Synchronous Ethernet Test

For most, the migration to an all-Ethernet or all-IP network will be a gradual process as network operators endeavor to maximize the lifespan of their existing TDM assets. However, the pace is quickening with the development of the IEEE 1588v2 standard. This standard enables the backhaul network to migrate to all-Ethernet, which provides much-required bandwidth at a far lower cost-per-bit. It is of significant interest to network operators seeking to grow their revenue by capitalizing on bandwidth-hungry applications like mobile broadband, music and video downloads.

The Synchronization Challenge

Although Ethernet has been the technology of choice for a range on LAN and WAN applications for decades, using it in the mobile backhaul network presents a major challenge. Here, accurate synchronization of base stations to nanoseconds accuracy is critical to minimize service disruptions and eliminate dropped connections as calls move between adjacent cells. Highly accurate synchronization also ensures that the radio spectrum is not spread into the adjacent channels. Plus, without stringent phase synchronization, the multiple signals in LTE’s multiple-input/multiple-output (MIMO) architecture can simply cancel one another out. And this is where IEEE1588v2 comes in.

IEEE1588v2 (also known as Precision Time Protocol, PTP) is an industry-standard protocol that enables the precise transfer of frequency and time to synchronize clocks over packet-based Ethernet networks. It synchronizes the local slave clock on each network device with a system Grandmaster clock and uses traffic time-stamping, with sub-nanoseconds granularity, to deliver the very high accuracies of synchronization needed to ensure the stability of base station frequency and handovers. Timestamps between master and slave devices are sent within specific PTP packets and in its basic form the protocol is administration-free.

The Timestamp

Of course, the precision and performance of the IEEE 1588v2 protocol is based on the precision of the timestamp. The timestamps of incoming and outgoing packets clearly need to be recorded and assessed to ensure synchronization of master and slave devices. Differences in time and frequency between clocks and subsequent equipment corrections need to be evaluated, while clocks must be measured to ensure they are within their specified limits. Further, delays and drifts in sync and their effect on the transfer of timing through the network need to be considered too.

Evaluating Packet Transport

Calnex Solutions has extensive experience in sync and packet testing technologies. The Calnex Paragon family enables you to offer independently proven packet-transport products that not only meet industry standards, but reliably work under real-world conditions too.

Uniquely, the Calnex Paragon lets you capture real-world Packet Delay Variation (PDV) profiles from your existing network and replay those same profiles in a controlled lab environment, enabling you to prove your 1588v2, CES and NTP Products will work in the complex world of Ethernet switches, routers and gateways before deployment.

The Paragon-i tool allows Installation and Troubleshooting in the networks to guarantee quality of Next-gen Ethernet Mobile Backhaul networks. The test files from these tools can also be replayed in the Calnex lab systems to re-create network issues and conditions.