This section summarizes requirements for ADSL hardware.
Support is provided in the Windows NT Server operating system for ADSL adapters and external ADSL modems, such as those using USB, which provide a faster method for moving data over regular phone lines. ADSL adapters are not required for any server type, but if an adapter is included in a server, it must meet the requirements in this section. ADSL is not required in a server system, but if present, it must comply with these requirements.
Please review the white paper, An Interoperable End-to-End Broadband Service Architecture over ADSL Systems Version 3.0, which discusses end-to-end service interoperability over ADSL. This paper, which is available from the web site at http://www.microsoft.com/hwdev/publicnet/, was jointly developed by over 30 leading ADSL vendors. The core idea of this white paper (PPP over ATM over ADSL) has been adopted by the ADSL Forum.
Recommended
System designers should integrate the ADSL modem and higher layer transmission and media access functions on a single network device. A typical implementation integrates an ADSL modem and ATM interface on a single PCI network adapter. Another example is a device that connects to the server using the USB or IEEE 1394 bus.
If external ADSL modems are provided (other than IEEE 1394 or USB), it should have an ATM interface for the ADSL modem to server connection. In addition, an Ethernet interface can also be included.
Required
For the integrated ADSL modem, the following network adapter requirements must be met:
For the integrated ADSL modem exposing an ATM interface, the following requirements must be met as defined in “Network Adapter Requirements” earlier in this chapter:
For the integrated ADSL modem exposing an Ethernet interface, the following requirements must be met as defined in “Network Adapter Requirements” earlier in this chapter:
Recommended
An integrated ADSL modem should expose ATM to the operating system. For ATM-specific requirements when an ATM/ADSL solution is implemented, see the requirements in “ATM Adapter Requirements” earlier in this chapter. This should comply with the PPP over ATM architecture discussed earlier.
Note: ATM/ADSL is a requirement for UADSL implementations. Currently there are both ATM/ADSL and Ethernet/ADSL based implementations to provide full rate ADSL services in the market. For compatibility with the Universal ADSL based services that will be rolled out within the next couple of years, PPP/ATM/ADSL is the required implementation.
Recommended
The ADSL modem must support DMT line encoding, which is recognized as the industry standard for ADSL by ANSI as the T1.413 Issue 2 specification and also by the Universal ADSL Working Group. For information, see the web site at http://www.uawg.org.
Note: DMT is a requirement for UADSL implementations. The UAWG has adopted DMT specified by T1.413, with modifications being made to work in a splitterless environment.
Recommended
On a rate adaptive digital subscriber line (RA-ADSL), the downstream and upstream data rates are independently set either by an automatic adaptive algorithm or by manual selection.
RA-ADSL provides the capability to optimize the transmission speed and performance over a wide range of telephone-line loop distances. Adaptive channel equalization ensures more robust performance in the presence of channel impairments and narrow-band interference.
This also helps telephone companies to provision RA-ADSL access on their existing networks. RA-ADSL products can be provisioned on many telephone lines without costly and time-consuming network upgrades.