Inter-VPC connectivity (for example, AWS Transit Gateway, VPC endpoints)

What is the purpose of AWS Transit Gateway, and how does it facilitate inter-VPC connectivity?

AWS Transit Gateway is a service that enables customers to connect their Amazon Virtual Private Clouds (VPCs) and their on-premises networks via a central hub. It simplifies network management and minimizes the complexity involved in establishing peering connections across multiple VPCs and VPNs. With Transit Gateway, you can create a scalable and flexible network topology, where you can route traffic through a single entry and exit point, ensuring efficient management of inter-VPC connectivity.

Can you explain how AWS Transit Gateway differs from VPC peering?

AWS Transit Gateway and VPC peering both facilitate connectivity between VPCs, but they do so in fundamentally different ways. VPC peering allows for direct network connectivity between two VPCs within the same or across different AWS accounts, and the traffic remains private, but it does not scale well because it requires separate peering connections for each VPC pair. Transit Gateway, on the other hand, acts as a network transit hub, allowing multiple VPCs to connect to a single entity, thereby simplifying management and scaling more effectively, as it reduces the number of individual connections needed.

What are VPC endpoints, and when would one use them?

VPC endpoints are virtual devices that enable VPCs to privately connect to supported AWS services without requiring an internet gateway, NAT device, VPN connection, or AWS Direct Connect connection. There are two types of VPC endpoints: interface endpoints (powered by AWS PrivateLink) and gateway endpoints. They are used when you want to keep traffic between your VPC and other AWS services within the AWS network for increased security and lower latency.

Describe the security benefits of using an AWS Transit Gateway.

AWS Transit Gateway enhances security by offering central management of network traffic, integration with AWS services such as AWS Resource Access Manager (for resource sharing) and Identity and Access Management (IAM) for fine-grained access control, and by supporting route table policies to enforce controlled network traffic flows between VPCs. Additionally, it can be integrated with AWS Network Firewall or third-party firewall appliances to centralize and simplify the inspection and filtering of inter-VPC traffic, essentially providing a strong perimeter for multiple VPCs.

When would one prefer to use an AWS PrivateLink instead of a VPC endpoint?

AWS PrivateLink is preferred when you need to expose your services to other VPCs or when you need private connectivity to third-party services hosted on AWS. Unlike VPC endpoints that connect you to AWS services, AWS PrivateLink allows for the private connection to services hosted in other VPCs. This prevents data from going over the public internet and keeps it within the AWS network, which can increase security and reduce exposure to threats.

How do security groups and network ACLs integrate with AWS Transit Gateway?

Security groups and network ACLs can be used to regulate traffic at the VPC level, but with AWS Transit Gateway, you use Transit Gateway route tables to route traffic accordingly. While security groups act as a firewall for EC2 instances, and NACLs provide a layer of security at the subnet level within VPCs, the Transit Gateway route tables are used to control traffic flow among the connected VPCs and other network attachments, such as VPNs, AWS Direct Connect gateways, and more. However, security groups and NACLs are still applicable and can provide an additional layer of security alongside the Transit Gateway’s policies.

Can you explain how AWS Transit Gateway interconnects with AWS Direct Connect and VPN solutions?

AWS Transit Gateway can act as a central hub that interconnects VPCs with AWS Direct Connect and VPN solutions. Through Direct Connect, it provides a private, high-bandwidth connection that can be used for hybrid cloud architectures, permitting on-premises networks to connect to VPCs via the Transit Gateway. Similarly, for VPNs, AWS Transit Gateway supports site-to-site VPN connections, allowing secure communication between on-premises data centers and VPCs over the internet. This capacity supports a seamless and secure hybrid environment that leverages the benefits of both cloud-based and on-premises resources.

In what scenarios would you configure Transit Gateway route tables to isolate traffic between VPCs?

You would configure Transit Gateway route tables to isolate traffic between VPCs when you need to apply specific policies for compliance, security, or operational isolation reasons. For example, you might have development, staging, and production environments that require separation to prevent unintended access or impact to your production systems. By using separate route tables, you can ensure that traffic between these environments is strictly controlled according to the principle of least privilege.

Can you detail the process to monitor traffic going through AWS Transit Gateway?

To monitor traffic going through AWS Transit Gateway, you can use Amazon CloudWatch, which provides visibility into the traffic flow and performance metrics of Transit Gateway. You can monitor various metrics such as bytes in/out, packets in/out, and packet drop counts. Additionally, you can use VPC Flow Logs to capture the information about the IP traffic going to and from network interfaces in your VPC, which can then be stored in Amazon S3 or CloudWatch Logs for analysis and auditing purposes.

What is AWS Transit Gateway Network Manager, and how does it assist in managing inter-VPC connectivity?

AWS Transit Gateway Network Manager is a service that enables you to centrally monitor your global network traffic and connectivity within AWS. It provides a visual dashboard for managing and monitoring your AWS Transit Gateways, VPN connections, and AWS Direct Connect gateways along with your on-premises and VPC routing information. By using Network Manager, you gain a consolidated view of your network topology, which simplifies management and reduces operational overhead when dealing with inter-VPC connectivity and hybrid cloud environments.

How can AWS Transit Gateway help in reducing costs associated with inter-VPC connectivity?

AWS Transit Gateway can help reduce costs by minimizing the need for multiple connections between each pair of VPCs. Since Transit Gateway acts as a centralized hub, it removes the necessity for a full mesh network and thereby decreases the complexity of VPC peering connections, which can grow exponentially as more VPCs are added to the network. With Transit Gateway, you pay for a single connection from each VPC to the Transit Gateway rather than multiple VPC peering connections, which can result in lower operational costs.

Describe a scenario where you would use VPC Endpoints in combination with AWS Transit Gateway?

A scenario where you would use VPC Endpoints in combination with AWS Transit Gateway is when you have multiple VPCs that need to privately access AWS services such as Amazon S3 or DynamoDB without traversing the public internet, while also needing to maintain connectivity between these VPCs. By creating VPC endpoints, the VPCs can privately access AWS services. The AWS Transit Gateway can then manage and route inter-VPC traffic as well as traffic to and from on-premises networks through a single centralized gateway, providing a comprehensive connectivity solution that enhances both security and efficiency.