NYCPHP Meetup

[Tim Sailer]

On Fri, Apr 23, 2004 at 03:09:09PM -0400, Aaron Fischer wrote:
> Hmm.. is there anything to the "DSL is dedicated, Cable is shared" 
> thing then?  I took a networking class a couple years ago and they made 

No. It's marketing. Think of the DSLAM as a big mongo network switch
(which it is). If you have a 10Mbps uplink to your office switch,
and 24 ports of 10mbps to each of 24 computers, yes, each of them
has a *dedicated 10 mbps line". Guess what? They all share the
same uplink. Now, most DSL providers ( like Verizon 'can you heaer me 
now? WHAT?') do OC3 or better for the COs, it's still shared.

Cable, on the other hand, will suffer more from local abuse, since the
*local medium* (coax) is shared, so the potential of local abusers
affecting the throughput for others in greater. However, providers
throttle the abusers after a time, so wait it out for 20-30 minutes
until the local clown gets bandwidth-capped at 128k. :)

> a point of covering this in the DSL/Cable comparison.  I've been 
> disseminating this little tidbit of info ever since.
> 
> From my experience I haven't noticed big slowdowns in service on DSL.  
> Stays pretty consistent all the time.  A friend of mine has cablemodem 
> and he notices big slowdowns around 6-8 p.m. when big populations are 
> arriving home, checking email, hopping on the web, etc.  On the flip 
> side, when it's fast, it's definitely a lot faster than my DSL.

Right. It all gets down to where the sharing is done, and how it's
provisioned. I have a 384/1500 link from cloud9, and I bet that when I
pull large files for long times, that 1.5mbps affects the home surfers.

Tim

PS: Just to qualify my statements, I know a little about this stuff,
as I own/operate Coastal Internet (www.buoy.com).

-- 
Tim Sailer <sailer at bnl.gov> 
Information and Special Technologies Program
Office of CounterIntelligence 
Brookhaven National Laboratory  (631) 344-3001