RE: [ns] Changing the header size for one-way TCP

[Neundorf Alexander <Alexander.Neundorf.extern@icn.siemens.de>]

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> -----Original Message-----
> From:	Lloyd Wood [SMTP:l.wood@eim.surrey.ac.uk]
> Sent:	Thursday, November 29, 2001 2:34 PM
> To:	Neundorf Alexander
> Cc:	ns-users@ISI.EDU
> Subject:	RE: [ns] Changing the header size for one-way TCP
> 
> On Thu, 29 Nov 2001, Neundorf Alexander wrote:
> 
> > 	Cool, after some years researching using ns you finally found
> > that it doesn't add header sizes....
> 
> Any simulation is by necessity an abstraction of details not
> considered important. ns was begun to investigate tcp algorithms,
> rather than engineering numbers; a computer science approach rather
> than engineering performance optimisation.
> 
> Most engineers complaining about the lack of the simulation detail
> wouldn't know how to write the simulator in the first place, never
> mind fix it...
> 
> L.
> 
> I suppose people will start complaining about IPSec and accurate
> header compression overhead next.
> 
> 
	The problem is that there is no layer architecture in ns, and that the development is kind of closed. After hacking ns for 4 months now, I think writing the basic simulator is a matter of, let's say some weeks at most. 
	The heavy part are the more advanced algorithms, e.g tcp, routing, advanced queueing and so on. But they could be ported.
	Now that there is the GNU Scientific Library (see www.lwn.net) together with the STL you wouldn't really have to care about an efficient scheduler, good random numbers and so on.
	Adding a ch->size_+=IP_HDR_SIZE+TCP_HDR_SIZE; in an appropriate place is not so hard IMHO.

	Bye
	Alex