SDN Controller TWAMP Test Session Delay Measurement
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Solution Overview
Problem
In software-defined networks (SDNs), measuring data path performance between network elements (NEs) is challenging due to increased latency in the control plane-data plane link, which affects the accuracy of performance metrics like delay and jitter.
Innovation Solution
Implementing a method that uses Two-Way Active Measurement Protocol (TWAMP) test messages and control messages within the SDN controller to initiate test sessions across NEs, allowing for the calculation of delay and jitter by analyzing timestamps in reply messages, and configuring NEs to forward test messages along specific paths for performance measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If TWAMP test messages are used to measure performance metrics, then measurement capability is provided, but increased latency in control plane-data plane link reduces measurement accuracy
Solution Approach 1:
The measurement process is segmented into multiple independent test sessions, each measuring performance between specific pairs of network elements. The network controller divides the overall performance measurement task into discrete test sessions that can be executed independently, allowing accurate measurement of individual link latencies without being affected by overall system latency variations.
Solution Approach 2:
The network controller acts as an intermediary that initiates and coordinates test sessions between network elements. It sends control messages to configure test sessions and collects reply messages containing timestamps, mediating the measurement process to eliminate the impact of control plane-data plane link latency on the actual performance measurements between data plane elements.
2Reliability
If test sessions are initiated between all network elements, then complete performance coverage is achieved, but control message overhead and processing complexity increase
Solution Approach 1:
The test session configuration is made dynamic, allowing the network controller to adaptively select which network elements should participate in test sessions based on current network conditions, topology changes, and measurement priorities. This dynamic approach ensures comprehensive coverage of critical paths while avoiding unnecessary test sessions that would increase complexity.
Solution Approach 2:
The system changes parameters such as test session duration, message intervals, and participating network elements based on network conditions. By adjusting these parameters, the system maintains reliable performance measurement coverage while optimizing the balance between measurement completeness and control message overhead.
Data Source
AI summary
A method in a network controller of a control plane in a software defined network (SDN) coupled to a plurality of network elements (NEs) of a data plane in the SDN is described. The method includes at least sending a first control message to an ingress NE of the plurality of NEs to initiate a first test session; sending a second control message to an egress NE of the plurality of NEs to initiate a second test session; sending the test message to the ingress NE to cause the ingress NE to transmit the outgoing message from the ingress NE; receiving the first reply message from the ingress NE; receiving the second reply message from the egress NE; and calculating an indication of a delay between the ingress NE and the egress NE.