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 Post subject: [Fixed] GNS 3 Bug ? "Frame is Too Long" from Wireshark
PostPosted: Fri Apr 13, 2012 8:07 am 
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Joined: Fri Apr 13, 2012 7:58 am
Posts: 1
Hello everybody,

I post here because I think I've found a Gns3's bug.
I use GNS 0.82 (last stable Wireshark, Winpcap, IOS 12.4-12)

I've a fonctionnaly topology ,i use EIGRP. In my topology , I want to test EIGRP load balancing.
Unfortunately, Wireshark bug ...
When i make Ping between differents computer of my topology, I can watch trafic with GNS3/Wireshark, no problem.
When I charge the network (with iperf, netcat of sftp for example), and look the trafic over Wireshark, I've the bug: "Frame too long" after few seconds. => Winpcap or Wireshark recevied / think recieved a frame longer than 65535 octets....

I've test several version of Wireshark and Winpcap , 2 differents computers (2003 server et Win XP) => same problem
What can I do ?




Last edited by flaviojs on Thu May 29, 2014 4:41 pm, edited 1 time in total.
fixed


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 Post subject: Re: GNS 3 Bug ? "Frame is Too Long" from Wireshark
PostPosted: Tue Nov 13, 2012 7:32 pm 
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Joined: Tue Nov 13, 2012 7:15 pm
Posts: 2
I get the same error... running gns3 under windows7x64.

It's not possible for me to capture real-internet traffic between two virtual routers (C3640) that i route through my virtual networt.

Any Ideas?


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 Post subject: Re: GNS 3 Bug ? "Frame is Too Long" from Wireshark
PostPosted: Thu May 22, 2014 1:43 pm 
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Joined: Thu May 22, 2014 1:38 pm
Posts: 1
The problem is still here. Do I understand correctly that real interface speed on interfaces in GNS3 is 1mbit/s ?


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 Post subject: Re: GNS 3 Bug ? "Frame is Too Long" from Wireshark
PostPosted: Wed May 28, 2014 1:13 pm 
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Joined: Wed May 22, 2013 7:48 am
Posts: 93
Location: Portugal
Related link: http://ask.wireshark.org/questions/2362 ... with-gns-3

Ok, seems like GNS3 uses the dynamips filter called "capture" to dump packets to a .cap file.
Which means I can probably fix it by splitting big packets into multiple chunks.

Can you provide me with a capture file or _detailed_ instructions on how to trigger it?
Different changes might be needed depending on what is triggering it:
* either it's sending a huge (tcp?) packet that is meant to be split by the network card during transmission
* or it's a bunch of packets sent together as one
* or another scenario I can't think of right now

PS-I wonder where libpcap/winpcap has the 64KiB packet limit? I can't find it...

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Dynamips maintainer and sporadic developer
https://github.com/GNS3/dynamips


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 Post subject: Re: GNS 3 Bug ? "Frame is Too Long" from Wireshark
PostPosted: Wed May 28, 2014 6:37 pm 
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Joined: Wed May 22, 2013 7:48 am
Posts: 93
Location: Portugal
All the limits I found:
  • WinPcap NICs (Network Interface Cards) have a packet limit of 32KiB (BPF_MAXBUFSIZE in pcap/bfp.h)
  • libpcap DLPIs (Data Link Provider Interfaces) have a packet limit of 32KiB or 64KiB
  • libpcap filters have a packet limit of 50KiB
  • the other cases aren't limited (analysis stuff ignored)

In short:
  1. libpcap/WinPcap doesn't have a global packet size limit of 64KiB
  2. the limits I found do not affect our particular case
  3. the file format supports packets up to 4GiB in size.

We are setting low snapshot values (max packet size) and we don't respect it's value when dumping.
I'll change it to be configurable, default to the max value supported by wireshark and respect it while dumping.

However the fact remains that there was a packet bigger than 64KiB, so I still need a sample capture file or detailed instructions on how to reproduce it.

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Dynamips maintainer and sporadic developer
https://github.com/GNS3/dynamips


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 Post subject: Re: GNS 3 Bug ? "Frame is Too Long" from Wireshark
PostPosted: Wed May 28, 2014 7:02 pm 
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Joined: Wed May 22, 2013 7:48 am
Posts: 93
Location: Portugal
Related bug report: https://github.com/GNS3/dynamips/issues/41

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Dynamips maintainer and sporadic developer
https://github.com/GNS3/dynamips


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 Post subject: Re: GNS 3 Bug ? "Frame is Too Long" from Wireshark
PostPosted: Thu May 29, 2014 4:40 pm 
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Joined: Wed May 22, 2013 7:48 am
Posts: 93
Location: Portugal
The issue has been fixed and will be a part of dynamips 0.2.13.

It ended up being a thread safety issue that could produce corrupt capture files.

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Dynamips maintainer and sporadic developer
https://github.com/GNS3/dynamips


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 Post subject: Re: [Fixed] GNS 3 Bug ? "Frame is Too Long" from Wireshark
PostPosted: Thu May 29, 2014 5:52 pm 
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Joined: Sat Oct 11, 2008 1:41 pm
Posts: 2668
Location: Canada
Excellent job :)



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Jeremy, GNS3 Programmer & Benevolent Dictator for Life.


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