Ericsson RBS 2106 Reference Manual page 444

Channel Distribution Function
Figure 146
Messages are sent forward to their destinations without adding, deleting
or changing information.
Messages addressed to MO CF are sent to MO CF. All other messages
are sent to the TRXs.
The function terminates when MO CF has lost its data link connection.
At termination, MO CF is disconnected from the shared terrestrial
signalling channel. The signalling link to/from the TRXs is undisturbed
at the disconnection.
It also terminates when the channel distribution function becomes re-
configured in such a way that signalling to any TRX is no longer
performed on a shared terrestrial signalling channel. This is the normal
way to terminate this function.
56.3.4 Multidrop
For an RBS configured for multidrop, the function is initiated during
restart of the CMRU.
For an RBS not configured for multidrop, the function is initiated when
the parameter Network Topology is set by the OMT to indicate
multidrop (cascade).
The multidrop connected RBSs are connected so that each RBS uses its
port A towards the BSC and port B towards the next RBS. The latter
RBS is connected in the same way with port A towards the previous
RBS (and indirectly the BSC) and port B towards the next RBS etc.
Only RBSs supporting multidrop can be included in the multidrop
connection chain. The figure illustrates the case with three RBSs.
442 (485)
Shared terrestrial
signalling channel
Sharing terrestrial signalling channel
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CF
TRX
01_0299B
EN/LZT 720 0008 P2A
2001-11-28