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transit gateway sharing configuration

This document explains how to use the Transit Gateway sharing feature to enable communication between VPCs in two different projects.

Image Transit Gateway sharing configuration

Step 1. Preparation​

The sharing configuration for the Transit Gateway described in this document assumes that VPCs and Virtual Machines have already been created in two different projects. Please refer to the service documents for VPC and Virtual Machine creation and the information below to create VPCs and Virtual Machines for this scenario.

Example of VPC / Virtual Machine creation​
FieldProject AProject B
ProjectShared projectProject receiving share
VPC IP10.0.0.0/16172.16.0.0/16
Virtual Machine IP10.0.1.167172.16.3.124

Step 2. Create and share Transit Gateway​

Here’s how to create a Transit Gateway in Project A and share it with Project B:

  1. Follow Create Transit Gateway to create a Transit Gateway in Project A.

    • The Transit Gateway created in Project A will be referred to as Tgw-1.

  2. Follow Share Transit Gateway to share the Transit Gateway (Tgw-1) created in Project A with Project B.

  3. In Project B's Transit Gateway list, verify that the Transit Gateway (Tgw-1) has been shared correctly.

Step 3. Create Attachments and configure routes​

To configure the resources and traffic that connect to the Transit Gateway, create Attachments in each project and set up routes.

  1. Project A: Follow Create Attachment to create an Attachment for Tgw-1. When creating the Attachment, select the VPC (10.0.0.0/16) and the subnet (the subnet where the Virtual Machine is located) for communication.

  2. Project B: Follow Create Attachment to create an Attachment for Tgw-1. Select the VPC (172.16.0.0/16) and the subnet (the subnet where the Virtual Machine is located) for communication.

    Guide

    If the Sharing acceptance setting was set to Automatic when creating the Transit Gateway in Project A, the Attachment created in Project B will be created immediately. However, if set to [Manual], the Transit Gateway will be in the Pending Approve status, and approval from Project A will be required. For more details on approval, refer to Approve Attachment.

  3. Follow Modify association and Add route to connect the created Attachments to the route table and configure routing.

    DestinationTarget
    Attachment of Project A10.0.0.0/16
    Attachment of Project B172.16.0.0/16

Step 4. Set the route table of the VPC​

To route the traffic received from the Transit Gateway, configure the route table in each project's VPC.

  1. Project A: Follow Add route to add a route to the VPC's route table for the Transit Gateway.

    DestinationTarget TypeTarget
    172.16.0.0/16Transit GatewayTgw-1 (Transit Gateway created in Project A)

  2. Project B: Follow Add route to add a route to the VPC's route table for the Transit Gateway.

    DestinationTarget TypeTarget
    10.0.0.0/16Transit GatewayTgw-1 (Transit Gateway created in Project A)

Step 5. Verify the results​

  1. In Project A, perform a ping test from the Virtual Machine (10.0.1.167) to the Virtual Machine in Project B (172.16.3.124) to verify that the Transit Gateway has been shared correctly.

    Verification
    ping 172.16.3.124

  2. In Project B, perform a ping test from the Virtual Machine (172.16.3.124) to the Virtual Machine in Project A (10.0.1.167) to verify that the connection works in both directions.

    Check results
    ping 10.0.1.167