1588-2008. The first profile is specifically developed for the distribution of frequency using unicast IPv4 transmission, and required adaptation of the IEEE1588 protocol to make it suitable for the telecom environment. The objectives, reasons, and results of this adaptation are explained in this article. Since the distribution of phase/time is also gaining importance in telecom, the article briefly discusses the objectives, reasons, and upcoming work for the definition of another profile that will leverage other functions and clocks defined in IEEE1588.

Impact of network equipment on packet delay variation in the context of packet-based timing transmission

The evolution of packet networks introduces a service requirement that neither packet equipment nor packet network were originally engineered to deliver, that is, accurate timing distribution. This article concentrates on the factors which affect the latency of packet delivery and specifically on the variable part of this latency. Change in the latency of packet delivery is called packet delay variation. PDV impacts the quality of timing distribution in the absence of specific assistance. We show the behavior of different packet equipment. We describe the possible root cause of the demonstrated behavior and put in perspective their effect on timing flows. We show that some equipment would require assistance in distributing timing packet, while others have limited bounded impact on PDV without any special assistance.