Broadband is a high-bandwidth, high-speed #Wide Area Network (WAN) service that allow home connection to the Internet by utilising the existing network infrastructure such as phone wiring, cable TV coaxial cable or satellite. It provides always-on connectivity, that is the immediate access to the Internet service, in contrast to dial-up connection.
Several WAN technologies are identified as Broadband technology, as shown below:
ISDN is a set of technologies developed to carry voice, video and data across Public Switched Telephone Network (PSTN) by existing telephone lines. It utilises #Circuit Switching and primarily operates at Physical Layer#, Data Link Layer# and Network Layer#. ISDN offers bandwidth from 128kbps up to 384kbps. It was the first #broadband service deployed in the home but nowadays, it has been outshone by Digital Subscriber Line (DSL) and Cable Modem.
DSL is a #Broadband technology that provides high-speed Internet via existing telephone cabling similar to Integrated Services Digital Network (ISDN). It is generally referred to as xDSL due to variety of existing flavours of DSL including Asymmetric DSL (ADSL) and Symmetric DSL (SDSL). The former offers faster download speeds than upload speeds and is usually subscribed by casual Internet users. The latter offers equal bandwidth in both directions, which is preferred in commercial settings.
Cable Modem is a #Broadband technology that utilises the existing coaxial cabling which was providing just the TV services before the technology. It is capable of offering high-speed connectivity as fast as Ethernet, which means it can run at the speed of greater than 10Mbps. However, since the connection must be permanently established, dialling multiple locations is not possible. Instead, it will directly connect to the Internet. Distance is not a limitation factor to it since the provider can easily amplify the signals if necessary.