Model: MC-1-M (2U)
Doc. Ref. no. : - m05/om/101
Issue no. 14
Page 95 of 103
User’s Manual
15.7 Optional Module – PTP/IEEE-1588 Output
Precision Time Protocol (PTP or IEEE 1588) is a time synchronization protocol that offers sub-
microsecond accuracy over a standard Ethernet connection. This accuracy can be achieved by adding a
hardware time stamping unit to the network ports that are used for PTP time synchronization. The time
stamping unit captures the exact time when a PTP synchronization packet is sent or received. These
timestamps are then taken into account to compensate for transfer delays introduced by the Ethernet
network.
GPS master Clock provides full implementation of IEEE 1588-2008 ordinary clock. The PTP card can be
configured as PTP master. As a PTP grandmaster the GPS Master Clock typically synchronizes PTP
slaves on the network to UTC time. The user can also add time zone offset to UTC time and synchronize
PTP slaves to local time. The grandmaster’s accuracy with respect to GPS in healthy condition is within
±100ns. The PTP module of GPS master Clock supports PTP Version 2 as specified in IEEE 1588-2008
standard.
The existing network infrastructure components play a big role in a PTP network and directly influence the
level of accuracy that can be achieved by the clients. Asymmetric network connections degrade the
accuracy; therefore classic layer 2 and 3 Ethernet switches with their ‘store and forward’ technology are
not suitable for PTP networks and should be avoided. In large networks, special switches with built-in
PTP functionality help to maintain high accuracy even over several subnets and longer distances. These
components act as "Boundary Clocks" (BC) or "Transparent Clocks" (TC). They compensate their internal
packet processing times by using timestamping units on each port. When acting as a Boundary Clock,
they synchronize to the Grandmaster clock, and in turn act as a Master to the other subnets they are
connected to. When acting as a Transparent Clock, then the "residence time" of the Masters' Sync-
packet is measured and added to the packet as a correction value.
For configuration, available modes of IEEE1588-2008 protocol please refer the Appendix G.
