Though the ATM standard is recognized as the most perspective universal standard of transfer of diverse information (the speech, video and data), however and it is not deprived of shortcomings, difficult and long process of control of a constant virtual channel of PVC is basic of which so far.
At the same time the overwhelming part of servers and the user equipment of the Internet support the TCP/IP and Ethernet protocols. Therefore upon transition to the ATM technology it is necessary to use as much as possible a stack of already existing TCP/IP protocols as the main instrument of broadband Internet access. It concerns not only the transport and network TCP/IP level, but also channel level. Told first of all treats the protocol (to be exact, to a stack of the RRR protocol ("Point to point protocol") which is the protocol of channel level of a stack of the TCP/IP protocols and regulates procedures of transfer of frames of information on consecutive communication channels.
Except the considered method of network functioning of ADSL with use of the ATM technology which briefly call "RRR over ATM", there is also some other: "Classical IP over ATM" ("Classical IP and ARP over ATM" or IPOA), the Emulation of Local Networks specification developed by Forum ATM (LAN emulation or LANE), the new specification of the Forum ATM "Multiprotocol Over ATM" (or MPOA).
The ATM technology is recommended both the Forum ADSL, and ITU-T and for the equipment of the ADSL line now (i.e., the modem of knot of access of ATU-C and the remote modem in the user of ATU-R). It is explained first of all by what the ATM is the standard of a network of broadband access of B-ISDN.
Our lag in development of networks of data transmission played a positive role - operators did not manage to make essential investments in the equipment of the switched networks of narrow-band ISDN, and also in development of subscriber sites of networks of data transmission on the basis of the equipment HDSL and IDSL.
On the architecture the equipment DLC represents the multiplexer on the basis of temporary division of channels with various user interfaces and the linear interface for direct connection to an optical fiber. Thus, association of a set of subscriber lines in one high-speed digital stream arriving on automatic telephone exchange (network knot) on an optical cable is provided.