Description of the problem

Huawei SDH series equipment OSN3500 two-way 2mbits clock signal frame structure description

Processing

NGSDH series equipment supports two clock signal outputs, and the physical specification meets the G.703 requirements, but G.703 is only the physical layer or electrical interface specification for E1, and five application modes exist in E1 itself:

1) Non-framed

2) Framed PCM30 (CRC4 not enabled)

3) Framed PCM30-CRC4 (CRC4 on)

4) Framing PCM31 (CRC4 not on)

5) Framing PCM31-CRC4 (CRC4 on)

According to the G704 specification, if you need to support SSM, you must support compound frame synchronization, which uses the SA4 bits of the odd frames of the SMF (subcomplex frame) to form a 4-bit SSM message. See Annex G.704 for the extraction method.

There are two ways to synchronize the frame duplication: TS16-based duplicate frame synchronization; TS0-based duplicate frame synchronization; CRC4 checksum, which must be done after the duplicate frame synchronization to be able to perform calculations and detections. Our external clock chip SA586 can support PCM30-CRC4 and PCM31-CRC4 modes, and PCM30-CRC4 mode is adopted by default, which also supports TS16 and TS0 frame synchronization.

The key to ensure the synchronization of the double frame is to synchronize the two sides of the device synchronization mode and encoding mode is the same to synchronize.

Therefore, in the clock docking test, not only the SSM protocol configuration needs to be the same on both sides, but also the clock encoding mode and the synchronization mode of double frames need to be configured consistently in order to complete the clock docking.

The related technical information in this chapter and the troubleshooting process of SDH equipment are collected and organized by Shenzhen Optical Transmission Network Technology Company Limited ( www.opticaltrans.com), please retain the reproduction! Our company specializes in the sale of Huawei SDH optical transmission equipment, SDH transmission equipment.