B-ISDN REFERENCE MODEL

SEMINAR ON B-ISDN REFERENCE MODEL :B-ISDN ATM makes it a reality. The Services Digital Network (ISDN) developed more than 80 s. She made a basic channel that could operate at 64 kbit / s (channel B) and combinations thereof and (channel D) others formed the basis for communication in the network. In the new world-ISDN, which is supposed to provide data, voice and other communication services over a common network with a wide range of data types. To understand much of the terminology of the ATM-earth, one must understand the reference model B-ISDN. Like the ISO model defines seven layers of network software layers, this model defines the layers of the ATM network.
The header is divided into the following areas.
Generic Flow Control (GFC)
virtual channel identifier (VCI)
Virtual Path Identifier (VPI)
payload type (PT)
Cell Loss Priority (CLP)
Header Error Control (HEC)
Network - and - The Interface
It is necessary that the switches know how to send the call along. There are several techniques that could be taken, but more useful for users 1P called Private Network Network Interface (PNNI) The PNNI is an interface between the switches used to disseminate information on the status and structure of the circuit network to establish to ensure that the bandwidth of reasonable quality and service contract can be established and provide for certain functions of network management. Convergence sublayer: the role envisaged in this layer differ depending on the service provided. It provides a bit error correction and can use explicit time stamps to transfer timing information.
Segmentation and reassembly sublayer:
At this convergence layer protocol data unit substrate is segmented, and a header added. Header contains three fields sequence number is used to detect cell insertion and cell loss. Serial number of protection is used to detect and correct errors that occur in the serial number. basename convergence used to indicate the presence of the function of surface convergence.