[Planetlab-users] Re: Networking-related issues

[Hecker W]

Hi Sapan,

Any updates on the tcpdump issue? Do you know when the problem can be solved?

I recently figure out a way to "sort" the pcap trace, so that I can
correct the packet reordering introduced by Planetlab. Therefore if
you guys can deploy the current beta version (with packet reordering)
to all the node will be helpful to me.
NSDI deadline will be in about two months. It is best if we can have
some working system soon.

Thanks,
-Zhichun

On Mon, Jul 28, 2008 at 12:11 PM, Sapan Bhatia <sapanb at cs.princeton.edu> wrote:
> Well, somebody else actually observed it on planetlab-7 -- which is a better
> proof than several successful runs :)
>
> We'll keep you posted on any further developments.
>
> Sapan
>
> On Mon, Jul 28, 2008 at 3:07 PM, Hecker W <heckerme at gmail.com> wrote:
>>
>> 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
>> >
>
>
>
> --
> Sapan Bhatia
> www.cs.princeton.edu/~sapanb
>