Local loop

The subscriber line ( in Germany TAL or Asl abbreviated, in Austria the local loop; . Engl Local Loop), also known as trunk or last mile, provides the connection between the local exchange of the network operator and the telephone connection of the service user (subscriber, Subscriber ) within the within a telephone network house dar.

The TAL is a cable that per participant typically consists of a pair of copper wires ( CuDa ) (ie two electric lines ). In the old federal states of Germany were regularly two pairs, so a cable with four wires ( star-quad, four electric lines) laid per participant.

Connection cables for ISDN primary rate interfaces, which consist of two pairs or two fibers are also referred to as the local loop.

Routing

In Germany the local loop first leads from the main distributor in the local exchange ( sometimes in a remote peripheral device ) to the street cabinet in the main cable, then the cable distributors continue until the completion point line technology in the branch cable and from there into an installation cable finally to the first TAE the participant. In some cases, multiple subscriber lines can be switched from the main distribution to the street cabinet via connecting cable multiplexer for wire shortage in the main cable; for wire shortage in the branch cables PCM multiplexer come ( PCMxA, PCM5D ) are used.

Change the telecommunications provider

The local loop is an important component, since it can be replaced as a single part is difficult or impossible to alternative suppliers and is usually controlled by a local access network monopolist in the liberalization of a telephone network.

To enable competitors to realize the access to the connection of the customer in an economical manner, provides a regulatory body for a proper classification of the inputs of the incumbent. The possibilities of competitors, control of the local loop and the connection of the customer to obtain, consist of full unbundling of the local loop, line sharing - each with a collocated at the main distribution site - as well as bitstream access, which requires a less expensive network interconnection and the another technique (DSLAM and concentrator ) of the incumbent according to individual specifications of competitors is shared. Connecting cables pass through multiplexer can not be opened by the main distributor collocation from the competition.

For other inputs, such as call -by-call, preselection ( provider code ) or DSL resale, however, the connection remains under the control of the incumbent and the competitor may use third-party services only via the connection provided by the incumbent operator.

Alternatives to the individual subscriber line

Instead of the local loop of the telephone network can be realized telephony and Internet access via Ethernet, cable modems, wireless (Wireless Local Loop, WiMAX ), cellular or the power line (power line ). These alternative connection options in Germany, thanks to the availability of cheap offers, also used more and more.

Internet access via the subscriber line

Through newer technologies such as DSL subscriber lines can be upgraded to allow telephone calls in addition to also fast internet access. To this must be from the DSLAM location to the network termination at the subscriber local loops to be executed as a continuous single copper pair without multiplexer and the line length may be only a few kilometers because of signal attenuation depending on the wire diameter, xDSL process and the desired data rate. As part of the migration of the conventional circuit-switched fixed-line network to an IP-based Next Generation Network all connecting lines are expanded DSL functionality in the access network in the longer term.

When expansion of the telephone network of the new federal states in Germany preferably glass fibers were laid as a subscriber line ( OPAL ), with the result that the conventional DSL technology is here not applicable and other access techniques must be used. Since 2005 employed by Deutsche Telekom outdoor DSLAMs to offer VDSL can.

Connection variants

Connection variants for the telephone subscriber line:

  • Fiber In The Loop ( FITL )
  • Fiber To The Basement ( FTTB )
  • Fiber To The Home (FTTH )
  • Fiber To The Loop ( FTTL )
  • Fiber To The Node ( FTTN ) also known as Fiber To The Curb ( FTTC )
  • Such TAL is called a hybrid subscriber line.
  • Such a constructed network called hybrid access network.
  • Used by Deutsche Telekom at the VDSL2 network in conurbations
Main distribution frame Demarcation point Intermediate consumption Mobile telephony Powerline Central Office Convergence (telecommunications)
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