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Options for Small/Medium Enterprises when adopting SDNs
Introduction
Software Defined Networking (SDN) is slowly becoming the norm for multi-national
corporations and large businesses. The traditional network architecture is now
becoming outdated due to the rapid development of end devices and flexibility
required when managing traffic flow. The Open Network Foundation (2012) describe
the SDN architecture as “a decoupling of the control plane and the data plane”
removing the underlying intelligence from the hardware to a centralised location,
allowing for “unprecedented programmability, automation and network control.”
The development of the Openflow protocol, the core of SDN, as the first
communications interface between the control plane and the data plane has allowed
for SDN to develop and flourish. Companies such as Google, Facebook, Microsoft
and Verizon have adopted SDN into their internal networks and data centres, which
give a good indication that SDNs are here to stay. Vahdut (2015), a Technical Lead
in Networks at Google suggests that “As far back as 10 years ago Google realised
that at any price they could not buy and build a datacentre to meet their speed and
scale requirements” forcing them to lay the foundations of a new way – SDN.
A Medium sized Enterprise faces an entirely different challenge when adopting
network changes. Defined by the European Union as having “50 – 250 employees
and balance sheet total of < €43m” it is clear that resources available will be limited
when comparing to the likes of Google. The nature of SDN allows for the use of
Open-Source software and non – proprietary hardware, which on the face of it,
seems an excellent option for medium sized businesses and an obvious reduction of
costs however, a deeper understanding is required.
Market Options
When purchasing hardware and software, there will be a stringent process to ensure
that the purchase adds value to the business. There are many considerations such
as cost, security, support, scalability and futureproofing. Directly dealing with network
equipment, there is a variation depending on devices but on switching equipment
specifically, Blalock (2016) suggests that “wired switches should be replaced every 5
years”, although this can be as little as 2 years due to the increased rate of

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development in networking. This is due to improved technology, security issues and
business requirements. Everyone want their connection to be more secure and
faster, but it must add value to a business.
Traditional networking equipment is dominated by market leaders such as Cisco and
Juniper. They offer fully tested hardware, highly functional software in their Operating
Systems and a comprehensive support system, therefore the traditional network
infrastructure seems to offer multiple benefits. The ease of buying, installing and
configuring a Cisco switch(s) by a certified professional takes the headache away
from the business but the management of a traditional network requires multiple
hardware configurations and updates, multiple security risk points as each OS must
be configured individually.
Multiple Openflow (and other Control – Data plane interface) enabled switches allow
for a central control point with the OS taken away from the underlying hardware and
run from a single access point as demonstrated by sdxcentral.com in Fig.1.
How SDNs Work
Fig 1

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The market leaders have been forced to move with the times and also develop to
support this approach. Cisco in it 4th quarter earning report (2016) suggest a
restructuring of its workforce, moving away from traditional networking and towards
software “invest in key priority areas such as security, IoT, collaboration, next
generation data centre and cloud”. Further evidence showing the shift towards SDN
as Cisco have developed their own propriatory software in the form of SDN
Controllers.
The Controllers facilitate the communication between the control pane and the data
plane, the underlying hardware on the data plane needs to be Openflow compatible.
With Cisco development of controllers that are compatible with their own proprietary
hardware, they are able to stay relevant and competitive in the SDN era. Again the
trusted name along with the benefits of SDN seems like the perfect partnership for
progressive businesses who want to be relevant in their network solutions.
Conversly however is the development of open – source software and non –
proprietary hardware for use in SDNs. Hardware, switches more specifically that
have no proprieatry OS, allowing a network administrator to install their own open
source software, and using an open source controller, mainain and administer the
network. The cost of non proprietary hardware is very cheap as the underlying
hardware capability is generic (when port speed is comparable). The cost lies in the
overlaying software, which in this case is free as is it open source, as are the
controllers. This appears perfect for a medium business where costs are highly
scrutinised.
To gain a greater understanding of what option is more prudent, the process
undertaken when purchasing network equipment must be examined more carefully.
For an SME looking to upgrade and advance their technology there are five main
considerations to be taken into account.
a) Business Value. The procurement of new hardware/software must provide
value to the business, offering advancement and growth opportunities. Market
leaders offering up to date and highly functional equipment allows a business
to avail of current services offered, especially regarding speed and security.
An SDN approach to the network infrastructure must offer the business
justification of the procurement by providing value.

