QuestionQ46

Network Design

A company has two teams: Team A and Team B. Team A has VPCs running in Account A. The team uses a transit gateway (TGW-A) to route traffic among workloads running in the different VPCs. Likewise, Team В has VPCs running in Account B. Team В uses a separate transit gateway (TGW-B) to route traffic among workloads running in the different VPCs.

The company's network team manages routing for Team A and Team В. The network team wants to retire TGW-B and use one transit gateway to manage routing for the VPCs of both teams.

Which solution meets this requirement with the LEAST operational overhead?

  • A Create a resource share for TGW-A Share TGW-A with Account B. Create VPC attachments for the VPCs in Account В. Configure routing for the VPCs in TGW-A route tables. Update the route tables of the VPCs in Account В to forward traffic to TGW-Delete TGW-B attachments and TGW-B.
  • B Create a resource share for TGW-A. Share TGW-A with Account В. Replicate the TGW-B configuration to TGW-A to automatically start routing changes for the VPCs in Account В. Delete TGW-B when routing changes are complete.
  • C Create a new transit gateway (TGW-C) in Account A. Create a resource share for TGW-Share TGW-C with Account B. Create VPC attachments for the VPCs in Account A and Account В. Configure routing for all the VPCs in TGW-C route tables. Update the route tables for the VPCs in Account A and Account В to forward traffic to TGW-Delete TGW-A attachments and TGW-B attachments. Delete TGW-A and TGW-B.
  • D Create a new transit gateway (TGW-C) in a new account (Account C). Create a resource share for TGW-C. Share TGW-C with Account A and Account B. Create VPC attachments for the VPCs in Account A and Account В. Configure routing for all the VPCs in TGW-C route tables. Update the route tables for the VPCs in Account A and Account В to forward traffic to TGW-C. Delete TGW-A attachments and TGW-B attachments. Delete TGW-A and TGW-B.
Explanation

An AWS Transit Gateway owner can use AWS Resource Access Manager (AWS RAM) to share an existing transit gateway with another AWS account. The receiving account can create VPC attachments for its own VPCs, while the transit gateway owner manages the transit gateway route tables. Sharing and extending TGW-A therefore retains Team A's existing attachments and routing design, requiring only the migration of Team B's VPC connectivity before TGW-B is deleted.

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