Endace Measurement Systems Limited
http://www.endace.com
EDM01.05-04r1 DAG 3.6GE User Manual
Copyright, all rights reserved.
22
Revision 7. 22 September 2005.
5.2.2 Two Cards no Reference Time Synchronization
Description
When two DAG cards are used in a single host PC with no reference
clock, the cards are to be synchronized in some way if timestamps
between the two cards are to be compared. For example, if two cards
monitor different directions of a single full-duplex link.
Synchronization between two DAG cards is achieved in two ways. One
card can be a clock master for the second, or one can synchronise to the
host and also act as a master for the second.
Synchronizing
cards
If both cards are to be accurately synchronized, but not so for absolute
time of packet time-stamps being correct, then one card is configured as
the clock master for the other.
Locking cards
together
Although the master card’s clock will drift against UTC, the cards are
locked together.
The cards are locked together by connecting the synchronization
connector ports of both cards with a standard RJ-45 Ethernet cross-over
cable.
Configure one of the cards as the master, the other defaults to being a
slave.
dag@endace:~$ dagclock –d dag0 none overout
muxin none
muxout over
status Not Synchronized Threshold 596ns Failures 0
Resyncs 0
error Freq 0ppb Phase 0ns Worst Freq 0ppb Worst Phase
0ns
crystal Actual 100000000Hz Synthesized 67108864Hz
input Total 0 Bad 0 Singles Missed 0 Longest Sequence
Missed 0
start Thu Apr 28 14:48:34 2005
host Thu Apr 28 14:48:34 2005
dag No active input - Free running
The slave card configuration is not shown, the default configuration is
sufficient.
Continued on next page
