April 16, 2024

Path Diversity vs Network Congestion in SDWAN Performance

8 min read
Discover the impact of path diversity and network congestion on SDWAN performance.
A network of interconnected nodes

A network of interconnected nodes

In today’s world, where businesses rely heavily on cloud-based applications and real-time communication, the traditional WAN model is no longer capable of meeting the growing demands of modern networking. To address this, Software-Defined WAN (SDWAN) has emerged as a game-changing technology that promises to solve many of the challenges faced by IT professionals. One of the key benefits of SDWAN is the ability to utilize multiple pathways for traffic routing, commonly known as path diversity. However, this approach can also cause network congestion. In this article, we explore the trade-off between path diversity and congestion management in SDWAN performance.

Understanding SDWAN and Its Importance in Modern Networking

SDWAN is an overlay technology that creates a virtual network on top of an existing WAN infrastructure. The goal of SDWAN is to provide centralized management and policy enforcement, while also improving visibility, security, and performance. In essence, the technology abstracts the underlying network and allows administrators to define policies based on application requirements rather than network topology.

The importance of SDWAN in modern networking cannot be overstated. With the rise of cloud computing, IoT, and other digital transformation initiatives, businesses need a network infrastructure that can scale, adapt and remain agile. SDWAN provides this flexibility by enabling businesses to connect to various WAN resources, including MPLS, broadband, LTE, and satellite links, with automated traffic routing based on a predefined set of rules.

Another benefit of SDWAN is its ability to optimize network traffic. By using intelligent routing algorithms, SDWAN can prioritize critical applications and ensure that they receive the necessary bandwidth and resources. This can improve application performance and reduce latency, which is especially important for real-time applications like video conferencing and VoIP.

Furthermore, SDWAN can enhance network security by providing end-to-end encryption and segmentation. This means that traffic is encrypted from end-to-end, preventing unauthorized access and ensuring data privacy. Additionally, SDWAN can segment traffic based on application or user, which can help prevent lateral movement in the event of a security breach.

Traditional WAN vs SDWAN: A Comparison

For many years, IT departments have relied on a traditional WAN model, which typically utilizes expensive MPLS circuits as the primary mode of connectivity. While MPLS is reliable and secure, it also has limitations in terms of bandwidth, agility, and flexibility. Furthermore, businesses with multiple locations face the challenge of manually managing and configuring each site, which can be time-consuming and prone to errors.

SDWAN, on the other hand, offers a more dynamic approach to networking. It leverages the ubiquity of broadband connections and uses software-defined techniques to optimize the performance of applications. SDWAN solutions also allow administrators to prioritize network traffic and enforce security policies across the entire network, providing a consistent user experience regardless of location.

One of the key benefits of SDWAN is its ability to reduce costs. By utilizing broadband connections, businesses can significantly reduce their WAN expenses, as broadband is typically less expensive than MPLS circuits. Additionally, SDWAN solutions can help businesses avoid costly downtime by automatically rerouting traffic in the event of a network outage.

Another advantage of SDWAN is its ability to simplify network management. With traditional WANs, IT departments must manually configure and manage each site, which can be a time-consuming and complex process. SDWAN solutions, on the other hand, offer centralized management and configuration, allowing administrators to easily monitor and control the entire network from a single location.

What is Path Diversity and How Does it Affect SDWAN Performance?

Path diversity is a technique that SDWAN uses to spread traffic across multiple network paths to avoid a single point of failure or to optimize bandwidth utilization. The goal of path diversity is to ensure that traffic flows efficiently and effectively, minimizing latency and packet loss. However, having too many paths can lead to network congestion, which can negatively impact performance.

When numerous paths are used for a specific application, it can be challenging to maintain performance levels. This is because each path will have its own bandwidth, latency, and packet loss characteristics, which can result in unpredictable results when switched dynamically. Furthermore, SDWAN controller technology cannot always keep up with the trends of path performance through a predictor algorithm, and it can take several iterations for the best path to be chosen.

Another factor that can affect path diversity is the geographical location of the network paths. If the paths are located in different regions or countries, there may be differences in network infrastructure and regulations that can impact performance. For example, some countries may have stricter data privacy laws that can slow down traffic or require additional encryption.

Additionally, the type of traffic being transmitted can also impact the effectiveness of path diversity. For example, real-time applications like video conferencing or VoIP may require a more stable and reliable path, while non-real-time applications like email or file transfers may be more tolerant of latency or packet loss.

The Impact of Network Congestion on SDWAN Performance

Congestion occurs when data traffic exceeds the network’s capacity, leading to delays and ultimately packet loss. In an SDWAN environment, multiple paths can increase traffic significantly, and in some cases, the total amount of traffic may exceed the bandwidth of the available paths, leading to congestion. Network congestion can affect application performance, causing slow response times, choppy voice and video calls, and other issues, resulting in the inability to fully utilize cloud applications.

One common way to address network congestion is by setting up Quality of Service (QoS) policies. QoS is a set of techniques that prioritizes different types of traffic based on their importance to the business. For example, VoIP traffic might receive higher priority than email traffic, since real-time communication requires low latency and lossless packets. QoS can help with congestion, but it cannot entirely eliminate the effects of saturation.

