ISDN Terminology Explanation 25, ISDN Terminology Explanation

1. Integrated Services Digital Network (ISDN) is a communication network developed on the basis of Integrated Digital Network (IDN).

It can provide end-to-end digital connectivity to carry a variety of telecom services and customers, including voice and non-voice.

Access to the network is possible through a limited set of standard multi-purpose user network interfaces.

The N-ISDN service opens the function of domestic and international long-distance direct dialingLocal calls, domestic and international general users, and n-isdn

Users are interconnected. Second, the characteristics of the business.

1.Integration of communication services (fax, image, video, conference television, data communication).

2.Achieve high reliability and high-quality communication.

3.Easy and flexible to use (can connect eight terminals, three terminal devices communicate at the same time).

4.The cost is low.

3. Business applications.

A variety of additional services such as remote communication, image and multi-file access, and caller user number recognition.

For example: the expansion and interconnection of local area networks;Visual**, high-speed fax;Remote Digital, Medical;Image Supervisor.

visual system. Fourth, the type of business.

1) Bearer business:

1. Unrestricted 64KB s.

2. Voice service.

1kHz audio service.

2) Terminal business:

1. Voice digital integrated business.

2. PC desktop system.

3. Data transmission service (64KB S-128KB S).

4. Leased line backup service.

5. High-speed remote access to computer network business.

6. LAN interconnection.

7. Visible business.

8. Conference TV business.

9. G2, G3 fax business.

c) Supplementary services:

1. Caller line identification is provided.

2. Caller line identification limitations.

3. Sub-address.

4. Multi-user number.

5. Terminal mobility.

6. User-to-user signaling.

7. Direct dial-in.

The differences between B-ISDN and N-ISDN are mainly manifested in the following aspects:

1) N-ISDN is based on the public ** switching network currently in use, while B-ISDN is based on optical fiber as the trunk and user loop transmission medium.

2) N-ISDN adopts synchronous time-division multiplexing technology, and B-ISDN adopts asynchronous transmission mode ATM technology.

3) N-ISDN pathways and their rates are predetermined, B-ISDN uses the concept of pathways, but its rates are not predetermined.

5) The main technical characteristics of the asynchronous transmission mode.

1) ATM is a connection-oriented technology that uses small, fixed-length data transmission units (cells) with a length of 53 bytes.

3) ATM dynamically allocates network bandwidth in the form of statistical time division multiplexing, which has a small network transmission delay and adapts to the requirements of real-time communication.

4) ATM does not have link error correction and flow control, the protocol is simple, and the data exchange efficiency is high.

5) The data transmission rate of ATM is 155Mbps, and there are currently three rates: 25Mbps, 50Mpbs and 100Mbps.

Answer]: The three main features of an ISDN are:

1) End-to-end digital connectivity. **The Integrated Digital Network (IDN) has been digitized internally, but in the case of network access to the network, users are still transmitting analog voice signals online. Therefore, the first problem of the transition from IDN to ISDN is to realize the digitization of user line transmission, and to solve this problem, in order to achieve end-to-end digital connection and make IDN an ISDN.

2) Integrated business. With end-to-end digital connectivity, it is possible to open a variety of services such as voice, data, text, and images, and realize the integration of services. The Integrated Services Digital Network (ISD) can not only transmit existing communication services, but also develop new services.

3) Standard multi-purpose network interface. The so-called "multi-purpose" means that the access interface can be common to a variety of services, that is, different services or different terminals can access the comprehensive service digital network through the same interface.

N-ISDN advantages.

N-ISDN), which is developed on the basis of the first line, can provide voice, data, image and other comprehensive services on an ordinary line, and provide the society with economic, high-speed, multi-functional, wide coverage, and simple access means of communication.

Its biggest advantage is that it can integrate various types of telecommunications services, such as fax, video, conference television, etc., into a network. All users who join this network can use only a pair of telephone cables to connect different terminals for different types of high-speed and high-quality business communications.

Limitations of n-ISDN.

The N-ISDN evolved on the basis of the digital ** network, its main service is the 64Kbit S circuit switching service, although it integrates the packet switching service, but this synthesis is only realized on the user-network interface, and its network is still provided by independent and separate circuit switching and packet switching entities to provide different services. N-ISDN can usually only provide telecom services within the PCM primary group rate, which makes N-ISDN less adaptable to the development of technology, and also makes ISDN have inherent limitations, which are manifested in the following aspects:

1. N-ISDN uses traditional copper wire to transmit, so that the rate at which the user quietly grinds into the network interface cannot be higher than the rate of the PCM primary group, and this rate cannot be used to transmit high-speed data or image services (such as ** signals, etc.), so that it cannot adapt to the needs of new business development.

2. The network switching system of N-ISDN is quite complex, although it provides comprehensive services including packet switching services on a network interface of the user, the network is actually a single network where circuit switching and packet switching coexist, and only two standard communication rates of B channel and D channel can be obtained in the user loop.

3. N-ISDN has great limitations on the introduction of new services, because N-ISDN can only support existing telecom services at a fixed rate (such as 64K bits, 84Kbits, 920kbits, etc.), which will be difficult to adapt to the requirements of bursting, variable rate characteristics and multiple rate characteristics of future telecom services.