At 10:14 PM 6/29/2005 +1200, Simon Lyall wrote:
>On Wed, 29 Jun 2005, Jamie Baddeley wrote:
> > Have you considered multicast as an option, and if so, what stopped you
> > from deploying it? Client support or Network support?
>
>Does anyone have full end to end support of multicast? I would guess with
>bitstream and people having layer-2 all the way it might be possible to
>do it these days.
In a pure L2 network multicast is a dangerous technology. Think of what
happens to a 10meg user when a 100meg user kicks off a 25meg multicast stream.
The trend seems to be to use multicast inside tunnels in this environment.
Thats the way the Access Grid folks are going. It also allows user groups
within a network to opt in and out of multicast sessions. Theres quite a
few tunnels tools around.
>Not sure what it would be any practical use for though. Lots of chickens
>and eggs here.
yes. A few "broken network" days ahead.
Multicast is good for synchronous events - like TV watching or LOTR
Premieres etc. But for asynchronous events - like day to day watching of
video, which is tending towards "on-demand", then multicast has almost no
value. With the usual availability of bandwidth, I feel multicast is going
to be of declining importance but will be implemented more for niche
applications, which will become more important in themselves.
The "tv" world is fascinated by "video on demand" and the radio
(Audio) world is fascinated by Podcasting (aka on-demand listening -
mobile). Neither of these is aided by multicast and in themselves they
don't impose huge demands on both servers and networks.
What we do know is 50x 2meg streams doesn't require 100Mbps. The technology
certainly doesn't work that way - the playout buffer is your friend. So
unicast streams are not overly heavy on the network or the server.
Having said all that, we will be playing with multicast and probably making
it available. The other thing we'll be playing with is better quality and
alternate compressions. We're very close to be able to originate those nice
HD streams we demo'd last year. So maybe NZNOG-06 will be in 10Mbps HD
streams.......
Rich
