ORBIT-USER: Topologies in ORBIT

[Ivan Seskar]

Hi Emmanouil,

your options for rate control are either through driver that supports
manual setting of transmit rate (thus disabling auto-rate) or by using
noise to try to force the auto-rate algorithm into a particular state
(not something that is easy to do especially if you are talking about
arbitrary topology). As for the first method, once you "decide" on a
driver it will be fairly easy to extend the topology creation framework
to support rate control.

As for the RTT (if I understand correctly what you are trying to do) it
is usually the function of rate and number of retries (i.e. level of
interference) so, at least in theory, you should be able to control that
with additional sources (in addition to rate control).

Ivan.

PS: There are various version of Madwifi driver that are supporting rate
setting but almost all require you to modify the source one way or
another; I am sure there will be others on the list who will be able to
give you more hints ...

-----Original Message-----
From: owner-orbit-user at winlab.rutgers.edu
[mailto:owner-orbit-user at winlab.rutgers.edu] On Behalf Of Emmanouil
Koukoumidis
Sent: Saturday, December 22, 2007 11:06 AM
To: orbit-user at winlab.rutgers.edu; Amit Kumar
Subject: ORBIT-USER: Topologies in ORBIT

Hi,

I would like to use ORBIT to take some measurements for my research.
For that reason I would like to have some kind of  "topology" meaning
that I would like to have links that differ in rate and RTT between
different pairs of nodes.
But I in tut_topo_2.rb
<http://www.orbit-lab.org/attachment/wiki/Tutorial/HowToTopology2/tut_to
po_2.rb>
I read that:

85
<http://www.orbit-lab.org/attachment/wiki/Tutorial/HowToTopology2/tut_to
po_2.rb#L85> 
    //  /# addLink(A,B,spec) -> add a link between nodes A and B, and
configure that link/
86
<http://www.orbit-lab.org/attachment/wiki/Tutorial/HowToTopology2/tut_to
po_2.rb#L86> 
    //  /#                      with the characteristics given in the 
'spec' hash/
87
<http://www.orbit-lab.org/attachment/wiki/Tutorial/HowToTopology2/tut_to
po_2.rb#L87> 
    //  /#                      e.g. spec = [ rate=54 , per=0.10 , 
etc... ]/
88
<http://www.orbit-lab.org/attachment/wiki/Tutorial/HowToTopology2/tut_to
po_2.rb#L88> 
    //  /#  So far (Nov.07) no 'spec' selection other than 'asymmetric' 
is currently implemented, /
89
<http://www.orbit-lab.org/attachment/wiki/Tutorial/HowToTopology2/tut_to
po_2.rb#L89> 
    //  /#  thus the other 'specs' are just here as placeholders /
illustrations./ 90
<http://www.orbit-lab.org/attachment/wiki/Tutorial/HowToTopology2/tut_to
po_2.rb#L90> 
    //  t.addLink(*"myNode_1"*,*"myNode_2"*,{ :rate =>54, :per =>0.1,
:asymmetric => *true* })
91
<http://www.orbit-lab.org/attachment/wiki/Tutorial/HowToTopology2/tut_to
po_2.rb#L91> 
      t.addLink(*"myNode_2"*,*"myNode_3"*,{ :rate =>12, :per =>0.2,
:asymmetric => *true* })
92
<http://www.orbit-lab.org/attachment/wiki/Tutorial/HowToTopology2/tut_to
po_2.rb#L92> 
      t.addLink(*"myNode_3"*,*"myNode_4"*,{ :rate =>6, :per =>0.4,
:asymmetric => *true* })


Does this mean that there is currently no way to do it ? Or is there an
alternative way apart from trying to simulate it within my applications
or using a software router?  Any ORBIT specific way?
If not...any advice about alternative (non-ORBIT specific) ways would be
greatly appreciated...

Thank you very much!
Emmanouil