RAD Data Communications has announced that its ETX-204A mobile demarcation device (MDD) has successfully met mobile backhaul requirements for high quality clock recovery over a packet switched network (PSN) in tests conducted by a major incumbent carrier in Asia. The tests featured live network conditions, including high volumes of multi-CoS data traffic transmitted together with clock signals over the same link.

RAD’s MDDs are equipped with the SyncToP suite of synchronization and Timing over Packet technologies, such as the IEEE 1588v2 (1588-2008) Precision Timing Protocol, that are designed to provide clocking accuracy at SDH/SONET levels over packet transport. “Since PSNs – which are where communications services are migrating – do not include inherent synchronization mechanisms, they require complementary clock transfer solutions and nowhere is this issue of greater importance than in mobile backhaul,” explains Shoval Bolotin, Head of Marketing, Synchronization and Timing over Packet Solutions at RAD Data Communications. “To ensure service quality for mobile traffic and avoid dropped calls, mobile networks require exceptionally stringent phase and frequency accuracy, which calls for equally exceptional high performance clocking capabilities,” he continues, “and that is precisely what we have demonstrated in these tests.”

Ensuring Mobile Service Quality with Backhaul Synchronization
Key synchronization metrics typically consist of fractional frequency offset (FFO) for frequency accuracy, as well as maximum time interval error (MTIE) and time deviation (TDEV) for clock (phase) stability. Mobile networks require an FFO of 16 ppb (parts per billion) or better and conformance with the ITU-T G.823/G.824 Traffic Interface MTIE limits. In some cases, the base station vendor or network operator will also require compliance with G.823/G.824 specifications for the Synchronization Interface MTIE and TDEV limits. “The SyncToP-enabled ETX-204A has conformed to all standards without fail,” says Bolotin, “both in the lab and in a live network environment.”

The tests consisted of two ETX-204A devices connected over a Gigabit Ethernet link: A feeder device receiving input from a Stratum 1 PRC (primary reference clock) via a 1588 Grand Master and a slave device connected to a clock tester to verify clock accuracy. The network between MDDs included Layer 2 switches, as well as core and edge elements. In addition to the PTP clock streams, traffic included multi-priority data representing several classes of service. Test results clearly showed that the recovered clock was accurately “locked” to the PRC, without experiencing unacceptable wander or jitter impairments. Furthermore, by exercising traffic management and monitoring, the ETX-204A MDDs maintained consistent quality of service for critical clock streams and high priority data, even during congestion.

“These results exemplify the unique proposition RAD’s SyncToP-powered MDDs offer to backhaul operators,” concluded Bolotin. “With enhanced SLA assurance tools and Timing over Packet capabilities that include 1588v2, Synchronous Ethernet, NTR, and ACR, these multi-functional demarcation devices generate a lot of interest among carriers and backhaul providers, who need cost-effective solutions to deliver and manage their premium backhaul SLAs.”