[tg] IP fragmentation issue.

[Hugues VAN PETEGHEM]

Hi,

Yes, I'm using Ethernet and I know that the IP MTU over Ethernet is 1500 
bytes. But as 'tg' is in the "application layer" (above "network layer" -> 
IP), IP fragmentation must be invisible for 'tg'. Isn't it ?

H

On Thursday 15 April 2004 15:50, Arthur de Castro Callado wrote:
> What network technology are you using? Ethernet?
>
> Ethernet frames must have up to 1500 bytes, no more. This limits the size
> of the packet in a way that when one wants to transmit segments with more
> than is allowed (bytes 1500 - headers), the segment will be divided into
> pieces before sending.
>
> Arthur.
>
> On Thu, 15 Apr 2004, Hugues VAN PETEGHEM wrote:
> > Hi all,
> >
> > I got an IP fragmentation problem using 'tg'. Here is the problem
> > statement :
> >
> > ---------                                      ---------
> >
> > | pc10 |--------------------------------| pc6 |
> >
> > ---------10.0.0.10               10.0.2.2--------
> >
> > I'm trying to generate a simple data flow from pc10 (10.0.0.10) to pc6
> > (10.0.2.2). Here are the 'tg' input files :
> >
> > # pc10
> > on 0:15 tcp 10.0.2.2.80
> > at 5 setup
> > at 6 arrival 0.5 length 2000
> > packet 300
> >
> > # pc6
> > on 0:15 tcp 0.0.0.0.80 server
> > at 1 wait
> >
> > After a couple of minutes, I use 'dcat' to transform the log files in
> > text files and here are the first lines of both files :
> >
> > # pc10
> > (...)
> > Event Time      Type            Address         Id      Length
> > -----------------------------------------------------------------
> >
> > 5.010170        Setup
> > 6.509204        Transmit        10.0.2.2.80     0       2000
> > 7.009049        Transmit        10.0.2.2.80     2000    2000
> > 7.508948        Transmit        10.0.2.2.80     4000    2000
> > 8.008956        Transmit        10.0.2.2.80     6000    2000
> > (...)
> >
> > >From the client side, everything goes perfectly. Each packet is sent to
> >
> > 10.0.2.2:80 every 0.5 second. These packet have a 2000 bytes length.
> >
> > # pc6
> > (...)
> > Event Time      Type            Address         Id      Length
> > -----------------------------------------------------------------
> >
> > 0.004769        Setup
> > 19.742468       Accept          10.0.0.10.1207  Association 5
> > 21.238312       Receive         10.0.0.10.1207  0       2000
> > 21.737539       Receive         10.0.0.10.1207  2000    1448
> > 21.737888       Receive         10.0.0.10.1207  3448    552
> > 22.237457       Receive         10.0.0.10.1207  4000    1448
> > 22.237830       Receive         10.0.0.10.1207  5448    552
> > (...)
> >
> > >From the server side, the first packet is well received, but after that,
> >
> > everyhing is "wrong". I mean, it receive the data, but fragmented.
> >
> > I think it is a 'tg' (or 'dcat') problem. Have someone faced this before
> > ? If not, could you try it and tell me if you have the same problem.
> >
> > Thanking you in advance :
> >
> > H
> > --
> > Hugues VAN PETEGHEM
> > Institut d'Informatique - FUNDP
> > ---------------------------------------------
> > Web : http://www.info.fundp.ac.be/~hvp/
> > _______________________________________________
> > tg mailing list
> > tg at postel.org
> > http://www.postel.org/mailman/listinfo/tg

-- 
Hugues VAN PETEGHEM
Institut d'Informatique - FUNDP
---------------------------------------------
Web : http://www.info.fundp.ac.be/~hvp/