85
Types of Point-to-Point Connections
PBX Networking
Connection via an Active Transmission System
For distances exceeding the range of a direct connection, an active transmission system can increase the
range to up to 50 km. Normally the L1 master is the transmission system for the two connected PBXs. For the
protocol layers L2 and L3, one PBX is normally the protocol master and the other PBX is the protocol slave.
Connection by an active transmission system
N
Note:
The active transmission system itself gets its L1 clock either from the network
operator or from a clock generator connected by wire.
Connection via the Public Network
Point-to-point connections via the public network of a network operator can be used for bridging distances
beyond 50 km. Due to the long distance involved, for technical reasons it is not possible to synchronise the L2
protocol. Consequently, the public network is normally the protocol master for protocol layers L1 and L2. One
PBX is therefore the L3 master and the other PBX the L3 slave.
Point-to-point connection via a public network
PBX 1
L1 slave
L2 master
L3 master
PBX 2
L1 slave
L2 slave
L3 slave
Transmission
System
L1 master
PBX 1
L1 slave
L2 slave
L3 master
PBX 2
L1 slave
L2 slave
L3 slave
Public
network
L1 master
L2 master
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