3Com 10014299 manual Function group includes, Preparations before Configuration

ISDN BRI Interface 129

equipment complying with relevant ISDN standard of ITU-T able to access ISDN easily.

User-network interface specification of ISDN:

In ITU-T I.411 recommendations, reference configurations for ISDN user-network interfaces are given according to concepts of function group (a group of functions required by users to access ISDN) and reference point (a point used to distinguish function groups), as shown in the following diagram.

Figure 47 Reference configuration of ISDN user-network interface

5 4 3 2 1

TE2

TE1

TA

NT2 NT1

ST U

RS

The function group includes:

■Network terminal 1 (NT1): It mainly fulfills functions of OSI layer 1 including the subscriber line transmission function, loop test and D channel contention.

■Network terminal 2 (NT2): Also called intelligent network terminal, including layer 1-layer 3 of OSI.

■Type-1 terminal equipment (TE1): Also called ISDN standard terminal, which is user equipment conforming to ISDN interface standard (such as digital phone set).

■Type-2 terminal equipment (TE2): Also called non-ISDN standard terminal, which is user equipment not conforming to ISDN interface standard.

■Terminal adapter (TA): It implements adaptation function, making TE2 to access ISDN standard interface.

The reference point includes:

■R reference point: It is between non-ISDN equipment and TA

■S reference point: It is between user terminal and NT2.

■T reference point: It is between NT1 and NT2.

■U reference point: It is between NT1 and line terminal.

Preparations before Configuration

Be clear about the following items before the configuration: