The requirement precisely describes the functionality of Cisco Catalyst SD-WAN Cloud OnRamp for IaaS, which automates public cloud connectivity. By entering AWS credentials (such as an IAM role or API keys) into the Cisco SD-WAN Manager, the platform automatically queries AWS APIs to discover existing host VPCs and active workloads. Using this discovered data, the platform completely automates the deployment of a Transit VPC containing virtual SD-WAN edge routers (e.g., Cisco Catalyst 8000V or CSR1000V) to interconnect the private SD-WAN fabric with the selected AWS VPCs. This automated deployment eliminates manual infrastructure configuration, enabling administrators to easily choose which private SD-WAN segments connect to specific cloud networks.

A. AWS Direct Connect This is a manual, physical Layer 2/3 cloud networking service that does not automatically discover cloud infrastructure or provision SD-WAN integration using user API credentials.

C. IPsec VPN While IPsec secures the underlying tunnels, building standard IPsec VPNs is a manual process that lacks native API-based automation to discover AWS cloud resources via user credentials.

D. Segment routing Segment routing is a transport architecture used for internal traffic engineering within an enterprise network, not an API-driven automation tool for AWS VPC discovery and integration.

Cisco Systems. "Cisco SD-WAN Cloud OnRamp for Infrastructure as a Service (IaaS) White Paper." Section: Cloud OnRamp for IaaS; Interconnecting Cisco Catalyst SD-WAN with AWS Transit Gateway. Document ID: c11-742817. Available at: https://www.cisco.com/c/en/us/solutions/collateral/enterprise-networks/sd-wan/white-paper-c11-742817.html

Cisco Systems. "Cisco Catalyst SD-WAN Cloud OnRamp Configuration Guide, Cisco IOS XE Catalyst SD-WAN Release 17.x." Chapter: AWS Integration. Section: Create AWS Cloud Account. Available at: https://www.cisco.com/c/en/us/td/docs/routers/sdwan/configuration/cloudonramp/ios-xe-17/cloud-onramp-book-xe/cloud-onramp-multi-cloud-aws.html