User Documentation

User Manual Managed Switches
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power systems. All devices ultimately get their time from a clock known as the grandmaster clock. In
its basic form, the protocol is intended to be administration free.”
How does an Ethernet switch affect 1588 synchronization?
The following content is taken from the NIST website at http: //ieee1588.nist.gov/switch.htm:
“An Ethernet switch potentially introduces multi-microsecond fluctuations in the latency between the
1588 grandmaster clock and a 1588 slave clock. Uncorrected these fluctuations will cause
synchronization errors. The magnitude of these fluctuations depends on the design of the Ethernet
switch and the details of the communication traffic. Experiments with prototype implementations of
IEEE 1588 indicate that with suitable care the effect of these fluctuations can be successfully
managed. For example, use of appropriate statistics in the 1588 devices to recognized significant
fluctuations and use suitable averaging techniques in the algorithms controlling the correction of the
local 1588 clock will be the good design means to achieve the highest time accuracy.”
Can Ethernet switches be designed to avoid the effects of these fluctuations?
A switch can be designed to support IEEE 1588 while avoiding the effects of queuing. In this case
two modifications to the usual design of an Ethernet switch are necessary:
The Boundary Clock and Transparent Clock functionalities defined by IEEE 1588 must be
implemented in the switch.
The switch must be configured such that it does not pass IEEE 1588 message traffic using the
normal communication mechanisms of the switch.
Such an Ethernet switch will synchronize clocks directly connected to one of its ports to the highest
possible accuracy.
NOTE: The Weidmüller Premium Line managed Switches only supports
software-based IEEE 1588 PTP V1.