... | ... | @@ -125,9 +125,8 @@ signal in the slave. This shift tracks changes in delay in the medium, |
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so as to guarantee constant (ideally zero) phase with respect to the
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master clock signal. With SyncE, if the transmission delay in your fiber
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changes, the phase of the clock signal you recover also drifts with
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respect to that in your master.
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The SyncE standard comprises of two elements:
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respect to that in your master. What's more, the SyncE standard
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comprises of two elements:
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1. slow protocol to configure the frequency distribution hierarchy in
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the network
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... | ... | @@ -136,15 +135,14 @@ The SyncE standard comprises of two elements: |
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In WR, the protocol (1) is not used which is rather uncommon in SyncE
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networks but it is allowed by SyncE. The timing characteristics (2) of
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SyncE have a lot of legacy burden (compatibility
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with SDH). Consequently, SyncE equipment must be tolerant to quite "bad"
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clock input. WR is not tolerant to the corner-cases required by SyncE,
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see the report on [SyncE Characteristics of a White Rabbit
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SyncE have a lot of legacy burden (compatibility with SDH).
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Consequently, SyncE equipment must be tolerant to quite "bad" clock
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input. WR is not tolerant to the corner-cases required by SyncE, see the
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report on [SyncE Characteristics of a White Rabbit
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Switch](https://www.ohwr.org/project/white-rabbit/uploads/6de0c67da6a12f470af5a921279711ce/WR-SyncE-characteristics-report.v3-2015-02-27.pdf)
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. Making WR PLL tolerant to clock characteristics required by ITU-T
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G.8262 might result in deterioration of WR performance (e.g. requires
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change in PLL bandwidth) or require much more expensive oscillator.
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change in PLL bandwidth) or require much more expensive oscillator.
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ITU-T itself recognized that the SyncE specification is outdated and
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most of SyncE equipment can do much better than the specifications.
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Therefore, ITU-T is working on enhanced SyncE
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... | ... | @@ -154,8 +152,9 @@ low priority, at the moment it seems that eEEC will not be directly |
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usable with WR.
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??Authors: Javier Serrano, Maciej Lipinski,
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[CERN](http://cern.ch??)
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\---
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[CERN](http://cern.ch??)
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-----
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## Switch management
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... | ... | |