Re: [ns] A few issues (fulltcp, parameters...) related to webtraf.**

[Lloyd Wood <l.wood@eim.surrey.ac.uk>]

On Thu, 2 Aug 2001, David Ros wrote:

> Xiaowei Yang wrote:
> >
> > I recently downloaded ns-2.1b8 (released June 06, '01) and modified
> > the webtraf.** to support FullTcp. When the code tried to recycle a
> > FullTcp agent for multiple connections, I ran into the error that the
> > agent was not listening. Then I traced the FullTcpAgent code, it seems
> > that in FullTcpAgent, the "closed_" member variable is
> > redeclared. But, in the member function FullTcpAgent::reset(), this
> > variable is not reset (it calls the parent's reset function, which
> > resets its own "closed_" variable and does not reset the child's
> > "closed_" variable.). Therefore, if we want to reuse the same Fulltcp
> > agent for multiple connections, as the example shown in
> > tcl/ex/web-traffic.tcl, the closed_ remains 1 after
> > FullTcpAgent::reset() is called . In finish(), we will never reach the
> > point where the "done" procedure declared in tcl is called. It seems
> > to me there is no reason to redeclare the variable "closed_" again in
> > FullTcpAgent.
> > 
> 
> Hi,
> 
> This problem was already discussed and fixed by Felix Hernandez about a
> year ago; see his post:
> 
> http://www.isi.edu/nsnam/archive/ns-users/webarch/2000/msg03812.html

6 Aug 2000.
 
> Alas, the fixes suggested by Felix have -- AFAIK -- never been taken
> into account in newer versions of tcp-full...

Well, not exactly as Felix suggested.

http://www.isi.edu/cgi-bin/nsnam/cvsweb/ns-2/tcp-full.cc

1.81 Wed Aug 23 1:05:13 US/Pacific 2000 by haoboy 
Diffs to 1.80 

Fix for done{} callback by Felix Hernandex Campos
<fhernand@cs.unc.edu>

that doesn't address the reuse problem.

L.

> Besides, if you want to recycle FullTcp agents you'll also need to
> insert a call to reset() in FullTcpAgent::listen(). Otherwise, the
> "listening" agent may reply with "RST" segments (well, in fact, with the
> closest thing to a RST segment that tcp-full can generate) to every
> incoming segment.

<L.Wood@surrey.ac.uk>PGP<http://www.ee.surrey.ac.uk/Personal/L.Wood/>