Fibre Channel Link Recovery Delayed NOS Message
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Solution Overview
Problem
The delay in FC link initialization due to immediate detection of optical signal interruptions in Fibre Channel (FC) switches leads to unnecessary resource wastage and prolonged communication disruption, even if the failure recovers before initialization is complete.
Innovation Solution
A method is introduced to delay the issuance of a Not Operational State (NOS) message upon detecting an optical signal interruption, allowing a predetermined timeout period for potential recovery, during which idle messages are sent to maintain synchronization, thereby preventing unnecessary FC link initialization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If FC link failure detection triggers immediate FC initialization, then failover protection can restore physical connections quickly (under 50 ms), but the full reestablishment of FC link is delayed until initialization completes (up to 10 seconds)
Solution Approach 1:
The patent applies preliminary action by pre-configuring the FC switch to delay the NOS message transmission by a predetermined timeout period before actually triggering FC initialization. This preliminary delay allows the system to wait and see if the failure recovers before committing to full initialization, thereby reducing unnecessary initialization time while maintaining failover protection capability.
2Productivity
If FC initialization is triggered immediately upon failure detection, then link reestablishment procedure starts promptly, but communication resources are wasted during unnecessary initialization
Solution Approach 1:
The system performs a preliminary delay action by waiting for a predetermined timeout period before triggering FC initialization. This preliminary step filters out temporary failures that would otherwise trigger unnecessary initialization sequences, conserving communication resources while maintaining the ability to reestablish links when needed.
Solution Approach 2:
The patent applies preliminary anti-action by using the delay mechanism to prevent premature or unnecessary FC initialization. The timeout period acts as a protective buffer that stops the initialization trigger from acting immediately on transient failures, thereby avoiding wasted communication resources.
3Speed
If immediate NOS message transmission is used, then failure detection responsiveness is high, but service disruption time increases due to prolonged initialization
Solution Approach 1:
The system implements a preliminary delay action where the NOS message transmission is postponed by a predetermined timeout period. This allows the failure detection mechanism to remain responsive while the delay prevents premature initialization triggers, thereby reducing overall service disruption time when failures are temporary.
Data Source
AI summary
An optical system is provided that converts optical signals received over an optical trunk from a first optical switch to client optical signals intended for a second optical switch. The first and second optical switches operate in accordance with a Fiber Channel (FC) protocol. An interruption of the optical signals on the optical trunk is detected. Responsive to the interruption, a Not Operational State (NOS) message sent to the second optical switch is delayed so as to delay triggering of an FC link initialization in the second optical switch. While the NOS message is delayed, idle messages are sent to the second optical switch.