System information

FCD 901 48
Issue R2A, 07.2009
XMP1 Release 5.5 System Description
Single-channel protection switching
Aastra Proprietary Information Page 2-41
2.5.5 Single-channel protection switching
Single-channel protection switching is a special ring polling function. This
function permits a protection path to be switched for a converter.
Two channels that can be routed in the network via different paths must
each be switched in the starting and end node to a converter.
Single-channel protection switching is possible for the KZU SUB, KZU EX,
KZU FEK, DSK 64k, DSK V.24, DSK X.21, DSK V.35 and DSK WT
modules.
In the transmit direction, converter n is involved in a channel link between
port a and port b. In the receive direction, converter n is connected to port
a and port b. The subscriber is connected to converter n. The protection
path is switched via port b. "Protection switching" must be entered as
operating mode in the "Circuits" mask.
Note: In the central card slot information of the ports via which
the channel path is routed with single-channel protection
switching, info no. 2 "Interrupt signalling immediately in case of
failure" must be set.
In the example depicted below, converter 11/1 is linked to port 14/3/5. Port
13/2/10 is defined as protection port.
Normal operation:
Port 14/3/5 and port 13/2/10 monitor the data transmitted by converter 11/1.
Transmission is effected via link 1. The converter receives its information
from port 14/3/5.
Protection link:
As soon as link 1 fails, AIS is transmitted in the service digits. Converter
11/1 identifies AIS and switches over immediately to the receive data of port
13/2/10 of the protection link. The receive data are applied to converter 11/5
and are passed on to the subscriber.
Figure 2.22: Single-channel protection switching
Conv.
P
P
n
P
P
Port a
Port b
11/1
Conv.
Port a
Port b
Node 1
Node 2
14/3/5
13/2/10
Subscr.
Subscr.
Link 1
Protection link