All things related to multicast

[Tom Pusateri <>]

In message 
<>
 you write:
>On Tue, 11 Oct 2005 13:40:38 -0500
> John Kristoff 
> <>
>  wrote:
>> On Tue, 11 Oct 2005 10:56:03 -0700 (PDT)
>> Leonard Giuliano 
>> <>
>>  wrote:
>> 
>> > 5+ years, so maybe tunneling over them will be more effective.
>> 
>> Am I the only one who sees the irony in this (AMT and other related
>> solutions)?  Isn't this just MBONEv2?  :-)
>> 
>> John
>
>My first rule of technology is that really good engineering only comes after 
>t
>he first iteration.
>
>That certainly applies here :)
>
>Marshall

Actually, I think we've learned a bit.

MBONEv1 was about connecting islands of multicast in any random way
to connect interested parties. And the worst part about it was the
broadcast and prune, not the tunnel part.

AMT is really about tunneling from a multicast core network or
internetwork through the edge provider where multicast isn't being
enabled for non-technical reasons. It basically replicates at the
leaves of the multicast tree because either the switches are not
multicast enabled or the edge provider doesn't want to allow multicast
content in from external sources.

In my opinion, this latter problem will never go away, because
you're not trying to solve a technical problem. So AMT or something
equivalent (like application level multicast) is here to stay because
it solves a real problem.

In addition, AMT provides the security aspects of a unicast stream
at the edge while allowing the bandwidth savings at the source and
across the core required to scale. Its a very practical solution.

Multicast is most useful when nothing else will work. If you can
solve the problem with unicast, then use unicast. Don't force the
use of multicast just because its cool. But if you have a 20 Mbps
stream that you're sending to a million receivers, you'll be hard
pressed to find a server that can handle it. So you can either use
IP multicast or application level multicast. At some point, it
becomes more expensive to keep building application level multicast
networks for every application you want to deploy. This draws people
to IP multicast.

Thanks,
Tom