Re: [Testbed-admins] Event system questions

[Robert P Ricci <ricci@cs.utah.edu>]

Thus spake Manuel Requena on Thu, Oct 01, 2009 at 01:40:05PM +0200:
> 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?

Hard to say - many switches send synchronization packets (for spanning
tree, etc.), and this might be what they are - are the source MAC
adresses ones the belong to the nodes themselves?

None of the Emulab software should be automatically sending packets on
the experimental net (except for the traffic generators, if you have
them set up...)
 
> If I "Replay Events" in the web interface, I can see my UDP packets. What I
> have forgotten in order to launch the events when an experiment is created /
> swapped in?
> 
> Moreover, I have some general questions:
> 
> - 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:
> 
> "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?
> 
> - 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?
> 
> Best regards,
> Manuel
> 
> 
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-- 
/-----------------------------------------------------------
| Robert P Ricci <ricci@cs.utah.edu> | <ricci@flux.utah.edu>
| Research Associate, University of Utah Flux Group
| www.flux.utah.edu | www.emulab.net
\-----------------------------------------------------------