The big advantage of offering telecom services in the cloud is that these services can be orchestrated and delivered with the aid of software. Software-defined wide area networks (SD-WAN) connectivity can be delivered as a service using software orchestration.
An SD-WAN can be used to deliver enterprise services such as virtual private networks (VPNs), WAN acceleration, and bandwidth optimization. By using commodity off-the-shelf (COTS) hardware in branch offices, SD-WAN as a service using orchestration can be delivered with the aid of virtual customer premises (vCPE) or lightweight CPE equipment.
SD-WAN as a Service Architecture
MEF is an organization that works toward SD-WAN standardization, including defining SD-WAN as a Service and outlining its architecture.
MEF identified these components that makeup SD-WAN as a Service:
- SD-WAN Edge, which could either be formed by a physical device, such as a CPE, or by a virtual CPE that’s based on a virtual network function (VNF). The SD-WAN Edge performs several critical functions. It acts as the security-policy enforcer and conducts WAN optimization tasks that include data deduplication, compression, and packet buffering. It also creates and removes encrypted tunnels over underlay networks, whether it’s a wired or wireless connection.
- SD-WAN Controller centralizes management to the SD-WAN Edge and to the SD-WAN Gateway.
- Service Orchestrator manages the SD-WAN service lifecycle – fulfillment, performance monitoring, analytics, security, and policy management.
- SD-WAN Gateway allows SD-WAN connected sites to interconnect with VPN technologies. It also starts and ends both SD-WAN tunnels and VPN connections.
- Subscriber Web Portal is added to the enterprise’s existing managed services portal. It works in conjunction with the service orchestrator to monitor the SD-WAN as a service.
Managed SD-WAN as a Service
MEF defines SD-WAN managed services as the process of “using overlay networking technologies to deliver agile, assured and orchestrated application-driven connectivity services.”
Service providers see SD-WAN as a service as a new revenue opportunity where they can manage WAN services for enterprise businesses. SD-WAN can be appealing to end users and enterprises that don’t want to manage the WAN network or applications and would like to outsource these services to a service provider.
In a managed SD-WAN service, a customer pays a service provider a service fee to install and deliver connectivity, along with any applications, monitoring, and maintenance services associated with the connection itself. This provides many opportunities for value-added services, such as security and applications performance enhancement. These could also include service level agreements (SLAs) that guarantee specific minimum service levels.
However, enterprises may choose to implement and manage their own SD-WAN solution if they prefer to save costs and manage the network itself.
In order to deliver SD-WAN as a service using orchestration, a service provider needs an SD-WAN orchestration platform to control and manage the service. This typically involves some combination of SDN controller and network virtualization software that can automate the provisioning and operation of the software and elements required, many of which would be based in the cloud.
The SDN controller can be thought of as the “brain” that sees the networks and when combined with components of a virtualized network, like a virtualized infrastructure manager (VIM), can manage network resources. With a VIM, the SDN controller can determine what network connections and cloud resources customers will need for an SD-WAN service or applications.
The orchestration process also manages service chaining — a process by which several different services or applications can be linked together from a data center to supply the customer with the combination of services they need. Service chaining is how you perform network function virtualization (NFV) by chaining together virtual network functions (VNFs) like a VIM.
One the main goals of SD-WAN orchestration in the cloud is to enable customer provisioning, whereby a customer could go to a Web portal and order services that can be automatically configured and delivered with the SD-WAN platform, without requiring human intervention. This requires the aid of open, interoperable SD-WAN tools and protocols that may include RESTful Application Programming Interfaces (APIs) and automated configuration standards such as Netconf, YANG, and topology and orchestration specification for cloud applications (TOSCA).
Many different networking vendors and service providers are working on SD-WAN platforms and services. Some of the operators to announce SD-WAN services include AT&T, CenturyLink, Colt, Masergy, Singtel, Sprint, and Verizon. Leading providers of SD-WAN platforms and orchestration software include Ciena, Cisco, VeloCloud, Silver Peak, Versa, and Viptela — among many others.
Updated April 2019