Re: link dynamics bug

[Kannan Varadhan <kannan@ISI.EDU>]

> From: Hyogon Kim <hkim@bellcore.com>
> Date: Fri, 10 Apr 1998 15:10:43 EDT

> Hi, I installed ns-2.1b2 on SunOs 4.1.4 platform, and I am 
> having trouble modelling link going up and down. First, I found
> a bug in tcl/rtglib/dynamics.tcl in line 208. It was written
> "lindes" instead of "lindex". I fixed it and them recompiled,
> but I still get other errors for all three below:
> 
> 	#ns rtmodel Exponential {1 0.1} $n0 $n1
> 	ns rtmodel Deterministic {0.5 2.0 1.0 200.0} $n0 $n1
> 	#ns rtmodel Manual {2.0 down} $n0 $n1
> 
> the error message is 
> 
> 	Unknown operation down or subbordinate operation failed
> 
> Did anyone try this and succeed? Or 2.1b2 is not stable yet
> for link dynamics modeling? I will greatly appreciate any
> tip.

No, ns-2.1b2 and the rtglib code in it, are fairly stable.
There is a bug in the multiPath routing code that will get
looked at some day.  Other than that, I have used it extensively.

Barring that typo that you have identified, it should work ok.

So, here are some quick questions:

	1. Did you mean `ns' or `$ns' in the above commands?
	2. If I use $ns, I can plug your commands in into simple-dyn.tcl,
	and ``almost'' get them to work.
		-- The Exponential did not generate any interesting events
		   in the 8 seconds that simple-dyn runs for.  However, it
		   appears ok for longer simulations.
		-- The Deterministic works ok.
		-- You have the order of options inverted for
		   the Manual command, so the following works:

			$ns rtmodel Manual {down 2.0}  $n0 $n1

Hope this helps?


Kannan

PS:  simple-dyn.tcl did not turn on the routing correctly.  The following
patch may be useful:

owe ex 48> cvs diff -D now -c simple-dyn.tcl
Index: simple-dyn.tcl
===================================================================
RCS file: /usr/src/mash/repository/vint/ns-2/tcl/ex/simple-dyn.tcl,v
retrieving revision 1.6
diff -c -r1.6 simple-dyn.tcl
*** simple-dyn.tcl      1997/11/04 21:54:34     1.6
--- simple-dyn.tcl      1998/04/10 19:46:49
***************
*** 49,54 ****
--- 49,56 ----
  
  $ns connect $cbr0 $null1
  
+ $ns rtproto DV                ;# or use Session
+ 
  $ns rtmodel Deterministic {} $n0
  [$ns link $n0 $n1] trace-dynamics $ns stdout
  


--
kannan@isi.edu
http://www.isi.edu/~kannan