Re: [pim] IPv6 Inter-domain Multicasting and Address Assignments

On Thu, Feb 22, 2007 at 08:36:39PM -0500, Marshall Eubanks wrote:
> 
> On 2/22/07, Tim Chown <[email protected]> wrote:
> 
> This has been used since at least early 2003; it was first presented
> at the Summer 2003
> IETF in Vienna - see
> 
> http://www.6net.org/events/workshop-2004/durand.pdf

Yes, Embedded-RP came out of 6NET work.    There was a lot of early IPv6
multicast development and testing done in 6NET and on the m6bone which
emerged from TF-NGN just before 6NET started.

> >A big win for v6 is that you dont need an ASN for GLOP like v4, you can
> >just form multicast groups from your unicast allocated prefix(es).
> >
> 
> Note that there has been a big discussion about assignment of IPv6
> addresses - see
> 
> http://www.arin.net/policy/proposals/2005_1.html

This is a good point - if you want provider independent multicats group
addresses you need provider independent unicast space to base the 3306
or embedded-rp group address upon.
 
> >And with a lot of /64's in an IPv6 site, you can (as we have) assign an
> 
> Most assignments are /48s

To sites, yes, but if you want to allow more unique multicast group 
addresses to be used, what we decided to do was issue a /64 per application.
By doing that the application can determine how to utilise the multicast
group bits and they won't clash with other groups as they would if your
3306 addresses were purely generated from a /48.   Well, we're trying this
at the moment to see how it works.   An allocation service would certainly
be useful, something to respond to a request to 'please allocate me a 32 
bit group ID for this 96 bit group prefix' would be nice.

Another thing we're tinkering with is organisational SAP style advertisements
where an application has a /64 based 3306 prefix and then uses group ID zero
for the announcements.   For that example p2p app, it allows a site's 
available services to be discovered anywhere via a 'well known' group.

But the point is that v6 multicast has the big win of allowing a site to
create its own globally unique multicast group addresses (lots of them!)
from just its unicast prefix.    No need for an ASN.    And thus to be able
to also try new creative schemes to use that address space.   Something you 
just can't do in v4.

-- 
Tim