• Traditionally, enterprises utilized dedicated and private, but
bandwidth constrained, and expensive MPLS networks for
communications between branch offices, to/from headquarter
locations, and to access applications and data housed in data
Need of SD-WAN
• Enterprises needed a method of allowing each enterprise location to
quickly, with business grade performance, and continuous uptime, access
1) every other location in the network;
2) data center-located applications and data;
3) all cloud applications
• SD-WAN is the application of software-based network technologies to WAN
connections to more effectively route all network traffic between
headquarters or data centers, remote and branch offices, and the cloud.
• Unlike previous WAN technologies, SD-WAN is fully controlled by a
centralized software application, creating a virtual network on top of the
circuits, known as an overlay.
• MPLS alone was inadequate from an architecture or bandwidth perspective,
especially for cloud and real-time applications.
Working of SD-WAN
• An SD-WAN uses software and a centralized control function to more
intelligently steer or direct traffic across the WAN.
• An SD-WAN handles traffic based on priority, quality of service and security
requirements in accordance with business needs.
• Sending SaaS and IaaS traffic directly across the internet delivers the best
application Quality of Experience for end users.
• Accessing these “trusted” applications directly from the branch, across the
internet provides the needed security to protect the enterprise from threats.
• MPLS is a protocol for efficient network traffic flow between multiple locations.
• It is a routing technique in telecommunications networks that directs data from one
node to the next based on short path labels rather than long network addresses, thus
avoiding complex lookups in a routing table and speeding traffic flows.
• There is a big limitation on how long it takes to deploy
• High bandwidth cost that MPLS demands can be out of reach
• Built-in data protection is not offered
MPLS vs. SD-WAN
• Packet loss issues
• Enhanced performance
• Embedded security
• Your company has an SD-WAN box (essentially a plug ‘n play
router), performing real-time traffic shaping at each site.
only connects to your company’s other sites
• A common configuration is keeping a (much smaller), MPLS
network for real-time apps, and utilizing the public Internet
(controlled by the SD-WAN).
• In a cloud-enabled SD-WAN architecture, the solution offers an onsite
SD-WAN box connecting to a cloud (virtual) gateway.
• A common configuration is to have in-house real-time apps running on a
small MPLS network and have cloud apps (and everything else), running
over the public Internet, controlled by an SD-WAN.
• Best Fit : Companies running big-name cloud applications, such as Office
365, AWS, Drop Box, Azure, Salesforce, etc.
3. Cloud-enabled plus backbone
• “Cloud-enabled plus backbone” SD-WAN architecture offers an on-site
SD-WAN box connecting your site to the SD-WAN provider’s nearest
network point of presence (POP), where your traffic hops on the SD-
WAN provider’s private, fiber optic, network backbone.
• Best Fit - A company running a lot of real-time network applications,
wanting to completely scrap their MPLS network.
Is it business proven?
• SD-WAN has been commercially available for almost 5 years from the
market founders, and now market leaders
• It’s a huge growth industry (IDC predicts 40.4% compound annual growth
rate from 2017 to 2022 to reach $4.5 billion) so there are lots of new
vendors keen to get a share of the market.
• To date we have seen more than 60 “SD-WAN vendors” enter the market.
• Speed to market - proof of concepts to date, time to market with SD-WAN
deployment is just one week (or less in many cases).
• 29% of enterprises have deployed.
• 30% more considering deployment.
• 53% anticipate increased investment in network security through SD-WAN.
• The superior functionality of SD-WAN means it has the capacity to galvanise
the weakest link of the network, ensuring that it will always be strong
enough to keep business data flowing, without interruption and at a much
• The days of manually architecting a new link are over. With SD-WAN there
will always be another galvanised link ready and waiting to take over.
• For businesses with a large number of branch offices in particular, this is
easily the future of networking technology – and it won’t be long before it
SDN in Wide-Area Networks: A Survey
SD-WAN working : https://www.cisco.com/c/en_in/solutions/enterprise-
Architecture of SD-WAN :