HDLC Traffic Manager Timer Adjustment via Transit Delay Measurement
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Solution Overview
Problem
Current communication networks in ASON and GMPLS face challenges in determining accurate timer values for synchronization between master and slave nodes, leading to potential loss of control plane packets and connectivity issues due to frame slips during connection establishment and tear down, which results in slower restoration times and inefficient dynamic connection setup.
Innovation Solution
A method and system for determining High Level Data Link Control (HDLC) Traffic Manager (HTM) timer values based on measured packet transit delay between nodes, using a Direct Measurement overhead byte to calculate latency and set timers dynamically, ensuring efficient coordination during mode switches and minimizing message loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If timer values are set based on worst case round trip delay, then control plane packet loss is prevented, but mesh restoration time and dynamic connection setup time increase
Solution Approach 1:
The patent applies dynamics by transitioning from static worst-case timer values to dynamic timer values that are automatically adjusted based on measured round trip delay (RTD). The system measures actual RTD between nodes and configures timer values dynamically, allowing timers to adapt to current network conditions rather than using fixed conservative estimates. This resolves the contradiction by making timer values responsive to actual performance while maintaining reliability thresholds.
Solution Approach 2:
The patent changes the parameter of timer duration from a fixed worst-case value to a variable value based on measured RTD. By continuously monitoring actual delay and adjusting timer parameters accordingly, the system optimizes the balance between reliability (preventing packet loss) and speed (reducing restoration time). The timer value becomes a dynamic parameter rather than a static configuration.
2Reliability
If timer values are set based on worst case round trip delay, then control plane connectivity is maintained, but dynamic connection setup efficiency decreases
Solution Approach 1:
The system dynamically adjusts timer values based on measured RTD to optimize connection setup efficiency. Instead of using fixed conservative timers that slow down all operations, the dynamic approach allows faster setup when actual delays are smaller while maintaining connectivity reliability. This resolves the contradiction by adapting timer behavior to actual network performance.
Solution Approach 2:
The system performs self-configuration by automatically measuring RTD and adjusting its own timer parameters without manual intervention. This self-service capability enables the network to optimize its own performance characteristics, improving connection setup efficiency while maintaining reliability through automated adaptation rather than manual tuning.
3Ease of manufacture
If pre-defined timer durations are used, then implementation is simplified, but timer accuracy decreases leading to slower restoration
Solution Approach 1:
The system implements self-measurement and self-configuration, where nodes automatically measure RTD and configure their own timer values. This eliminates the need for manual timer configuration while achieving accurate, optimized values. The self-service approach resolves the contradiction by automating the measurement process, making accurate timer configuration as simple as deploying the measurement functionality.
Solution Approach 2:
The system uses feedback from RTD measurements to automatically adjust timer values. By continuously monitoring actual delay and using this feedback to configure timers, the system achieves accurate timer settings without manual intervention. The feedback loop resolves the contradiction by using measured data to optimize timer parameters automatically.
Data Source
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AI summary
A method and system for determining timers in an High Level Data Link Control (HDLC) Traffic Manager (HTM) state machine are disclosed. According to one aspect, the invention provides for determining a transit delay between two nodes by sending a first packet having a delay measurement byte to a second node that is on a link between the first node and the second node. The method also includes receiving a second packet with the delay measurement byte from the second node. The delay measurement byte sent by the second node is adjusted by the second node to indicate its receipt by the second node. A measured delay value is determined. The measured delay value is the delay between a time of sending the first packet to the second node and receiving the second packet from the second node. The measured delay value is determined by the hardware of the first node. Upon determining the measured delay value, timer values of the HTM state machine are set based on the measured delay value.