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Question

Difficulty: MediumCost-Effective Network Routing and Data Transfer Optimization

A genomic research institution hosts an analytics pipeline on Amazon EC2 instances in a private subnet of a VPC. The pipeline processes raw sequence data and uploads approximately 30 TB30\text{ TB} of processed datasets monthly to an Amazon S3 bucket within the same AWS Region. Currently, the subnet's route table routes all internet-bound and AWS service traffic through a NAT Gateway. The institution wants to significantly reduce its data transfer costs without making code changes to the pipeline or compromising the private status of the EC2 instances. Which architectural change will achieve the maximum cost reduction for this workload?

  1. A
    Deploy an Interface VPC Endpoint (AWS PrivateLink) for Amazon S3 in the private subnet, and update the application configuration to point to the new endpoint.
  2. Create a Gateway VPC Endpoint for Amazon S3, and associate it with the route table of the private subnet.Answer
  3. C
    Establish an AWS Site-to-Site VPN connection to route the S3 traffic through an on-premises network gateway to bypass the NAT Gateway.
  4. D
    Assign public IP addresses to the EC2 instances, and route the S3 traffic directly through an Internet Gateway instead of the NAT Gateway.

Answer

Create a Gateway VPC Endpoint for Amazon S3, and associate it with the route table of the private subnet.
Creating a Gateway VPC Endpoint for Amazon S3 is the most cost-effective solution. Gateway VPC Endpoints are available at no additional cost (no hourly charges and no data processing fees). By associating the endpoint with the private subnet's route table, traffic destined for S3 is routed directly through the AWS network using private IP addresses. This bypasses the NAT Gateway entirely, requires no changes to the application code, and maintains the private status of the EC2 instances.

Step-by-Step Solution

1
Analyze the current data transfer route and the associated costs.
The private EC2 instances transfer 30 TB30\text{ TB} of data monthly to Amazon S3 through a NAT Gateway, which incurs a NAT Gateway data processing fee of 0.0450.045 USD per GB.
Identifying the root cause of the high data transfer costs requires analyzing the current network path.
2
Evaluate alternative private routing options for Amazon S3 traffic.
Gateway VPC Endpoints for Amazon S3 provide a direct, secure connection to S3 using private IP addresses. They do not charge hourly fees or per-GB data processing fees.
Choosing the most cost-effective alternative requires comparing the pricing models of NAT Gateway, Interface VPC Endpoints, and Gateway VPC Endpoints.
3
Configure the route table to redirect the traffic.
Associate the Gateway VPC Endpoint with the private subnet's route table. This adds a route pointing to the S3 prefix list with the Gateway Endpoint as the target.
Associating the endpoint with the route table ensures that all S3 traffic from the subnet bypasses the NAT Gateway automatically without requiring application code changes.

Key Concept

Gateway VPC Endpoints provide free, private routing to Amazon S3 and DynamoDB.
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Topics

Cost-Effective Network Routing and Data Transfer Optimization