INToSR: Building A Novel In-band Network Telemetry over SRv6

Traditional network measurements mainly focus on end-to-end performance. In-band Network Telemetry (INT) makes a change by embedding telemetry instructions in the packet header and obtaining the status information of each network device. This information forms telemetry metadata forwarded with the packet hop by hop, such that we can observe network conditions more comprehensively. However, INT cannot control the route path or focus on the measurement of critical nodes, while the measurement of all nodes costs a lot. This paper proposes INToSR, a novel In-band Network Telemetry that fully leverages the flexible path programming capabilities of Segment Routing over IPv6 (SRv6). It first defines new SRv6 Endpoint Behaviors and puts INT instructions in the Arguments field. Thus, INToSR enables path control by setting an INT path using the SegmentList of SRv6 and monitors the metrics of critical nodes like queue length, link workload, and packet latency, achieving fine-grained network measurement. INToSR is also lightweight because it reduces the embedded telemetry metadata, the header overhead, and the processing delay. An experimental testbed has been built, including Tofino chips, which implement INToSR in the data plane, as well as the SDN controller and the INT report processing platform in the control plane. The experiment results have verified the feasibility of INToSR, which achieves the nanosecond-level network measurement and outperforms two existing methods. Finally, the accuracy of INToSR is evaluated in locating network congestion, which provides references for optimizing network performance.