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Re: Real Media and M-Bone feeds
- From: Andy McConnell
- Date: Tue Oct 05 11:42:43 1999
(BOn Tue, 5 Oct 1999, Alex P. Rudnev wrote:
(B}> > just forget about it and spend our life doing something
(B}> > useful instead?
(B}> because, although it is getting less expensive quickly, transport costs
(B}> money. multicast promises to reduce that cost near sources.
(B}Multicast is just not more than one case of data caching on the fly. It
(B}can be used for the local networks, just with the net of the media
(B}replicators. In principle there is not big difference between multicast
(B}and www caching except first is an example of the _real-time caching_ and
(B}second is usially _store-and-forward_ caching.
(BIt it really comparable to caching? I see multicasting as more of a
(Btraffic reduction, rather than a cache.
(B}This days we can see the weakness of the global-multicasting - and I think
(B}it should be replaced by the media-caching servers (with the ability to
(B}replicate data on the fly - in case of live media stream, and short or
(B}long tome _store-and-forward_ in case of Video-on-demand stream) - and
(B}with just this multicasting on the very end of the data tree. But an
(B}attempts to build over-the-world multicast network - brr... it's possible
(B}(if you should dig some mountain every day, you'll build a tunnel at last;
(B}but may be it's easy to run this mountain over?).
(BYour model would work, but it requires a LOT more coordination and
(Bcooperation than even multicast requires. Are you sugesting that networks
(Bimplement machines that sniff into the data, identify those streams,
(Bintercept them, and then coordinate with the streams' sources to stop
(Bsending the unicasts behind the cache, and send the stream to the cache
(Bonly? Or will your new machine simply "spoof" the source? If the latter,
(Bthen you haven't told the sender to reduce the traffic.
(BYou mentioned your doubt of building an over-the-world multicast
(Bnetwork... but what you are sugesting seems to be an over-the-world
(Bcaching mechanism. If we are going to build an over-the-world anything,
(Bwhy not build on the IP model, which is already over-the-world?
(BThe whole reason for multicast is to reduce the traffic at the source, not
(Bnecessarily just then receivers. And the concept behind ip multicast is
(Bto replicate as closely as possible the IP model - send trafic to an IP
(Baddress, and let the layer 3 devices forward the packet to the right
(Bshared-media networks as required.
(B}And - your NANOG forum is the excellent example. RealVideo streaming work
(B}fine; Multicast don't work at all; why do you try to use weak schema
(B}instead of the strong one? No enougph bandwidth - install stream
(B}replicators inb the key points; build _replication on the fly_ schemas
(B}(such as CCP for the www caching on the fly), etc. No, even with all
(B}attempts Cisco and some other are trying this days - multicast is more
(B}dead than alive. I can get 10,000 multimedia sources by RealVideo or
(B}StreamVideo - and I can't get nothing usefull by multicast. If I could
(B}install RV-cache engine (cache on the fly) - I should choose this
(BYou can get a lot more software for Windows, too, but that doesn't make it
(Bthe right solution all the time. How much software was available for
(BLinux just two years ago? Market share is a poor measurement of the
(Bquality and capability of a solution.
(BAndy McConnell IP Operations Manager email@example.com
(BNTT America Network and IP Service Division +1 408 873 3757
$B??8~N}(B $B0BEHN6(B NTT$B%"%a%j%+(BIP$B%*%Z%l!<%7%g%sC4Ev2]D9(B
(B"What right does Congress have to go around making laws just because they
(Bdeem it necessary?"
(B - M. Barry, Mayor of Washington, DC