B-ISDN Protocol Structure (ATM, BBC)

Protocol Structure -

B ISDN: Broadband Integrated Services Digital Network (Broadband ISDN)

ATM adaptation layer (AAL). This layer is responsible for mapping the service offered by ATM to the service expected by the higher layers. It has two sublayers.

ATM Layer. This layer is independent of the physical medium over which transmission is to take place. It has those functions: Generic flow control (GFC) function, Cell header generation and extraction, Cell multiplex and demultiplex.

Physical layer. This consists of two sublayers: Transport Convergence (TC) and Physical medium (PM)

The management plane consists of two functions to perform layer management and plane management.

The plane management is not layered as the other layers are. This is because it relies needs information on all aspects of the system to provide management facilities for the systems as a whole.

The layer management provides information and control facilities for the protocol entities that exists in each individual layer. This includes operation and maintenance (OAM) functions for each layer.

The control plane is responsible for the supervision of connections, including call set-up, call release and maintenance.

The user plane provides for the transfer of user information. It also includes mechanisms to perform error recovery, flow control etc.

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