Overview of ISDN integrated business Digital Network (1)

ISDN: integrated business Digital Network

Integrated Service Digital Network ISDN) is a digital telephone connection system. For decades, telephone communication has been using analog connection, while ISDN is the first protocol that defines digital communication, this protocol supports high-speed transmission services for voice, data, video, and graphics on the standard line. (B channel) is responsible for transmitting various media at the same time. The occupied bandwidth is 64 kb/s. Some switches limit the bandwidth to 56 kb/s ). Data Channel D) is mainly responsible for processing signaling. The transmission rate ranges from 16 kb/s to 64 kb/s, depending on the service type. ISDN is not limited to public telephone networks, but can also be transmitted through a group exchange network, an telegraph network, or a cable TV network. There are two basic service types for ISDN:

• Basic Rate Interface (BRI: Basic Rate Interface): consists of two B channels of 64 kb/s and a D channel of 16 kb/s. The total Rate is 144 kb/s. This service is mainly applicable to PC users. The bri of the u interface provided by Telco supports two-line digital connections with a transmission rate of 160 kb/s. Operation to reduce noise impact through ECHO elimination. Various data encoding methods use 2B1Q in North America and 4B3T in European countries) to provide a higher data transfer rate for single-line local loops.
• Main Speed Interface PRI: Primary Rate Interface): can meet the user's higher requirements. The typical PRI consists of 23 B channels and a 64 kb/s D channel, with a total rate of 1536 kb/s. In Europe, PRI is composed of 30 B channels and a 64 KB/s D channel. The total rate is 1984kb/s. Through NFASNon-Facility Associated Signaling), PRI also supports multiple PRI lines with a 64 kb/s D channel.

CCITT is now ITU-T) Research Group launched a group of ISDN recommendation protocols for the first time in 1984. Prior to this, each region had its own ISDN version. The Code setting mechanism allows you to enable nation-specific information elements for country-specific information units to support the use of their own information units in the data structure in each region. The generic National ISDN unit is National ISDN, which is proposed by Bellcore and applies to the United States. The National ISDN contains four types of private network information. It does not contain any single eight-byte Information Unit. Compared with other information units, the SEGMENT, FACILITY, and REGISTER information types, SEGMENT information, and extended efficacy information units are added to the National ISDN, which also change the meaning of some field values, and added some new field values.

Due to bandwidth and service restrictions, the traditional ISDN is called narrowband ISDN, which is opposite to the current broadband ISDNBISDN.