The Role of QoS in Managing Network Congestion in SDWAN

QoS policies can help alleviate congestion in a network by prioritizing critical traffic, but it cannot solve the problems of high volume or lack of bandwidth. In an SDWAN environment, QoS helps assign priorities to traffic, but it cannot influence the overall bandwidth consumption of an application. In contrast, path diversity seeks to optimize the transmission of data within the available bandwidth by choosing the best path, therefore preserving the maximum bandwidth possible.

How to Optimize Path Diversity for Improved SDWAN Performance

Optimizing path diversity involves selecting the best combination of multiple paths based on various parameters such as packet loss, latency, availability, and others. A good path selection algorithm will ensure that the selected path minimizes network congestion and provides the best possible performance. Selection algorithms must take into account the historical data about network performance, the trend of network bottlenecks, and the reaction time of the decision-maker.

Once a path has been chosen, it is essential to ensure that the path is available and that the application can accommodate the requirements of the path. Administrators must carefully monitor the performance of the path to ensure it is meeting the defined characteristics and make changes when necessary.

Tips for Mitigating Network Congestion in SDWAN Environments

One way to mitigate network congestion is to ensure that each branch site has multiple WAN links. This provides options for the SDWAN controller to choose alternative paths when the primary paths are congested. An SDWAN solution should be designed to detect network congestion and quickly re-route traffic to an alternate path to alleviate congestion.

Another way to manage network congestion is through deep packet inspection (DPI). DPI helps identify packets of traffic that can be offloaded to another path, thus reducing congestion. Furthermore, DPI can help prioritize traffic, ensuring that critical applications receive sufficient bandwidth at all times.

Measuring SDWAN Performance: Key Metrics to Consider

Measuring the performance of an SDWAN solution is essential to detect and fix problems quickly. Administrators should measure the performance of both the application and the network. Some of the key metrics to consider include response times, round-trip times, packet loss rates, and jitter. These metrics provide insight into the overall health of the network and reveal where potential problems may exist.

It’s vital to monitor these metrics regularly and use them to identify trends and patterns that may be useful in making decisions about network optimization and path management.

Real-World Examples of Path Diversity and Network Congestion in SDWAN Performance

Real-world examples of path diversity and network congestion in SDWAN environments are commonplace. One scenario involves multiple users in a branch office that places a high demand on a specific application, such as video conferencing software. Under normal circumstances, the application may work correctly, but if traffic increases, sending video data over the same path can saturate the available bandwidth and cause congestion, such that choosing a different path could help maintain network performance.

A different scenario is where a large file download occurs over a single path, saturating it such that other types of traffic experience network congestion. In this case, the SDWAN controller would detect the saturation and route traffic through an alternate path, leading to better performance and fewer issues.

Best Practices for Optimizing SDWAN Performance Through Path Diversity and Congestion Management

To optimize SDWAN performance through path diversity and congestion management, there are several best practices that businesses should follow:

  • Monitor application and network performance regularly
  • Configure QoS policies to prioritize critical traffic
  • Implement path diversity with traffic load balancing mechanisms
  • Ensure that applications are compatible with multiple paths
  • Use DPI to detect congestion and offload traffic over multiple paths

Future Trends in SDWAN Performance Optimization

SDWAN adoption is expected to continue growing, and with it, new trends will emerge to optimize performance. One emerging trend is machine learning, which uses historic performance data to predict network latency, congestion, and other factors that might affect SDWAN performance. Other trends such as edge computing, network automation, and the use of AI will play critical roles in the development of new SDWAN solutions.

Managing Security Risks in an SDWAN Environment

An SDWAN environment introduces new security risks that businesses need to be aware of and address. With data traveling over multiple paths, it’s important to encrypt data and authenticate communications. Cybersecurity policies should be updated to reflect the new network topology and environment, and firewalls should be configured to ensure that data traffic is not compromised.

Choosing the Right SDWAN Solution for Your Business Needs

When choosing an SDWAN solution, businesses should consider a variety of factors such as cost, scalability, security, and vendor reputation. It’s important to analyze the business’s requirements and select a solution that meets those requirements most effectively.

Case Studies: Successful Implementation of Path Diversity and Network Congestion Management in SDWAN

Case studies provide valuable insights into how SDWAN solutions can help businesses meet their networking challenges. One example is a retail chain that experienced slow and unreliable performance when accessing critical applications. By implementing an SDWAN solution that utilized path diversity, the company reduced latency and packet loss, improved application performance, and reduced costs associated with WAN connectivity.

Another example involves a healthcare organization that struggled with network congestion due to an increase in patient records and imaging files. By implementing an SDWAN solution that included DPI and QoS policies, the healthcare organization was able to prioritize critical traffic and mitigate congestion, leading to improvements in patient care and satisfaction.


SDWAN is a revolutionary technology that brings significant benefits to modern networking. The ability to utilize multiple pathways for traffic routing provides path diversity, which can optimize performance, but can also lead to network congestion. It’s important to balance path diversity with congestion management, using techniques such as QoS policies, DPI, and traffic load balancing. By following best practices, businesses can achieve maximum benefits from their SDWAN solutions, and prepare for emerging trends in performance optimization and security.

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