[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
>
>
>
>
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