<s>
PTPd	B-Protocol
is	O
an	O
open	O
source	O
implementation	O
of	O
the	O
Precision	B-Protocol
Time	I-Protocol
Protocol	I-Protocol
for	O
Unix-like	B-Operating_System
computers	O
.	O
</s>
<s>
PTPd	B-Protocol
is	O
a	O
complete	O
,	O
BSD	O
licensed	O
,	O
open	O
source	O
code	O
implementation	O
of	O
the	O
IEEE	B-Protocol
1588-2008	I-Protocol
PTP	O
specification	O
.	O
</s>
<s>
Currently	O
only	O
Unix-like	B-Operating_System
computers	O
can	O
run	O
the	O
software	O
,	O
but	O
this	O
essentially	O
means	O
that	O
FreeBSD	O
,	O
Linux	O
,	O
Mac	O
OSX	O
,	O
Minix3	O
and	O
QNX	O
computers	O
can	O
participate	O
in	O
PTP	O
networks	O
.	O
</s>
<s>
PTPd	B-Protocol
can	O
act	O
as	O
a	O
master	O
on	O
a	O
system	O
with	O
an	O
external	O
time	O
source	O
,	O
such	O
as	O
a	O
GPS	O
card	O
,	O
or	O
NTP	O
running	O
as	O
a	O
client	O
.	O
</s>
<s>
ptpd2	O
was	O
intended	O
to	O
be	O
a	O
complete	O
open	O
source	O
implementation	O
of	O
the	O
IEEE	B-Protocol
1588-2008	I-Protocol
(	O
PTPv2	O
)	O
PTP	O
specification	O
.	O
</s>
<s>
ptpv2d	O
is	O
GPL	O
re-licensed	O
open	O
source	O
code	O
of	O
IEEE	B-Protocol
1588	I-Protocol
version	O
1	O
,	O
version	O
2	O
and	O
IEEE	B-Protocol
802.1AS	I-Protocol
including	O
hardware	O
timestamping	O
for	O
Freescale	O
MPC831x	O
family	O
of	O
processors	O
.	O
</s>
<s>
PTPd	B-Protocol
accuracy	O
depends	O
on	O
how	O
IEEE	B-Protocol
1588	I-Protocol
packets	O
are	O
timestamped	O
on	O
the	O
participating	O
machines	O
.	O
</s>
<s>
When	O
IEEE	B-Protocol
1588	I-Protocol
packets	O
are	O
timestamped	O
in	O
software	O
,	O
interrupt	O
latency	O
,	O
OS	O
scheduling	O
,	O
and	O
other	O
software	O
issues	O
reduce	O
the	O
accuracy	O
of	O
the	O
acquired	O
timestamps	O
,	O
and	O
therefore	O
,	O
the	O
accuracy	O
of	O
time	O
synchronization	O
.	O
</s>
<s>
The	O
presence	O
of	O
hardware-assisted	B-General_Concept
timestamping	O
makes	O
it	O
possible	O
to	O
acquire	O
more	O
precise	O
send	O
and	O
receive	O
timestamps	O
.	O
</s>
<s>
A	O
test	O
in	O
2010	O
on	O
an	O
Intel	O
Gigabit	O
network	B-Protocol
card	I-Protocol
noted	O
offset	O
converging	O
to	O
varying	O
between	O
around	O
1	O
–	O
100	O
microseconds	O
in	O
a	O
pure	O
software	O
implementation	O
,	O
and	O
to	O
around	O
a	O
microsecond	O
when	O
using	O
hardware-assisted	B-General_Concept
PTP	O
.	O
</s>
