OTN Interface BDI-to-AIS Mapping for Bidirectional Switching
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Solution Overview
Problem
Current OTN technologies do not provide seamless bidirectional signaling for unidirectional failures, leading to insufficient protection switching in optical networks, which is inadequate for handling increased data demands and emerging applications like VoIP, IPTV, and high-definition video-on-demand.
Innovation Solution
The method involves generating an alarm indication signal in response to a Backward Defect Indication (BDI) signal from a remote network element, enabling bidirectional routing switching by triggering the network element to switch its routing to the remote element, ensuring protection switching in both directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If OTN interfaces are used to transport IP traffic over DWDM network, then the capacity and integration of DWDM and IP technologies is improved, but the bidirectional signaling capability for unidirectional failures deteriorates
Solution Approach 1:
The patent segments the failure detection and signaling functions into distinct components: the BDI signal path for detecting unidirectional failures and the AIS signal path for generating alarm indications. This segmentation allows independent optimization of each function while maintaining overall system reliability.
Solution Approach 2:
The patent introduces the BDI (Backward Defect Indication) signal as an intermediary mechanism that carries failure information from the receiving end back to the transmitting end. This intermediary signal enables bidirectional awareness of unidirectional failures without requiring complex bidirectional transmission testing.
2Reliability
If protection switching is implemented in OTN networks, then the reliability of communication is improved, but the complexity of signaling and routing control increases
Solution Approach 1:
The patent implements preliminary action by pre-configuring protection paths and establishing BDI signal monitoring before failures occur. When a failure is detected, the protection switching is already prepared and can be activated immediately, reducing the complexity of real-time decision-making.
Solution Approach 2:
The patent employs feedback mechanisms where the BDI signal provides continuous information about the health of the transmission path. This feedback enables automatic protection switching decisions without complex centralized control, simplifying the overall signaling architecture.
3Measurement precision
If unidirectional failure detection is implemented, then the precision of failure detection is improved, but the bidirectional routing protection capability deteriorates
Solution Approach 1:
The patent transitions from unidirectional failure detection to bidirectional protection by adding the BDI signal dimension. The BDI signal travels in the opposite direction (backward) to convey failure information, creating a two-dimensional signaling approach that enables bidirectional routing protection while maintaining precise failure detection.
Solution Approach 2:
The patent uses inversion by sending the BDI signal in the opposite direction of the data flow. Instead of trying to detect failures in the forward direction only, the system inverts the approach by having the receiving end detect failures and send notification backward, enabling bidirectional protection awareness.
Data Source
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AI summary
In an OTN (Optical Transport Network), an OTN interface of a network element may receive a BDI (Backwards Defect Indicator) signal from a far end network element to which OTN frames are being transmitted. A BDI signal indicates the occurrence of a unidirectional failure in the transmission of OTN frames to which the far end network element responds by switching its routing to the network element. The OTN interface generates an AIS (Alarm Indication Signal) for its network element so that the network element switches network communication channels to the far end network element to ensure bidirectional switching upon a unidirectional failure.