Hi,

   Well, I finally got to work on IGMPv3 for Linux.
Bad
Mistake! This looks like it'll be some seriously heavy
work,
if I'm going to do this properly, and not just make
some
half-hearted effort.

   First, IGMPv3 starts off apparently trivial - an
extended
IGMP header, a few #defines, one function, and a
couple
of structures. No biggie. But then it starts to get
fun.....

   Auxiliary data structures are the next layer in
IGMPv3.
The draft IGMPv3 document doesn't define any, but
there
is one for authentication, also in draft form, which
begins
to make things complicated.

   Parallel to all of this (and part of IGMPv3) is SSM
(Source Specific Multicast). Built around that, is
MSNIP
(Multicast Source Notification of Interest Protocol),
which
then has extensions for proxying. There's an RTCP
extension for SSM, but I'm going to ignore that. MSNIP
looks like it is going to be the biggest chunk of the
code.
The bulk of the API extensions, structures, etc, are
all
MSNIP stuff.

   I've included a diff for igmp.h, which inserts my
(shaky)
interpretation of the relevent draft documents' specs
for the
required structures, defines and functions. I've
backetted
the new code with #if define's. That way, it's visible
as to
what bit of code is intended for what, and the
extensions
can be selectively compiled in. (I've a nasty
suspicion that
there's going to be a fair amount of overhead involved
in
all this.)

   I want to get my interpretation of the API out
-now-,
because if I'm incorrect, I'd rather know about it
sooner,
rather than later. I'll get the back-end code out,
eventually,
but I'm sure you don't want to see a bunch of stubs
and
half-chewed code. (My hamster got into the computer.)

   I might miss a reply on the list, so if anyone is
interested
in the IGMPv3 stuff, I'd be grateful if you could CC
the
reply to imipak@yahoo.com. Also, if anyone else is
working on Linux IGMPv3 code, if they could drop me a
note, it would be helpful. Diversity is a good thing,
but
too much causes migranes in 8 out of 10 cats.

Thanks,

Jonathan Day


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