# 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.

![\[Peered transit gateways\]](http://docs.aws.amazon.com/network-manager/latest/tgwnm/images/transit-gateway-peering.png)


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`.

1. 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`.

1. Ensure that **Include return path in results** is selected.

1. 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.  
![\[Route analyzer results\]](http://docs.aws.amazon.com/network-manager/latest/tgwnm/images/nm-route-analyzer-peering.png)

1. 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`.

1. 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](https://docs.aws.amazon.com/vpc/latest/tgw/how-transit-gateways-work.html#TGW_Scenarios).