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SD-WAN vs. load balancing: How are they different?

SD-WAN can use load balancing for WAN connections, but it doesn't require load balancing to work. Compare some of the similarities and differences between the two.

Load balancing is a traditional networking technique commonly used within data centers, while software-defined WAN is a newer technology that can use load-balancing capabilities for WAN connections.

Below, we compare SD-WAN vs. load balancing and discuss the similarities and differences between the two.

Load balancing

Load balancing spreads traffic across multiple paths, enabling better efficiency and lower latency for applications, especially in heavy traffic situations. Organizations can run load balancing as low as the network interface layer and as high up as the data center or cloud.

Because multiple paths exist for load balancing, a degree of failover exists; if one path becomes inaccessible, the other continues. Having two links that are in active/standby mode -- one working and one waiting for failure -- isn't considered load balancing because the traffic isn't shared across the two links.

In most cases, organizations load balance within the data center. Load balancing does not require a WAN, although it can also be done with WAN connections. Because WAN connections are notoriously difficult to set up and manage, however, most companies only have a single WAN connection per branch location, which makes it impossible to load balance.

load balancing
Load balancing distributes network traffic across multiple paths to reduce heavy traffic flow across a single server.

SD-WAN

SD-WAN makes deploying and managing WAN connections easier, as it opens up the opportunity to add multiple links between a headquarters and branch offices. SD-WAN can enable load balancing across multiple links, which balances the traffic load across the links and even provides resiliency in the case of a single link failure.

SD-WAN connectivity architecture
SD-WAN can use multiple connectivity links, like MPLS and broadband, to distribute traffic across the WAN.

SD-WAN does not require load balancing either, as a single link can be used to connect the two locations. When SD-WAN is combined with load balancing, however, it becomes a potent option that brings branch offices better connectivity to the applications and data they need to run their local operations. Often, an SD-WAN will use different transports, like MPLS, Ethernet and 4G LTE. In these cases, the traffic can even be load balanced across asymmetric transports, as it recognizes the differences in bandwidth and latency that each will provide.

Next Steps

Explore this glossary on all things SD-WAN

Find out when to use SD-WAN instead of DMVPN or IPsec

Learn what type of devices you need in SD-WAN deployment

This was last published in December 2019

Dig Deeper on Software-defined WAN (SD-WAN)

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How has your organization handled load balancing within the WAN, if at all?
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