Software-Defined Wide Area Network (SD-WAN) Architectures and Technologies
Overview
SD-WAN is a solution that applies Software-Defined Networking (SDN) technology to WANs.
It enhances enterprise WANs with features such as automated configuration, centralized control, and high programmability.
Key Components of SD-WAN
SDN Controller - Acts as the network's brain, providing orchestration, control, and management.
Network Layer - Consists of both physical (underlay) and virtual (overlay) networks.
Service Layer - Interfaces for presenting and provisioning SD-WAN services.
SD-WAN Emergence and Benefits
SD-WAN emerged to address challenges in traditional WANs such as limited flexibility, complex management, and high costs.
Key benefits include:
Robust connectivity with multi-cloud and multi-network access.
Superior application experience through intelligent traffic steering.
High performance with advanced branch devices.
Simplified O&M (Operations and Maintenance) with centralized management.
Architecture and Technologies
Networking Sub-solution - Facilitates flexible and reliable WAN interconnection through hybrid WAN links and overlay networks.
Application Experience Sub-solution - Uses application identification and traffic steering to ensure high-quality service delivery.
Security Sub-solution - Encompasses system and service security, utilizing technologies like ACLs and firewalls.
O&M Sub-solution - Enhances monitoring and fault management.
Site Deployment and Interconnection
Types of Sites
SD-WAN Sites: Managed by the SDN controller with interconnections via SD-WAN technology.
Legacy Sites: Use traditional networking, requiring interconnection solutions.
CPE (Customer Premises Equipment)
Forms: Traditional CPE, uCPE, vCPE.
Supports various WAN-side and LAN-side connection modes.
Traffic Management and Optimization
Traffic Steering: Adjusts traffic paths based on application requirements and link quality, ensuring optimal application experience.
WAN Optimization: Improves transmission quality and efficiency, using techniques like FEC (Forward Error Correction) and redundant packet transmission.
Security Considerations
System Security: Protects SDN controllers and network devices from attacks.
Service Security: Ensures secure data transmission with encryption and access control.
Business Models
Carrier/MSP Resale Model: SD-WAN services resold by carriers or managed service providers.
Enterprise-Built Model: Enterprise-owned and operated SD-WAN networks.
Use Cases and Scenarios
Common Scenarios
Site-to-site and site-to-cloud interconnections.
Access to SaaS and public cloud applications.
Best Practices and Case Studies
SD-WAN applications in finance, large enterprises, and managed service providers.
Future Outlook
Evolution of technologies like 5G and SRv6, and their impact on SD-WAN development.
Additional Notes
The book also covers migration strategies, fault diagnostics, and intelligent O&M to enhance network management and efficiency.
Security continues to be a top priority, especially with increasing cyber threats and the need for robust network defenses.