Modify Transit Gateway Properties After Creation

Question

When a Transit Gateway (TGW) is created, either in CloudFormation or in the console, several properties can be configured, specifically:

- AutoAcceptSharedAttachments
- DefaultRouteTableAssociation
- DefaultRouteTablePropagation 
- Description 
- DnsSupport 
- VpnEcmpSupport

Once the TGW is created, Is there a way for a user to change these properties after creation without having to re-create the TGW again?

Accepted Answer

Transit Gateway (TGW) allow the [modification ](https://docs.aws.amazon.com/vpc/latest/tgw/tgw-transit-gateways.html#tgw-modifying)of certain properties after the creation.

> When you modify a transit gateway, the modified options are applied to new transit gateway attachments only. Your existing transit gateway attachments are not modified.

Refer to [Modify a transit gateway](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_ModifyTransitGateway.html) in the user guide or the AWS [CLI](https://docs.aws.amazon.com/cli/latest/reference/ec2/modify-transit-gateway.html)/[API](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_ModifyTransitGateway.html) docs for options that can be modified after creation.

Modify Transit Gateway Properties After Creation

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