[Planetlab-users] question about packet loss

[Andy Bavier]

Hi,

In your experiment, are both the sender *and* receiver PlanetLab
nodes?  If so, can you retry your experiment with only the sender or
receiver being a PL node?  I would expect the packet loss to occur on
the sending side, since PL doesn't do any limiting of receive
bandwidth.

If you can give me a way of reproducing your problem on some nodes,
I'll look into it more closely.

Andy

On Fri, Aug 8, 2008 at 8:02 AM, Daekyeong Moon <dkmoon at cs.berkeley.edu> wrote:
> Hi,
>
> I'm seeing weird udp loss.
> I'm replaying traffic traces from some Internet application.
> The replayer is a very simple udp application injecting packets from a pcap
> file according to the packet interval recorded in the file.
>
> Each sender generates at most 50 udp packets per second for 2 minutes, and
> each packet is 300 bytes on average.
> So, each sender consumes about 120Kbps, which is not much.
>
> A receiver receives packets from 7 senders (approximately 840Kbps), and
> reports timestamp using SO_TIMESTAMP.
> But, I found that the receiver sometimes doesn't receive any packet for more
> than 10 seconds.
> (select() call with 10 second timeout also fires.)
>
> Since, the traces don't have such big gap and the receiver receives from the
> 7 senders, this is quite abnormal.
> I repeated 200 times with random planet lab nodes in the US, and I don't
> think it's the issue of particular nodes.
>
> I'm just guessing it could be related to the receiver's bandwidth
> limitation.
> (e.g. dropping all packets until the next time window if bandwidth usage in
> a certain time window exceeds the Shared BW limit)
>
> Anybody experienced the same issue?
>
>
> Thanks,
>
> DK
>
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