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b) Security. Security threats via technology is a very important issue for SMEs.
A Josefsbergs, Chief Information Officer of GoDaddy (2016) suggests that
“Ransomware and spear-phishing scams are getting more advanced”. The
SDN approach must offer a high level of security to SMEs in order to operate
continuously and provide data protection for itself and its customers. The
nature of SDN however centralises control of the network offering less points
of attack on the network infrastructure. SDN security is also championed by
the NSA, which uses it within its own network due to the centralised and more
complete control over its own network which contains the most sensitive of
data. Bryan Larish, NSAs Technical Director Enterprise Connectivity and
Specialist IT Services (2015) says, “We, as an enterprise, need to control our
network” and goes on further to say “We need to do it predictably and
efficiently if we’re going to make it secure”.
c) Cost. For an SME to invest in new Hardware/Software the cost is possibly the
most important issue. Existing equipment and network infrastructure will be
providing the required service to the business in its current state however the
investment in new equipment to facilitate SDN again must offer value in actual
profit returns. The procurement of Hardware/Software must fit in with the
company’s strategic plan and the direction its wishes to take.
d) Support. Procurement of standalone equipment is one consideration but the
support and expertise of the upkeep is of great importance to an SME. Many
SMEs use 3rd party IT support services, with SLAs offering a level of support
deemed necessary to the business. Only the businesses at the larger end of
the SME scale may have dedicated in house IT support staff.
Hardware/Software warranties with vendors ensure a level of support above
in house expertise. SDN must have the same level of support to give
businesses peace of mind.
e) Scalability. For a business to be able to grow the surrounding IT infrastructure
must be able to grow with it. With many SDN controllers being developed for
data centre environments, scalability for an SME would not be an issue as
currently capabilities of controllers are above and beyond the requirements of
an SME.

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From these considerations, only business value will make no difference when opting
for a vendor controlled or non – proprietary transition. This decision is entirely
business based and whether SDN of any form can offer value is something only the
management can decide based on its strategic plan. Each other option poses
questions as whether a vendor controlled or non – proprietary is the best road to
take if the decision to opt for SDN is taken.
Vendor Controlled Hardware/Software
Vendor controlled equipment offers a packaged solution for a companies who wish
to avail of the service. Traditional market leader Cisco offer the IWAN (Intelligent
WAN) service for larger companies and Cisco ACI as a data centre solution however
not a LAN service which is more appropriate for an SME. They do offer an SDN
controller – Cisco Open SDN controller described by Cisco on their products website
as “a commercial distribution of OpenDaylight that delivers business agility through
automation of standards-based network infrastructure” which back be bought as a
standalone product or leased on a 3 yearly basis. The SDN controller is the hub in
an SDN, providing a southbound API (implementation of protocols between the
controller and the hardware) and a northbound API (communication between the
user facing GUI and the controller).
Brocade offer a packaged service for their Vyatta Controller, again a commercial
release of the OpenDaylight controller, at “$100 per node per year license or $275
per node for a 3 year license and inclusive of a support bundle”. For the larger SME,
upwards of 150 staff this can become extremely expensive. Each of the 150
employees having a desktop this would equate to $15000 per year. A large yearly
outlay, although this does include the support of Brocade, which will offer peace of
mind to the company availing of the service.
The company would also re-equip with hardware compatible to Openflow. Some
providers such as Brocade and HP upgrades available for existing equipment to
cater for SDN for little or no cost, however this is rarely available for low-end plug
and go equipment generally found in SMEs. Proprietary hardware is not as
expensive as in a traditional network as the driving software is removed from the
hardware and contained within the controller. Many vendors are now offering
whitebox and britebox switches. White box switches are original design manufacturer

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(ODM) bare metal switches packaged with a pre-installed OS, however the OS is not
integrated with the hardware so can be changed with any OS of your choice.
Branded white box or Britebox switches are the same package as a whitebox switch
but with a brand attached – such as Cisco or Juniper. This is done by the vendors to
offer customers the comfort of the know brand instead of buying directly from an
ODM and also to offer their own OS for use. The cost of re-equipping however,
coupled with the purchase or lease of a commercial SDN controller would be a
substantial investment for an SME.
Non – Proprietary Hardware/Software
Non – proprietary hardware allows a user to utilise the actual function of the
equipment, primarily switches, without having a hard wired OS installed on it. Bare
metal switches offered by ODMs offer this as it only contains the functioning
hardware with no OS installed at all, giving the customer the choice of software they
wish to use. This at first glance would be a reduction in cost, however this does not
seem to be the case. For bare metal switches to be Openflow compatible they must
contain Open Network Install Environment (ONIE). This allows any OS that is
compatible with the Openflow protocol to be installed. Although at data centre level
there are many bare metal switches available at a reduced cost to traditional
switches, there is very little on offer for the SME.
Currently there are a number of open source SDN controllers available to anyone
who wishes to utilise them. Many, such as NOX and POX are made as a platform to
encourage development in C++ for NOX and Python for POX. There are also
packaged controllers that are ready to download and use. The forefront of these is
the OpenDaylight (ODL) controller. The latest release of the ODL controller named
Lithium, which is free to download and use, is described by the ODL project as “a
highly available, modular, extensible, scalable, and multi-protocol Controller
infrastructure built for SDN deployment on modern heterogeneous multi-vendor
networks”. Again being designed for data centre use its capabilities would be more
than sufficient to deal with an SME.
Availing of the free software is an excellent option for an SME but carries the
responsibility of self-support. There is no warranty or support service offered as a
standalone piece of free software therefore must be completely managed by the

