Getting started with IBM Cloud Transit Gateway

Use IBM Cloud® Transit Gateway to interconnect IBM Cloud classic and Virtual Private Cloud (VPC) infrastructures worldwide, keeping traffic within the IBM Cloud network. With IBM Cloud Transit Gateway, organizations can define and control communication between resources on the IBM Cloud network, providing dynamic scalability, high availability, and private, in-transit data between IBM Cloud data centers. Transit gateways are commonly implemented to support hybrid workloads, frequent data transfers, private workloads, or to ease administration of the IBM Cloud environment.

With IBM Cloud Transit Gateway, you can connect:

  • VPCs within the same region (local routing)

  • VPCs across different regions (global routing)

  • VPCs to IBM Cloud classic infrastructure

  • Power Virtual Server workspaces

  • VPN gateways for site-to-site or client VPN connectivity

  • On-premises networks using Direct Link connections

  • External networks by using Generic Routing Encapsulation (GRE) tunnels

  • Network resources across multiple IBM Cloud accounts (with appropriate access authorization)

Choosing your routing behavior

When you create a transit gateway, you choose how networks communicate across it:

  • Local routing – Connects networks within the same region
  • Global routing – Connects networks across different regions

When using global routing, you can optionally configure redundancy groups to support high availability across regions.

Design considerations

Before you begin configuring your transit gateway, consider the following points:

  • Whether your networks need to communicate within a single region or across multiple regions
  • Whether your architecture requires high availability across regions
  • How traffic must flow between connected networks

These decisions influence your routing choice and whether additional configurations, such as redundancy groups, are appropriate for your deployment.

Procedure

To get started using IBM Cloud Transit Gateway:

  1. Review About IBM Cloud Transit Gateway for an overview of features, and see Interconnectivity patterns for use cases that match your topology.

  2. Plan your topology and prerequisites. Identify the networks that you want to connect (VPC, classic, Power Virtual Server, VPN, Direct Link, GRE) and ensure no overlapping CIDRs. For more information, see Planning for IBM Cloud Transit Gateway.

  3. Configure IAM permissions to allow users or service IDs to manage Transit Gateway resources. For more information, see Using IAM permissions with IBM Cloud Transit Gateway.

  4. Create a transit gateway in the target region. For more information, see Ordering an IBM Cloud Transit Gateway.

  5. Add connections and configure routing. Attach networks, enable route propagation, and verify routes using route reports. Resolve routing conflicts (for example, overlapping CIDRs) using prefix filters.

    For more information, see Adding a connection and Generating a route report.

    When using global routing, you can optionally configure redundancy groups to support high availability across multiple regions and improve resilience of your network connectivity.

  6. Configure Transit Gateway connection authorization. Control which accounts or networks are allowed to attach to the gateway and exchange traffic. Ensure that appropriate IAM permissions are also in place for the underlying resources, such as VPCs or Direct Link connections. For more information, see Using IAM permissions with IBM Cloud Transit Gateway.

  7. Test traffic flow and validate resilience. Confirm connectivity between networks, verify routes using route reports, and test failover scenarios (for example, redundant GRE tunnels) to ensure that traffic continues to flow as expected when paths are unavailable. For more information, see Monitoring Transit Gateway.