Background

A Global Banking concern needed to measure end to end application latency across London in a test environment. One key element of the puzzle was missing however; the network latency measurement and monitoring equipment they employed needed a 1PPS signal derived from GPS in datacentres where access to the roof was just not possible.

They called upon Chronos’ time and timing expertise to solve this problem. The Bank had at first considered using two standalone Rubidium standards at the two sites: Chronos recommended the use of the Symmetricom telecom PTP TimeProvider equipment to transport a 1PPS between the two sites via Ethernet.

Chronos’ Network Expert Billy Marshall explained; “Although standalone Rubidium standards would give a very good inherent stability, there was no guarantee that over a six to eight week test envelope they would not significantly drift apart. The best option therefore was to use telecom profile PTP to transport timing across the same network as the data; in fact in this test environment we were not even able to set appropriate priority on the timing packets”.

A TimeProvider 5000 Grandmaster clock was employed at one end of the network; connected to a TimeProvider 500 PTP Slave at the other. Both clocks have a 1PPS output, and the time for the timestamps was derived from an external NTP source.

Synchronisation of the two 1PPS signals was in the order of one microsecond; a factor of a thousand more accurate than the Bank had actually hoped for.

Chronos has been the leader in synchronisation for telecom networks for twenty five years, and this vast knowledge of the issues involved in time and timing applications can readily be employed in other industry areas.

A spokesperson from the Bank said “I knew from how quickly Chronos understood our requirement and made their recommendation that we had contracted the right people. The whole exercise was conducted in a highly professional manner, and to get microsecond accuracy across these sites for the length of time we needed to make all our measurements was frankly astonishing”.

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