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SME using the software. The existing support staff must be retrained in a new and
not widely known skill. Learning to use the controller is not an issue but what to do
when things go wrong may provide a greater challenge. Those SMEs using 3rd party
support service may find that it is something not covered or supported by the service
provider. As SDNs are currently implemented on WAN and data centre networks,
there is very little in the way of support for smaller companies.
Integration Issues
Integrating SDN into existing infrastructure provides a whole new challenge for the
SME. It would be simple to swap old equipment for new SDN compatible equipment,
but it is not feasible as it would cause large scale business disruption that could not
be justified. Sezer et al (2013) suggests that “the transition to SDN requires
simultaneous support of SDN and legacy equipment”. A gradual introduction of SDN
compatible software within the traditional network, creating a hybrid network is an
option available. This then poses further challenges in the inter-operability between
new and legacy equipment. Such challenges are overcome in data centres with
Network Virtualization Function (NVF), a form of SDN which separates the network
into logical areas that share physical resources. NVF again is a highly specialized
area in which an SME would have to consider the cost benefit when implementing it
into its own infrastructure, again requiring specialist training for existing or new staff
to support it.
Conclusion
There are many considerations for an SME when deciding what path to take when
adopting SDN and even whether it is needed at all. The open-source controllers
available are highly functional and would meet the traffic flow needs of any sized
SME, and even though they come as a standalone piece of software there is a large
development and support community surrounding the various projects. This alone
would not be enough for an SME as it would require an onsite specialist or use a 3rd
party support service that are not available for an open-source controller. The risk to
business continuity would be too great for an SME to adopt an unsupported service,
let alone the capital expenditure it would require to fund equipment.
The pre-packaged services offered by vendors to SMEs is very limited as the
attention is focused towards large scale networks and data centres. Supported

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controllers are available but, as seen previously, at great cost. This is before the
procurement of hardware needed to become compatible with Openflow and SDN.
Vendors not offering a service to a smaller network infrastructure creates a question
mark over the adoption of SDN by an SME.
SDN was developed from a need to have more control and programmability of large
scale networks. The cost and labour overhead of administering a WAN and data
centre, containing hundreds of devices, is large and a central controlling point of
multiple devices offers to solve a problem and provide opportunity. Companies
classified as an SME would not have the number of devices in which this problem
would arise. 5-10 networking devices could easily handle the workload generated by
an SME at the larger end of the scale, therefore the need to centralise control is not
an absolute necessary from an administrative perspective. Current 3rd party
Managed IT service providers such as http://www.ergogroup.ie/ will offer network
administration as part of an SLA, also in house experience support staff should have
a good knowledge of traditional internal networking, hardware configuration and
administration. As far as administration is concerned, it would be unnecessary for an
SME to adopt SDNs at all to retain full control of its network.
One area that would an SME would benefit by adopting SDN would be the dynamic
change of Quality of Service (QoS) policies. An SDN controller would be able to
deploy new policies on an ad hoc basis, depending on the requirement at the time.
For instance, if an SME had a video conference between multiple staff members the
QoS policy could be changed to facilitate the video streaming protocol. Traditionally
QoS policies were complicated and very laborious to change, going device to device,
and very rarely changed when initially configured. Although this would be of great
advantage for the times it is required it still would not present an ample reason to
adopt an SDN.
All evidence points to the conclusion that SDN is not yet required, or not yet ready
for the SME in any shape. Further development in what is still a relatively new field
could change this in the not so distant future, and there will be, at some point, a
solution that would not out-price an SME and allow it to avail of this smart, scalable
and relevant concept – SDN.

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References
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