Question

Difficulty: MediumHybrid and Multi-Account Network Connectivity Design

An international media broadcasting company is designing a hybrid network architecture for its multi-account AWS environment. The environment consists of 50 spoke VPCs in a single AWS Region, which host various parts of a media processing pipeline. The company needs to establish a highly available, transitive connection between all VPCs and two on-premises sites: a primary production facility and a backup recovery center. The primary path must run over a 10 Gbps AWS Direct Connect connection. The backup path must use an IPsec VPN over the internet. The solution must minimize routing configuration complexity, automatically fail over to the backup path if the primary path is unavailable, and allow direct VPC-to-VPC communication. Which combination of actions should a solutions architect take to meet these requirements? (Select TWO.)

  1. Deploy an AWS Transit Gateway and attach all 50 spoke VPCs to it. Create a Direct Connect gateway, associate it with a transit virtual interface (transit VIF) on the Direct Connect connection, and attach the Direct Connect gateway to the Transit Gateway.Answer
  2. Create an AWS Site-to-Site VPN connection and terminate it on the AWS Transit Gateway. Advertise the same on-premises network prefixes over both the Direct Connect gateway and the VPN connection, using AS PATH prepending on the backup VPN connection to ensure the Direct Connect path is preferred.Answer
  3. C
    Establish VPC peering connections between all 50 spoke VPCs to enable inter-VPC traffic. Create a Direct Connect gateway and attach it to a virtual private gateway (VGW) in each spoke VPC to handle hybrid routing.
  4. D
    Create a centralized egress VPC with a single NAT Gateway in one Availability Zone to route all outbound internet-bound traffic from the 50 spoke VPCs via the AWS Transit Gateway, modifying the spoke VPC route tables to point all 0.0.0.0/0 traffic to the Transit Gateway.

Answer

The correct solution is to deploy an AWS Transit Gateway to connect the 50 spoke VPCs, routing hybrid traffic through a Direct Connect gateway with a transit virtual interface (transit VIF), while establishing a Site-to-Site VPN terminating on the Transit Gateway with AS PATH prepending on the VPN connection to ensure the Direct Connect path is preferred.
The correct solution involves deploying an AWS Transit Gateway to consolidate connectivity for the 50 spoke VPCs. The primary 10 Gbps path is established using a transit virtual interface (transit VIF) associated with a Direct Connect gateway attached to the Transit Gateway. The backup path is configured using a Site-to-Site VPN attachment directly on the Transit Gateway. To ensure the Direct Connect path is preferred, the same routes are advertised on both connections, but with AS PATH prepending configured on the VPN path.

Step-by-Step Solution

1
Select the hub-and-spoke connectivity pattern.
AWS Transit Gateway is selected to connect the 50 spoke VPCs, enabling scalable VPC-to-VPC and hybrid communications.
Standard VPC peering is difficult to scale for 50 VPCs, and virtual private gateways do not support transitive routing or sufficient associations.
2
Configure the primary hybrid path using AWS Direct Connect.
A transit virtual interface (transit VIF) is created on the Direct Connect connection, associated with a Direct Connect gateway, and attached to the Transit Gateway.
Transit VIFs are required when connecting Direct Connect to a Transit Gateway to enable hybrid routing to multiple VPCs.
3
Configure the backup hybrid path and path preference.
A Site-to-Site VPN connection is terminated on the Transit Gateway, and AS PATH prepending is configured on the VPN connection to make it less preferred than the Direct Connect path.
This guarantees high availability with automatic failover to the VPN while ensuring the Direct Connect connection is the primary path.

Key Concept

AWS Transit Gateway acts as a cloud router, enabling transitive routing between multiple VPCs and on-premises networks using transit VIFs for Direct Connect and Site-to-Site VPNs for failover.
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