Re: [ns2]: TCP-connections get pruned ?!

["Christoph Haenle" <christoph@starburstcom.com>]

Hi Kannan,

> COuld you send me a copy of your simulation script?

> 
> > Hi everybody,
> > 
> > I just setup a large network with a couple of TCP-connections and an
SRM
> > connection in ns-2.0b18.
> > First, the TCP-connections start and later (>3sec) the SRM agents join
the
> > multicast-group 0x8001.
> > 
> > I looks to me that for some strange reason, the traffic originating
from
> > TCP-connections is treated and routed like multicast traffic, i.e. it
is
> > broadcast along some spanning tree and pruned back:
> > 
> > Here is the relevant part of my tracefile:
> > 
> > ======================================
> > [...]
> > + 0.0370431 71 69 tcp 1000 ------ 0 71.12 198.1 0 1
> > - 0.0370431 71 69 tcp 1000 ------ 0 71.12 198.1 0 1
> > + 0.0378431 69 70 tcp 1000 ------ 0 71.12 198.1 0 1
> > - 0.0378431 69 70 tcp 1000 ------ 0 71.12 198.1 0 1
> > + 0.0378431 69 72 tcp 1000 ------ 0 71.12 198.1 0 1
> > - 0.0378431 69 72 tcp 1000 ------ 0 71.12 198.1 0 1
> > + 0.0378431 69 182 tcp 1000 ------ 0 71.12 198.1 0 1
> > - 0.0378431 69 182 tcp 1000 ------ 0 71.12 198.1 0 1
> > + 0.0386431 70 69 graft 80 ------ 30 70.0 69.0 -1 2
> > - 0.0386431 70 69 graft 80 ------ 30 70.0 69.0 -1 2
> + 0.0386431 72 69 graft 80 ------ 30 72.0 69.0 -1 3
> > - 0.0386431 72 69 graft 80 ------ 30 72.0 69.0 -1 3
> > + 0.0430244 182 141 tcp 1000 ------ 0 71.12 198.1 0 1
> > - 0.0430244 182 141 tcp 1000 ------ 0 71.12 198.1 0 1
> > [...]
> > 
> > The packet with sequence number 1 originates at node 71 and has
destination
> > 198. As shown, it gets routed first to node 69, but then node 69 routes
it
> > to node 70, 72 and 182 simultaneously for some reason. Furthermore,
node 70
> > and 72 send back a prune (which appears as a "graft" in the logfile due
to
> > a minor bug, but it's actually a prune).
> > 
> > Can anybody tell me what's going on here?
> > 
> >     TX,
> >        
> >        -Chris.
> > 

I'd wish I could. I'm using a graphical front end (TkIned) for
interactively setting up network topology, traffic, etc. I use a tcl-script
to interact between Tkined and ns, thus, I don't actually have a script
that is interpreted by ns.
I checked if I easily could generate one with my interactive configuration
program, but it appears to be a heavy task. I'll thus have a closer look
myself at the problem and post another mail if I can't get the problem
fixed.

Thanks so far,

      -Chris.