Re: New draft on embedding the RP address in IPv6 multicast address

[Greg Shepherd <shep@juniper.net>]

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On Thu, 10 Oct 2002, Marshall Eubanks wrote:

> On Thu, 10 Oct 2002 15:07:58 -0700 (PDT)
>  Leonard Giuliano <lenny@juniper.net> wrote:
> >
> > Most PIM implementations switch to the SPT, and stay on it, so you are
> > always going to have this problem.
> >
>
> Yes, but in the ASM service model, there is no need to find the
> addresses etc. of all of the source members, and pass this information around.
>
> In PIM-SM ASM _as practiced_ basically the RP's handle source discovery in a
> distributed fashion. It would not be a bad idea to make this explicit, and I am
> a firm believer in the separation of control and data.
>
> > I think it was Dave M who said that years of concern about state has
> > solved the state problem- there's no mcast traffic.  Let's have a state
> > problem first, then worry about fixing it.
> >
>
> The biggest use of multicast at present, by an order of magnitude or more, is
> the distribution of financial data. Has any of this migrated to SSM ? It could,
> maybe, but will it ?
>
> The amount of money that rides on these multicast packets to me provides a very
> good indication that ASM will stick around.

Not a fair comparison. Financial networks are walled-gardens. In the core
distribution layer of the network, all S,Gs are well-known and in many
casses are ~gauranteed to be delivered too the edge layers by static
S,G-joins - VERY SSM-like.

The growth in many-to-many at the edge networks is beginning to highlight
the need for BiDir - over the next 2 years.

Greg

> Marshall
>
> >
> > On Thu, 10 Oct 2002, Marshall Eubanks wrote:
> >
> > -) 2000 member multi-player games come to mind. I believe that these have
> > -) been done (as military simulations).
> > -)
> > -) SSM will have state and flows that goes as N^2 in this case - the
> > -) real question is, can there be multi-domain solutions that only require
> > -) state and flows of order N.
> > -)
> > -) Regards
> > -) Marshall
> > -)
> > -) Leonard Giuliano wrote:
> > -) > -) >
> > -) > -) > However, you might be able to make ASM "SSM like" in that, if you
> > -) > -) > find the group address by some means out of band, you can join to
> > the RP
> > -) > -) > and either send or receive.
> > -) > -)
> > -) > -) This is actually what is expected to happen.  The steps look like:
> > -) > -)
> > -) >
> > -) > Going back a bit, if this ASM mechanism will rely on SSM-like group
> > -) > discovery, why not just use SSM in the first place?
> > -) >
> > -) > The main problem with SSM in IPv4 is that ASM was already in use, and
> > -) > there aren't enough implementations/deployments of SSM yet.  But v6 need
> > -) > not carry the same albatross of legacy mechanisms around it's neck.
> > It's
> > -) > a chance to do things right from the start.
> > -) >
> > -) > Does anyone actually see any real cases where SSM won't be at least
> > "good
> > -) > enough?"  Is all the complexity of ASM, and the duct tape solutions
> > being
> > -) > discussed worth it just so that SDR will work?
> > -) >
> > -) >
> > -) > -Lenny
> > -) >
> > -)
> > -)
> > -) --
> > -)                                   Regards
> > -)                                   Marshall Eubanks
> > -)
> > -)
> > -) T.M. Eubanks
> > -) Multicast Technologies, Inc
> > -) 10301 Democracy Lane, Suite 410
> > -) Fairfax, Virginia 22030
> > -) Phone : 703-293-9624       Fax     : 703-293-9609
> > -) e-mail : tme@multicasttech.com
> > -) http://www.multicasttech.com
> > -)
> > -) Test your network for multicast :
> > -) http://www.multicasttech.com/mt/
> > -)   Status of Multicast on the Web  :
> > -)   http://www.multicasttech.com/status/index.html
> > -)
> >
> >
>
>