[AG-TECH] Bridge Traffic/Router Issues

Thomas Uram turam at mcs.anl.gov
Sun Jul 19 20:21:16 CDT 2009

I am curious to look at the logfiles. The client does periodically  
connect to bridges and momentarily receive traffic from them. Do you  
have a record of the events on the router for comparison with the  
venue client logs?

On Jul 18, 2009, at 6:23 AM, "Mike Weaver" <weaver at ascr.doe.gov> wrote:

> OK, here's a weird one.  AG 3.2b1 on Fedora 11.  Started the venue  
> client w/
> default settings (in particular, unicast mode).  Went to the ANL venue
> server lobby.  Had some issues w/ RAT & D-Bus.  Did some  
> investigation and
> then got side-tracked with other tasks.  Sometime later I got bumped  
> from
> the venue server, but the client was still running.  Sometime later  
> still
> (sorry about the uncertainty of the timing) we started noticing  
> timeout
> issues on our LAN.  Web browsing would hang at various stages (DNS,
> connecting..., transferring...) for 20-30 seconds, every 10-15  
> minutes.
> Sometimes long enough to timeout the connection.  Clicking refresh  
> would
> bring the page up fine.  One other possibly relevant detail; I was  
> running
> the venue client as root.
> Users also started complaining about getting disconnected when  
> remoted in
> (RDP & Citrix).  Long story-short, we tracked it down to CPU  
> utilization
> spikes on our router (Cisco 7206, FastEthernet PIC).  The CPU  
> utilization
> (sometimes as high as 100%) was almost entirely from interrupts, no  
> process
> or memory issues.  While investigating NetFlow data, I notice a  
> large number
> of flows to the Auckland University bridge server in New Zealand.  I  
> found &
> exited the running venue client and the network problems stopped.  No
> guarantee that the venue client was to blame, but the problem  
> persisted
> steadily for almost a week, and hasn't reoccurred in over 2 days  
> coincident
> with exiting the venue client.  Pretty strong circumstantial  
> evidence IMHO.
> Looking at the venue client logs, the start of the network issues
> corresponded almost exactly with entering the lobby.  There are a  
> number of
> errors related to contacting bridges, but most are due to DNS issues  
> as we
> block a lot of central & southeast Asian networks  
> (.ru, .kr, .cn, .tw, .hk,
> etc...).  If someone is interested (hint hint Tom), I can provide  
> the logs,
> but their pretty big due the length of time the client was running  
> so I
> didn't want to post them to the list.
> Any idea what kind of traffic might be flowing between the venue  
> client and
> a bridge in these circumstances?  Anything periodic on the order of  
> every
> 10-15 minutes?  We're trying to characterize the data and determine  
> why the
> router was having issues with it.
> I'd appreciate any thoughts or ideas that anyone might have on this.
> Mike
> --
> Mike Weaver
> US Department of Energy
> ASCR/SC-21.1
> Germantown Building
> Voice: 301-903-0072
> Fax: 301-903-7774
> Email: weaver at ascr.doe.gov

More information about the ag-tech mailing list