[brite-users] Top-down hierarchical topology generation seems not to work for me!!

Oliver Holland oliver.holland@kcl.ac.uk
Tue Aug 12 15:36:02 EDT 2003

hi Anukool,

Thanks for your reply. I was aware of how the hierarchical topology
generation in brite should work (as was explained by you).

By arb. units I simply mean arbitrary units, used to specify the plane
sizes or distances etc. in the simulation seeing as I don't know the
units used to specify HS etc (although I suspect they are km). I think I
have the correct parameters specified, but the outputs in the .brite
export don't seem to make sense. I specified the AS HS as 1000, and the
router HS as 100, but all of the resulting nodes in the generated
topology seem to be positioned in a 100*100 plane.

Please see the .brite export which I included in my previous post. The
parameters I used are listed at the top. Can you see where I went wrong?
Or can you send me a .brite output (using the Java exe) where you have
used the 2-level top-down topology generation with HS's for the AS's and
routers set as 1000 and 100 respectively. Sounds simple, but that is all
I am trying to do and I am very much bemused about why it doesn't work.

Thanks again,


On Tue, 2003-08-12 at 17:32, Anukool Lakhina wrote:
> Hi Oliver,
> I'm not sure what you mean by arb units.   What exactly are you trying to
> accomplish?  
> Recall that the HS parameter specifies the side of the big square and the
> LS parameter specifies the subdivision of that big square into smaller
> squares.   Since you're using the top down generation, you'll build an AS
> topology first in the plane specified by the HS and LS units of the AS
> model.  Then for each AS, you'll generate a router level topology in
> another plane, whose size is dictated by the HS and LS of the router
> model. 
> Anukool
> On 12 Aug 2003, Oliver Holland wrote:
> > Hi all,
> > 
> > Sorry if this is a no-brainer question.
> > 
> > The (top-down) hierarchical topology generation seems not to work for
> > me!! Am I missing some configuration parameters?
> > 
> > Using the configuration parameters I have specified (see attached file),
> > you would expect the ASs to be separated by a max ~1400 arb units (HS
> > for ASs specified as 1000 arb units), and the routers in each AS to be
> > separated by max ~140 arb units (HS for router level specified as 100
> > arb units). But the brite output I get seems to be only using the router
> > setting of HS (i.e. only separation of max ~140 arb units for nodes, and
> > positioning of all nodes in the topology in a 100*100 plane). Am I doing
> > something wrong? Note that I am using the Java exe for generation, but
> > the results are the same for c++ exe. The top-down 2-level hierarchy is
> > definitely specified in the 'topology type' box at the top of the gui.
> > 
> > I have included the .brite output for reference.
> > 
> > Thanks,
> > 
> > Oliver Holland.
> > 
> > Ps. I have improved the brite ns2 export format, so that (i) it works
> > with the current version of tcl used in ns2 (which is probably very
> > similar to the versions that have been used for a least the last couple
> > of years), and (ii) it specifies node positions and link orientations in
> > ns2, hence you can see the node positions/link orientations correctly in
> > nam. Once I have reduced node sizes in nam for the ns2 export files (so
> > that the new nam outputs don't only produce nodes that are in the right
> > positions, but nodes are also not so large that you can't see what is
> > going on!) I will submit it to the brite mailing list.
> > 
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