Marconi OMS 1200
Technical Product Description
221 02-ZAP 701 25/1 Rev C 2006-08-04
© Ericsson AB 2006
03PHB00004AAV-CUA
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6.14.1 SASE
Mode
disabled
The OMS 1200 uses the T3 timing source to time the SDH interfaces. The S1 byte of
the SDH interfaces indicates the operator assigned SSMB quality of the T3 input
signal.
Figure 6-1: SASE Mode Disabled
OMS1200
SASE
T3
T4
SSMB=0010 (G.811)
Configured
to G.812
1
2
1
2
1 = Priority for STM-
N outputs
Key
= Priority for
T4 outputs
STM-n
interface
SSMB=0100 (G.812)
SSMB=0100 (G.812)
STM-n
interface
The SASE does not forward the correct SSMB value from SDH input interface to SDH
output interface. It also fails to indicate that the synchronisation source has been
looped back. This could, in certain situations, lead to the creation of a timing loop in
the network. These problems lead to the introduction of the 'SASE' Mode operation.
6.14.2 SASE
Mode
In SASE Mode the OMS 1200 overwrites the outgoing STM-n SSMB in the direction
that provided the T4 source with a Do-Not-Use (DNU) SSMB. However, if the quality
of the received timing source decreases, the transmitted timing source will still
continue to carry the configured SSMB.
Figure 6-2: SASE Mode
OMS1200
(SASE Mode)
SASE
T3
T4
SSMB=0010 (G.811)
Configured
to G.812
1
2
1
2
1 = Priority for
STM-N sources
Key
= Priority for
T4 sources
STM-n
interface
SSMB=1111 (DNU)
SSMB=0100 (G.812)
2 = Priority for
SSU outputs
1
STM-n
interface