Phased AWS Transit Gateway to AWS Cloud WAN Migration with Terraform and Network MCP Server

Migrating large-scale cloud networks can be a daunting task, especially when transitioning between core networking services like AWS Transit Gateway and AWS Cloud WAN. AWS has released a comprehensive guide outlining a phased migration strategy designed to simplify this complex process. The approach leverages Terraform for Infrastructure as Code (IaC) to automate deployments and the AWS Network MCP Server for robust validation throughout the migration lifecycle. The article highlights the challenges faced by organizations managing hundreds of Amazon Virtual Private Cloud (Amazon VPC) connections across global infrastructures. Manual tracking of route propagation and verification of failover during such transitions are often difficult and prone to errors, leading to potential disruptions in production workloads. To address these issues, the proposed six-phase migration method aims to provide a structured and repeatable process. A crucial aspect of this strategy is the use of AWS Network MCP Server and AWS API MCP Server. These tools facilitate an automated discovery phase, allowing users to inventory their existing AWS Transit Gateway topology through natural language queries, eliminating the need for manual CLI discovery. This initial step also helps in determining the optimal number of AWS Cloud WAN segments and Core Network Edges (CNEs) required based on the current network architecture. The migration process includes pre-phase validation steps to consider hybrid connectivity requirements and potential impacts, ensuring a smooth transition. Post-phase validation is also integrated to confirm that routes are propagated correctly. By adopting this phased approach, organizations can achieve several benefits: reduced risk through incremental validation at each step, enhanced operational efficiency by automating previously manual and coordination-intensive processes, and improved visibility into complex routing scenarios through the MCP Server's discovery tools. This method is particularly valuable for maintaining minimal or no downtime for production workloads during significant network infrastructure changes.