scope:

This first part of EN 301 174 specifies the stage three of the pan-European Broadband Integrated Services Digital Network (B-ISDN) Frame Relaying bearer service as provided by European public telecommunications operators at the T reference point or coincident S and T reference point (as defined in CCITT Recommendation I.413 [4]) by means of the Broadband Digital Subscriber Signalling System No. two (DSS2). Stage three identifies the protocol procedures and switching functions needed to support a telecommunications service (see CCITT Recommendation I.130 [3]).

In addition, the present document specifies the protocol requirements at the T reference point where the service is provided to the user via a private ISDN.

The present document does not specify the additional protocol requirements where the service is provided to the user via a telecommunications network that is not a B-ISDN.

The present document specifies the procedures for the establishing, maintaining and clearing of Broadband-Integrated Services Digital Network (B-ISDN) Frame Relaying connections at the user-network interface. The capability specified in the present document also allows the user of the Frame Relaying bearer service to access a frame handler in a B-ISDN.

The present document specifies extensions to ITU-T Recommendation Q.2931 as modified by EN 300 443-1, and does not repeat states, information elements, messages and procedures contained therein, but only specifies extensions related to the support of frame relay bearer service.

The present document does not cover procedures for the negotiation and modification/renegotiation of traffic parameters.

The present document supports only single step all control with one virtual connection supporting only one frame relay connection. Multiple frame relay switched virtual connections (each identified by a DLCI value at the FR-SSCS level) over a single broadband virtual channel connection is not supported.

Whenever differences exist in procedures, messages and/or information elements, these are clearly pointed out and fully specified. Information elements of ITU-T Recommendation Q.2931 as modified by EN 300 443-1 which are applicable for B-ISDN calls providing frame relaying bearer service, but require no enhancements are handled by direct reference to ITU-T Recommendation Q.2931 as modified by EN 300 443-1.