Bernard, your observation in some ways actually made my point. The following is not a straightforward matter, however, if one wished to take a purist's perspective, IMO.
>So, T1 should really be viewed as a member of the xDSL family.<
A T1 employs certain rules which all DSLs of the 1.5 Mb/s rate are not obligated to conform to. When I lease a T1, I more often than not can be assured that it conforms to certain T1E1 framing criteria (D4, ESF, etc.), timing and synchronization rules (master-slave relationship of some convention, even if it's arbitrary), and signaling capabilities which are embedded within its bit stream.
E.g., the abcd on-hook/off-hook supervisory capabilities per DS0 channel; the framing bit itself (which contains a number of sub-channels for user data and carrier maintenance purposes); and other integral qualities that allow it to conform to the conventions of an industry-accepted digital hierarchy.
These same attributes cannot be said in quite the same way for many of the xDSLs. Although, you are probably correct re: the HDSLs, based on the manner in which they are being deployed by the xLECs. FWIW.
[Tim, can you chime in here and shed some more light on this issue, even if it's boring everyone else, including Bernard, to sleep? ]
Regards, Frank_C. |
