The era of the software-defined WAN


By Andrew Collins
Tuesday, 06 December, 2016


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After making a splash in the data centre, software-defined networking (SDN) is now becoming increasingly relevant for the enterprise WAN, with analysts saying the software-defined WAN (SD-WAN) has the potential to reduce capital and operational expenditure, hasten network provisioning and increase network availability.

In their recent paper, ‘Cloud and Drive for WAN Efficiencies Power Move to SD-WAN’, IDC analysts Brad Casemore, Rohit Mehra and Nav Chander discussed how SD-WAN can help organisations meet the network requirements of their branches and remote sites.

The SD-WAN was preceded by the hybrid WAN, the analysts said, adding that a typical hybrid WAN includes “at least two WAN connections from each branch office, leveraging two or more different access technologies” such as MPLS, broadband internet and mobile internet.

“SD-WAN leverages hybrid WANs, but it includes a centralised, application-based policy controller; analytics for application and network visibility; a software overlay that abstracts underlying networks; and an optional SD-WAN forwarder (routing capability) that together provides intelligent path selection across WAN links, based on the application policies defined on the controller,” the IDC analysts said.

In the Gartner report, ‘Technology Overview for SD-WAN’, authors Andrew Lerner and Neil Rickard explained that SD-WAN “abstracts the underlying network transport/connectivity to present a business-centric or application-centric approach”.

In an SD-WAN solution, centrally managed WAN edge devices are deployed in branch offices in order to create logical connections with other branch edge devices across the physical WAN, the Gartner analysts said. “These logical connections create secure paths across multiple WAN connections and carriers, such as hybrid internet and multiprotocol label switching (MPLS) architectures.”

An SD-WAN enables traditional device-based command line interface configurations to be replaced by centralised, network-wide control and orchestration, the Gartner analysts added. “This enables enterprises to centrally configure and manage WAN traffic via graphical user interfaces, based on business-related policies, while providing increased visibility.”

Persuasive drivers

According to IDC, the application of SDN to the WAN follows its application to the data centre.

“The requirements associated with cloud computing have already reverberated through data centre networking, with SDN arising as an architectural approach that provides the network with the agility and responsiveness — through automated provisioning, programmatic management and integration with cloud orchestration platforms — that it lacked previously,” Casemore, Mehra and Chander said.

The growth of the cloud now means that the WAN is experiencing greater pressure, too. “As public and private cloud continue to grow, WAN performance becomes critical for latency-sensitive workloads and inter-data centre business continuity.”

So as organisations prepare for and implement cloud, they need to consider WAN architectures as well as data centre infrastructure, the IDC analysts said, adding that “the WAN is an increasingly critical foundational element in the realisation of hybrid cloud for enterprises worldwide”.

Those organisations that are adopting hybrid cloud need to think about how to get the same benefits and agility in the WAN that they’re trying to get from implementing SDN in the data centre and the campus, the analysts said. “Indeed, SD-WAN provides the complementary capstone for hybrid cloud application delivery.”

In its report, Gartner also highlighted the impact of cloud on the enterprise WAN, with Lerner and Rickard stating, “The emergence of public cloud computing has rendered traditional enterprise WAN architectures to be suboptimal, from a price and performance perspective.”

Compared to traditional approaches, SD-WAN is better equipped to handle the changing network traffic patterns that arise from cloud computing, they said. “SD-WANs resolve some of the most pressing WAN problems clients currently face when building and managing hybrid WANs, and will face with growing frequency going forward.”

These problems include the high cost of WAN connectivity; complex, static and manual network configurations; and the inability to provide security and visibility for WAN traffic.

Peter Hall, an advisor at IBRS, said that although cloud is a factor behind enterprises adopting SD-WAN, “cloud adoption by itself is not the primary driver” and that “being able to utilise more flexible internet connection methods and have a mix available will be an attraction to organisations”.

Hall said, “Organisations are looking for more reliable, robust, secure, managed bandwidth with improved cost-effectiveness. Larger organisations face the most challenges and are likely to have evolved to highly complex networks which are now also being integrated into cloud environments. SD-WAN solutions can help remove complexity, simplifying management, and enable more rapid deployment of changes and additions to the network.”

When asked about drivers behind the adoption of SD-WAN locally, Hall said that Australian adoption is being influenced by service providers and what offerings they’re making available. “This includes the major players like Telstra and Optus, and new boys on the block like MyRepublic, who are based in Singapore but entering the Australian market, but as yet not made an impact.”

