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Re: [Testbed-admins] Event system questions
When I swap in or modify an experiment, the events are not
scheduled. I know it because I launch some "tcpdump" in the
nodes. Are there some log files to see when the events are
scheduled? I don't see my UDP packets (every 5ms during 20 secs with
a length of 500 bytes). But in the first 2 secs and every 10ms, I
see some UDP packets (not mine ones) of 62 bytes (ethernet length)
between the 2 nodes. What are these packets?
Hi. The notion of when an experiment has officially started might not
be obvious; it is when the experiment state changes to active (you can
see that in the web interface). This is also when the email that says
the experiment has swapped, is sent.
I have no idea what the other packets are. You can probably google for
information about how to use tcpdump info to dissect packets and
figure out what they are.
- How the nodes are synchronized? What precision you can get?
"Emulab nodes are kept in sync with NTP", but where the NTP server
is? boss? ops? When nodes boot I get the following:
The ntp server is typically ops.
In fact, what testbed are we talking about?
"Starting ntpd.
Oct 1 07:29:09 tbsdelay0 ntpdate[1021]: no server suitable for
synchronization found
WARNING: ntpdate failed!"
So I guess my nodes are not synchronized. What I have to modify?
Nodes configuration? Some tables? Emulab software installation?
There is supposed to be a CNAME in the local named file that directs
ntp.xxx.yyy to the local ops node. Do you have that CNAME?
- In the "at" command, how the "0.0 time" is specified? When I "Replay
events", I guess that the "0.0 time" is more or less when I select the
option in the web interface. Could I specify the "0.0 time" at
13:15, for
example, and the rest of the "+XX" events are scheduled accordingly?
No, there is no way to do this. It is probably not a difficult change
to the parser though, if you wanted to give it a try and send us
patches.
Lbs