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Understanding AWS Transit Gateway: Concepts, Quotas, Billing, and Practical Use Cases

Introduction

In today's cloud-driven world, managing complex networks efficiently is crucial for businesses. AWS Transit Gateway is a powerful service that simplifies network management by acting as a hub to interconnect your VPCs and on-premises networks. This post will delve into the importance of AWS Transit Gateway, its key concepts, quotas, billing, and practical use cases.

What is AWS Transit Gateway?

AWS Transit Gateway is a networking service that enables you to connect multiple Amazon Virtual Private Clouds (VPCs) and on-premises networks via a single gateway. It acts as a hub for your network traffic, reducing the complexity and management overhead of having multiple VPC-to-VPC connections.

Key Concepts

  • Transit Gateway: The central hub that interconnects your VPCs and on-premises networks.
  • Attachments: Connections to the Transit Gateway from VPCs, VPNs, Direct Connect gateways, and Transit Gateway Connect.
  • Route Tables: Control the routing of traffic through the Transit Gateway.
  • Propagation: Automatically adds routes to route tables based on attachments.
  • Peering: Connects Transit Gateways across different AWS regions.

transit gateway image

Why Use AWS Transit Gateway?

Simplified Network Management

By acting as a hub, AWS Transit Gateway reduces the complexity of managing peering relationships between VPCs. You no longer need to set up and manage individual connections between every VPC in your network.

Scalability

AWS Transit Gateway supports high bandwidth connections, making it suitable for large-scale deployments. It can handle thousands of VPCs and on-premises connections, providing a scalable solution for your network infrastructure.

Enhanced Security

Transit Gateway allows for the implementation of centralized security policies, ensuring consistent security across your network. You can use security services like AWS Network Firewall and AWS PrivateLink with Transit Gateway.

tgw-security

Quotas and Limits

Understanding the quotas and limits of AWS Transit Gateway is essential for planning and scaling your network.

  • Maximum Transit Gateways per AWS Account: 5
  • Maximum Attachments per Transit Gateway: 5,000
  • Maximum Route Tables per Transit Gateway: 20
  • Maximum Routes per Route Table: 10,000
  • Inter-VPC Traffic: Supports up to 100 Gbps of burst bandwidth per VPC attachment.
  • VPN Connections: Supports up to 1.25 Gbps per VPN connection.
  • Direct Connect: Bandwidth depends on the Direct Connect connection capacity, which can go up to 10 Gbps or more per connection.

For the latest and detailed quota information, refer to the AWS Transit Gateway Quotas documentation.

Billing and Pricing

AWS Transit Gateway pricing is based on the number of attachments and the amount of data processed. Here are the key components of the billing structure:

  • Attachment Fee: $0.05 per hour for each VPC, VPN, Direct Connect, or Transit Gateway Connect attachment to your Transit Gateway.
  • Data Processing Fee: $0.02 per GB of data processed through the Transit Gateway.

For detailed pricing information, please refer to the AWS Transit Gateway Pricing page.

Example Pricing

Let's assume you have a Transit Gateway (us-east-1) with the following setup and you created a route to send traffic to another VPC via the Transit Gateway. 100 GB of data was sent from an Amazon Elastic Compute Cloud (EC2) instance in that VPC to another VPC.:

  • 3 VPC attachments
  • 2 VPN connections
  • 1 Direct Connect gateway

  • Attachment Fee: Assuming 1 hour of usage for all attachments:

    • 3 VPC attachments: 3 * $0.05 = $0.15
    • 2 VPN connections: 2 * $0.05 = $0.10
    • 1 Direct Connect gateway: 1 * $0.05 = $0.05
    • Total Attachment Fee: $0.15 + $0.10 + $0.05 = $0.30
  • Data Processing Fee: The cost for 100 GB of data processed would be:

    • 100 GB * $0.02/GB = $2.00
  • Total Cost:

    • Attachment Fee: $0.30
    • Data Processing Fee: $2.00
    • Total: $2.30

Practical Use Cases

Multi-VPC Architecture

In a multi-VPC architecture, AWS Transit Gateway can be used to interconnect multiple VPCs within the same region or across different regions. This setup is ideal for organizations that need to isolate workloads for security, compliance, or administrative purposes.

Hybrid Cloud Connectivity

AWS Transit Gateway provides a robust solution for hybrid cloud connectivity. By attaching VPN connections or AWS Direct Connect gateways, you can seamlessly integrate your on-premises network with your AWS environment, ensuring consistent and reliable network performance.

Centralized Network Management

For enterprises with complex network architectures, AWS Transit Gateway simplifies network management by centralizing traffic control. You can manage routing policies, monitor traffic, and enforce security policies from a single point.

Disaster Recovery

Using AWS Transit Gateway, you can set up a resilient and robust disaster recovery architecture. By connecting your primary and secondary sites through Transit Gateway, you ensure quick failover and recovery in case of an outage.

aws transit example

PDF: https://d1.awsstatic.com/architecture-diagrams/ArchitectureDiagrams/hybrid-connectivity-to-transit-gateway-ra.pdf?ntwd_hyb5

Conclusion

AWS Transit Gateway is a game-changer for managing complex network infrastructures. Its ability to simplify connections, enhance security, and scale efficiently makes it an indispensable tool for modern cloud architectures. Whether you are building a multi-VPC setup, integrating on-premises networks, or centralizing your network management, AWS Transit Gateway provides a reliable and efficient solution.

For more information, check out the AWS Transit Gateway Documentation.


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