Monday, July 18, 2016

When Interconnection Fails Due to Inconsistent Timeslot Numbering Modes

The services in certain timeslots are intermittently available during the equipment interconnection. During the problem investigation, it is found that the timeslot numbering modes are not consistent.

Fault Type

  • Equipment interconnection failure

Symptom

The OptiX OSN devices form a chain network that connects to an optical interface switch. The user configures VC-12 pass-through services in timeslots 1-38 on the OptiX OSN device. The services in timeslots 1-2, 4-5, and 7-8 are intermittently available on the switch. If the user configures VC-12 pass-through services in timeslots 1-63, this problem does not occur.

Cause Analysis

The timeslot numbering modes are not consistent. Currently, timeslot numbering modes are classified into sequential mode and interleaved mode, and Huawei equipment adopts the sequential mode by default. According to the user, the services are intermittently available. Thus, it can be inferred that the service configurations are correct, and the problem may be caused by the inconsistent timeslot numbering modes between the switch and the transmission device.

Procedure

  1. Through investigation, the switch of the user adopts the interleaved mode, which is inconsistent with the default timeslot numbering mode of Huawei equipment.
  2. The T2000 V100R002 that is used by the user can directly use the line numbers (Lucent mode) to create services in timeslots 1-38. After being reconfigured, the services on the switch become normal.

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