Masterclock
GMR
User
Manual
v2
–
2016.12
56
Precision
Time
Protocol
(PTP
–
IEEE
1588)
IEEE
1588
‐
2008
defines
the
Precision
Time
Protocol
(PTP)
with
a
goal
of
achieving
very
high
precision
for
time
‐
synchronization
over
a
packet
‐
based
network
such
as
Ethernet.
The
most
important
innovation
of
1588
is
the
introduction
of
“hardware
‐
assisted
time
stamping:”
time
‐
stamping
embedded
in
the
PTP
messages
using
special
1588
Ethernet
hardware.
This
is
the
key
difference
from
NTP.
All
GMR1000/GMR5000’s
that
have
PTP
available
use
this
hardware
assisted
time
‐
stamping.
In
networks
which
have
a
PTP
infrastructure,
sub
‐
microsecond
accuracy
is
possible.
If
the
network
does
not
have
a
PTP
infrastructure
(standard
switches
which
do
not
have
PTP
time
‐
stamping),
accuracies
of
better
than
100
microseconds
can
be
achieved
(assumes
the
PTP
endpoints
support
PTP
hardware
time
‐
stamping,
i.e.
the
grandmaster
and
the
slave).
On
the
GMR5000,
PTP
can
be
ordered
at
the
time
of
purchase
or
as
a
field
upgrade
software
option.
For
a
GMR1000,
PTP
must
be
ordered
at
the
time
of
purchase.
The
GMR1000
cannot
be
field
upgraded.
By
default,
a
GMR1000/GMR5000
is
an
ordinary
clock
(i.e.
it
can
be
a
master,
slave,
or
transparent).
The
two
ports
on
a
GMR5000
are
also
a
transparent
clock.
CONFIGURATION
METHODS
PTP
configuration
can
be
done
using
either
WinDiscovery,
SSH,
or
telnet.
WinDiscovery
offers
basic
and
advanced
configuration
options.
SSH
and
telnet
allow
the
user
to
set
one
of
the
default
profiles
described
Annex
J
of
the
IEEE
Std
1588
‐
2008.
Individual
settings
of
the
various
PTP
parameters
is
also
available
via
telnet/SSH.
WINDISCOVERY
PTP
CONFIGURATION
To
configure
using
WinDiscovery,
follow
the
standard
steps
to
discover
a
PTP
capable
device.
Then
select
the
device
and
open
the
Device
Settings
dialog.
If
PTP
is
available,
the
“Precision
Time
Protocol”
button
will
be
available.
Click
the
button
to
open
the
PTP
configuration
dialog.
The
dialog
allows
you
to
enter
the
basic
PTP
settings.
The
network
protocol
used
is
UDP
(Layer
3).
A
future
release
is
planned
which
will
support
802.3
(Layer
2)
and
PTP
profiles
(such
as
E2E
default
profile,
P2P
default
profile,
and
others).
Default
Domain
A
domain
consists
of
one
or
more
PTP
devices
communicating
with
each
other.
The
default
domain
for
PTP
devices
is
domain
“0”.
Multiple
domains
are
allowed
and
the
input
range
is
0
to
127.
All
devices
will
receive
all
PTP
packets
but
they
will
only
process
and
respond
to
packets
within
their
configured
domain
number.
Priority
#1
and
#2
Priority
is
one
of
several
parameters
used
to
determine
which
device
on
the
network
will
be
the
grandmaster.
The
lower
the
number,
the
higher
the
priority
with
priority
0
being
the
highest.
The
range
of
values
is
0
‐
255.
Priority
#1
is
used
early
in
the
grandmaster
selection
process.
Priority
#2
occurs
late
in
the
selection
process.