Point-to-Point Connection Technology
230
PBX Networking
Master/Slave
For an ISDN connection, it is possible to determine which PBX is the protocol
master and which the protocol slave. This relationship can be determined for
all three protocol layers independently of one another.
For each protocol layer, the PBX at the other end always has to be suitably
configured. If one PBX is the protocol master for a layer, the other PBX must
be the protocol slave for this same layer. Normally all three protocol layers are
configured identically. In the case of a trunk line, the network operator is the
protocol master for all three layers.
L1 Clock
To enable PBXs in the ISDN network to communicate with each other, they
must be “clock-aligned”. The L1 protocol master sets the clock for layer 1, and
the L1 protocol slave adopts (synchronises to) this clock.
When planning a PBX networking scheme, you must make sure that the L1
clock propagates from a master via a number of PBXs.
Example: propagation of the L1 clock
If more than one port with the setting
L1 Type
= “Slave” is configured on an
Forum 5004/5008/5012 and the setting
L1 sync possible
has been
activated, then one of the ports is automatically defined as the L1 clock
source. The Forum 5004/5008/5012 will automatically switch the clock
source to another port configured as an L1 clock source (if a line fails, for
example).
Please note:
Reciprocal or circular application of the L1 clock is not allowed.
Example: In the above case you could reverse the L1 slave/master setting for
the connection between PBX 1 and PBX 3. However, if you then activate the
setting
L1 sync possible
for the port of PBX 1, this may cause parts of the PBX
network to stop functioning temporarily.
PBX 3
PBX 2
Point-to-point
connection
Trunk line
Network
operator
PBX1
M
S
M
S
M
M
S
S
Содержание Forum 500 Series
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