Features and architecture of ISDN network

ISDN. Main and additional kinds of service

1.Purpose of the work

Researching of the ISDN adapter possibilities by means of special software RVS-COM Lite. Set up of autoresponder, faxing by using an ISDN adapter and data transfer.

2.Key positions

Features and architecture of ISDN network

Integrated services digital network (ISDN) is a communication system with data, voice, and video transmission services, in which the main type of switching is channel switching and data are transmitted in digital form.

ISDN provides digitization of telephone network to transmit voice, text, graphics, music, video and other types of information to the end user and to receive it together from one terminal.

Important mean which provide the efficiency of the line usage is installing connect on demand -only for the duration of the session of data transmission. After its ending the physical connection is terminated. Unlike rented channels using communication channels on demand allows you to access the network or interrupt the link depending on the specific conditions or events which occurred on the network.

An important feature is the establishment of bandwidth on demand. When the bandwidth of one B channel exceeds the second connects automatically. To increase throughput by using PPP protocol, which is typically used to connect to the Internet, the standard Multilink PPP (MPPP) is developed. It allows to combine few B channels and create one logical channel with more bandwidth.

The structure of ISDN network is shown on Figure 1.

Figure 1- The structure of ISDN network

The main components of ISDN are:

-ISDN-stations (ISDN switches);

-ISDN terminals (digital telephones);

-internal ISDN adapter to connect a PC to ISDN network;

-external devices (blocks) to connect A PC to AN ISDN or LAN network as an alternative to adapters;

-blocks Network Terminator (NT1);

-communication lines (PRI and BRI interfaces).

There are two types of ISDN terminals. Dedicated ISDN terminals are called terminal equipment type 1, TE1. Terminals which are developed not for ISDN, such as DTE are called terminal equipment type 2, TE2. Terminals TE1 are connected to ISDN network by digital communication lines. Terminals TE2 are connected to the ISDN through a Terminal Adapter, TA.

Terminal ISDN adapter can be either a stand-alone device or circuit boards inside TE2. If TA is implemented as a standalone device, it is connected to TE2 through a standard interface of the physical layer (e.g. EIA232, v.24 or v.35).

The next point of connection in ISDN which is outside devices TE1 and TE2 is network terminal NT1 or NT2.

NT1 form digital subscriber line (DSL) which connects customer equipment with ISDN network. In most cases the NT1 is part of the network equipment, so customer equipment is manufactured without built-in NT1.

Nt2 are more complex devices of channel or data link level, which provide the concentration of user interfaces and their multiplexing. This type of equipment is the PBX, switching several interfaces BRI.

There is certain number of check points standardized in ISDN. These checkpoints provide logical interfaces between functional groups, such as the NT1 and TA. Check points of ISDN are "R" (checkpoint between non-specialized equipment TA and ISDN), "S" (check point between the user Terminals and NT2), "T" (check point of the NT1 and between devices NT1 and NT2) and "U" (check point between devices NT1 and the equipment of line shutdown in the commercial communication networks). The check point "U" corresponds to the connection of NT1 device to the network (see Figure 2).

Figure 2-ISDN configuration example

Дата добавления: 2015-09-06