EDM01-36v10 DAG_9.2X2_Card_User_Guide - Synchronizing clock time
©2010 - 2012 Endace Technology Ltd. Confidential - Version 10 - May 2012
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Two cards no reference
Overview
If you are using two DAG cards in a single host computer with no reference clock, you must synchronize
the DAG cards using the same method if you wish to compare the timestamps between the two DAG
cards. You may wish to do this for example if the two DAG cards monitor different directions of a single
full-duplex link. You can synchronize the DAG cards in two ways:
•
One DAG card can be a clock master for the second. This is useful if you want both DAG cards to be
accurately synchronized with each other, but not so for absolute time of packet time-stamps, or
•
One DAG card can synchronize to the host and also act as a master for the second DAG card.
Synchronizing with each other
Although the master DAG card’s clock drifts against UTC, the DAG cards will be locked together. This is
achieved by connecting the time synchronization connectors of both DAG cards using a
DUCK crossover
cable
(page 62) - a 4-pin to RJ45 Adapter may be required.
Configure one of the DAG cards as the master so that the other defaults to being a slave as follows:
dagclock –dX none overout
(Where X is the device number of the DAG card you want to configure).
Output:
muxin none
muxout over
status Not Synchronised Threshold 596ns Failures 0 Resyncs 0
error Freq 0ppb Phase 0ns Worst Freq 213ppb Worst Phase 251ns
crystal Actual 100000000Hz Synthesized 67108864Hz
input Total 0 Bad 0 Singles Missed 0 Longest Sequence Missed 0
start Thu Apr 28 14:48:34 2007
host Thu Apr 28 14:48:34 2007
dag No active input - Free running
Note:
The slave DAG card configuration is not shown as the default configuration will work.
Synchronizing with host
To prevent the DAG card clock time-stamps drifting against UTC, the master DAG card can be
synchronized to the host computer’s clock which in turn utilizes NTP. This provides a master signal to the
slave DAG card.
Configure one DAG card to synchronize to the computer clock and output a RS-422 synchronization signal
to the second DAG card as follows:
dagclock –dX none overin overout
(Where X is the device number of the DAG card you want to configure).
Output:
muxin over
muxout over
status Synchronised Threshold 11921ns Failures 0 Resyncs 0
error Freq -691ppb Phase -394ns Worst Freq 147ppb Worst Phase 424ns
crystal Actual 49999354Hz Synthesized 16777216Hz
input Total 87464 Bad 0 Singles Missed 0 Longest Sequence Missed 0
start Wed Apr 27 14:27:41 2007
host Thu Apr 28 14:59:14 2007
dag Thu Apr 28 14:59:14 2007
Note:
The slave DAG card configuration is not shown, the default configuration is sufficient.
