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In the late 1990s, procuring and maintaining networking hardware in-house was tremendously expensive. Even if you managed to source a refurbished networking equipment, the cost of laying the wiring and employing skilled personnel to keep things running smoothly exerts a heavy toll on IT budgets and manpower.

Along came cloud computing, which offloaded some of the simple storage and connectivity burdens to centralised third-party servers. This was the start of mass virtualisation of computing. It brought down the prices of hardware and maintenance aspects somewhat.

Fast forward to today: many people use the terms network-as-a-service (NaaS) and software-defined networking (SDN) interchangeably. Often times, we use the term SDN to which they actually mean NaaS. What is the difference, exactly? Let us take a step back to understand how these two terms came to be.


It certainly took a while for nascent cloud technology to gain traction among businesses. Many of these businesses saw more advantages in maintaining on-premises infrastructure.
That rift eventually led to a halfway approach comprising hybrid and multi-cloud to suit very specific corporate networking needs. What was undeniable was that the global reach of the internet has been taken for granted. Traditional wide-area networking is now a bottleneck of accelerated globalisation.
Before cloud computing finally became mainstream, technological advances in smart phones, mobile telecommunications and networking boosted the versatility and appeal of virtualisation further. Anything-as-a-Service (XaaS) started to become viable and reliable. Ordinary people were using virtualised services without even knowing what went on at the back end.
In retrospect, the increasing appeal of virtualised services had caused hardware-based on-premise networking to also grow in sophistication and affordability. The complexities and costs of keeping pace with cloud computing eventually led to an existential review: how long can we keep traditional physical networking viable by tagging-on new hardware and software to legacy infrastructure?
The rise of software-defined networks
Traditional network control has and continues to be a distributed model of supplying connectivity. This worked well until cloud computing changed user expectations and needs. The contender to traditional networking had to be cloud-like, centralised yet controllable; and virtualised for maximum versatility.
The technology that emerged: Software-defined networking.
What is Software-defined Networking (SDN)?
As a term popularised by network firm CISCO, Software Defined Networking (SDN) “makes a network more flexible and easier to manage. SDN centralises management by abstracting the control plane from the data forwarding function in the discrete networking devices”.
With SDN, centralisation is the key characteristic for bandwidth management, restoration, security and control policies. With centralisation comes a holistic view over the entire network. This results in better oversight, security, analytics (for business intelligence) and self-help (with zero-touch deployment).
The abstraction of applications from the hardware (physical connectivity) enables the use of application programming interfaces (APIs) to orchestrate and manage the network infrastructure in a more flexible and extensible way. With abstraction also comes software-programmability and automated provisioning and monitoring.
Another powerful trait of SDN is the openness of the network for multi-vendor interoperability. For example, Epsilon’s DCConnect allows integration of other applications within a common software and network environment.
Due to its openness, extensibility and programmability, SDN is the underlying technology (foundation) for the Network-as-a-Service (NaaS) model. Network service providers would use open APIs to sell and resell customisable network services to a broader range of customers. This empowers them with compelling features such as pay-as-you-use billing and bandwidth-on-demand.
Leaving the hardware aspects of networking to centralised specialty providers such as Epsilon frees up considerable IT resources from corporate users. Additionally, economies of scale are reaped, while a software-defined network architecture opens up limitless possibilities.
What about SD-WAN and SDN?
While many IT departments continued to retain their heavy investments in traditional networks, SDN was transforming the networking paradigm. It enables carriers and service providers to deliver their services on-demand, while reducing high operational costs and improving network performance and scalability.
For those laggards hanging on to legacy networking, one small-scale implementation to bridge the divide was software-defined wide-area networking (SD-WAN). This protocol is a cost-effective alternative to traditional Multiprotocol Label Switching (MPLS), for scalable and secure enterprise networking.
Both SDN and SD-WAN are based on the same methodology: Separating the control plane from the data plane to make networking more intelligent. They might look and sound the same, but they are quite different from one another. The major difference between SDN and SD-WAN is what they are used for.
Software Defined Networking (SDN)Software Defined WAN (SD-WAN)
Manages a LAN or a service provider’s core networkEnables connections between networks and users across geographies
Programmable by the user to deliver bandwidth on-demandProgrammable to deliver operational simplification, integrated security and traffic prioritization
Similarities of separating the control and data planeSimilarities of separating the control and data plane
Offers visibility into the core network performance and real-time analyticsOffers visibility into the WAN environment and real-time analytics
Provides a centralised view for automation of network servicesFocuses on software-defined application routing capabilities
For large enterprises with increasingly-distributed and complex IT infrastructure, the challenge has been in managing the network with full visibility. They need the scalability to grow and meet new business objectives.
With the adoption of cloud-based applications and services, enterprises are moving more of their IT capital expenditure (CAPEX) into operating expenditure (OPEX). As they continue to expand, MPLS is simply too expensive to scale their WAN infrastructure. It does not provide the flexibility to deploy services remotely.
Enterprises can reduce WAN complexity by using an SD-WAN overlay to simply extend the edge to multiple branch office locations and remote users in a secure and orchestrated manner.
Once SDN is put in place, its vast potential has led to the commercialisation of networking services to other parties: Networking-as-a Service.
What is Network-as-a-Service (NaaS)?
To put it simply, NaaS is a model for delivering network services on a customisable basis: on-demand services with flexible terms, either on a subscription or flat-fee basis.
Similar to the other XaaS models such as Software-as-a-Service (SaaS) or Platform-as-a-Service (PaaS), the NaaS network and its services are all managed by the service provider.
In the case of an Epsilon customer, the interface to all that SDN power is the ‘application layer’ called Infiny, where they gain control over the services they are using and also the visibility. With an SDN-native infrastructure and a powerful self-service platform, customers have the ability to configure how they provision their services. They can adjust the network services to their ever-evolving business requirements.
Ultimately, NaaS takes away the complicated nature of networking. It presents network services to customers through simple interface that opens the door to a wide range of interconnection and voice offering:
High-performance connectivity between the leading global data centres locations
Scalable, private and secure direct connection to an ecosystem of world-leading cloud service providers.
Connect to the world’s leading internet exchanges globally though remote peering
Procure geographic, national, mobile and toll-free numbers in over 100 countries through a single platform
Visualising NaaS vs SDN
To recap, SDN is the foundation of virtualised networking which NaaS builds upon as a business model. SDN is the enabler of the NaaS model and can exist without the latter, but NaaS will not be possible with traditional physical networking architectures.
For the visually-oriented, imagine how a building is designed, built and managed. You can liken NaaS to an Architect, and SDN to a Building Engineer. Both are important when it comes to the actual building.
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