Network Latency Measurement via Hardware Timestamping
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Solution Overview
Problem
Current mechanisms for determining network metrics like latency and round trip time (RTT) are imprecise and costly, particularly in high-speed networks, due to difficulties in synchronizing clocks between devices and relying on complex methods or layer 3 mechanisms that lack precision.
Innovation Solution
The technique involves inserting multiple timestamps into metric measurement messages using a hardware clock at both ingress and egress ports of network devices, allowing for precise RTT estimation and layer 2 hop-by-hop latency measurements, which are more accurate and cost-effective by utilizing processor and hardware clocks for clock cycle measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple timestamps are inserted into metric measurement messages using hardware clocks, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces software-based timing mechanisms with hardware clock circuits that directly generate timestamps. This substitution of mechanical/hardware systems for software-based solutions provides precise time measurement without requiring complex software synchronization protocols, thereby improving measurement precision while controlling device complexity through hardware integration.
Solution Approach 2:
The network device performs timestamping automatically using its own internal hardware clocks without requiring external time synchronization from other devices. Each device independently generates timestamps based on its local hardware clock, eliminating the need for complex inter-device clock synchronization mechanisms while maintaining high measurement precision.
2Measurement precision
If hardware clocks are used for timestamp generation, then measurement precision is improved, but cost increases
Solution Approach 1:
The patent employs inexpensive hardware clock circuits that are integrated directly into the network device's existing infrastructure. These hardware clocks are simple, cost-effective components that provide sufficient precision for measurement purposes without requiring expensive external time synchronization equipment or specialized hardware, thereby achieving high measurement precision at low manufacturing cost.
3Productivity
If layer 2 mechanisms are used for metric measurement, then productivity is improved, but measurement precision worsens due to lack of clock synchronization
Solution Approach 1:
The patent replaces the need for complex clock synchronization mechanisms by using hardware clocks that generate timestamps independently at each network device. This hardware-based approach allows layer 2 metric measurement to achieve high precision without requiring inter-device synchronization, thereby maintaining high productivity while improving measurement precision through hardware timestamp generation.
Data Source
AI summary
A metric measurement mechanism is used to determine network characteristics such as latency and round trip time with more precision than that available from layer three metric measurement mechanisms. The metric measurement mechanism can use the same architecture used by layer three metric measurement mechanisms while more accurately measuring network latency and isolating network device processing delays.