How do I gather information to troubleshoot transit gateway issues?

Resolution

When you submit a transit gateway support request, gather and provide the following information to help AWS Support diagnose and resolve your issue. For example, provide details about your current network status, network configuration, traffic flow, route information, test results, and logs.

For timing and impact details, take the following actions:

• Specify the date and time of the issue. For example, provide 10:00 AM UTC, November 13, 2025.
• Describe the connectivity issues that occur.
• Specify whether you recently set up your transit gateway or if it was working before the issue started.
• List all recent changes to the network configuration. This includes modifications to sources, destinations, applications, firewalls, and architectural updates or system adjustments.
• Describe the severity and scope of impact. For example, include the number of affected users and systems, affected business-critical functions, and whether the issue causes a complete outage or partial degradation of services.

For network architecture information, take the following actions:

• Provide your transit gateway ID. For example, provide tgw-1234567890abcdef0.
• Identify the affected transit gateway attachments and provide their corresponding attachment IDs in the format tgw-attach-abcdef01234567890.
• Include an architecture diagram of your traffic flow.

For traffic details, take the following actions:

• Provide source and destination IP addresses for the affected resources
• Specify the destination port, protocol, or application that you use for traffic
• Describe the expected path that traffic should take through the transit gateway

For test results, take the following actions:

• Provide error messages or screenshots of errors that you receive.
• Provide additional evidence or test results from your troubleshooting.
• Run the following traceroute command to get test outputs:

  traceroute DESTINATION IP ADDRESS -n

  Note: Replace DESTINATION IP ADDRESS with your destination IP address. Provide the bidirectional ping test outputs and traceroute results between the affected resources.

For Amazon CloudWatch logs, If you turned on transit gateway flow logs and Amazon Virtual Private Cloud (Amazon VPC) flow logs, then provide flow logs that show when the issue starts.

Related information

Work with flow logs

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