[Planetlab-users] TCPDUMP response side traffic lost

[Hecker W]

Thanks Sapan. Please let me know the domain name of those beta nodes.
I will test again.

-Zhichun

On Mon, Jul 21, 2008 at 12:40 PM, Sapan Bhatia <sapanb at cs.princeton.edu> wrote:
> Hi Hecker,
>
> Greg Banks wrote a script that reproduces the case in which a raw
> socket intermittently misses TCP payloads. I hope that this problem
> will be fixed in the next RC, which Stephen is going to build and roll
> out to the beta nodes today. I'll ask you to test your program again
> on these freshly installed beta nodes.
>
> Sapan
>
>
>
>
> On Mon, Jul 21, 2008 at 2:09 PM, Hecker W <heckerme at gmail.com> wrote:
>> Hi Sapan,
>>
>> Please let me know if you understand the problem well now. Or you need
>> anything from us. Thanks.
>>
>> -Zhichun
>>
>> On Tue, Jul 15, 2008 at 5:07 PM, Hecker W <heckerme at gmail.com> wrote:
>>> Thanks Sapan. I just saw your message today.
>>>
>>> The silence period I mentioned is not only for the TCP handshakes but
>>> also for the payload packets.
>>>
>>> I did some tests on the machine you mention in another email
>>> (plantlab-7 and echo). I have put the traces I produced by downloading
>>> files in different size from my university online at
>>> http://mot.cs.northwestern.edu/Planetlab/.
>>>
>>> You can take a look at the traces to see the problem.  I have tried
>>> different files with different sizes on the planetlab-7 and echo. .
>>> For the traces captured on echo.cs.princeton.edu, the incoming traffic
>>> always have loses. For the
>>> traces of planetlab-7, in some cases I can get full traces even with
>>> SYN/ACK. But in other cases it repeated the behavior I mentioned. I
>>> notice after the stabilization period, there are no noticeable packet
>>> loss even when the downloading speed is high, so it seems not due to
>>> the disk bottleneck.
>>>
>>> Here are the traces and corresponding file sizes
>>> TRACE           FILESIZE
>>> testfull*pcap   4572765
>>> testsmall*pcap  25376
>>> testtiny*pcap   2219
>>>
>>> For planetlab-7 node
>>> testfull2.pcap, testsmall1.pcap have obvious packet loss at the
>>> initial silence period.
>>>
>>> Thanks,
>>> -Zhichun
>>>
>>>
>>> On Mon, Jul 14, 2008 at 2:42 PM, Sapan Bhatia <sapanb at cs.princeton.edu> wrote:
>>>>
>>>> Hi Zhichun,
>>>>
>>>> I can't reproduce this problem. I tried some simple tests (wget a
>>>> small file, wget a big file) but I could capture all incoming packets.
>>>>
>>>> Is the initial period of silence that you've encountered restricted to
>>>> the TCP handshake? If that's the case, then it's expected - and you
>>>> need to do something special to be able to see it. But you should not
>>>> be missing any payload packets because of this.
>>>>
>>>> If not, then could you give me a test case to work with?
>>>>
>>>> Sapan
>>>>
>>>> On Thu, Jul 10, 2008 at 9:47 PM, Hecker W <heckerme at gmail.com> wrote:
>>>> > I need to issue HTTP requests from Planetlab nodes and
>>>> > to dump the whole TCP connection traces. I found it worked
>>>> > on the FC4 version. But for the FC8 version, after the initial
>>>> > SYN packet sent out, I cannot capture the server response
>>>> > traffic until 0.6 second later. All the packets responded from
>>>> > web servers are lost within this 0.6 second time window. After that
>>>> > I can get all the traffic from both side.  I tried the big web objects to
>>>> > make
>>>> > sure its downloading time is longer than 1 seconds, and find this problem is
>>>> > persistent.
>>>> >
>>>> > I am not sure whether it is due to the new version of Planetlab needs
>>>> > 0.6 seconds to recognize that the new connection is issued so that it begin
>>>> > to
>>>> > allow TCPDUMP to see the packets?
>>>> >
>>>> > I guess it is not expected behavior, doesn't it? I did not use any raw
>>>> > socket API.
>>>> >
>>>> > The problem is similar to the problem mentioned by Greg in the previous
>>>> > post.
>>>> >
>>>> > If anyone needs the pcap trace to see the problem please reply the post. I
>>>> > will make it available online.
>>>> >
>>>> > Thanks
>>>> > -Zhichun
>>>> >
>>>> >
>>>> >
>>>> >
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>>>> >
>>>>
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