Re: [ns] Classifier definition and population

[Haobo Yu <haoboy@packetdesign.com>]

> i have 2 questions on unicast routing:
>
> * a node's classifier is firstly defined by the base
> routing module "register" method:
>
> set classifier_ [new Classifier/Hash/Dest 32]
>
> why a HASH classifier ? (i would expect an ADDRESS
> classifier )

A hash classifier is a more general implementation of an address
classifier. It allows classification on src, dst, and flow id. Hash/Dest
is its subclass; cvs log said that it reduces memory usage than an address
classifier, I can be wrong, but I think it's because it uses hashes rather
than allocating a whole array according to shift+mask of an address.

> * a node's classifier is populated with the
> "add-route" method; actually this method is invoked in
> a STATIC routing procedure, "compute-flat-routes",
> while "add-route" is nowhere to be found neither in
> rtObject nor in Agent/rtProto/DV "compute-routes"
> procedures  (actually in rtObject compute-routes there
> is an invocation to "add-routes" that should be used
> for multipath routing -----> ????????)
>
> WHY ? how does NS populate node's classifiers in a
> dynamic routing context ?

In DV only add-routes is called, which in turn calls add-route
to actually populate classfiers (ns-node.tcl). So it does not matter that
add-route is not called directly.

- Haobo