Wiki source code of Time Synchronization Source Failover
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6.1 | 7 | In real-world deployments, redundancy and recovery mechanisms are essential to ensure that accurate time synchronization is maintained should one of the time synchronization sources fail. |
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1.1 | 8 | This test aims to evaluate the time error measured at the output of each Telecom Boundary Clock after the primary time synchronization source/Grandmaster fails and a switch-over to the secondary Grandmaster is initiated. |
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6.1 | 10 | For this test, all the Boundary Clocks were directly locked to both Grandmasters (T-GMs); T-GM-A served as the primary T-GM and T-GM-B as the backup GM; for this, all BCs had local priorities configured to prioritize and lock to GM-A on PTP and SyncE. Two different Microchip TimeProvider® 4500 were used as GM-A and GM-B. |
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1.1 | 11 | We executed two different scenarios for this test, once with Microchip’s Sync-Only Redundancy feature enabled between both T-GMs. In the Sync-Only Redundancy feature, the two T-GMs are synchronized to each other and GNSS reference. We then simulated a “fiber cut” by disconnecting all the physical T-BC connections to T-GM-A to initiate the failover to T-GM-B; after a measurement period of 1000s including the failover, the measurement was restarted and all cables were reconnected to T-GM-A, initiating a switch back to T-GM-A from all T-BCs on PTP and SyncE. |
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| 13 | [[Figure 121: Test run 1, Sync-Only Redundancy disabled with Cable pull - Setup>>image:434865443411066881_5.17-cable.png||alt="Figure 121" width="550"]] | ||
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| 15 | For the second run, we disabled the Sync-Only Redundancy feature on the GMs and disconnected the GNSS from GM-A, causing the BCs to switch to GM-B; after measuring for 1000s including the failover, the measurement was restarted and the GNSS connection to GM-A was re-established, and all BCs locked back to GM-A on PTP and SyncE. | ||
| 16 | The Calnex Paragon-Neo PAM4 and the Keysight Time Sync Analyzer were used to measure the PTP and SyncE output of all the BCs. | ||
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| 18 | [[Figure 122: Test run 2, Sync-Only Redundancy disabled with GNSS disconnection - Setup>>image:434865443411001345_5.17-GNSS.png||alt="Figure 122" width="550"]] | ||
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| 20 | In both runs, a two-way time error threshold of the Class level of accuracy 6B was set, which is, as per ITU-T G.8271, +/- 130ns, but all BCs even passed 6C, which is defined as +/- 65ns. | ||
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6.1 | 21 | For the MTIE, the ITU-T G.823 E1 SEC wander limit mask was applied as the threshold throughout all procedures and switchovers, which, once again, all T-BCs were well within. |
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