Updated on Apr 2, 2024 by

What Is IFIT?

IFIT, proposed by Huawei, is an industry-standard protocol known as In-situ Flow Information Telemetry (IFIT). It enables direct measurement of network performance indicators by marking real service packets with IFIT headers. With real-time reporting and visualization on the GUI of iMaster NCE-IP, IFIT offers high precision and flexibility for intelligent O&M, working in conjunction with big data platforms and intelligent algorithms.

Why Do We Need IFIT?

The advent of 5G and cloud computing has ushered in significant changes in the services and architecture of IP networks. Notably, the development of 5G technology has given rise to a multitude of new services, including HD video, virtual reality (VR), and the Internet of Vehicles (IoV). Simultaneously, the cloudification of network devices and services has emerged as a popular choice for achieving unified management and reducing operations and maintenance (O&M) costs. However, these advancements in services and architecture present a range of challenges for bearer networks, such as the need for ultra-bandwidth, hyperconnectivity, low latency, and high reliability.


Conventional network O&M methods are inadequate in meeting the reliability requirements imposed by the new services and architecture. Two major issues are the passive detection of service faults and the inefficiency in fault demarcation and localization. In most cases, O&M personnel rely solely on user complaints or work orders from related service departments to identify the scope of faults. This approach hampers the quick detection of faults and forces a passive response, leading to increased troubleshooting pressure and potentially resulting in a subpar user experience.

Moreover, the demarcation and localization of faults often require collaboration among multiple teams, lacking a clear mechanism for demarcation and well-defined responsibilities. Troubleshooting becomes inefficient as devices must be manually checked one by one to identify the faulty device, which then needs to be restarted or have its traffic redirected to another device. Additionally, traditional Operations, Administration, and Maintenance (OAM) technologies rely on simulating service flows using test packets, limiting their ability to accurately replicate performance deterioration or fault scenarios observed in live network environments.

In response to this situation, Huawei has introduced the IFIT protocol. IFIT is an in-band measurement technology that marks genuine service packets or inserts measurement information into them. Unlike out-of-band measurement technologies, IFIT reflects real-time network performance indicators and proactively detects service faults. It outperforms existing in-band measurement technologies and can work with big data analytics and intelligent algorithms to build an intelligent O&M system, promoting network automation and intelligence.

How Does IFIT Operate?

Below, we outline the fundamental workings of IFIT to demonstrate the implementation of its aforementioned advantages.

Accurate Fault Localization with IFIT:

Let's take the example of IFIT over SRv6 scenario. In this case, an IFIT header is encapsulated into a Segment Routing Header (SRH) and consists of three components: Flow Instruction Indicator (FII), which marks the start and length of the IFIT header, Flow Instruction Header (FIH), which uniquely identifies a service flow, and Flow Instruction Extension Header (FIEH), which defines extended functions.

The FIH includes the L and D fields, enabling packet loss and delay measurements using alternating coloring. Coloring involves marking packets for specific measurements, achieved by setting the packet loss coloring bit (L) or delay coloring bit (D) to 0 or 1. By coloring genuine service packets and leveraging time synchronization protocols like 1588v2, IFIT can proactively detect minor network changes and accurately reflect packet loss and delay on the network.

Additionally, the FIEH contains the E field, which defines two IFIT measurement modes: E2E (end-to-end) and hop-by-hop (trace). The E2E mode is suitable for overall service quality monitoring, while the trace mode is used for hop-by-hop demarcation in low-quality services or on-demand hop-by-hop monitoring for VIP services. The difference lies in whether IFIT needs to be enabled on all IFIT-capable nodes along the service flow path.


In most cases, E2E IFIT and trace IFIT are used in conjunction. When the E2E IFIT measurement data exceeds a threshold, trace IFIT is automatically triggered. This allows for quick fault demarcation and localization by restoring the actual service flow forwarding path.

