DSL factoids

[Pat Miller]

There are a lot of misconceptions going on here about DSL

the copper pair is only used between your place ant the co (unless the co
won't give you/your ISP shelf space)

Once in the CO the copper is fed into a DSLAM. This breaks the signal into
two voice goes to the voice (channel bank, coil, etc.) The Data gets decoded
and switched to the ISP of your choice. Typacly your ISP needs a leased line to each
co that it wants to serve customers out of. There may be a common ISP ATM
line (that would make sense for some of the smaller ISP's then they could
split the cost via usage).

 Not all ISP's use CPE (Customer Premise equipment) that is compatible with
the DSLAM that is used by the RBOC. SBC's only offer certain brands of ADSL.
So CLECs/ISPs need shelf space to put in their own DSLAMs.  RBOCS claim
there is little space, but there CO's are becoming mostly empty
because equipment is so much smaller; and to cut
distances and competitors, RBOCs have started to put shelfs with slicks/channel
banks & DSLAMs in each neighborhood. When doing this the copper distance
becomes a few blocks or less, but if those are considered a part of the
CO--requiring CLECs the ability to use available space--they are making the
space so small that there is no room for clecs.

Different DSL flavors (SDSL ADSL HDSL...) and speeds use different distances.
	HDSL requires 4 wires but is high speed...
	SDSL offers same speed in each direction...
	ADSL (async?) is faster on the download)... 
	SDSL causes less interference than the type of ADSL encoding SBC
		uses...

Longer distances require/yield lower speeds.

-- 
Pat Miller--Communications/Transport Consultant
voice 816-210-4077                    | fax 816-968-968-5 (you-you5)
full/expanded info/sig on web/finger--+-Heartland TEC #145 155