[140275] in North American Network Operators' Group
Re: How do you put a TV station on the Mbone?
daemon@ATHENA.MIT.EDU (Jeffrey S. Young)
Sun May 8 04:10:36 2011
In-Reply-To: <BANLkTin2sOq7P2MBq9M2onq=hm4Pubp=tg@mail.gmail.com>
From: "Jeffrey S. Young" <young@jsyoung.net>
Date: Sun, 8 May 2011 18:09:51 +1000
To: Michael Dillon <wavetossed@googlemail.com>
Cc: "nanog@nanog.org" <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On 08/05/2011, at 4:10 PM, Michael Dillon <wavetossed@googlemail.com> wrote:=
>> Many years ago I was the MCI side of the Real Broadcast Network. Real Ne=
tworks arranged to broadcast a
>> Rolling Stones concert. We had the ability to multicast on the Mbone and=
unicast from Real Networks caches.
>> We figured that we'd get a hit rate of 70% multicast (those who wanted to=
see the event as it happened) and
>> 30% unicast (those who would wait and watch it later).
>=20
> You do realize that unicast from Real Networks caches *IS* multicast,
> just not IP Multicast. Akamai runs a very large and successful multicast
> network which shows that there is great demand for multicast services,
> just not the low level kind provided by IP Multicast.
>=20
> In fact, the most important use for IP Multicast is to work around the
> problem of the "best route". In the financial industry, they don't want
> their traffic to take the best route, because that creates a chain
> of single points of failure. So instead, they build two multicast trees,
> send a copy of each packet into each tree, and arrange that the
> paths which the trees use are entirely separate. That means
> separacy of circuits and routers and switches.
>=20
> -- Michael Dillon
>=20
In 1997, Real Networks caches were sending unicast. If they now operate
differently I'm not aware (Real dumped the relationship in the DSL heyday
to chase eyeballs -- iMCI was a backbone). =20
But you've got one over on me, I've never heard of Akamai's "multicast"
and given that they don't run a backbone to my knowledge it sounds as if
they're using their server installs to route packets or have an interesting=20=
way of source routing or tunneling multiple streams of the same data=20
through ISP networks. =20
As for the financial industry I was only aware of some of the reliable mcast=
software in use to push ticker information to trading desks.
All very interesting but the point was that the world of entertainment video=
consumption has long since become on-demand; many of the points being=20
made for the use of IP multicast as a pseudo-broadcast mechanism have=20
been made before (and will be made again). I personally think P2P is a much=
more interesting topic for (legally) distributing video these days and P4P
may even solve the inter provider problem that multicast never seemed to
crack.
jy=
