Access network

The access network in telecommunications, engl. access network, has evolved as a separate network from the telephone network. Previously, each phone was connected via a pair of copper wires with a switch between the two, there was no controlling elements. So very many exchanges were required to achieve a coverage along with the limited reach of the local loop (ULL ). With the digitization of the telephone network in the train of the development of ISDN and the access network has become increasingly digitized. ISDN lines are connected via digital concentrators and multiplexers in PCM technology to the exchanges. To save costs, was tried in countries with high port density to reduce the number of exchanges. In order to the existing wiring does not need to expand, had to be inserted reinforcing and controlling network elements between the phone and exchange. These network elements are referred to in the jargon of the access networks as " Access Node ' s, while the exchanges " Service Nodes " hot. Access Nodes use in the access area often glass fibers to transmit multiplexed telephone channels. Usually to Synchronous Digital Hierarchy - technology (SDH ), but also passive optical networks ( PON) were installed (especially in Japan). Depending on how far extends the optical fiber in the access network, it is called "Fiber to the Curb " ( FTTC ), "fiber to the building" ( FTTB ), " fiber to the home " (FTTH ), " Fiber to the Terminal" ( FTTT ).

Broadband Access Network

In generalized usage not only the access network voice telephony is now being referred to, but it will also by the " wide-band " access network spoken. Among the classic access network is understood to be upgraded with fiber optic and DSL technology. Using Outdoor DSLAM and VDSL bit rates up to 50 Mbit / s can be provided for a subscriber. Even the mobile phone networks and the cable television network now use this term for the part of their networks, which includes the local loop and provides access to higher network levels.

V interfaces

The interface between access nodes and service nodes has been standardized: ITU- T refers to them as V interface. Concentrators and multiplexers are connected via so-called V1 and V2 interfaces to the switch. Larger port networks are connected via a V5 interface.

In Germany now include almost all new operators, which have their own subscriber lines and access nodes, but do not have a nationwide network of switching centers, at their Access Nodes via V5 interfaces to the switching facilities of the DTAG. Commercial and technical conditions for this interface via V5 are regulated in Germany by the Federal Network Agency as well as collocation.

The V5 interface is a 2-Mbit/s-Schnittstelle (E1). Functionally similar to the V5 interface between a switching center of the EWSD and APE.