WAN optimization was initially designed to overcome the shortcomings of multiprotocol label switching (MPLS) circuits. With MPLS, organizations leased a certain amount of bandwidth from their MPLS provider, and acquiring additional bandwidth (through deployment of additional MPLS circuits) was extremely expensive. WAN optimization was initially designed to maximize the usage of the limited bandwidth leased by an organization.

This is accomplished in a variety of different ways. A WAN optimization appliance typically has a wide range of functionality, such as:

• Compressing and deduplicating network traffic data
• Prioritizing data based upon business needs
• Caching commonly-accessed content
• Applying protocol-specific optimizations
• Implementing Forward Error Correction (FEC).

As organizations transition away from full reliance upon MPLS networking, bandwidth management is less of a pressing concern. However, deployment of a WAN optimization appliance still has numerous benefits for the modern enterprise.

Benefits of WAN Optimization

Since 2004, when WAN optimization began, corporate WANs have changed dramatically. Network traffic is carried over different infrastructure, hosted on different types of endpoints, and used in different ways. Despite this, WAN optimization can still provide significant benefits to the modern enterprise. Three of the main offerings of WAN optimization appliances are bandwidth management, decreased latency, and packet loss reduction.

• Bandwidth Management

Bandwidth management was one of the earliest priorities for WAN optimization. At the time, many companies were completely reliant upon MPLS bandwidth for reliable, high-performance networking.

While MPLS is a very effective solution for high-performance networking, it isn’t perfect. One of the major issues with MPLS is that it is extremely expensive to deploy new MPLS circuits and lease additional MPLS bandwidth.

The cost of MPLS bandwidth drove early investment in WAN optimization. By optimizing their use of limited MPLS bandwidth, organizations could put off investment in additional MPLS circuits.

While MPLS is still in use today, the advent of software-defined WAN (SD-WAN) has provided an alternative to MPLS. By optimizing routing of traffic over MPLS and broadband Internet connections, SD-WAN mitigates many of the bandwidth considerations that drove early WAN optimization investment. However, bandwidth limitations do still exist (i.e. in throughput limits on network firewalls), so bandwidth management by WAN optimization appliances is still of value to the modern business.

• Decreased Latency

SD-WAN largely solves the bandwidth problems of implementing a corporate WAN; however, any network will have some performance issues. With global corporate WANs running over the public Internet, network latency becomes a serious concern.

Routing on the public Internet is notoriously unreliable and one of the major drivers for initial investment in MPLS. SD-WAN helps to solve some of these problems by intelligently routing traffic over multiple different transport media so that failure or degraded service from one medium does not significantly impact the organization. However, some latency impacts will still exist due to unreliable routing on the public Internet.

WAN optimization helps to solve this problem by performing caching of frequently-accessed resources and protocol-specific traffic optimization. By ensuring that traffic makes the long trip to a remote server only when necessary and ensuring that it does so optimally, WAN optimization can dramatically improve network latency in most cases.

• Reduced Packet Loss

A final major goal of WAN optimization is to reduce packet loss. When routing traffic over any network, some packets are lost in transit. On the public Internet, with its unreliable routing, packet loss is even worse.

The impact of packet loss varies depending upon the application. Sending video over the network, i.e. for live video conferencing, is the application where packet loss is most noticeable. With live video, less than 0.5% packet loss is recommended to ensure that issues are not perceptible to users (compared to 1% for audio or more for other applications). Network protocols like the Transport Control Protocol (TCP), have built-in mechanisms for dealing with packet loss. However, these largely involve acknowledging each packet at the recipient’s end and having the sender retransmit any lost packets. Every required retransmission increases bandwidth usage and network latency (since multiple round-trip cycles are needed to get the packet).

WAN optimization can help to solve the packet loss problem through the use of Forward Error Correction (FEC). FEC enables receiving stations to regenerate lost packets without retransmission, decreasing latency, bandwidth usage, and overhead on the sender. 

Making the Most of WAN Optimization

With WAN optimization, an organization can ensure that business traffic is optimally routed over the corporate WAN and suffers from minimized network latency and packet loss. When a one second delay in a webpage causes a 7% reduction in customer conversions, optimizing an organization’s network infrastructure to ensure rapid application performance can have a significant impact on profitability.

However, optimization of the corporate WAN is only helpful if all business traffic flows over the corporate WAN and that the WAN offers high-performance, reliable network connectivity. SD-WAN based upon the public Internet suffers from the reliability issues of the public Internet, and the increased adoption of cloud computing for business-critical applications means that deployment of cloud-native SD-WAN is essential to minimizing network latency.