[CentOS-devel] Use of PTPd on CentOS 6

James Hogarth

james.hogarth at gmail.com
Tue Jan 19 17:43:22 UTC 2016

On 18 Jan 2016 09:22, "Claudio Scordino" <claudio at evidence.eu.com> wrote:
> I need to create a reliable and accurate synchronization between two
CentOS 6 machines connected through a direct Ethernet connection.
> I've seen that on Linux several implementation of the IEEE 1588 Precision
Time Protocol (PTP) exist:
> PTPd:
> Apparently, this is the original implentation
> Apparently, it is still maintained
> PTPd2:
> A new version meant to supersede the previous implementation
> Apparently unmaintained
> For CentOS 6, available only in the EPEL repositories
> PTPv2d:
> A further implementation
> Unmaintained as well
> linuxptp:
> A specific implementation for Linux
> Maintained
> Available on the CentOS repositories
> Suggested by the RedHat documentation for both RedHat 6 and RedHat 7
> My questions follow:
> Why does the RedHat documentation suggest the use of linuxptp for RedHat
6 (based on Linux kernel 2.6) despite the linuxptp documentation says that
a Linux kernel version 3.0 or newer is needed ?

Because Red Hat backport many drivers and features so the 2.6.32 (not just
2.6) version number is totally irrelevant as to the actual features
available in the kernel.

> Which are differences between PTPd2 and Linuxptp in terms of reliability
and timing accuracy ?

No idea but there's probably a good reason RH picked up linuxptp as the
formally supported version and the other is only in EPEL and not supported
by them.

> Which one should I prefer on CentOS 6 and on CentOS 7, respectively ?

Keep in the same for both to ease your maintenance burden in your
configuration management.

> Why either PTPd2 and Linuxptp do not synchronize immediately and often
need me to start/stop the service several times or manually change system
time through date to make the machine synchronize ?

Sorry don't use it here so don't have a test bed... If there is a verbose
or debug arguments check those for more detailed logs.
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