Re: [ns] Hierarchical addressing and mcast

[John Heidemann <johnh@ISI.EDU>]

On Wed, 18 Oct 2000 17:02:40 PDT, "B. Scott Michel" wrote: 
>I've searched through the archives, and I'm still banging my head against my
>desk. I have a feeling this a documentation issue, but here goes anyway:
>
>(a) Hiearchical addressing and dense-mode multicast cannot, will not, and
>never will work together.
>
>(b) Hierarchical addressing and shared-tree multicast do coexist, but
>specifying this multicast protocol must be done AFTER all of the agents are
>attached to their nodes and their dst_addr_ is set to the desired multicast
>group.
>
>I'm hoping those two statements are true. If they are, the documentation on
>how to use ns needs to be updated. It is NOT obvious from the mcast examples
>that DM is incompatible with hiearchical addressing. It is also NOT obvious
>that SM needs to be turned no AFTER agents are linked to their nodes.
>
>I haven't bothered with centralised multicast or BST.

There are parts of ns that don't work together, often because
interactions between routing and the rest of the code.  We hope to
take another whack at routing with cleaner APIs in the next six months
or so.  Of course we're willing to accept patches to fix problems.
Unfortunately, given a choice between making sure ALL n x n features
work together and insuring that basic features work in basic
scenarios, the choice is often for the later.

(The alternative is to not including a feature until it works well
with everything.  In practice, this really means never adding new
features, so you can see why we take a different path.  I can
understand why it's frustrating for users... although given some of
the contributed code it seems like everyone adopts this policy :-)

   -John Heidemann