Evaluating connectivity options for multiple VPCs

Question: Can you explain what a VPC peering connection is and when it would be an appropriate choice for connecting multiple VPCs?

A VPC peering connection is a networking connection between two VPCs that enables you to route traffic between them using private IPv4 or IPv6 addresses. VPC peering would be appropriate when you have a straightforward networking setup that requires direct connectivity between two VPCs, without the need for a transit VPC or connectivity to on-premises networks. It’s also a cost-effective solution with no bandwidth bottlenecks.

Question: How does AWS Transit Gateway facilitate connectivity between multiple VPCs, and what advantages does it offer over VPC peering in larger networks?

AWS Transit Gateway acts as a network transit hub that allows you to connect multiple VPCs and on-premises networks through a central point. It simplifies network management, reduces operational costs, and scales automatically for the addition of new VPCs or VPN connections. Unlike VPC peering, which requires individual connections between pairs of VPCs, Transit Gateway provides a hub-and-spoke model that simplifies routing and management for larger, more complex networks.

Question: What limitations should you be aware of when considering VPC peering for connecting multiple VPCs?

VPC peering has several limitations, such as no transitive peering (you can’t route traffic through a peering connection to a VPC that is connected to another VPC), no overlapping CIDR blocks, and a limit on the number of active and pending VPC peering connections per VPC. Additionally, VPC peering does not support edge-to-edge routing through a gateway or private connection.

Question: Describe a scenario where AWS Direct Connect would be a more beneficial option for connecting multiple VPCs compared to using VPC peering or Transit Gateway.

AWS Direct Connect would be more beneficial when you need a dedicated, consistent network connection between your on-premises environment and multiple VPCs for applications requiring high throughput and low latency. It’s suitable for large data transfers, like migration of virtual machines or datasets, and when compliance requirements dictate a private connection rather than traversing the public internet.

Question: What is the maximum number of VPCs that can be attached to a single Transit Gateway, and how does it influence connectivity strategies for large-scale AWS deployments?

As of the knowledge cutoff date for this exam, a single AWS Transit Gateway can support attachment of up to 5,000 VPCs. This high limit enables organizations to adopt a hub-and-spoke model for large-scale AWS deployments, simplifying the network topology and reducing the complexity of managing multiple VPC connections.

Question: Explain the role of route tables in managing traffic between connected VPCs and how they are used with Transit Gateway.

Route tables are used to control the routing of traffic between the VPC subnets and Transit Gateway. When a VPC is attached to a Transit Gateway, a route table entry is added to direct traffic to the Transit Gateway for specific destinations. Route table propagation can also be enabled, allowing the Transit Gateway to automatically populate routes in a VPC route table, simplifying the routing configuration.

Question: How can AWS Resource Access Manager (RAM) be utilized when sharing network connectivity resources, such as a Transit Gateway, across multiple AWS accounts?

AWS Resource Access Manager (RAM) allows you to share AWS resources like Transit Gateways across different AWS accounts within your organization. This enables you to create a single Transit Gateway and share it with multiple accounts, thus centralizing network management and reducing operational costs, without requiring a separate Transit Gateway for each account.

Question: What is a VPN CloudHub, and when is it the right choice for connecting multiple VPCs?

VPN CloudHub is suitable for organizations that have multiple branch offices requiring secure communication with the VPCs at low to moderate bandwidth requirements. It uses a hub-and-spoke model to facilitate communications between sites using AWS VPN connections, without requiring internet-based connectivity.

Question: In the context of VPC connectivity options, discuss the use case for implementing an AWS Shared VPC, and how does it differ from traditional VPC setups?

An AWS Shared VPC (also known as VPC sharing) allows multiple AWS accounts to use the same VPC while keeping their resources isolated. This is useful for large organizations that want to maintain a common network infrastructure for multiple teams or projects within the same VPC. It differs from traditional VPC setups by enabling resource sharing and centralizing network management without the need for peering or Transit Gateway attachments.

Question: What are some considerations for security and compliance when connecting multiple VPCs, especially across different regions or accounts?

When connecting VPCs across regions or accounts, it’s essential to consider data sovereignty laws, encryption requirements for in-transit data, access controls, and network segmentation. Additionally, proper configuration of security groups, network ACLs, and consistent IAM policies across accounts and regions is crucial to maintain a robust security posture.

Question: Describe how AWS PrivateLink can be used in scenarios involving multiple VPCs and outline its benefits over traditional AWS service endpoints.

AWS PrivateLink allows you to expose services across different VPCs securely and privately while minimizing the exposure of data to the public internet. It provides private connectivity to services hosted in VPCs, enhances security by not requiring an Internet Gateway, and reduces the risk of data exfiltration. It also enables service consumers to access services through their VPC’s private IP space, unlike traditional AWS service endpoints that are accessible within a VPC but may traverse the AWS public network.

Question: Discuss the impact of inter-region VPC peering on latency and data transfer costs when connecting VPCs that reside in different AWS regions.

Inter-region VPC peering allows for the private transfer of data between VPCs in different regions, which can lead to higher latency compared to intra-region peering due to the physical distance that data must travel. As for costs, AWS charges for inter-region data transfer at a different (typically higher) rate than intra-region transfer. Thus, when planning inter-region connectivity, these factors should be accounted for, particularly if applications are sensitive to latency or when bandwidth usage is expected to be high.