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Re: Classifier and Routing?



Sun,

	here's what i've been able to understand from ns-node.tcl and 
classifier.h and .cc:
	- The same kind of classifier (classifier-address.cc) is used both for 
port and address classification.
	- This classifier applys a bit shift to the address field to get rid of 
either the address or the port #. Then a mask (with a bitwise AND) to make sure 
the address (port#) is correctly taken.
	- at an ns node the classifier is set-up like this (pretty much):

	DA     slot
	self   -> dmux -> agents
	n1     -> link1
	n2     -> link2
	n3     -> link1
	
	for a topology, say, like this:
	
	n2---------n0--------n1-------n3 	
	    link2      link1
	    
	Where dmux is a port classifier (an address classifier with a shift&mask 
to get the port #).
	I hope that clarifies it, and if i have made mistakes people on the list 
can correct me (please do so).
	Sincerely,
	
	Tarik.

> From: K Sun <[email protected]>
> To: Tarik Alj <[email protected]>
> cc: [email protected]
> Subject: Re: Classifier and Routing?
> Date: Sat, 2 Oct 1999 22:21:14 +0100 (GMT Daylight Time)
> X-Authentication: IMSP
> MIME-Version: 1.0
> 
> Hello,
> 
> > 	The classifier at a node is filled in ns-node.tcl, Node instproc 
> > add-route; wich is called in ns-route.tcl's Simulator compute-flat-routes. 
> 
>     Thanks a lot! In the meantime, I am really sorry that I was not 
> careful enough although I wanted. Currently, I know deeplier the 
> relation between classifier and routing. Really thank you for your help.
> 
> 
> > Concerning the classify() function, i 'm also trying to figure it out, 
> > particularly the port classification: it seems classification happens on 
adress 
> > and on port # at the same time? 
> 
>     Yes, it is a problem indeed. According to my understanding, 
> classifiation does not happens on address and on port at the same 
> time. The slot array of port classifier has been set just after we 
> attach an agent to this node. So, the slot array of port classifier 
> always keep right. Everytime, Routing just configures the slot array of 
> address classifier ( in the Unicast Node). The statement about 
> add-route on page 37 gives me such impresssion. 
> 
> 
> > What if I need to access to different headers at 
> > the same time to classify?     
> 
>     I do not know this question clearly. Why you need to access to 
> different headers at the same time to classifier? I think the routing 
> only use address field of a packet.
> 
>    I really appreciate your help !
> 
>    Best Regards,
> 
>    Sun Kai
>   
> 
>...