Re: [Mldonkey-users] Re: here's a guy that I stupidly offended because this wasn't clear

[Goswin Brederlow]

Sven Hartge <address@hidden> writes:

> Stephane Goulet <address@hidden> wrote:
> 
> >> And Multicasting only makes sense, if you _exactly_ send the same data to
> >> many peers, and by _exactly_ I mean the the same time the same data.
>  
> >> But since many peers request different chunks and even different
> >> start-points inside one chunk, this ends up in Unicasts anyway.
> 
> > Aint some implementation possible?
> > 
> > Lets say you have file verypopular.rar
> > Lots of ppl waiting in queue for it
> > Your client choses that it's popular enough
> > Your client tells those waiting, be ready i'm gonna multicast to you
> > verypopular.rar
> > You begin streaming in a udp like form the data, others may join in the
> > stream after
> > And you stream a chunk, or more..
> 
> Right, this way mpeg is streamed. But this only makes sense for very
> popular files, as you pointed out. But then this would be very
> effective.

Actually it makes sense for any file 2 clients want, with FEC (forward
error correction).

You have N(say 20) original chunks in a file. With FEC you can
generate up to 256 (or 64K) chunks with redundant data. Any N(=20 out
of 256 or 64k) chunks are enough to restore the file.

If 2 clients want the same file you have to find a original or
redundant chunk that both clients don't have. With both clients
needing 20 out of 256 (or 64k) chunks its garantied that such a chunk
exists. Even with 12 clients it would be garantied. You then generate
that chunk (unless its an original) and stream it.

Of cause you would have to have the complete file to generate
redundant chunks.

> > What do you think of this?
> 
> Problem here: No ISP known to me provides access to the MBone service,
> only the big ones like CW, WorldCom, etc. did and only at high fees or
> bundled with a big pipe.

And thats good. Otherwise every hacked windows system would flood the
backbone with multicast packages to infect more systems or to bring
down whitehouse.gov

MfG
        Goswin