System information

FCD 901 48
Issue R2A, 07.2009
XMP1 Release 5.5 System Description
Protection
Page 3-18 Proprietary Information Aastra
3.7 Protection
The reliability and maintenance of transmisssion networks are important
aspects to be taken into consideration when using multiplexers. In this
conjunction, redundancy configurations are playing a decisive role. The
redundancy of both transmission channels and certain multiplexer modules
is reasonable.
The SDH expansion in the XMP1 multiplexer supports the following
protection types:
• Sub-Network Connection Protection SNCP 1+1
• Multiplex Section Protection MSP 1+1
• 2 Mbit/s protection (internal)
• Module protection
3.7.1 Traffic protection
3.7.1.1 SNCP Sub-Network Connection Protection
In SNCP configurations, the entire transmission path or individual path
segments between the transmitter and receiver can be protected. Such a
SNCP configuration can also cover several multiplexers.
In case of a failure of the operating path, the system switches over
automatically to the protection path (standby path).
The following drawing shows the principle SNCP concept.
The payload to be protected and available as virtual container (VC) is
transmitted via two different interfaces and transmission paths to the
receiver. In the receiver, both VCs are monitored and one of them will be
selected.
The SDH expansion in the XMP1 supports the following SNCP types as
defined by ITU-T G.841:
• SNC/I (inherent)
• SNC/N (non-intrusive)
Operating path
Protection path
Path Segment
Doubling Selector
VC-xy
VC-xy
Figure 3.8: Principle of Sub-Network Connection Protection (SNCP)