ODU Frame APS Byte Preservation in OTN Tunneling

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Solution Overview

Problem

Current Optical Transport Networks (OTN) inefficiently handle Automatic Protection Switching (APS) switching-coordination bytes, leading to loss of transparency and incomplete bidirectional switching, as APS K-bytes are terminated within the OTN cloud, limiting compliance with client APS protocols and causing unnecessary alarms.

Innovation Solution

The method involves encapsulating APS switching-coordination bytes from both work and protect signals in an Optical channel Data Unit (ODU) frame's overhead segment, allowing the active signal to be transmitted as a single signal over the OTN network, preserving protection protocol information and enabling transparent transportation of client traffic across the OTN cloud.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If APS switching-coordination bytes are transmitted in conventional OTN manner, then network resource utilization is improved, but bidirectional communication completeness deteriorates and alarms increase

Engineering Contradiction:

Improvenetwork resource utilizationVSAvoidbidirectional communication completeness

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The overhead segment of the ODU frame is segmented to include dedicated fields for APS K1/K2 bytes from both working and protection signals. This segmentation allows preservation of APS coordination information while maintaining efficient single-signal OTN transport, resolving the contradiction between resource utilization and communication completeness.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The ODU frame structure acts as an intermediary carrier that embeds APS switching-coordination bytes within its overhead segment. This intermediary mechanism enables bidirectional APS communication to be preserved during OTN tunneling without requiring separate dedicated channels, thus improving both reliability and resource efficiency.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If APS K-bytes are terminated during handoffs in OTN, then device complexity is reduced, but support for client APS protocols deteriorates

Engineering Contradiction:

Improvehandoff processing complexityVSAvoidclient APS protocol support

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

APS switching-coordination bytes are extracted from the payload and placed in the overhead segment of the ODU frame. This extraction allows OTN devices to handle APS bytes efficiently without complex handoff processing, while still maintaining full support for client APS protocols through transparent transmission.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The ODU overhead segment is designed to serve multiple functions: carrying OTN management information and simultaneously transporting APS switching-coordination bytes. This multi-functionality enables the system to support various client APS protocols while maintaining simplified OTN device operation.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If work and protect lines are fully redundant with discrete designations, then protection switching reliability is improved, but network resource efficiency deteriorates

Engineering Contradiction:

Improveprotection switching reliabilityVSAvoidnetwork resource efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The working and protection signals are merged into a single ODU signal for OTN transport. The overhead segment of this single signal contains APS coordination bytes from both original signals, enabling full protection switching reliability while improving network resource efficiency by eliminating redundant physical channels.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS8958701B2Methods and systems of preserving client overhead bytes in optical transport network tunneling applications

Publication Date: 2015.02.17 CIENA CORP

AI summary

A method, a network, and a node each implement the transmission of Automatic Protection Switching (APS) switching coordination bytes across an OTN network. A working signal and a protection signal are received, one of which is designated as an active signal. The active signal is encapsulated in an Optical channel Data Unit (ODU) signal. APS switching coordination bytes from the working and protection signals are placed in an overhead segment of the ODU signal. The ODU signal is transmitted into and received from an Optical Transport Network (OTN) network. The working and protection signals are recreated based on the active signal encapsulated in the ODU signal and the APS switching coordination bytes in the overhead segment. The recreated working and protection signals are transmitted. In this manner, a single ODU signal may be used to transmit both the working and protection signals.