Exfo FTB-800 Series for FTB-1 Manual de usuario descargar pdf (Pagina 549)

100

101

Glossary

NetBlazer 539

1588 PTP

 Peer Delay mechanism uses message Pdelay Request, Pdelay

Response, and if required Pdelay Response Follow Up. This

mechanism is restricted to topologies where each peer-to-peer port

communicates PTP messages with, at most, one other such port. Peer

Delay is not supported by the Telecom Profile.

In order to minimize traffic on the network, PTP can operate in different

modes:

 Two-way operation uses Sync/Follow Up, Delay Request, and Delay

Response messages.

 One-way operation uses only the Sync/Follow Up messages. This

mode of operation is used to synchronize a Client clock in frequency

only. The Master clock and Client clock phases are not aligned.

 Two-step clock mode uses the optional Follow Up message to carry

the T1 time stamp.

 One-step clock mode uses the Sync message to carry the T1 time

stamp; no Follow Up message is transmitted by the Master clock,

therefore less traffic on the network.

Client clock synchronization is achieved with a 2-part process:

 Part 1: Path delay measurement using bidirectional messages

Mean path delay measurement (MPD) = ((T2-T1) + (T4-T3)) / 2

 Part 2: Clock phase offset correction

Offset = (T2-T1) - MPD

The offset information is used by the Client clock to adjust the frequency of

its oscillator in order to keep the phase offset close to zero.

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Exfo FTB-800 Series for FTB-1 Manual de usuario Pagina 549

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