Masterclock
GMR
User
Manual
v2
–
2016.12
57
Delay
Mechanism
Delay
Mechanism
is
the
method
used
to
calculate
the
network
path
delays.
All
devices
on
the
network
must
use
the
same
delay
mechanism
(even
if
they
are
in
different
PTP
domains).
End
To
End
(E2E)
only
requires
the
master
and
slave
to
support
PTP.
It
does
not
require
the
network
infrastructure
to
support
PTP.
If
the
intervening
infrastructure
of
the
local
network
does
not
support
PTP,
accuracies
of
20
‐
100
microseconds
can
typically
be
achieved.
If
the
intervening
network
devices
does
support
E2E
PTP
(i.e.
a
transparent
clock)
sub
‐
microsecond
accuracies
can
be
achieved.
Peer
To
Peer
(P2P)
reduces
the
overall
network
traffic
and
can
improve
the
accuracy
compared
the
E2E,
but
all
of
the
network
infrastructure
must
support
the
P2P
delay
mechanism.
Synchronization
mode
Two
methods
are
available
for
sending
time
stamps
across
the
network,
One
Step
and
Two
Step.
Assuming
all
network
devices
do
their
time
stamping
in
hardware
(in
general
this
should
be
true,
and
is
true
for
all
Masterclock
equipment)
both
methods
will
give
an
accurate
time.
If
there
are
a
large
number
of
PTP
devices,
One
Step
is
preferred
because
it
requires
fewer
packets.
Announce
Interval
Announce
interval
specifies
the
time
interval
between
successive
Announce
messages.
The
Announce
message
is
used
by
the
devices
on
the
network
to
determine
which
device
should
be
the
grandmaster.
Typically,
a
value
of
1
or
2
seconds
is
recommended.
Sync
Interval
Sync
Interval
specifies
how
often
the
grandmaster
sends
a
Sync
message
which
starts
the
process
of
updating
the
time
in
a
PTP
slave.
Typically,
a
value
of
1
or
2
seconds
is
recommended.
To
set
PTP
back
to
defaults,
click
the
“Set
PTP
to
defaults
and
reboot
button”.
Answering
‘yes’
will
perform
the
action
and
the
GMR1000/GMR5000
will
automatically
reboot.
After
rebooting,
it
will
take
approximately
30
seconds
before
the
reboot
process
is
completed.
If
this
device
is
the
grandmaster,
it
will
typically
another
30
seconds
before
devices
on
the
network
will
synchronize
to
it.
After
30
seconds,
close
the
“Device
Settings”
dialog
and
re
‐
open
it
to
refresh
the
PTP
settings.
If
needed,
the
user
can
select
the
“Advanced
(data
sets)”
button.
This
gives
the
user
access
to
the
low
level
PTP
data
sets
defined
in
the
PTP
–
IEEE
1588
standard.
It
is
beyond
the
scope
of
this
document
to
discuss
the
PTP
data
sets.
Please
refer
to
online
sources
for
help
with
these
values.
See
the
detailed
description
of
the
telnet/SSH
PTP
interface
to
get
additional
information
for
settings
in
the
data
sets.
PTP
CONFIGURATION
USING
TELNET/SSH
To
login
via
telnet
or
SSH,
first
determine
the
IP
address
of
the
device.
This
can
be
accomplished
by
using
WinDiscovery
or
momentarily
pressing
the
Reset
button.
When
the
reset
button
is
pressed
for
a
moment
the
IPv4
and
IPv6
address
will
be
shown
on
the
front
panel
display.
NOTE:
pressing
the
Reset
button
for
more
than
one
second
will
cause
the
device
to
set
itself
back
to
defaults.
The
default
telnet
password
is
“public”.
There
is
no
user
name.
The
default
user
name
for
SSH
is
“public”
and
the
password
is
“publicpass”.
Example
SSH
settings
for
Teraterm
are
shown
to
the
left.
