A metro network is a 10G ring consisting of OSN 3500 with high service capacity to carry and fulfill the services demanded by customers. The Siemens RNC device is a 155M ATM POS port, and the OSN 3500 device provides ports at STM-1 rate, and the counterpart device that reaches through the transport network is the core network device.

At the beginning of the cutover that night, the fiber jumpers connected the STM-1 rate processing board SLH1 and the corresponding interface board OU08 of OSN 3500 equipment to the ATM rate ports of Siemens RNC equipment and the core network equipment at the two end sites. After confirming the normal transmission service and equipment status, the RNC service still could not start.

Alarm information

No

Processing

1) Work with the core network colleagues to confirm the configuration of J0, J1 and C2 bytes of the relevant docking ports, and found that the RNC service still could not start after the change.

(2) Verify the site hopping fiber to ensure that the docking hopping fiber does not produce a mandarin duck fiber and other misconnections.

(3) The port operating mode is consistent, and there is no problem of unsupported port rate.

(4) Finally found that both ends are non-channelized ATM, non-channelized should be configured VC4 services, the V12 level of service deletion, configure the VC4 level of service, after processing the RNC service back to normal.

Root Cause

1) Inconsistent configuration of the corresponding J1 and C2 bytes of the docking port results in service failure. The C2 byte is used to indicate the multiplexing structure of the VC frame and the type of service to be carried (for example, PDH service or ATM service).Incorrect setting of the C2 byte will result in failure of the docking.

The J0 and J1 bytes are tracking bytes used by the receiver to confirm the status of continuous connection with the transmitter. It can be set to any same character between devices of the same vendor, but it has to be set to some agreed-upon same character between devices of different vendors for mutual docking to be successful.

2) Both ends are non-channelized ATM, non-channelized means using VC4 to transmit, configuring V12 cross is not possible.

3) ATM rate ports are not supported to interface with STM rate ports.

Recommendations and Summary

For the above form of networking, regardless of whether the other device is a channelized POS port or a non-channelized POS port, it is recommended to configure VC4 level services at the transmission level to avoid similar troubles, reduce low-order cross occupancy of the device, and enhance reliability.

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