Link bonding is more than just a fatter pipe — it’s a means to achieve cost savings, guaranteed traffic delivery, and more
From chemistry and finance to relationships and physics, connections shape our world. Amidst ionic bonds, familial bonds, municipal bonds, and more, a technological form of bonding — link aggregation — showcases the power of combining networking resources to improve operational efficiencies for enterprise businesses.
What is link aggregation?
Link aggregation combines multiple LAN or WAN interfaces into a single virtual connection to increase bandwidth availability, efficiency, and application resiliency. For link aggregation in the WAN, any type of connection works, including wired, cellular, satellite, and Wi-Fi as WAN. This technology is also referred to as link bonding, intelligent bonding, WAN bonding, teaming, and bundling.
Unpacking the features within WAN link bonding
There are three primary features of link aggregation, or bonding, each with a unique purpose.
Flow duplication
Flow duplication, which typically includes two WAN connections that are bonded to support a mission-critical application, aims to create an unbreakable WAN connection for scenarios where data delivery is vital. Using flow duplication, application data is duplicated and sent across two WAN links. That way, if there is any congestion on one of the links, there is no impact on the delivery of the application data.
Flow duplication is primarily used in vehicles roaming between different cellular providers' coverage areas or when roaming between cellular and satellite networks. If you have more than two links available — through a dual WAN router — the bonding technology can automatically determine which two links are the strongest and therefore the most reliable choices for critical traffic. However, it is important to note that because application data is being duplicated and sent simultaneously across two links, flow duplication uses double the data. In short, this feature should be reserved for your most mission-critical traffic to save costs.
Flow balancing
The goal of flow balancing is to improve cost efficiency by assigning weights to different WAN connections based on data pricing and allowances. For example, an IT administrator can bond a wired link with a cellular link and assign 80% of the traffic to move across the cheaper link while the remaining traffic uses the more expensive link. This feature applies mostly to fixed sites using a mix of applications and network traffic.
When using flow balancing, it’s important to ensure that there is sufficient bandwidth available on both links to carry 100% of the assigned traffic in case one link happens to fail or experiences congestion.
Bandwidth aggregation
Bandwidth aggregation is what most people think of when they hear the term “link bonding.” The goal of bandwidth aggregation is simple: to increase the bandwidth by combining WAN links to create a fatter pipe. Bandwidth bonding is beneficial in use cases such as a police cruiser or city bus that only needs to stream video during an incident or event.
The caveat of bandwidth aggregation is that the aggregated bandwidth will adopt the latency of the slowest connection. If that is an issue, using a slower WAN link as a network failover solution may be better than using it as a bonding solution, as bandwidth aggregation works best when using connections that have the same latency profile (such as two cellular modems).
Each of these intelligent bonding features can be established using policies created through an SD-WAN router. Applications are prioritized via the router, and administrators can then designate which traffic takes advantage of which WAN bonding feature. Individual features can also be used simultaneously across two or more bonded links. For example, if two or more links are bonded together, flow duplication can be implemented for business-critical traffic, and bandwidth aggregation can be used for real-time video traffic.
Exploring common link bonding use cases
After answering the question “What is link aggregation?” it’s time to apply the technology to real-life scenarios. From vehicles to sites, flow duplication, flow balancing, and bandwidth aggregation bring key advantages to enterprise businesses.
Link aggregation for mission-critical communication in vehicles
Dual modem routers in vehicles can accommodate multiple connectivity options, including cellular and satellite. For first responders, utility fleets, and more, WAN bonding using these various connections plays a key role in application resiliency and improved throughput when it matters most.
While flow duplication supports critical communications by replicating flows across both WAN connections as the vehicle moves between coverage areas, bandwidth aggregation supports a fatter pipe for video uploads.
Link aggregation for connecting sites
Many fixed sites will choose to bond wired and cellular WAN connections together. In this scenario, enterprise businesses will likely lean most heavily on the flow balancing feature to balance cost profiles between metered and non-metered data plans properly. Additionally, bandwidth aggregation can support the needs of higher bandwidth from remote sites based on their unique use cases (such as video surveillance needs, etc.).
Link aggregation for emergency kits
Amidst response to natural disasters and other emergencies, intelligent bonding features can combine cellular and satellite connections to maximize efficiencies when there is little room for error. Flow duplication will ensure critical information is sent and received, while bandwidth aggregation can support higher bandwidth needs for things such as providing Wi-Fi hotspot connectivity for multiple devices.