System information

FCD 901 48
Issue R2A, 07.2009
XMP1 Release 5.5 System Description
Module protection
Aastra Proprietary Information Page 3-25
3.7.2 Module protection
3.7.2.1 SDH Core Unit Protection
The SDH Core Unit Protection is a SCU protection implemented at the
equipment level. This protection covers the functions of the switching matrix
and the synchronization functions of the SDH Core Unit. Since the SDH
Core Unit also supports the connection of external 2 Mbit/s signals, these
signals will also be protected by a SDH Core Unit Protection configuration.
The 2 Mbit/s signals are routed and applied to the interfaces via Y-cables.
For such a protection configuration, two SCU modules are mounted in the
XMP1 subrack in two contiguous card slots. These two SCU modules are
interconnected by means of the SCU-FP front panel.
One SCU acts as Master, the other one as Slave.
The SDH Core Protection configuration is non-revertive, i.e. there will be no
automatic reversion from the Protection SCU (Slave SCU) to the primary
SCU (Master SCU) once the latter operates again correctly, e.g. after
replacement of a faulty module.
3.7.2.2 CU-E Protection
The CU-E is mounted as sub-module on the Central Unit of the XMP1 node.
The Central Unit in the XMP1 node can be doubled.
With Central Unit redundancy, the CU-E sub-module must be mounted on
both Central Units.
In case of a Central Unit switchover, switchover also takes place from one
CU-E sub-module to the other. Thus, it is ensured that an active CU-E is
never on a passive Central Unit.