User Manual

Architecture
Nortel Networks Confidential
3–16
PE/DCL/DD/0063
411–9001–063
Standard 12.07/EN September 2000
GSM/BSS V12
Standby CSWM updating
The standby side is brought up to date in the following steps:
asynchronous software downloading
asynchronous data updating
synchronous data updating
The active CSWM side downloads standby CSWM software asynchronously
without disturbing operations on the active side.
Asynchronous data updating is performed in the following phases:
The active CSWM instructs the standby CSWM to reinitialize its database.
The active CSWM copies the database and sends it to standby side.
The active CSWM stores status transitions that occur during updating and sends
at the end of the sequence. It then starts synchronous updating.
Synchronous updating is performed each time the BSC sends configuration data or
when the CSWM performs defense actions.
The active CSWM sends one or more update messages to the standby side before
sending an acknowledgement or event report to the BSC.
3.2.2 Data Signaling Concentration unit (DSC)
The DSC is controlled by the CSWM. It communicates with the CSWM via the
O&M bus. It serves channel multiplexing, demultiplexing, and Operations and
Maintenance (O&M) functions.
3.2.2.1 Multiplexing and demultiplexing
The CSWM uses the DSC to set up communication between the BSC and the other
entities that make up the BTS. The LAPD protocol ignores the DSC that serves
concentrator and routing functions.
The DSC reads level 2 addresses (TEI) contained in LAPD frames and, using a
routing table, sends the information onto another time slot. The time slot may be
concentrated (a number of TEI arrive) or not (single TEI).
3.2.2.2 Operations and Maintenance (O&M) functions
Configuration
The CSWM sends the following to the DSC:
overall configuration
connect and disconnect configurations