[Planetlab-users] Re: Networking-related issues

[Hecker W]

I did my experiment in many runs. On planetlab-7 it always OK. However
on alice the packet always reordered. It looks like not a matter of
chance.

For my analysis it is important I can get the CORRECT pcap traces, so
that I can recover the files and other messages in the traces. My code
does not work on these reordered traces. I searched online and  did
not find any tool which can fix the reordering problem for the traces.
If possible, please fix the problem. Thanks a lot!

-Zhichun

On Mon, Jul 28, 2008 at 11:50 AM, Sapan Bhatia <sapanb at cs.princeton.edu> wrote:
> Hi Zichun,
>
> Somebody was experimenting with delta. Sorry about that. It has been
> restored to a working state, but in case you still see problems, please
> continue to use planetlab-7 and alice.
>
> planetlab-7 and alice have more-or-less the same software -- that you didn't
> notice the reordering issue on planetlab-7 is probably a matter of chance.
> We noticed the packet-reordering problem earlier today. How important is it
> for your analysis? Is it easy to work around, given that the packets are
> timestamped?
>
> Sapan
>
>
>
> On Mon, Jul 28, 2008 at 2:40 PM, Hecker W <heckerme at gmail.com> wrote:
>>
>> Hi Sapan,
>>
>> I have tested my code on alice,delta and planetlab-7. I got totally
>> different results on these three nodes!
>> 1) For planetlab-7, the problem has been solved. I have been
>> successfully run the TCPDUMP. I got the TCP SYN/ACK and all the
>> payloads. I have done tcp reassembly and recovered the file I
>> transfer. They are indeed same!
>> 2) For alice, I think I might get all the payload packets. However,
>> the TCP SYN/ACK packet comes AFTER the TCP ACK packet from the
>> senders, although TCP SYN/ACK packet's timestamp is earlier. In other
>> words, the tcpdump trace is not sorted by the timestamp which make my
>> analysis tool fail.
>> 3) For delta, I only get outgoing direction traffic (same for TCP and
>> UDP).
>>
>> If you guys can make every node like planetlab-7, my problem is
>> solved. Thanks a lot!
>>
>> If you guys need me to provide any trace or other information, please
>> just let me know.
>>
>> -Zhichun
>>
>> On Sun, Jul 27, 2008 at 11:14 PM, Sapan Bhatia <sapanb at cs.princeton.edu>
>> wrote:
>> > Hello,
>> >
>> > The following issues have (hopefully) been resolved on a set of alpha
>> > nodes (listed below). If you complained about any of them, then please
>> > kindly retry your code to verify the fixes.
>> >
>> > * Intermittent loss of TCP payload packets with packet sockets
>> > * Syn/Ack packets not showing up in tcpdump
>> > * TCP-related ICMP error messages not showing up in tcpdump.
>> >
>> > The nodes are: [alice,delta].cs.princeton.edu and
>> > planetlab-7.cs.princeton.edu.
>> >
>> > Please verify all three nodes, if possible.
>> >
>> > Thanks in advance,
>> > Sapan
>> >
>
>
>
> --
> Sapan Bhatia
> www.cs.princeton.edu/~sapanb
>