Re: Bandwidth

Albert Lunde (albert-lunde@nwu.edu)
Tue, 25 Nov 1997 10:17:05 CST


Message-Id: <199711251617.LAA05740@www10.w3.org>
To: jmkgre@essex.ac.uk
Date: Tue, 25 Nov 1997 10:17:05 CST
Cc: albert-lunde@nwu.edu, www-html@w3.org
In-Reply-To: <SIMEON.9711251420.C@s1691.essex.ac.uk>; from "James Green" at Nov 25, 97 2:34 pm
From: albert-lunde@nwu.edu (Albert Lunde)
Subject: Re: Bandwidth

> 
> 
> On Tue, 25 Nov 1997 7:58:53 CST Albert Lunde <albert-lunde@nwu.edu> 
> wrote:
> 
> > > Whilst they do help enormously, they do not solve the problem entirely. 
> > > For instance, in a live broadcast, people can hardly get the entire 
> > > file from a cache went the EOF hasn't been transmitted yet, can they? A 
> > > better system of single-distribution is needed.
> > [...] 
> > > Now, why couldn't there have been one file going to each country that 
> > > requests it, it gets stored temporarily in the country's main centre 
> > > (like Telehouse or LINK in the UK) where the appropriate ISPs are given 
> > > access to the file and they transmit it to their users.
> > 
> > This sounds a lot more like IP multi-casting and/or the MBONE, which
> > _has_ been applied to live audio/video transmission. I don't know
> > of applications of IP multi-casting to file-serving.
> > 
> > Doing much better with IP multi-casting than multi-level proxy caches
> > might require advance knowledge of who would want what files
> > where.
> 
> Not really, it would be upon demand. Think about it: User from country 
> X wants a file, so once that has come along, a local (country) copy is 
> ready. Only when the local space limit has been reached will the least 
> wanted files be overwritten.

You've just described what a proxy cache does, assuming that one
runs country-wide, as well as local proxy caches. HTTP 1.1 was
designed to improve support for multi-level proxy cache chains,
and I think they are in use in various parts of the world already.

--
    Albert Lunde                      Albert-Lunde@nwu.edu