absense of multicast deployment

Stephen Sprunk stephen at sprunk.org
Fri Mar 3 21:01:44 UTC 2006

Thus spake "Joe Abley" <jabley at isc.org>
> On 3-Mar-2006, at 11:48, Stephen Sprunk wrote:
>> That depends on your perspective.  There's a compelling need for  usable 
>> multicast in many environments, and so far there's nobody  (in the US) 
>> with a compelling need for IPv6, much less shim6.
> If there's such a compelling need for native multicast, why has it  seen 
> such limited deployment, and why is it available to such a tiny 
> proportion of the Internet?

Just because it's not widely available on the public network doesn't mean 
that it's not widely available on private networks connected to the public 
one.  There are tens of millions of users out there with access to Cisco 
IP/TV, Real, etc. over multicast, not to mention custom business apps 
(particularly common in the securities world) that use multicast.  They're 
self-contained, though, so you don't see the packets/users or even know 
they're out there.

I'm not terribly surprised the public Internet doesn't have real mcast yet; 
the cost to build replicating unicast servers is paid by content sources 
while the cost to deploy PIM SSM is paid by another, and as such the cheaper 
alternative doesn't necessarily win.  In a private network, one org can see 
the total costs for both and pick whichever one makes more sense.

If anything, it's in ISPs interests to keep things unicast since there's 
more bits to bill for.  At least until someone figures out how to bill for 
the traffic exiting the network at the other end (and that still leaves a 
problem for peering).


Stephen Sprunk        "Stupid people surround themselves with smart
CCIE #3723           people.  Smart people surround themselves with
K5SSS         smart people who disagree with them."  --Aaron Sorkin 

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