Protection; Figure 6: P12 Sncp With Two Samo1 Units - ABB FOX61 Series User Manual

5.2

Protection


FOX61x LEDE1
LEDE1 supports 1+1 subnetwork connection protection (SNCP) for P12 and
P0-nc signals.
P12 and P0-nc protection switching for signals from the network or aggre-
gate side takes place on a tributary unit, e.g. LEDE1. A P12 or P0-nc signal
transported over the network is received e.g. on one or two SAMO1 units as
a working and a protecting signal. The signal state of the working and pro-
tecting signal is brought via the PBUS to the LEDE1 unit. The LEDE1 unit
performs the selection according to the signal states of the two signals.
VC-12 VC-12
C-12 C-12
P-12 P-12
PBUS
P12
E1
LEDE1
Figure 6: P12 SNCP with two SAMO1 units
1+1 SNCP provides the following functions:
• The LEDE1 unit selects the received signal from one of the two P12 or
P0-nc signals and switches to the other P12 or P0-nc if this signal fails.
• The operation type can be revertive or non-revertive (future release).
• The switching type can be unidirectional or bidirectional.
The unidirectional protection switching uses no protocol. The bidirectional
protection switching uses the remote defect indication (RDI) as switching
criterion. This provides bidirectional protection switching also when only
one direction of a bidirectional connection fails.
The bidirectional switching type is only available for ports that are config-
ured for one of the terminated transport modes.
• There is no restriction about the selection of working and protecting P12
or P0-nc.
P12 and P0-nc protection switching takes place in the P12/P0-nc cross con-
nect function of the PBUS access circuit.
Protection switching action can be driven by two different request types:
• Traffic signal requests:
− Signal fail (SF).
F U N C T I O N A L D E S C R I P T I O N
21