SOT: DSL or Cable Modem?, Need for surf speed... Options

[neo914-6]

Just got "upgraded" to SBC "faster" DSL and found little difference. Maybe it's my old computer. (IMG:http://www.914world.com/bbs2/html/emoticons/confused24.gif)

[bperry]

DSL vs Cable. Hmmmm I could and did write volumes on this subject.
I started a company that went public (Efficient Networks, EFNT)
and became the worlds #1 DSL modem supplier in the late 90's.
(Siemens bought the company in 2001)
We supplied private labeled DSL modems for every major Telco
around the world.
I was heavily involved with ANSI T413 commitee which splintered
off to form the ADSL forum and then the DSL forum to push the
DSL standard out to compete with the rollout of cable modems.

I worked with numerous carriers all over the world helping
them define and bring up their SDSL/ADSL rollouts.

I made a ton of money off of DSL, so given a choice what do I
use for Internet connectivity: CABLE MODEM!

There is no simple answer, but technology wise, cable modem
stuff is just simpler, much cheaper to build, and faster with lower
latencies than ADSL.
And in the technology game, simpler, faster, and cheaper to make
usually wins.
Cable data encoding is much more efficient that DSL data encoding.
So if rates are identical, Cable will get better throughput.
That being said, alot depends on how the data plant is built out.
But for the most part, if things are not "broken" cable will usually
pretty easily beat ADSL for speed and latency.

--- Bill

---------- More info below----------------------------------------------

Alot of this comes down to the "NET heads" vs the "BELL heads",
i.e the ISP/Internet mindset vs the Telco mindset.

Telcos, know how to build things that are unbeliviably realiable.
In fact to a fault when it comes to data.
Internet data types tend to focus more on speed than on absolute
realiability.
Things like 100% uptime blows the mind of the NET head yet
things like TCP, sliding windows, and packet retries tend to blow
the minds of BELL heads.
NET heads tend focus on packets and Bell heads tend to focus on bits.
NET heads don't understand Bit Error rates and BELL heads don't
understand why a single bit error can cause transmission to stop
for 2 seconds and cause the retransmission of an entire packet.

DSL uses a VERY complex physical encoding on the
wires which is subject to higher error rates as distances increase.
This is why downstream speeds are reduced as the distance
from the central office increases; it is to reduce the error rate.
DSL also uses ATM encoding for the data layer which is really
good for constant data applications like voice but not so great
for variable sized data packets like IP/internet traffic.
The ATM encoding inserts a MINIMUM of 11% overhead.
For short packets like TCP acks, the overhead approaches 50%,
i.e packets are taking up twice as much bandwidth as a simpler
encoding method. Or in other words each TCP ACK uses up
twice the bandwidth on DSL due to the ATM encoding.

In the late 90's the Telcos finally figured out that using ATM was
not good on links where bandwidth is precious and TCP is being used.
Nearly all of them removed ATM encoding on the transcontental
fiber links between the US and Europe.

With DSL, the speed between you and the central office drops
as the distances increases, with Cable, the effective or usable
speed between you and the cable plant decreases with the
activity in your neighborhood.

Both have backend issues at their plant which are similar.
And once your data hits the main backbones, it no longer matters
if you originated the packet with DSL or Cable.

One funny thing with DSL is that during the meetings, there
were heated discussions about having DSL service WITHOUT voice.
The telco guys, laughed and said "who would ever do that".
They designed their rollout such that even today, in many cities
you cannot get DSL without the voice service.
So for many of the young 20-somethings that don't have a landline,
cable modem service is actually cheaper because they would have
to add a dummy voice line for $30+ to get ADSL.

ADSL was supposed to offer this great reliability and guaranteed
bandwidth, however, the way it is deployed, there is no
way to guarantee any bandwidth with the current ADSL implementation.
The Telcos rushed their deployement and didn't want to wait
for everyone to implement the other parts of the standard.
It is now too late to go back and implement this.

As far as realiability goes, that really depends on the backend
equipment.

The cable guys have SUCKED when changes/transitions have been
done. Outages have been for DAYS at a time, during these transitions.
Telcos handle this kind of stuff much better since they are
used to building networks that can never go down.

I could go on and on and on, but the bottom line is that for
residential ISP service, alot depends on the network layout,
backend equipment, and for cable, how loaded your neighbor hood is
with heavy users.

My feeling is that ADSL is rapidly becoming like 56k modem
service was in the late 90's. Nice, but faster things are becoming
available. If you doubt this, look at how it is priced, in most
regions, DSL is cheaper than Cable modem service.

For me, I'm getting near 5 mbit/sec data downloads through TCP!
That is hightly unlikely if not impossible using ADSL for most users.
So I gladly pay the extra money for cable over ADSL.
And for me, other than during the @home->ATTBI->Comcast
transitions and the recent Comcast encoding speedup.
Things have been very realiable.

Heck I still remember the early days back at Efficient when
we paid $600/month to get a 64k ISP service back in 1993!