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Software-defined networking: data centres' soft option

Software-defined networking promises cheaper, more flexible communications but is that winning over converts in the data centre?

"The networking industry is perhaps the last bastion of IT where old-fashioned barriers to entry continue to systematically and deliberately hold back innovation," declares Nick McKeown, professor of electrical engineering and computer science at Stanford University and the 2014 IET Appleton Lecture speaker. "The networking equipment vendors have sold a crock to the world [saying] that open-standards lead to more innovation. In fact, they have cleverly used open-standards to drive complexity, cost and margins sky high, while resisting major innovation and change."

That era, according to McKeown and others surrounding the networking industry, is coming to a close. How? Through a series of changes to the architecture of the switches, routers and servers that direct voice calls, emails, web traffic, video and everything else under the banner of software defined networking (SDN). The shift is away from single-purpose, custom-engineered hardware and towards highly programmable switches and servers.

"SDN was and is the biggest change to networking in 25 years, so of course they resisted it to start with. We probably would in their shoes too – they were living off lots of fat for a long time," McKeown adds.

The driving forces for a switch to SDN look straightforward. Today's networking hardware is expensive for a reason. It uses a lot of custom silicon to move packets at what network experts call 'wire speed'. At 40Gb/s, you need fast hardware. But proponents of SDN argue that it's possible to split functions so that custom hardware is only needed to move packets around. Software running on commodity servers can provide the intelligence of where they should go and why. Software should make it easier to add new services without having to replace of hardware. Yet uptake has been mixed.

Enterprise adoption muted

The networking hardware and software vendors behind it were initially confident that SDN would find appeal in large, enterprise data centres, with Internet giant Google's early enthusiasm for the idea often cited as the inspiration. But with that particular customer pool limited in size, many have also turned their attention to telcos and cloud service providers facing the pressures of hosting and managing applications and services for hundreds of different customers on thousands of virtual machines within multi-tenanted data centre infrastructure. Here, a variant of SDN called network function virtualisation (NFV) has started to take hold.

David Noguer Bau, service provider solutions manager at networking product vendor Juniper Networks, agrees that the general traction is toward very extensive virtualised environments in large-scale data centres, pointing out that the number of enterprises as opposed to cloud service providers and telcos that own data centres of that size is actually relatively small. "The wider plan was multi-tenant infrastructure supporting multiple customers needing high levels of network automation, which SDN provides," he says.

Virtualised networking

If you were to count ports in data centres, there are now more virtualised networking ports in the world than physical ports, "all built on hypervisor switches controlled using SDN", McKeown claims, using a variety of standards developed to support the technology. "Check-out OpenStack, Open vSwitch deployments, and so on. And of course Google (B4) and Microsoft (software-driven wide-area network) are very open about their large inter-DC SDN deployments."

Recent published research does suggest a drop-off in interest in virtualised networks for smaller organisations, however. A survey sponsored by Juniper Networks in Q3/2013 found that 64 per cent of US federal government departments had no plans to adopt SDN, highlighting what Juniper labelled a 'knowledge gap', which still does not appear to have been effectively bridged within many enterprises.

Separate figures compiled by Palmer Research and QuinStreet Enterprise in the 2014 'Data Centre Outlook: Data Centre Transformation - Where is Your Enterprise?' report – published at the end of 2013 – found more acceptance in the private sector, with only 39 per cent indicating no plans to implement SDN and 29 per cent saying the technology had either already been deployed (14 per cent) or was at the planning stage (15 per cent).

Gerry Feeney, head of SDN/NFV market development at NEC Europe, points to a "perceived wall of risk" for many organisations, with only those which have large research and development departments and/or significant problems with their existing data centre or network architecture willing to gamble on a relatively new, immature technology. "Certain big web-scale companies, like Google and Facebook, have the scale to do that, and they are not risk averse," he says, "whereas the big carriers are more concerned because of their traditional operating model."

Although SDN is taking root in the large enterprise data centre as well as the telco environment, smaller organisations do not have the resources to do this on their own, and the technology is "not ready for the faint-of-heart or past the early adopter stage yet", according to Cliff Grossner, directing analyst for data centre and cloud at market-watcher Infonetics Research.

"Stuff has been happening for three years on the commercial side," reckons Dan Pitt, executive director of the Open Networking Forum, the body for defining the OpenFlow protocol which forms the basis of many SDN systems. "It moves in fits-and-starts, yes, but if you look at the investment going on by service providers, vendors and enterprises there is a lot of learning happening. A lot are doing small trials in their labs, and most feel the need to get their hands dirty."

Although many switch/router manufacturers, including BigSwitch Networks, Cisco, HP and NEC, implemented SDN capabilities into their hardware as early as 2011, there remains no guarantee that customers are using those features in live environments rather than purchasing new switches and routers to gain higher volumes of faster Ethernet or MPLS ports – or any other functions.

"If you think that every switch shipping by the end of 2014 will be SDN-ready that is not the case," says Grossner, who agrees that there is a significant gap between the proportion of SDN-capable devices shipped and those that are actually used.

Cloud scale SDN

For cloud service providers, it is the scale and breadth of different services and applications which they host on their customer's behalf that is prompting them to seek lower-cost, faster and more efficient methods of using and managing the physical network resources required to deliver cloud services within their data centres. Juniper cites Jaguar Networks, a business-focused ISP and managed cloud service provider, as an early beta customer for its OpenStack-based Contrail SDN vRouter component launched in September 2013. Jaguar Networks added an SDN software control and a vRouter, which builds tunnels between virtual servers over the physical network to span multiple hosting facilities and branch offices.