Adding up the advantages

According to the analysts, SD-WAN has the potential to provide a variety of benefits to adopters. IDC’s Casemore, Mehra and Chander said that SD-WAN benefits can include “cost-effective delivery of business applications” and “improving branch IT efficiency through automation”.

Gartner’s Lerner and Rickard said that SD-WAN could provide “substantial” benefits compared to traditional WAN architectures, including reduced costs and improved provisioning times.

Reduced costs, they said, could come via several means, including:

  • lower acquisition costs for hardware, software and support of vendor-provided remote office WAN equipment, and
  • lower enterprise operational expenditures in managing and operating the WAN.

The time it takes to provision network changes at branch sites, they said, could be improved through SD-WAN’s simplified configuration, orchestration and zero-touch provisioning.

Be an adopter

Consistent with their position that the spread of cloud is a primary driver of SD-WAN adoption, IDC’s Casemore, Mehra and Chander said that SD-WAN will be particularly relevant for organisations that are planning to adopt — or have already adopted — hybrid cloud, especially those organisations that are using SaaS application services.

“In these cases, there is a strong motivation to reassess WAN architectures used for application delivery. What made eminent sense on the WAN when client/server applications were housed exclusively in an enterprise data centre does not make sense when applications reside in the public cloud as well as in the enterprise data centre or a private cloud,” they said.

The IDC analysts said that hybrid cloud demands a “policy-based approach to application delivery” at remote and branch sites, and that such an approach could potentially use broadband and mobile internet, as well as VPNs and MPLS.

In such a scenario, they said, organisations could also use SD-WAN for load-balancing across the WAN, or for monitoring application performance and sending traffic over whichever WAN links are best suited to the requirements of the application in question (such as cost-effectiveness or reliability).

IBRS’s Hall said that in Australia and New Zealand, SD-WAN is “likely be adopted with high growth rates within large organisations that need to manage larger deployments of systems, and have a large number of sites. They will be looking to take advantage of being able to manage larger amounts of bandwidth whilst using the most cost-effective internet connections available.”

As for which specific verticals in Australia are more likely to gain benefit from adopting SD-WAN, Hall said: “In terms of buying SD-WAN offerings the customers are the big telcos and service providers. Cloud service providers will want to use solutions in the services they offer. Large organisations that run completely in-house, or that include some cloud or hybrid cloud, that will adopt SD-WAN are likely to be in sectors like financial services industry, government, retail and large construction organisations.”

There are several deployment options available to organisations considering adopting SD-WAN, such as dealing directly with vendors and implementing it using in-house resources, or engaging a third party to help.

IDC’s Casemore, Mehra and Chander said, “Enterprises facing skills gaps or resource constraints will want to consider CSP [communications service providers] SD-WAN managed services, which reduce management overhead and related costs by providing comprehensive deployment and management of SD-WAN solutions, typically based on product offerings from market-leading SD-WAN vendors.”

As for Australian organisations, IBRS’s Hall said, “Major service providers will work directly with the vendors, whilst building their own in-house expertise.” For example, he said, “Telstra is working with Cisco, whilst Singtel/Optus is working with Viptela.”

Hall noted, “Third parties offering organisations services and assistance are most likely not traditional system integrators, but providers of managed or cloud services, especially those providing infrastructure as a service (IaaS).”

Flow-on effects

The adoption of SD-WAN technologies by organisations may have flow-on effects for the markets of other related solutions. According to IDC’s Casemore, Mehra and Chander, the SD-WAN market “will significantly cannibalise the WAN optimisation and, to a lesser extent, the branch router market during the next several years”.

The market for WAN optimisation would be especially impacted, they said, “with WAN optimisation ultimately becoming a subset or secondary market to SD-WAN”.

Given the threat SD-WAN poses to the WAN optimisation and branch router markets, the IDC analysts said, “It’s essential for vendors in those markets to extend their product portfolios, organically or through acquisition, to compete in the SD-WAN space.”

According to IBRS’s Hall, “WAN optimisation vendors are already rushing to evolve their solutions into SD-WAN offerings (eg, Riverbed). Over time we would expect to hear less about WAN optimisers, as SD-WAN will be where the focus will be.

“There is also going to be a shift away from dedicated network appliances as specific functionality will offered at a software level,” Hall predicted.

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