Abstract

The current hardware design of Dense Wavelength-Division Multiplexing (DWDM) coherent receivers involves a Drop and Continue design for line loopback operations, which causes the transmit side of a DWDM coherent transmitter to continue to push out Layer 1 (L1) frames to a far-end and frames on the receive direction are overwritten by frames that are in the transmit direction. This results in overlayed bidirectional protocols at the Client layers (e.g., Ethernet, Internet Protocol, etc.) to not converge or function as expected. A technique is proposed herein to transmit the presence of a Line/Facility Loopback configuration to a far-end via an unused bit of a Trail Trace Identifier (TTI) field. The far-end can check the set state of the bit and injects an Ethernet local fault (LF) indication (or equivalent) in the transmit direction of the Client port, which keeps the Client interface down on the far-end.

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Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

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