Re: bandwidth dimensioning
On Tue, Nov 08, 2005 at 07:51:30PM -0000, Eduardo Gargiulo wrote:
> Nate Duehr <nate@natetech.com> said:
>
> > Eduardo Gargiulo wrote:
> > > network. I'm thinking to pay a data link to feed a debian box and from there,
> > > via wireless links (802.11b), give internet access to aprox. 15 users. I want
> > > to guarantee 128 kb/s for every node. Which is the best way to calculate this?
> > >
First: as others have said: it depends on what you're doing and on what
your users are doing.
Take the easiest case: you need to provide (effectively) 128k to each
user continuously, guaranteed. The equivalent of an ISDN2 line each, all
the time.
16 x 128 = 2MB
This is the sort of thing that routers and Quality of Service and
forced bandwidth quotas and load balancing were invented for :)
In reality, the usage pattern per PC is much more asynmetrical: it's
probably 10:1 in terms of actual time on the net - most people spend far
more time reading their email / reading web pages than it actually takes
to download the page - effectively, their computer is virtually idle -
and is probably also more than 10:1 in favour of downlink (pulling
traffic down) rather than uplink (ping responses/DNS/ftp/web requests ...)
[My ISP provides 10M down but only 512k up on cable, for example]
Hard disk is cheaper than bandwidth: use a squid proxy to cache common
requests: build up mirrors of popular download sites if you can.
Andy
> >
> > You've already got it in your original message.
> >
> > 15 * 128KB seems to be a relatively simple calculation. Plus overhead
> > if the server is actually doing server duty like e-mail or web.
> >
> > Not sure what the question is here.
>
> I think there was a missunderstanding of my problem (probably because of my
> poor english).
>
> I don't think that the relationship between bandwidth and simultaneous users
> using that bandwidth is linear (FIXME). The problem is one internet connection
> to a linux box, and 15 wireless users (simultaneously connected in the worse
> case) with 128Kbps guaranteed. The question: How much bandwidth should I
> purchase to satisfy that requirement? You mean 15 * 128Kbps = ~2Mbps ??? I
> think it's too much for 15 users!!
>
> regards,
>
> --ejg
>
>
>
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