How do you put a TV station on the Mbone?

Scott Helms khelms at
Wed May 4 18:22:20 UTC 2011

On 5/4/2011 2:07 PM, Jeff Wheeler wrote:
> On Wed, May 4, 2011 at 12:45 PM, Leigh Porter
> <leigh.porter at>  wrote:
>> Agreed, it seems the only demand really for this live viewing is sport, news
>> and background programming like the mentioned breakfast television.
> I disagree with the general notion that multicast is not useful except
> for live content.  Allow me to give a couple of examples that would
> probably be implemented if we really had a multicast-enabled Internet,
> end-to-end:
> Most of us have some number of Windows machines on our networks,
> probably a large number.  These updates are pervasive, and yet they
> are largely delivered to end-users as unicast downloads.  If we all
> had mcast, the latest and greatest Windows Update would probably be
> available via mcast, and your PC would join the appropriate group,
> receive the update, and be able to install it, without any unicast
> traffic at all.  There may be several groups for users who have
> different access network speeds, and your machine may need to
> fall-back to unicast to retrieve last week's updates or get
> packets/chunks that it missed, but this is far from difficult to
> implement.

Local caching is MUCH more efficient than having the same traffic 
running in streams and depending on everyone's PC to try and update in 
the same time frame.
> While on-demand movies are unicast today, there's no reason a content
> provider couldn't take advantage of multicast for the most popular
> movies, let's say "new releases."  We know that the latest movies are
> more popular than older titles, because they consume much more shelf
> space at Blockbuster, and more storage slots in the corner RedBox.  I
> might receive the first few minutes of my on-demand movie by unicast,
> and "catch up" to a high-speed multicast stream which repeatedly
> "plays" the same movie, faster than the real-time data rate, for users
> with sufficient access speed to download it.  My set-top-box would
> transition from unicast to cached data it received via mcast,
> resulting in a large bandwidth savings for popular titles.

Same issue as above, even if I am watching the latest popular movie 
moving between a multicast and unicast stream everytime I pause it to 
get another beer isn't realistic.  The chances that there will be a 
multicast stream that will be in synch with me is not high at all.
> As you can see, multicast can be useful for distribution of popular
> time-shifted content and data, not just sports, news, and traditional
> live programming.

I don't think your examples demonstrate that nor do I think the service 
providers, even the folks that understand what is meant by the term, 
fear multicast at all.  They do feel threatened by the increase in 
unicast OTT video but multicast in large amounts without the layer 1/2 
service provider being engaged is a long way off.

Scott Helms
Vice President of Technology
ISP Alliance, Inc. DBA ZCorum
(678) 507-5000

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