V5 interface
V5 is a family of telephone network
V5 provided a standard set of protocols from the subscriber to the LE. The AN (or
The protocols are based on the principle of
V5 comes in two forms:
- V5.1 (ETS 300 324-1) in which there is a 1 to 1 correspondence between subscriber lines and bearer channels in the aggregate link to the exchange. A V5.1 interface relates to a single aggregate E1 (2 Mbit/s) link between a multiplexer and an exchange.
- V5.2 (ETS 300 347-1) which provides for concentration where there are not enough bearer channels in the aggregate link(s) to accommodate all subscribers at the same time. A single V5.2 interface can control up to 16 E1 links at once and can include protection of the signalling channels.
The layer 3 protocols
- Control protocol - This controls the setup and basic management of the V5 link from the Access Network (AN) to the Local Exchange (LE).
- PSTN protocol - Translation of the analogue signals for POTS into a digital form for transfer from AN to LE. (i.e. off-hook, digit dialling, on hook etc.).
- BCC protocol - In V5.2 since any channel could be allocated to the call, this protocol is assigned the job of managing the assignment of channels to a call. (Only in v5.2)
- Link control protocol - For managing up to 16 E1 links. It controls the status of the links (i.e. in service/out of service).
- Protection protocol - Used in V5.2; this protocol is duplicated on two or more channels on two or more links and provides instant failover in the event of one failing.
V5.1 only supports the Control, PSTN and ISDN protocols. V5.2 also supports BCC, Link Control and Protection protocols.
V5 layer 3 protocols are transported on a layer 2 protocol called LAPV5, a variation of the LAP-D or Link Access Procedures, D channel ISDN transport layer.
V5 is a protocol stack which controls circuit-switched communication paths.
Subsequent developments
Portions of V5 were re-used for a new service known as Narrowband Multimedia Delivery Service (or NMDS). In particular the PSTN protocol was re-used and combined with ISDN to provide a service to the subscriber. This allowed a digital connection to the subscribers house and the re-use of analogue phones across the digital connection. The AN reference point was replaced by an ISDN-like NTE. This NTE managed an analogue service and a basic rate ISDN service to the subscribers home.
See also
- SS7 Signaling System Seven - for communications between exchanges.
- OSI model
- BT Highway British Telecom's NMDS implementation.
References
- ETSI EN 300 347-1 (1999-12-28). V interfaces at the digital Local Exchange (LE); V5.2 interface for the support of Access Network (AN); Part 1: V5.2 interface specification (V2.2.2 ed.). Valbonne: ETSI. Retrieved 2008-07-04.
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: CS1 maint: numeric names: authors list (link) - ETSI EN 300 324-1 (2000-04-08). V interfaces at the digital Local Exchange (LE); V5.1 interface for the support of Access Network (AN); Pat 1: V5.1 interface specification (V2.1.1 ed.). Valbonne: ETSI. Retrieved 2008-07-04.
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: CS1 maint: numeric names: authors list (link)