Integrated Services Digital Network (ISDN)
Integrated Services Digital Network (ISDN) is a complete network framework designed around the concept of common channel signaling
Integrated Services Digital Network:
- ISDN provides two distinct kinds of signaling components to end-users in a telecommunications network.
- The first component supports traffic between the end-user and the network, and is called access signaling.
- The second signaling component of ISDN is network signaling, and is governed by the S87 suite of protocols.
- The ISDN interface is divided into three different types of channels.
- Information bearing channelscalled bearer channels (B channels) are used exclusively for end-user traffic (voice, data, and video). Out-of-band signaling channels, called data channels (D channels), are used to send signaling and control information across the interface to end-users.
Block diagram of an Integrated Services Digital Network(Figure 8.4):
ISDN end-users may select between two different interfaces
- The basic rate interface (BRI)
- The primary rate interface (PRI).
- The BRI is intended to serve small capacity terminals (such as single line telephones) while the PRI is intended for large capacity terminals.
- H channels are used by the ISDN backbone to provide efficient data transport of many users on a single physical connection.ISDN defines H0 channels (384 kbps), H11 (1536 kbps), and H12 channels (1920 kbps)
Types of Bearer Services In ISDN: