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To: Darren DeNunzio who wrote (3793)	5/19/1999 12:29:00 PM
From: Doughboy	Read Replies (1) \| Respond to of 12823

Interesting comparison. Can you tell us where you got this info? Also, what is the transmission rate for T1/E1? TIA. Doughboy.

To: Darren DeNunzio who wrote (3793)	5/19/1999 1:13:00 PM
From: WTC	Respond to of 12823

Re: DSL flavors and their data rates. This table is a reasonable summary of design or peak rates, but for all of the modulated DSLs, distance is a factor that limits top data rate beyond a radius from the Digital Subscriber Line Access Module (DSLAM), usually in the telco CO, but occasionally moving out now, to a field location. ADSL - there are shipping implementations that provide up to 8 Mb/s down, 1.5 Mb/s up (Alcatel, et.al.) CDSL, aka G.lite, has some implementations that may exceed the 128 kb/s upstream, but this is a reasonable characterization. HDSL - This is non-modulated, 2B1Q line code, so distance is not a factor with data rate. HDSL can do North American T1 (1.544 Mb/s) and usually also European E1 (2.048 Mb/s), out to significant distances with repeaters if necessary. RADSL is pretty much subsumed into ADSL now. S-HDSL is one half of a 4 wire HDSL circuit, so, 768 kb/s on 2 wires. More to the point, though, is the nearly ready standard for HDSL-2, a single pair T1/E1 capable new version of HDSL. It uses overlapping PAM modulation, and as I understand it, will not have a repeatered option like HDSL. S-HDSL, used to mean today's single pair high data rate DSL, may fade away with the coming of HDSL-2. It is not a protected transmission technology in the last FCC Advanced Services Order, and it is a known source of intra-binder group interference, which the FCC (and ILECs, and CLECs that are really thinking about the implications) want to grandfather or replace, like the old AMI T1 services. The vendors that supply S-HDSL will also make HDSL-2, and they will probably steer their customers to the newer, emission-friendlier technology. VDSL for access applciations does not have a standard yet (soon!) but there are certainly implementations that support 2.3Mb/s upstream. The carrier can typically extend the reach of VDSL if the data rates are reduced to the minimum consistent with customer requirements, and VDSL reach will be a bigger issue, probably, than squeezing out 2.3 Mb/s on the upstream. The downstream is usually stated as 52 Mb/s. The actual peak data rates will also depend on whether on not ADSL compatibility is accommodated, as well as distance and technical transmision parameters. One important caveat -- a very small percentage of ADSL deployments will actually run at the peak rate possible with the hardware and deployment circumstances, because it would cost the customer too much to provide that data rate all the way back into the network. A high percentage of HDSL variants do not operate at the T1 level, either; my sense is that 384/384 is the most prevalent data rate / price point for the business world that uses it, and that is provisioned via HDSL.