[tg] IP fragmentation issue.
Barbara Denny
b_a_denny at yahoo.com
Thu Apr 15 09:50:40 PDT 2004
Hi,
TG is an application. You are seeing what the
application would get if it used TCP. TCP does
affect the information bundling (Look more at
how TCP works) and the OS gets involved here
too. At the end of your data sending, you will
see TG at the sink got just as many bytes as
what was sent. If you want to see what is going in and
out of the network, use some type of sniffer
(like tcpdump or etherfind). The IP fragmentation
that goes on below is "invisible" to TG and TCP.
barbara
--- Arthur de Castro Callado <acc2 at cin.ufpe.br> 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
>
> _______________________________________________
> tg mailing list
> tg at postel.org
> http://www.postel.org/mailman/listinfo/tg
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