Huawei OptiX OSN 550 Configuration Manual page 110

3 Configuring SDH Services
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When the transmission path between NE1 and NE2 becomes faulty, the signal flow and timeslot
allocation are as follows:
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The difference between the two-fiber unidirectional MSP service and the two-fiber bidirectional
MSP service is as follows:
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Services are added to the ring on the source NE (NE1), pass through NE2, and finally are
dropped from the sink NE (NE3). The capacity of the services is 5xE1.
Traffic direction from NE3 to NE1: NE3→NE4→NE1
Services are added to the ring on the source NE (NE3), pass through NE4, and finally are
dropped from the sink NE (NE1). The capacity of the services is 5xE1.
VC-12s 1-5 of VC4-1 carry the five E1 services for transmission.
Traffic direction from NE1 to NE3: NE1→NE4→NE3→NE2→NE3
Services are added to the ring on the source NE (NE1) and switched from the original
working path to the protection path. Then, the services pass through NE4 and NE3. After
that, the services are switched from the protection path to the working path on NE2. Finally,
the services are dropped from NE3.
The services from NE3 to NE1 are not affected, and the traffic direction is NE3→NE4→
NE1.
The two-fiber unidirectional MSP service uses the diverse routes, whereas the two-fiber
bidirectional MSP service uses the uniform route.
In the case of the two-fiber unidirectional MSP service, different optical fibers are used for
the working timeslot and protection timeslot. That is, one optical fiber is used for carrying
the working service, and the other optical fiber is used for protection. In the case of the
two-fiber bidirectional MSP service, the same optical fiber is used for the working timeslot
and protection timeslot. That is, a certain capacity of the optical fiber is used for carrying
the working service, and a certain capacity of the optical fiber is used for protection.
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OptiX OSN 550 Multi-Service CPE Optical Transmission
System
Configuration Guide
Issue 02 (2011-06-30)