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What Is Intelligent Traffic Steering?

Intelligent traffic steering is a technology that uses intelligent algorithms to dynamically select the optimal path for network traffic. It can dynamically adjust network traffic paths based on the network topology and quality information, reduce network costs, improve network performance and reliability, and improve user experience. It is of great significance for enterprises to build SD-WAN networks.

Intelligent Traffic Steering Network Model

Intelligent traffic steering is implemented based on the overlay network. The following figure shows the network model.

Intelligent traffic steering network model
Intelligent traffic steering network model

A transport network (TN) is a WAN access network provided by a carrier to implement WAN interconnection of branches in an enterprise. A routing domain (RD) is a network domain in which there are reachable routes between devices although these devices reside in different TNs (for example, the Internet of China Unicom and the Internet of China Mobile).

As shown in the model, multiple overlay links are established between sites. When multiple links are available for traffic to reach the destination network, intelligent traffic steering can be used to dynamically select the optimal link for traffic based on the link quality, bandwidth, and priority requirements of applications. In addition, intelligent traffic steering monitors network quality in real time and dynamically adjusts traffic paths based on the real-time status of each link. This prevents user services from being affected by network quality, ensuring user experience.

Implementation of Intelligent Traffic Steering

Based on the overlay network, intelligent traffic steering provides the following functions:

  1. Collects network topology information and performance data, such as the network structure, link bandwidth, jitter, delay, and packet loss rate.
  2. Analyzes data and generates the optimal route. The intelligent traffic steering technology analyzes the collected network topology information and performance data, and generates an optimal routing table based on the preset algorithm and policy to select the optimal path for network traffic.
  3. Adjusts network paths in real time. The technology continuously collects information about network traffic, network topology, and performance, and dynamically adjusts network paths based on real-time conditions to ensure the optimal route for network traffic and prevent network congestion and data loss.

In intelligent traffic steering, there are two optimal path selection modes: preferential occupation and load balancing.

  • In preferential occupation mode, the link with the highest quality and optimal Service Level Agreement (SLA) is selected from multiple available links for data transmission.
    Preferential occupation mode
    Preferential occupation mode
  • In load balancing mode, data is distributed to available links with the same priority based on the interface bandwidth ratio.
    Load balancing mode
    Load balancing mode

Typical Applications of Intelligent Traffic Steering

Intelligent traffic steering has multiple typical application scenarios, including link quality-based traffic steering, load balancing-based traffic steering, application priority-based traffic steering, and bandwidth-based traffic steering.

Link Quality-based Traffic Steering

Active and standby links (high-priority and low-priority links respectively) are specified based on applications. When the quality of the active link does not meet the application SLA requirements, application traffic is automatically switched to the standby link.

In the following figure, when the MPLS link is not congested, its quality is good. In this case, the voice flow (VoIP flow) is transmitted over the MPLS link. CPEs monitor the link quality in real time. If the MPLS link quality deteriorates due to congestion and SLA of voice services cannot be ensured, the CPEs dynamically switch the voice traffic to the Internet link that has a light load and meets the SLA requirements.

In addition, the CPEs can detect link faults in real time. When detecting a fault on the MPLS link, the CPEs dynamically steer all service traffic on the MPLS link to the Internet link to ensure that the services are not affected.

Link quality-based traffic steering
Link quality-based traffic steering

Load Balancing-based Traffic Steering

When multiple links are available between two sites, the system performs load balancing on traffic based on the interface bandwidth ratio of the links.

In the following figure, an enterprise purchases two MPLS links from different carriers: 100 Mbit/s MPLS link from carrier A and 50 Mbit/s MPLS link from carrier B, which can be used as the primary links for the voice service. If the quality of the two MPLS links meets the SLA requirements of the voice service, voice service flows can be carried over both links in load balancing mode. Through real-time bandwidth utilization monitoring, the link bandwidth can be fully utilized.

Load balancing-based traffic steering
Load balancing-based traffic steering

Application Priority-based Traffic Steering

When application traffic is transmitted between sites and the bandwidth usage of a high-priority link exceeds the upper limit, traffic of the application with the lowest priority is steered to a low-priority link. If the link does not meet requirements, the traffic is steered to a link with a lower priority.

If the bandwidth usage of the high-priority link still exceeds the upper limit after the traffic of the application with the lowest priority is switched, the traffic of the application with the second lowest priority is switched to a low-priority link. Application traffic is steered in ascending order of the application priority until the bandwidth usage of the high-priority link falls below the upper threshold.

In the following figure, the MPLS link offers better quality than the Internet link and is configured as the primary link for both the voice and FTP services, with the Internet link being the secondary link. The voice service has a higher priority than the FTP service. As the traffic volume of the voice and FTP services increases, the MPLS link becomes congested. To ensure voice service experience, FTP service traffic is gradually migrated to the Internet link until congestion on the MPLS link is relieved. To fully utilize the MPLS link bandwidth, FTP service traffic can be configured to gradually switch back to the MPLS link when the MPLS link recovers.

Application priority-based traffic steering
Application priority-based traffic steering

Bandwidth-based Traffic Steering

There are two scenarios for bandwidth-based traffic steering:

  1. When the bandwidth of a link reaches a certain threshold or the remaining bandwidth is lower than a certain threshold, the link cannot be selected for new traffic of certain applications, preventing deterioration of application or link quality.
  2. The bandwidth of high-priority applications is preferentially guaranteed. To prevent high-priority applications from fully occupying the bandwidth, bandwidth limits can be configured for the applications. When the bandwidth usage of an application reaches a specified threshold, new traffic of the application is no longer transmitted over the corresponding link.

In the following figure, the video service requires high bandwidth. To ensure video application experience, when the video bandwidth usage is lower than a specified threshold, all video flows are transmitted over a high-priority link. When the video bandwidth usage is within a threshold range, the existing video flow continues to be transmitted over the high-priority link and the new video flow is transmitted over a low-priority link. When the video bandwidth usage exceeds a specified threshold, all video flows are switched to the low-priority link to ensure video application experience.

Bandwidth-based traffic steering
Bandwidth-based traffic steering

Commercial Benefits of Intelligent Traffic Steering

The intelligent traffic steering technology provides important commercial benefits in WAN construction of enterprises:

  1. Reduced network costs: The technology dynamically adjusts network paths based on information such as network load and link quality to prevent network congestion and data loss, saving bandwidth and hardware resources on enterprise networks and reducing network costs.
  2. Improved network performance and reliability: The technology selects the optimal network path for traffic based on different application scenarios and requirements to reduce network latency and packet loss rate, improving network performance and reliability.
  3. Improved user experience and satisfaction: The technology provides better links and guaranteed bandwidth for VIP applications, greatly improving user experience of VIP applications.

As such, the SD-WAN Solution with intelligent traffic steering is of great significance to network construction and business development of enterprises.

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