scope:

The present document specifies the functions for the emulation of a basic access over ATM, thus providing an efficient way to connect existing N-ISDN terminal equipment to a PINX over a digital ATM section. Such an ATM connection can be either a (semi-)permanent connection, but might also be a switched virtual connection as defined in related ATM Forum specifications. The objective of the present document therefore is to specify a mapping scheme for the three types of basic access information (two B channels: the B1 and B2 channels, the D channel as well as maintenance/control/status information) into ATM cells. Part of the maintenance/control/status information has to be terminated by an IWU and has to be substituted by other information applicable at the ATM connection. A reference configuration lays down that the point of emulation has to be placed at the network side of an extension line.