scope:

This European Telecommunication Standard (ETS) describes the interconnection between European standard Metropolitan Area Networks (MANs) by means of an Asynchronous Transfer Mode (ATM) based network. Connectionless service is provided directly or indirectly, according to ITU-T Recommendation I.327 [9]. ATM connections are to be established through ATM crossconnects between the user and Connectionless Servers (CLSs).

Direct interconnection of MANs, based on the Dual Queue Dual Bus (DQDB) protocol is specified in ETS 300 275 [6].

This ETS is restricted to the interconnection of MAN Switching Systems (MSSs) when the MAN users use the Connectionless Broadband Data Service (CBDS) as defined in ETS 300 217 [5]. CBDS may be provided by both types of networks (MAN and ATM-based). The requirements to allow communication between users connected to a MAN and users connected to an ATM-based network, both providing CBDS, is outside the scope of this ETS.

The interconnection of MSSs via ATM connections when MAN users use other services as defined in ETS 300 211 [4] is outside the scope of this ETS.

The defined interface applies to the case in which the MSS and the ATM-based network belong to the same network operator domain and to the case in which they belong to different ones, assuming as basis ETS 300 211 [4] and CCITT Recommendation I.321 [3]. The basic data transfer functionalities at the interface are the same for the two cases. Additional specific management functionalities may be required for each case.

This ETS provides the general principles and functional requirements and specifies the corresponding interface for interconnection of MSSs.

The specification of the interface between MSS and the ATM-based network is based on the Network Node Interface (NNI) and takes into account ITU-T Recommendations I.150 [7], I.361 [10], I.362 [11], I.363 [12], and I.327 [9], ETS 300 275 [6] and ETR 122.

This ETS defines the reference configuration, functional blocks and their corresponding Protocol Reference Models (PRMs) related to MSS interconnection.