Re: [ns] link utilization

[Onno Kievit <okievit@lucent.com>]

Your code should work. It seems to me that you get the wrong utilization,
because 1 byte is 8 bit (and not 1 bit is 8 byte as in your case). So try
something like this:

set linkmon [$ns link $node(2) $node(3)]
set bw [[$linkmon link] set bandwidth_]
set Lutil(counter) [expr $eBytes*8*100/$time/$bw]

good luck

Onno


Jonathan Hicks wrote:

> Hello,
> I am trying to dynamically calculate and use in my simulation the percentage
> of a link's bandwidth that is currently being utilized, working towards a
> load-balancing algorithm.
>
> Here is the approach that I am currently trying to take:
> my understanding is that monitor-queue has a member called bdepartures_ that
> measures the bytes being released from the queue and sent across the link.
> If I can measure this for a certain period of time, I can change it to Mbs
> and divide by the link's capacity.  This does not seem to be working for me.
>   Does anyone have any suggestions?
> thanks,
> Jonathan
>
> Here is the code I am attempting to use:
> --------------------------------------
> #Monitor the queue on link from n2 to n3
> set qmon [$ns monitor-queue $Node2 $Node3 $LFile]
> set counter 0
> proc calc {} {
>     global ns qmon LFile counter
>     #update after "time" seconds
>     set time 0.5
>     set capacity 10
>     set now [$ns now]
>     #amount of bytes leaving the queue, entering the link (I think)
>     set ebytes [$qmon set bdepartures_]
>     #convert bytes to Megabytes per second
>     set eMbytes [expr $ebytes/$time*8/1000000]
>     #The proportion of the link's capacity is being used up
>     set Lutil(counter) [expr $eMbytes/$capacity]
>     #put the bdepartures_ record back to zero
>     $qmon set bdepartures_ 0
>     set $counter [expr $counter + 1]
>     $ns after $time "calc"
> }
>
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