Hirschmann RS20 User Manual page 108

Synchronizing the System Time in the
Network
Reference
(Master clock)
PTP
UDP
Delay + Jitter
IP
MAC
Phy
PTP Precision Time Protocol (Application Layer)
UDP User Datagramm Protocol (Transport Layer)
IP Internet Protocol (Network Layer)
MAC Media Access Control
Phy Physical Layer
Figure 28: Delay and jitter for clock synchronization
To get around the delay and jitter in the protocol stack, IEEE 1588
recommends inserting a special hardware time stamp unit between the MAC
and Phy layers.
Devices/modules with the "-RT" suffix in their names are equipped with this
time stamp unit and support PTP version 1. Media modules MM23 and
MM33 support PTP version 1 and PTP version 2.
The delay and jitter in the LAN increase in the media and transmission
devices along the transmission path.
With the introduction of PTP version 2, two procedures are available for the
delay measurement:
End-to-End (E2E)
E2E corresponds to the procedure used by PTP version 1. Every slave
clock measures only the delay to its master clock.
108
Delay + Jitter
Delay + Jitter
LAN
7.3 Precision Time Protocol
Local
(Slave clock)
PTP
UDP
IP
MAC
Phy
Basic Configuration
Release 6.0 07/2010