In today's rapidly evolving technological landscape, organizations are increasingly turning to Software-Defined Wide Area Network (SD-WAN) solutions to enhance their network performance, reduce costs, and streamline operations. This comprehensive guide will walk you through the key steps and considerations involved in migrating from a traditional WAN architecture to SD-WAN, ensuring a smooth and efficient transition.
1. The Importance of Controller Deployment
The first crucial step in any SD-WAN deployment is setting up the controllers. Controllers act as the central management and control plane of the SD-WAN architecture, ensuring seamless communication and coordination across the network.
- Deployment Sequence: Typically, organizations start by deploying the controllers, followed by the migration of main data centers and hub sites. Finally, remote sites such as campuses and branches are transitioned. This sequence allows hub sites to route traffic between SD-WAN and non-SD-WAN sites during the migration period.
2. Controllers Deployment Options
One of the primary advantages of SD-WAN is the flexibility in controller deployment. Organizations can choose from several options based on their specific needs and compliance requirements:
Cisco-Hosted Cloud: The most popular option, with over 90% of customers opting for this model. Cisco handles provisioning, backup, and disaster recovery, offering SD-WAN control plane as a Software-as-a-Service (SaaS).
Public Cloud: Organizations can host controllers in public clouds like Azure and AWS, managed either by a service provider or in-house.
On-Premises: Suitable for organizations with strict compliance requirements, such as financial and government institutions. In this model, the organization is responsible for backups and disaster recovery.
3. Secure Controller Connections
Once deployed, controllers must establish secure connections. Organizations can choose between Transport Layer Security (TLS) using TCP transport or Datagram Transport Layer Security (DTLS) using UDP transport, with DTLS being the default.
4. WAN Edge Routers Onboarding
The secure onboarding of WAN edge devices is a critical aspect of SD-WAN deployment. Cisco SD-WAN uses a whitelisting model for authenticating and trusting vEdge devices. Each device is uniquely identified by its Chassis ID and certificate serial number.
Controllers Reachability: Ensuring WAN edge routers have reachability to all controllers via available transports is vital. This involves establishing control connections over each provisioned transport, starting with the vBond orchestrator.
Common Implementations for Controller Reachability:
- MPLS routed through a data center or regional hub.
- Public IP addresses of controllers redistributed into the MPLS cloud.
- Control plane connection through the Internet, although this is not recommended due to lack of redundancy.
5. Joining the Overlay Fabric
The process of joining a WAN edge device to the SD-WAN overlay fabric involves several steps:
- IP Reachability: The vEdge device obtains an IP address, default gateway, and DNS information via DHCP.
- Zero-Touch Provisioning: The device reaches the ZTP server to get information about the vBond orchestrator and organization name.
- Authentication: The device authenticates with its root-certificate and serial number.
- Connection to Management Plane: The Edge establishes a secure connection to vManage and downloads the configuration.
- Connection to Control Plane: The device connects to the vSmart controllers and joins the SD-WAN overlay fabric.
6. SD-WAN Operation, Administration, and Management (OAM)
SD-WAN offers significant advantages in terms of operation, administration, and management:
- Centralized Management: Simplifies operations and reduces change and deployment times.
- Transport-Independent Overlay: Allows the use of any combination of transports in an active/active fashion, reducing bandwidth costs.
- Sophisticated Security: Provides comprehensive control plane encryption and a zero-trust security model.
- Application Visibility: Enables real-time analysis, enforcement of service-level agreements (SLA), and tracking of performance metrics.
Conclusion
Migrating to SD-WAN can transform your network infrastructure, offering enhanced performance, reduced costs, and simplified management. By understanding the key steps and deployment options, you can ensure a successful transition to a modern, software-defined network architecture. Whether you opt for a Cisco-hosted cloud, public cloud, or on-premises deployment, the flexibility and benefits of SD-WAN make it a compelling choice for organizations of all sizes.
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