Televes OLT 769401, User Manual

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2.12.3.1 Ethernet without SyncE (e.g. 1000Base-T)
Systems without SyncE have the following characteristics:
Rx clock extracted from line (line timed)
Tx clock generated from free-running XO
Clock within 100 ppm (125 MHz+/- 0.01 percent)
No relationship between Rx and Tx
Each Ethernet interface (uni-dir or bi-dir) has own independent timing
2.12.3.2 Ethernet with SyncE (e.g. 1000Base-T)
Systems with SyncE have the following characteristics:
Rx clock extracted from line & transferred to timing engine
Tx clock generated from the timing card
Clock within 4.6 ppm when free-running
Tx clock uses traceable to PRC/PRS
Note SyncE clock input may replace XO or may be in addition to normal XO input
2.12.4 IEEE 1588v2
IEEE1588v2 (also known as Precision Time Protocol, PTP) is a two-way precision protocol independent of the physical layer with time and frequency
distribution protocol based on time-stamp information exchange 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 ITU-T defined profile of the IEEE 1588-2008 specification has been specifically optimized to support telecommunications applications such as
wireless Mobile Backhaul, GPON and LTE.
The OLT Equipment supports IEEE 1588v2 as the following standard type devices:
Ordinary Clock (Can be a Master or Slave clock)
Boundary Clock (Acts as a Master and a Slave clock)
Transparent clock
Following elements are defined:
Grandmaster
A network device physically attached to the primary time source. All clocks are synchronized to the grandmaster clock.
Ordinary Clock
An ordinary clock is a 1588 clock with a single PTP port that can operate in one of the following modes:
PTP Master: Distributes timing information over the network to one or more slave clocks, thus allowing the slave to
synchronize its clock to the master.
PTP Slave: Recovers the frequency and phase clock, from the timestamps sent by the Master.
Boundary Clock
The Boundary clock functions as both PTP master and slave. It acts as the slave to a Grand Master and derives the reference from
the Grand Master. Boundary clock starts its own PTP session with a number of downstream slaves. The boundary clock mitigates the
number of network hops and results in packet delay variations in the packet network between the Grand Master and Slave.