Example: Route analysis for peered transit gateways - AWS Network Manager

Example: Route analysis for peered transit gateways

In the following example, transit gateway 1 has two VPC attachments, and a peering attachment to transit gateway 2. Transit gateway 2 has a Site-to-Site VPN attachment to your on-premises network. You want to use the Route Analyzer to ensure that the VPCs and Site-to-Site VPN connections can route traffic to each other through the transit gateways.

Peered transit gateways

In the Route Analyzer, do the following:

  1. Under Source, specify transit gateway 1 and the transit gateway attachment for VPC A. Specify an IP address from the CIDR block of VPC A, for example, 10.0.0.7.

  2. Under Destination, specify transit gateway 2 and the VPN attachment. Specify an IP address from the range of the on-premises network, for example, 172.31.0.8.

  3. Ensure that Include return path in results is selected.

  4. Run the route analysis. In the results, verify the path between the source and destination. For example, the following results indicate that there is a forward path from transit gateway 1 to transit gateway 2, but no return path. Check the route table for transit gateway 2, and ensure that there is a static route that points to the peering attachment.

    Route analyzer results

  5. To run the analysis between VPC B and the VPN connection, modify the information under Source. Choose the transit gateway attachment for VPC B, and specify an IP address from the CIDR block of VPC B, for example, 10.2.0.9.

  6. Reload the results and verify the path between the source and destination.

For more information about the routing configuration for this scenario, see the transit gateway peering example.