Adaptive Fail-Over for Packet Label Swapping
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Solution Overview
Problem
Current Provider Backbone Transport (PBT) systems experience excessive flipping between working and protection paths due to sporadic or systematic packet loss failures, leading to stress and damage on circuit equipment, as they switch based on the loss of a specific number of sequential packets, which is inefficient and causes echo effects in hierarchical heartbeats.
Innovation Solution
The advanced fail-over method introduces intelligent timing and decision measures to prevent excessive flipping by increasing the number of missed packets required for path switching and dynamically adjusting detection and delay metrics, allowing for stabilization of the system during short-duration outages and resetting triggers after stability is achieved, thereby controlling the switching between working and protection paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the system switches paths based on loss of a specific number of sequential packets, then packet loss detection is achieved, but excessive flipping between working and protection paths occurs
Solution Approach 1:
The patent applies dynamics by making the failover threshold adaptive rather than static. The system dynamically adjusts the number of sequential packet losses required to trigger failover based on the observed packet loss rate. When packet loss rate is high, the threshold increases to prevent premature failover; when packet loss rate is low, the threshold decreases to enable faster detection. This dynamic adjustment resolves the contradiction by allowing reliable packet loss detection while maintaining path switching stability.
Solution Approach 2:
The patent changes the parameter of failover trigger threshold from a fixed value to a variable that adapts to network conditions. By monitoring packet loss rates and adjusting the threshold accordingly, the system can distinguish between temporary packet loss and genuine path failures. This parameter change enables the system to maintain stability during normal packet loss while still detecting actual failures, thus resolving the flipping issue.
2Loss of time
If the failover threshold is set low for quick detection, then response time is reduced, but unnecessary switching due to sporadic packet loss increases
Solution Approach 1:
The system dynamically adjusts the failover threshold based on real-time packet loss rate observations. When the packet loss rate is low (normal conditions), the threshold is set lower to enable quick failover detection. When the packet loss rate is high (indicating potential false positive conditions), the threshold is increased to prevent unnecessary switching. This dynamic behavior resolves the contradiction by adapting the detection sensitivity to current network conditions.
Solution Approach 2:
The system performs preliminary monitoring of packet loss rates before triggering failover. By observing the packet loss pattern over a period and establishing a baseline, the system can distinguish between normal sporadic loss and genuine path failures. This preliminary action allows the system to set appropriate thresholds in advance, reducing both detection time and false positives.
3Device complexity
If sequential packet loss monitoring is used, then simple detection logic is maintained, but echo effects in hierarchical heartbeats occur
Solution Approach 1:
The patent introduces an intermediary layer of packet loss rate analysis between the simple sequential monitoring and the failover decision. Instead of directly using sequential packet loss count, the system first calculates the packet loss rate as an intermediary metric, then uses this rate to adjust the failover threshold. This intermediary step filters out the echo effects caused by hierarchical heartbeats while maintaining relatively simple detection logic.
Solution Approach 2:
The system implements feedback by continuously monitoring packet loss rates and using this information to adjust the failover threshold dynamically. The feedback loop allows the system to learn from past packet loss patterns and adapt its detection behavior accordingly. This feedback mechanism eliminates echo effects by preventing the system from reacting to normal heartbeat variations while maintaining simple overall logic.
Data Source
AI summary
The present method for advanced fail-over packet label swapping for a packet network having a working path and a protection path, each of the working path and protection path interconnected by a near-end switch and a far-end switch includes: provisioning the working path, protection path, near-end switch, and far-end switch with a failure counter delay; monitoring heartbeat packets on one of the near-end switch and the far-end switch during a monitoring period to determine a number of packets that were not received by at least one of the switches during the monitoring period; determining if the determined number of packets exceeds a predetermined lost packet value for the failure counter delay; and responsive to the determined number of packets exceeding the predetermined lost packet value, delaying the monitoring for a period of time equal to the failure counter delay.