ADSL Bandwidth Monitoring

[Ted Mittelstaedt]

> -----Original Message-----
> From: owner-freebsd-questions at freebsd.org
> [mailto:owner-freebsd-questions at freebsd.org]On Behalf Of Tim Daneliuk
> Sent: Saturday, September 08, 2007 2:01 PM
> To: RW
> Cc: freebsd-questions at freebsd.org
> Subject: Re: ADSL Bandwidth Monitoring
> 
> 
> RW wrote:
> > On Sat, 08 Sep 2007 15:27:38 -0500
> > Tim Daneliuk <tundra at tundraware.com> wrote:
> > 
> >> Amitabh Kant wrote:
> >>> On 9/8/07, Bahman M. <b.movaqar at adempiere.org> wrote:
> >>>> I tested the connection by downloading 2~3 files simultaneously
> >>>> and used 'bmon' as Mel suggested in another reply (thanks to
> >>>> him).  As I'd already guessed the RX don't get bigger than 30~40%
> >>>> of the expected bandwidth.  I performed the test with some other
> >>>> files and there was no difference.
> >>>>
> >>>> Thanks,
> >>>>
> >>>> Bahman
> >>> The bandwidth being advertised by your ISP would be the maximum
> >>> thoughput allowed on your DSL lines with multiple DSL users sharing
> >>> the same bandwidth, something that is generally known as contention
> >>> ratio.
> >>>
> >>> See this link:
> >>> http://en.wikipedia.org/wiki/Contention_ratio
> >>>
> >>> Amitabh
> >> But you should be able to hit the advertised bandwidth.  To the best
> >> of my knowledge, DSL itself is NOT a shared medium.  It is a point-to-
> >> point technology from your premise to the Central Office.  The
> >> bandwidth *behind* the CO may be shared, but should be so large
> >> as to not be a bottleneck.   
> > 
> > It depends on your circumstances. Some people are constrained by
> > contention ratio some aren't. Some ISPs offer a better ratio for a
> > more expensive accounts.
> 
> I don't understand this.  If the actual DSL circuit is point-to-point -
> i.e., not shared between the premise and the DSLAM in the CO, just
> exactly *where* is the contention occuring?

Inside the ISP's router.

However even cheap ISP routers you can buy off Ebay for a couple grand
have enough bandwidth to route between multiple 100BaseT connections.  For
example the 7206 has 2 800Mbt backplanes.  That would mean you could
run 500 1.5Mbt DSL customers at full bore to a server on your local
network before contention would set in.  And an ISP with that many
customers can afford a more powerful router than a couple K used 7206.

The upshot is his ISP doesen't know how to troubleshoot DSL.

Ted