French cloud services provider Numergy (owned by French telco SFR) is also using an SDN platform from Nuage Networks (a subsidiary of Alcatel-Lucent) to connect virtual services across up to 12 of its data centres over the next three years. Its aim is to speed-up cloud service provisioning, improve network infrastructure control and provide a testbed to experiment with new network configurations beyond the restrictions of physical data centre environments.

Telcos and MNOs see traction

Most of the world's largest telcos and mobile network operators (MNOs), many of which are also cloud service providers, have also warmed to the potential benefits that both SDN and NFV can deliver. Over 26 have signed up to the European Telecommunications Standards Institute Network Functions Virtualisation Industry Specific Group (ETSI NFV ISG), first formed in late 2012. Figures from analyst Infonetics Research published in April 2014 suggest that over 90 per cent plan to implement either SDN or NFV in some guise, though it remains unclear if these are pilot projects or full commercial deployments.

Japanese telco NTT.Com has been using SDN technology developed in collaboration with VMware and NEC to interconnect its hosted cloud services with its business customers' on-premise systems since June 2012, with its Biz Hosting Enterprise Cloud infrastructure-as-a-service (IaaS) proposition using NEC's ProgrammableFlow OpenFlow SDN controller for on-demand provisioning and service automation.

"One of our customers, the Yamaha Motor Corporation, has consolidated a lot of its global IT estate into an enterprise cloud," says Len Padilla, VP of product strategy at NTT Europe. "The only things that need to be local – like manufacturing and R&D facilities – it has left them in place but everything else is stitched together with an overlay network. Not everything is in place yet, but it [Yamaha] takes advantage of new SDN features as we [NTT.Com] roll them out."

NTT.Com is also looking to use OpenFlow technologies to connect those cloud-hosted virtual services directly into virtual private network (VPNs) without having to deploy dedicated appliances at customers' premises, providing a portal which its customers can use to alter configurations or provision additional resources via the VPN.

"It requires a lot of manpower to receive a service order, define the customer virtual private network, and configure all those devices," says Yukio Ito, senior VP of infrastructure at NTT.Com. "We could get rid of the cost and human error by turning on the service, getting it connected to the network from the portal, monitoring CPU/RAM status, performing maintenance work, and adding, removing and rebooting VMs."

In the UK BT is working with various vendors including HP, Intel and Tail-F Systems to develop SDN/NFV functions within the data centre and at the network edge. It is particularly keen to reduce its management and maintenance operational-expenditure by replacing customer premise equipment – such as firewalls, load balancers, WAN optimisation devices and other dedicated devices in locations which previously had to be serviced by on-site engineers, with NFV functions that reside and run either on virtual x86 servers or commodity network switches and routers within its network infrastructure.

"Instead of buying a monolithic lump of tin – a box traditionally bought from Cisco, Alcatel-Lucent or whatever – we buy it as software and load onto a data centre-style server," reveals Andy Reid, chief network services architect at BT. "It may run in a public data centre in the first instance, but also on servers running at the carrier's central office. And where otherwise we might put normal network equipment, we can put 'vanilla' hardware capable of running lots of different things" – i.e., not just running what a proprietary vendors wants it to run.

Other telcos around Europe, including Spain's Telef'nica, Orange, Deutsche Telekom and Portugal Telecom, are working with the likes of Ericsson, Huawei, NEC, Nokia Solutions Networks and others to test virtual evolved packet core (vEPC) network infrastructure platforms for their mobile LTE (4G) networks. They will also look at where network functions previously performed in radio access network base stations can be moved into commodity servers and switches.

Expansion of OpenFlow support

The Open Networking Forum's Pitt predicts four things need to happen before SDN adoption will expand into mainstream enterprise usage. He believes many potential customers are waiting for a broader range and variety of OpenFlow-enabled switches, which he reckons are limited in volume and capabilities – one reason why the ONF is working with silicon manufacturers including Broadcom, Marvell, LSI, Freescale, Samtec and Mellanox as well as HP, Brocade, Cisco, Huawei and Ericsson to accelerate that development process. Pitt also highlights the need for "commercial, decent-quality" open-source SDN controllers, which "nobody quite knows how to make money out of [yet]". He also calls for a greater focus on the applications which run over SDN networks.

"We need network and business applications that ride above the whole SDN infrastructure to take advantage of it," says Pitt. "Somebody has to write that stuff - third-party [software vendors] or the enterprise customers themselves, small companies contributing niche apps... that is the next pin to fall."

Enterprise users and telcos alike will have to go the extra mile to familiarise themselves with virtual networking concepts and systems which are relatively new to the industry. It is a process that may be delayed by existing network engineers who feel their current skills do not fit the new regime well and so may resist the calls for change.

Potential buyers could also be forgiven for being confused by the volume and diversity of competing technology platforms vying for their attention.

Despite the reasons for resistance, both customers and suppliers are having to grasp what SDN means for them and make changes that will allow them to compete in this new environment. A variety of SDN-capable systems have emerged and slot into a portfolio that continues to grow. This trend could herald the beginning of the end for the traditional business model that has underpinned the profitability of today's leading suppliers.

McKeown points to a precedent in IT: "Just as Dell, HP and Compaq's high-margin servers were largely replaced by commodity 'whitebox' servers, so will networking equipment be replaced by whitebox switches. It might take years – the protectionists have deep pockets, and will try to make their customers churn their expensive hardware – but it will happen." 

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