Real-Time Data Transmission with IFIT:

In an intelligent O&M system, IFIT leverages telemetry to send measurement data to iMaster NCE-IP for real-time analysis. Telemetry is a technology that facilitates remote and rapid data collection from physical or virtual devices. Devices push information, such as interface traffic statistics, CPU usage, and memory usage, to collectors at regular intervals, ensuring faster data collection compared to the traditional pull mode (question-answer interaction). IFIT can flexibly collect data by subscribing to different sampling paths, enabling efficient management of more devices and obtaining high-precision measurement data. This data empowers fast fault localization and network quality optimization.

As illustrated in the figure below, a user subscribes to a device's data source through iMaster NCE-IP. The device collects measurement data based on the configured requirements and encapsulates it, including flow ID, flow direction, error information, and timestamp, into telemetry packets for reporting. iMaster NCE-IP receives and stores the measurement data, displaying analysis results on its GUI.

By utilizing the high-speed data collection capabilities of telemetry, which can collect data within seconds, IFIT ensures real-time transmission of measurement data to iMaster NCE-IP, facilitating efficient performance measurement.

What Are the Usage Scenarios of IFIT?

This section outlines the practical applications of IFIT in various scenarios, including the Internet Protocol Radio Access Network (IP RAN) mobile bearer network, intelligent cloud-network private line service, and one financial WAN, demonstrating the versatility of IFIT.

IP RAN Mobile Bearer Network

The IP RAN mobile bearer network is a large-scale network that supports different access modes and carries various mobile bearer services, such as high-definition video, which demand reliable link connectivity and optimal performance. To address this, Huawei introduces the E2E Enhanced Stream Quality Monitoring (ESQM) + trace IFIT hybrid measurement solution. ESQM collects statistics on TCP, SCTP, or GTP packets based on 5-tuple information. In this solution, E2E ESQM is initially performed, and trace IFIT is triggered when a base station flow's performance indicator exceeds the specified threshold. iMaster NCE-IP then consolidates the reported hop-by-hop measurement data for path restoration and fault localization.

This solution enables detailed monitoring of performance indicators for service flows at various levels, including base station flows, data flows, and signaling flows. By utilizing real-time performance data from base stations across the entire network, an intelligent O&M system based on big data analytics can be built. This system facilitates real-time SLA awareness and multi-dimensional visualization of base station services. It also enables analysis and evaluation of potential network risks, as well as automatic adjustment and optimization of network resources for intelligent and automated O&M.

Intelligent Cloud-Network Private Line Service

The intelligent cloud-network private line service plays a crucial role in intelligent cloud-network technology. Leveraging the extensive coverage of the mobile bearer network, it offers enterprise private line services more conveniently and enhances network deployment, operations, and O&M efficiency through end-to-end collaborative management. IFIT provides VPN service analysis and assurance for intelligent cloud-network private line services, including site-to-site private lines, site-to-cloud private lines, and cloud-network interconnection scenarios. Let's consider the site-to-cloud private line as an example to illustrate the E2E IFIT + trace IFIT solution. In this case, E2E IFIT is initially performed, and trace IFIT is triggered when the performance indicator of a VPN flow exceeds the specified threshold. iMaster NCE-IP then consolidates the reported hop-by-hop measurement data for path restoration and fault localization.

This solution enables granular querying of VPN service flow performance indicators, ranging from minute-level to yearly-level data. It also facilitates the overall analysis of VPN services based on parameters such as VPN name, VPN type, and service status. By adopting this approach, the solution achieves multi-dimensional exception identification, network health visualization, intelligent fault diagnosis, and closed-loop fault self-healing.

One Financial WAN

The one financial WAN leverages SRv6 technology to establish rapid and seamless network connections between the cloud and various access points, ensuring efficient service provisioning. The financial industry, with its stringent SLA requirements, demands robust O&M capabilities due to the diverse range of outlet services brought about by advancements in banking services. Alongside traditional production and office services, other prevalent services include security protection, IoT, and public cloud services. In response, Huawei presents the IFIT tunnel-level measurement solution.

This solution supports IFIT tunnel-level measurement in SRv6 scenarios. It periodically compares the currently used link with the optimal link for path selection and optimization, enabling intelligent traffic steering. Additionally, a core controller is deployed to provide centralized O&M for the entire financial network, enabling end-to-end management and scheduling.

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