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B-ISDN is an upgrade from ISDN that allows for high bandwidth applications. ISDN was intended to replace analog signals with digital signals for voice and data transmission. B-ISDN has a range of 155 mbps to 622 mbps and uses ATM for reliable signal transfer. However, it has not been widely implemented for Internet connectivity.
B-ISDN stands for Broadband Integrated Services Digital Network. It was designed to be the next step up from the basic Integrated Services Digital Network (ISDN), which uses the public switched telephone system to transfer data. B-ISDN allows the use of high bandwidth applications, which was problematic for ISDN.
Integrated Services Digital Network (ISDN) was first introduced in the late 1980s. It was originally intended to replace the analog signal used in the telephone system with a digital signal. This way it could be used for voice and data transmission. The idea was that if an agreement was reached for a worldwide standard for the use of ISDN, the price to produce ISDN chips would be less expensive, thus leading to a high rate of user demand. It took years to reach an agreement and by the time it was finalised, ISDN technology had been replaced by other modes of transmission.
The advantage of an ISDN network is that it uses existing telephone lines to carry data, video, voice and other signals simultaneously, using a digital signal. ISDN provides, depending on the type of signal transmitted and the specific interface type, a speed of 64 kilobits per second (kbps) to 128 kbps and can technically go up to 2 megabits per second (mbps). B-ISDN, considered high-end ISDN, has a range of 155 mbps to 622 mbps.
The demand for more bandwidth for use in the transfer of video and voice over the Internet was the main driving force behind the development of a new system. Basic rate ISDN, the standard interface used by ISDN, does not have the capacity to carry these signals on its channels. Businesses using a local area network (LAN), which typically moved at 10mbps, found that the normal 64kbps speed slowed overall connectivity significantly. This led to the introduction of B-ISDN, the broadband upgrade for ISDN.
Despite its high speed and availability for use in fiber optic networks, B-ISDN has not been widely implemented for use in networks or for Internet connectivity. For home networks, cable and DSL have been the primary technologies for network connections to the Internet. Businesses use a variety of connectivity types, mainly T1 and T3 lines, for Internet connectivity. Ethernet is still the primary choice for LANs either way.
B-ISDN uses asynchronous transfer mode (ATM). ATM uses small, same-sized data packets that create a more reliable signal than the typical variable-sized packets used by Ethernet networks, which is important for voice packets that need to be transferred in real time. ATM is now mainly used in digital subscriber lines (DSL) and some wireless technologies.
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