Basic Concepts - Huawei OptiX OSN 550 Configuration Manual

OptiX OSN 550 Multi-Service CPE Optical Transmission
System
Configuration Guide

3.1 Basic Concepts

The following basic concepts help you understand and configure the relevant SDH services
correctly.
Unidirectional Service
The unidirectional service indicates the service that is received and transmitted on different
paths. A unidirectional service created between NE A and NE B can only be transmitted from
NE A (source) to NE B (sink) or only be transmitted from NE B (sink) to NE A (source).
Bidirectional Service
The bidirectional service indicates the service that is received and transmitted on the same path.
A bidirectional service created between NE A and NE B can be transmitted and received from
NE A to NE B or from NE B to NE A.
MSP
The multiplex section protection (MSP) provides a function that switches the signals from the
working section to the protection section.
Shared MSP Ring
As an SDH ring structure, the shared MSP protection ring provides the working and protection
paths for each node in the ring network. When the service in the working path is abnormal or
interrupted, the service is automatically switched to the protection path for further transmission.
In this case, the service loss can be avoided.
Two-Fiber Shared MSP Ring
To form a two-fiber shared MSP ring, you need to use two fibers. In each fiber, one half of
channels are used as working timeslots, and the other half of channels are used as protection
timeslots. For example, in the case of an STM-4 service, VC-4s numbered 1 to 2 are used as
working timeslots and VC-4s numbered 3 to 4 are used as protection timeslots. When VC-4s
numbered 1 to 2 is abnormal or faulty, the service is switched to the corresponding protection
timeslots 3 to 4 for further transmission.
SNCP Principle
The sub-network connection protection (SNCP) is defined by the ITU-T Recommendations.
With 1+1 single-ended switching function, the SNCP is used for protecting services that travel
across different subnets. The SNCP is characterized by the dual-fed and selective-receiving
mode.
Principles for Generating SNCP Services
The SNCP is characterized by the dual-fed and selective receiving mode. Thus, to configure the
SNCP service, you should configure the dual-fed service and the selective receiving service. On
the U2000, the service can be automatically created. When the selective receiving service is
configured on the U2000, the dual-fed service of the NE can be automatically created. Thus,
Issue 02 (2011-06-30) Huawei Proprietary and Confidential
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3 Configuring SDH Services
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