What is Over the Top SD-WAN?

Over the Top (OTT) Software-Defined Wide Area Network (SD-WAN) is a solution for creating a virtual overlay on top of existing network infrastructure independent of the underlying transport links. This means that OTT SD-WAN can leverage pre-existing, available transport links such as broadband internet, cellular and MPLS by applying a separate management layer. This management layer enables the optimisation of available bandwidth and provides a centralised management platform. By optimising bandwidth, Over the Top SD-WAN improves cost efficiencies by reducing reliance on more expensive dedicated MPLS circuits, enables flexibility as organisations are no longer tied to vendors for communication links. OTT SD-WAN also improves network scalability as it reduces the complexity for connecting branch sites, remote workforces and cloud applications as limitations from underlying transport links can be mitigated.

Key Features of Over the Top SD-WAN

This virtual overlay allows the optimisation of bandwidth and enables intelligent traffic management through a centralised pane.

Intelligent traffic management allows dynamic path selection for routing traffic across multiple communication links. Through Quality of Service (QoS) policies and Artificial Intelligence (AI) analysis of network telemetry, OTT SD-WAN can choose the best network path for traffic to be routed, prioritising critical application traffic and reducing latency or degradation.

Benefits of Over the Top SD-WAN

Through routing traffic over pre-existing, more affordable broadband connections, OTT SD-WAN improves cost efficiencies and reduces the reliance on traditionally used MPLS circuits.

Routing, whilst using Quality of Service (QoS) policies, optimises application routing to ensure that traffic from essential applications is prioritised and provided with adequate resources to prevent degradation.

As Over the Top SD-WAN is entirely separated from the communication links, this means that in order to scale the network, no significant investments in hardware for OTT SD-WAN is required to accommodate more links.

These factors mean that OTT SD-WAN offers flexible, high performance connections for remote and mobile workforces.

Security Aspects

Over the Top SD-WAN provides security features as part of its overlay. These capabilities include features such as encryption, firewall and Intrusion Prevention Systems (IPS), which ensure the protection and integrity of the network by preventing breaches from occurring.

To protect the confidentiality of the network, OTT SD-WAN implements Zero Trust Principles by segmenting the network and applying strict access control measures. This means that users are constantly authenticated and only authorised users can access specific segments of the network, therefore reducing the attack plane for network breaches.

Use Cases

OTT SD-WAN supports connectivity for remote work, multi-cloud and IoT integrations.

One way that remote workers are supported is that SD-WAN edge devices can be installed in users' home offices to provide optimised, secure access to the network and cloud applications over home broadband, minimising the need for Virtual Private Networks (VPNs).

Alternatively, software-based remote access can be utilised to provide secure VPN connections without additional hardware.

OTT SD-WAN can also be used to connect branch offices and remote users to applications hosted across multiple cloud services. This is achieved by providing direct connections from branch-to-cloud and user-to-cloud without backhauling through a central data centre and a single SD-WAN edge device aggregating multiple cloud connections. 

Finally, OTT SD-WAN enables the use of Internet of Things (IoT) devices within the network. By segmenting and isolating the IoT traffic into its own subnetwork, this limits attack surfaces and protects IoT devices from threats.

Challenges and Considerations

As Over the Top SD-WAN sits on top of the underlying network infrastructure, this means that OTT SD-WAN does not have complete control over the infrastructure. This means that network administrators have to be responsible for the management of underlying infrastructure in order to ensure the optimal performance from the OTT SD-WAN.

This also means that OTT SD-WAN is heavily dependent on the quality of the underlying connections. Unlike MPLS, broadband internet rarely has Service Level Agreements (SLAs) for key degradation metrics such as latency, jitter and packet loss, which means that public internet transport is unpredictable.

OTT SD-WAN often uses components from multiple vendors such as edge devices, gateways, orchestrators and security integrations. Due to this, each require different provisioning and maintenance processes and therefore this adds management complexity for network administrators when compared to single vendor solutions.

Market Trends and Future Outlook

Over the Top SD-WAN is increasingly being adopted by organisations which wish to utilise pre-existing low-cost broadband backbones or are locked into long-term MPLS contracts. This is due to the OTT SD-WAN overlay being independent from the underlying network connections and enables businesses to transition towards SD-WAN whilst not having the additional cost of new underlay.

Leading OTT SD-WAN vendors offer SLA-backed connectivity by leveraging their own private backbone networks. This allows network to be transported between Points of Presence (PoPs) whilst still using public internet for first/last mile access, improving network reliability.

Artificial Intelligence (AI) and Machine Learning (ML) are increasingly being integrated into OTT SD-WAN solutions to provide intelligent traffic routing, automated network troubleshooting and real-time optimisations. These capabilities reduce the workload for network administrators and ensure the availability of network resources.

Conclusion

Over the Top SD-WAN offers a cost-effective and flexible solution by pairing pre-existing network connections with a unified management system that improves performance and security for distributed workforces. By leveraging multiple transport links, OTT SD-WAN improves networking efficiency, providing improved bandwidth for crucial applications and dynamically routes traffic across the most reliable and high performing routes.

As OTT SD-WAN acts only as an overlay, there is the caveat that there is no direct control over the network links and is therefore heavily dependent on the performance of the underlying infrastructure. However, as leading OTT SD-WAN vendors are beginning to more frequently offer SLA-backed security via their own private backbone networks, this issue is minimised only to the first/last mile access between users/network resources and the backbone PoPs.

Finally, the increasing adoption of Artificial Intelligence and Machine Learning for automated routing, security and performance capabilities significantly reduces the workload for network administrators as well as management complexity. Meanwhile, the added support for Internet of Things devices through network segmentations assists organisation with scalability. These help to future-proof the network, with OTT SD-WAN offering a transitional solution from traditional WAN to SD-WAN.

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