[bittorrent] New P2P protocols

larytet.8708132 at bloglines.com larytet.8708132 at bloglines.com
Sat Mar 26 19:26:12 EST 2005


> > >>-Multicast. Online codes applied to encoding a single chunk into 1k

> > >>    
> > >>
> > >P2P replaces multicast with something better designed
that works on
> > >internet scale or local scale. Traditional multicast on
large scale will
> > >never happen in the real world.
> > >  
> > >
>
> I disagree. P2P is massively inefficient - it consumes large amounts of

> > bandwidth with the same traffic going backwards and forwards over the

> > same links. Especially in restricted environments like ISPs and 
>
> University networks, with shared bandwidth, Multicast can massively 
>
> decrease the required bandwidth by allowing multiple recipients to get 

> > the benifit of a single transmission.
> 
> In BT, multiple recipients
get the benefit of a single point to point
> transmission. Multicast isnt
free, it uses links in a tree structure.
> P2P uses links in a graph structure.
Multicast is an attempt to do the
> same as peer to peer with a perfect tree
structured routing aware
> network. P2P is an attempt to do an approcimate
resilient fault tolerant
> version, generally using worse metrics than the
current routing topology
> (though as you point out you can use closer approximations).
Its a
> different approach to the same problem. Remember multicast is just
a bit
> of software replicating traffic too.


Modern router supporting
multicast replicates packets using network processors. This is very efficient
way to do this. 

Still i tend to agree that we are not going to see mutlicast
any time soon and one of the reasons that ISPs are not interested in providing
such services. 

Content is so expensive today that delivery costs are marginal
even without multicast. 

In the high speed local networks there is no need
in multicast because the networks are scalable enough.

seems to me that
multicast will have to wait for content copyright holders to give up on 3,000%
margins or whatever they have now.



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