V5 interface
The V5 interface is a standardized interface for connecting a digital local exchange with an access network . All narrowband services for analog ( POTS ) and digital subscribers ( ISDN ) can be offered to subscribers connected to the access network via this interface . The international standardization of the V5 interface and the network protocols open to this interface, the V5 protocols, make it possible to connect components of the access network from different network operators to exchanges. Alternative network operators therefore do not have to set up their own nationwide networks with switching centers, but can limit themselves to setting up regional access networks that can then use the switching services of the existing network at switching centers via V5 interfaces. The disclosed V5 interface is therefore an important aid in the deregulation of the telephone market.
V5 protocols
The V5 protocols control facilities of the access network , so-called "access nodes", which can be connected to a digital exchange via a V5.1 or V5.2 interface .
Characteristics of the V5.1 interface
- 2 Mbit / s interface ( E1 ) to the exchange
- Permanently assigned user channels: Each subscriber line on the access network has permanently assigned user channels on the V interface
- A maximum of 30 analog subscribers or 15 ISDN subscribers with a basic connection
Protocols on the V5.1 interface
- 1. Protocol component signaling:
- 2. Protocol component control information
- C channel: signaling and control channel
- 3. Protocol component
- Timing and synchronization information
Characteristics of the V5.2 interface
- up to 16 2 Mbit / s interfaces (E1)
- analog or ISDN subscribers (basic connection)
- dynamically assigned user channels: for example 4: 1 (480 subscribers, 120 channels are available)
Protocols on the V5.2 interface
- 1st channel: transmission channel
- 2nd channel: timing and synchronization information
- 3rd channel: C-channel
- - Signaling and control channel
- - Management of additional channels
- - Targeted assignment of a connection
- - Observation of 2Mbit / s routes
Layer-2
- Envelope function sublayer (EF layer)
- Data Link Sublayer (DL Layer)
| DL address | Layer 3 protocol | V5.1 | V5.2 |
|---|---|---|---|
| 0-8175 | ISDN (SAPI, TEI) | Yes | Yes |
| 8176 | PSTN | Yes | Yes |
| 8177 | Control protocol | Yes | Yes |
| 8178 | BCC protocol | No | Yes |
| 8179 | Protection protocol | No | Yes |
| 8180 | Link Control Protocol | No | Yes |
Layer-3
- PSTN protocol
- Connections of the analog telephone network are established, managed and cleared down in a controlled manner
- ISDN protocol
- Adaptation of the structure used in the D channel
- Control protocol
-
- Port control protocol
- Reservation of ISDN or PSTN ports for a connection or their release after the connection has ended
- Common Protocol
- General coordination of the ports (for example when the system is restarted)
- Bearer Channel Protocol
- Management of the physical time slots in the very flexible transmission path between EWSD and AN (only with V5.2)
- Protection protocol
- Synchronization of the various links of a V5.2 interface
- Link Control Protocol
- Monitoring of links with regard to blockages and blocking of faulty links (avoidance of connection disruptions)
standardization
The associated standards are:
- ITU-T G.964 V-interfaces at the digital local exchange (LE) - V5.1 interface (based on 2048 kbit / s) for the support of access network (AN)
- ITU-T G.965 V-interfaces at the digital local exchange (LE) - V5.2 interface (based on 2048 kbit / s) for the support of access network (AN)
- ETSI ETS 300324 and EN 300324 V interfaces at the digital Local Exchange (LE); V5.1 interface for the support of Access Network (AN)
- ETSI ETS 300347 and EN 300347 V interfaces at the digital Local Exchange (LE); V5.2 interface for the support of Access Network (AN)
- DIN EN 300347-1 V interfaces at the digital local exchange (LE); V5.2 interface to support the access network (AN); Part 1: Specification of the V5.2 interface