Generation and Detection of Alarms and Performance Events in the SDH Higher Order Signal Flow

The principle for locating fault is "line first, then tributary; higher order first, then lower
order".
Therefore, this section focuses only on the alarms and performance events generated between
the SDH interface and the cross-connect unit like Huawei GXCSA during maintenance. This section describes the signal flow and the procedure for handling each overhead byte by each module.

Alarm signals generated between the SDH interface and the cross-connect unit

Based on the positions of the various overhead byte processing in the STM-64, STM-16, STM-4, STM-1 frame, the overhead
bytes are classified into four modules:
Regenerator section overheads
Multiplex section overheads
Higher order path overheads
Lower order path overheads
If a fault occurs in the first two modules, it affects all the higher order paths. If a fault occurs in
the overhead bytes of a higher order path, however, it affects only this higher order path and its
lower order paths.
The following sections describe the signal flow and the processing of each overhead byte.

Downlink Signal Flow
In the higher order downstream signal flow, overhead bytes are extracted and terminated.
Frame Synchronizer and Regenerator Section Overhead Processor

Uplink Signal Flow
The overhead bytes are extracted and then terminated in the downlink signal flow of the higher
order path. Overhead bytes are generated and alarm signals are returned to the opposite NE in
the uplink signal flow of the higher order path.

Planning the 1+1 &1:N Linear MSP on Huawei Optix OSN2500

Capabilities of Supporting the 1+1 Linear MSP

When planning the 1+1 linear MSP for the OptiX OSN 2500, first consider the capabilities of
supporting the 1+1 linear MSP.
In the case of Huawei OptiX OSN 2500, the capabilities of supporting the 1+1 MSP are as follows:

• The OptiX OSN 2500 supports the 1+1 MSP at the STM-64, STM-16, STM-4, and STM-1
• levels.
• An OptiX OSN 2500 system supports a maximum of 12 1+1 linear MSP groups.
• The switching and bridging mode supports the single-ended and dual-ended switchings.
• The switching revertive mode supports the revertive mode and non-revertive mode.

Planning Principles
To rationally and effectively plan the 1+1 linear MSP, the planning principles should be
followed.

Adhere to the following principles when planning the 1+1 linear MSP.

• Do not use different optical interfaces on one multichannel optical interface board to form,1+1 protection group. Otherwise, the protection function is unavailable when the board fails.
• The switching and bridging mode should be set to the single-ended switching.The switching revertive mode should be set to the non-revertive mode.
• It is recommended that you set the B2_SD as the trigger condition of the linear MSP ring protection switching.

Capabilities of Supporting the 1:N Linear MSP
When planning the 1:N linear MSP for the OptiX OSN 2500, first consider the capabilities of
supporting the 1:N linear MSP.
The OptiX OSN 2500 supports the 1:N linear MSP at the following levels:

• 1:N (1≤N≤14) linear MSP at the STM-16 level
• 1:N (1≤N≤14) linear MSP at the STM-4 level
• 1:N (1≤N≤14) linear MSP at the STM-1 level

In the case of the OptiX OSN 2500, the capabilities of supporting the 1:N linear MSP are as
follows:

• An OptiX OSN 2500 system supports a maximum of 12 1:N linear MSP groups.
• The switching and bridging mode is the dual-ended switching.
• The switching revertive mode is the revertive.

Planning Principles
Adhere to the following principles when planning the 1:N linear MSP.

• Do not use different optical/electrical interfaces on the same multichannel optical/electrical interface board to form a 1:N protection group. Otherwise, the protection function is unavailable when the board fails.
• In the 1:N protection scheme, the protection route can carry extra services, but the extra services cannot be protected.
• It is recommended that you set the WTR time of the linear MSP ring to 600s.
• It is recommended that you set the B2_SD as the trigger condition of the linear MSP ring protection switching.