Re: where to add marker for packets (for diff-serv)

[Yuri Pryadkin <yuri@who.isi.edu>]

Urs Thuermann <thuerman@ibr.cs.tu-bs.de> writes:

> thuerman@ibr.cs.tu-bs.de (Urs Thuermann) writes:
> 
> >    I think of writing a Tcl proc that creates a new node, creates and
> >    instance of the marker, sets the target_ of the marker to the
> >    node's entry{} and then sets the node's entry{} to point to the
> >    marker.  Any thoughts on this?
> 
> Since in contrast to the ns documnetation a node has no entry_
> instance variable, I tried to insert my packet marker in place of the
> node's classifier:
> 
> 	set n [$ns node]
> 	set m [new Marker]
> 	$m target [$n set classifier_]
> 	$n set classifier_ $m

See 'Node instproc entry'

> 
> This does't work however since then the node will later try to install
> into the classifier's slot using the classifier_ instance variable
> which now points to my packet marker.
> 
> Is there another way to insert the packet marker between the node's
> entry point and the classifer?
> 
> Or do I have to define a special subclass of Node that will allow
> this?
> 
> 
> BTW, the packet marker is defined like
> 
> 	class Marker : public Connector { ... };
> 
> 	void Maker::recv(Packet *p, Handler *h) {
> 		/* determine flow aggregate for this packet,
> 		   measure average bandwidth and compare to porfile
> 		   then mark packet accordingly.
> 		*/
> 		...
> 
> 		send(p,h);
> 	}

You might consider using MultiFieldFilter for your purposes...

> 
> Like you might guess from this, I want to simulate diff-serv
> mechanisms.  If someone has code to share or other suggestions I'd
> really appreciate your answers.
> 
> 
> TIA
> 
> urs