Subject: Multicast / DVMRP not used anymore?

From: Hadmut Danisch <[email-masked]>
Date: Sun, 6 Feb 2005 22:07:59 +0100

Hi,

I was just surprised by the fact that the 
mrouted package was removed from Debian Linux, 
because mbone / DVMRP (Distance Vector Multicast Routing Protocol)
would not be used in Internet anymore.

I guess I've missed anything. Has multicast IP been 
abandoned or obsoleted? Can anyone give me a hint 
about where and why this has happened? 

What about the IETF broadcasts? Are they still delivered over
multicast?

regards
Hadmut

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From: Simon Leinen <[email-masked]>
Date: Mon, 07 Feb 2005 17:15:44 +0100

> would not be used in Internet anymore.

I guess it's mostly true that DVMRP is no longer used for
Internet-wide multicast routing.

> abandoned or obsoleted?

No, only DVMRP.  There were several issues with trying to maintain a
global DVMRP-based multicast infrastructure.

Multicast routing in the Internet is mostly based on PIM-SM
(Protocol-Independent Multicast, Sparse Mode) these days.

> Can anyone give me a hint about where and why this has happened?

> What about the IETF broadcasts? Are they still delivered over

Yes, and I'm in Switzerland, listening to a radio station in Oregon
over IP multicast right now, so the infrastructure is still there for
people to use.

However I don't know how wide the "reach" of Internet multicast is, in
particular outside our education/research networking community (and
even within that community, multicast is only available to a
minority).

Some broadband ISPs (at least here in Europe, but probably elsewhere
as well) have started to distribute TV-over-ADSL using IP multicast.
But I'm not sure whether they also provide their users with multicast
connectivity to the rest of the Internet.  Anyone knows?
-- 
Simon.

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From: Joel Jaeggli <[email-masked]>
Date: Mon, 7 Feb 2005 09:43:57 -0800 (PST)

> connectivity to the rest of the Internet.  Anyone knows?

By-in-large they are not interested in the interdomain case. There has 
been a substantial investment in similar rollouts among asian broadband 
isps...

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Joel Jaeggli  	       Unix Consulting 	       [email-masked] 
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From: "Marshall Eubanks" <[email-masked]>
Date: Mon, 07 Feb 2005 13:20:50 -0500

On Mon, 7 Feb 2005 09:43:57 -0800 (PST)
> been a substantial investment in similar rollouts among asian broadband 

Yes indeed. This seems to be limited replacing older distribution methods from the head end to
(somewhere close to) the set top box. I have yet to find one that is interested in 
interdomain multicast. (They already have infrastructure to get "their" channels, typically by
satellite, and they have no interest in other channels.) I think that this will only
change if sufficiently many internet video channels become popular enough that they can't ignore
them.

Regards
Marshall Eubanks

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From: Masataka Ohta <[email-masked]>
Date: Tue, 08 Feb 2005 04:50:59 +0900

Marshall Eubanks wrote:

> I have yet to find one that is interested in 

The situation can not change, because the currently standardized
multicast protocols and its underlying models are incompatible
to basic operation/revenue requirements of the real world ISPs.

That is, the protocols does not have proper revenue model to
support automatic negotiation between ISPs and between an end
user's multicast source and an ISP that manual configuration
by ISPs is inevitable.

As a result, current multicast sources are strongly tied to ISPs's
internal operations.

It is easier to use unicast for interdomain transmission between
ISPs or even between regions within ISPs.

The source of the problem is that multicast is resource reserving
communication that each group should be charged from its ISP
proportional to the area and time of each group, which can not be
controlled today.

							Masataka Ohta

PS

I am promoting broadcast with several ISPs in Japan and knows how
they are operating.