SDN Delay Measurement via Timestamp Copying
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Solution Overview
Problem
Current methods for measuring network delay in SDN systems are inadequate, particularly in service chains, as they require additional test streams, time synchronization across network elements, and support for NSH, which can be impractical and lead to measurement noise and scalability issues.
Innovation Solution
A centralized network delay measurement approach that records ingress and egress timestamps at a delay monitor device, calculates delay based on these timestamps, and accounts for measurement noise by sending measurement packets to network elements, allowing for accurate delay estimation without the need for time synchronization or additional test streams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional test streams are used for delay measurement, then measurement accuracy is improved, but system complexity and resource consumption increase
Solution Approach 1:
The patent creates a copy of the data packet and sends it to a delay monitor for timing measurement, while the original packet continues through the service chain. This copying approach allows delay measurement without adding separate test streams, resolving the contradiction by using a copy instead of a completely separate measurement mechanism.
Solution Approach 2:
The delay monitor serves multiple functions: it receives copied packets from the service chain, records ingress and egress timestamps, calculates delay metrics, and provides measurement data to the SDN controller. This multi-functionality eliminates the need for separate dedicated measurement infrastructure, reducing system complexity while maintaining measurement accuracy.
2Measurement precision
If time synchronization across network elements is implemented, then delay measurement accuracy is improved, but system complexity and configuration difficulty increase
Solution Approach 1:
The patent segments the timing measurement function from the data plane network elements and concentrates it in the delay monitor. The ingress network element only records the ingress timestamp, while the egress network element only records the egress timestamp. This segmentation eliminates the need for complex time synchronization across all network elements, as each element only needs to maintain timing accuracy locally.
Solution Approach 2:
The delay monitor acts as an intermediary that collects timing data from the service chain and performs the delay calculation. It receives the ingress timestamp from the ingress network element and the egress timestamp from the egress network element, then calculates the delay without requiring these elements to be time-synchronized with each other. This intermediary approach resolves the synchronization complexity.
3Measurement precision
If NSH support is required for delay measurement, then measurement capability is improved, but device compatibility and deployment flexibility decrease
Solution Approach 1:
The patent uses packet copying to extract timing information without requiring modifications to the packet format or NSH support. By creating a copy of the packet and sending it to the delay monitor, the system can measure delay using standard packet formats and existing network infrastructure, eliminating the need for NSH support while maintaining measurement capability.
4Measurement precision
If centralized delay monitoring is implemented, then measurement accuracy is improved, but processing load on the monitoring device increases
Solution Approach 1:
The patent implements partial monitoring by selecting specific packets (e.g., every Nth packet or packets matching certain criteria) for delay measurement rather than processing every packet through the complete measurement pipeline. This partial action approach maintains measurement accuracy for representative samples while significantly reducing the processing load on the delay monitor compared to exhaustive monitoring of all traffic.
Data Source
AI summary
Methods for delay measurement in a software-defined networking (SDN) system are disclosed. In one embodiment, one packet each is received from a first and a second network device. The time stamps of these packets are recorded in a set of ingress time stamps and a set of egress time stamps respectively if the first and second network devices are the ingress and egress network devices of a traffic flow and if both packets include indications for delay measurement. Then the method continues with a delay measure for the traffic flow based on at least the sets of the ingress time stamps and egress time stamps associated with the flow identifier of the traffic flow, and a measurement noise the electronic device obtained from sending measurement packets to the first and second network devices.