AWS VPC Demystified: Best Practices for Effective Design

Main objectives:

Benefits of using AWS VPC:

AWS Use case

Components of AWS VPC and design best practices

A VPC peering connection in AWS is a networking connection that facilitates the routing of traffic between two VPCs. It operates using private IPv4 or IPv6 addresses and allows instances in either VPC to communicate with each other as if they were on the same network. This connection can be established between your own VPCs or with a VPC in another AWS account. Additionally, VPCs can be located in different regions, making it possible to create an inter-region VPC peering connection. For organizations with multiple VPCs or data centers, Transit Gateway connects VPCs and on-premises networks through a central platform.

VPC

AWS uses the existing infrastructure of a VPC to create a VPC peering connection. Unlike a gateway or a VPN connection, VPC peering does not rely on a separate piece of physical hardware. Consequently, there is no single point of failure or bandwidth bottleneck, ensuring a highly available and secure network connection.

It is important to note that each VPC must be peered with each other, and there is no transitive VPC peering. This connection only routes traffic between the source and destination VPCs and does not support edge-to-edge routing. Therefore, it is not possible to leverage Direct Connect or an Internet Gateway in an account that is peered.

VPC Components

VPC peering offers full private IP connectivity between two VPCs, making it possible to peer VPCs across regions and different accounts. However, the VPC CIDR ranges must not overlap, or else the peering connection will not work. Overall, VPC peering is an efficient way to establish a secure, private network between VPCs within and outside an AWS account.

Benefits of using AWS VPC:

• Isolation and Security: AWS VPC provides a secure and isolated environment for your resources, which can be useful for handling sensitive data or applications. You can use security groups and NACLs to control access to your resources, and VPC endpoints for secure private communication between your VPC and other AWS services.
• Scalability: AWS VPC can be scaled up or down depending on the needs of your applications. You can create multiple VPCs to accommodate different projects, and use subnets to divide the VPC into smaller segments.
• Flexibility: AWS VPC is flexible and can be customized to meet your specific needs. You can use VPC peering to connect VPCs together, and use NAT gateways for instances in private subnets to access the internet or other AWS services.
• Cost-effective: Using AWS VPC can be cost-effective as you only pay for the resources that you use. You can use Reserved Instances for long-term commitments to save on costs, and use VPC endpoints to save on data transfer costs.

Use case

1. Secure Application Deployment: AWS VPC can be used to create an isolated network for deploying applications that require a high level of security. By using VPC, you can deploy your applications in an environment that is not accessible from the public internet, reducing the risk of unauthorized access.
2. Hybrid Cloud Infrastructure: AWS VPC can be used to create a hybrid cloud infrastructure that spans both on-premises and cloud environments. With VPC, you can establish a secure connection between your on-premises network and your VPC, enabling you to access your resources securely from both environments.
3. Multi-Tier Application Architecture: AWS VPC can be used to create a multi-tier application architecture that provides isolation between different tiers. By using VPC, you can create subnets for each tier and control traffic flow between them, reducing the risk of unauthorized access.
4. Global Application Deployment: AWS VPC can be used to deploy applications globally across multiple regions. By creating VPCs in each region and using VPC peering, you can create a global network that enables your application to be highly available and resilient.
5. Compliance and Regulatory Requirements: AWS VPC can be used to meet compliance and regulatory requirements, such as HIPAA or PCI DSS. By using VPC, you can create an isolated network that meets the specific requirements of these regulations.

Components of AWS VPC and design best practices

The VPC comes with several key components that make it work, including subnets, route tables, internet gateways, security groups, NACLs, VPC endpoints, and NAT gateways.

IP Address/subnet in VPC:

Designing the IP address space and subnets for your VPC is an important aspect of setting up your network. Proper planning and design can help ensure that your network is scalable, flexible, and secure. Here are some best practices for IP address and subnet design in VPC:

1. Choose the Right IP Address Space: When designing the IP address space for your VPC, it’s important to choose a range that is large enough to accommodate your future growth. It’s recommended to use a private IP address range as defined in RFC 1918, such as 10.0.0.0/8, 172.16.0.0/12, or 192.168.0.0/16. You should also avoid using IP address ranges that conflict with your on-premises network or other AWS services.
2. Use CIDR Blocks for Subnets: To divide your VPC into smaller segments, you can create subnets using Classless Inter-Domain Routing (CIDR) notation. For example, you can use a /24 CIDR block to create a subnet with 256 IP addresses. When creating subnets, it’s important to plan for future growth and create subnets that are large enough to accommodate your resources.
3. Consider Availability Zones: AWS recommends creating at least one subnet per availability zone to ensure high availability and fault tolerance. By creating subnets in different availability zones, you can distribute your resources across multiple physical locations and reduce the risk of a single point of failure.
4. Plan for Public and Private Subnets: To ensure security and isolation, it’s recommended to create public and private subnets in your VPC. Public subnets are associated with an internet gateway and allow resources to communicate with the public internet, while private subnets are not associated with an internet gateway and allow resources to communicate only within the VPC.
5. Use Security Groups and NACLs: To control access to your resources, you can use security groups and NACLs. Security groups act as virtual firewalls for your instances, while NACLs control inbound and outbound traffic at the subnet level. It’s important to design security groups and NACLs to restrict access to only the necessary ports and protocols.
6. Use Elastic IP Addresses (EIPs): To ensure that your instances have a consistent IP address that can be used to access them over the internet, you can use Elastic IP addresses (EIPs). EIPs are static IP addresses that can be associated with instances in your VPC. Which is different than Elastic Network Interface (ENI) which is used in attaching VPC to EC2 instances, creating a secondary network interface, and using them for internal IP failover.
7. Plan for VPC Peering: To connect VPCs together, you can use VPC peering. When planning for VPC peering, it’s important to choose non-overlapping IP address ranges and to configure the necessary route tables and security groups to allow traffic to flow between the peered VPCs.

VPC Route table design best practices

Route table

Planning and designing routing tables is a crucial task in setting up your VPC in AWS. Routing tables determine how network traffic is directed within your VPC, and contain routes that guide traffic to specific destinations. Here are some guidelines for crafting routing table designs in VPC:

1. Default Routing: By default, a VPC is created with a routing table that includes a local route to allow communication between instances within the VPC. To enable internet communication, you can add a default route that points to an internet gateway.
2. Route Prioritization: When creating routes in your routing table, it’s essential to prioritize them in the correct order. The routing table evaluates routes in the order that they’re added, so you should begin with more specific routes before moving on to less specific routes. For example, a more specific route for a particular destination should be added before a less specific default route.
3. Route Duplication: To avoid route duplication, it’s vital to create routes that don’t overlap. If multiple routes match a destination, the routing table selects the route with the most specific match. As a result, you should avoid creating routes that have overlapping CIDR blocks.
4. Route Propagation: To enable communication between your VPC and other resources, you can allow route propagation for VPC peering connections, VPN connections, or Direct Connect connections. Route propagation allows the routes from other VPCs to be propagated to your routing table.
5. Route Table Associations: You can create custom routing tables and associate them with particular subnets or instances to control traffic flow between subnets. By default, all subnets are associated with the main routing table, but you can design custom routing tables to manage traffic routing in your VPC.
6. Static Routes: You can add static routes to your routing table to direct traffic to specific destinations. For instance, you can add a static route for a destination via a VPN connection.
7. Route Monitoring: You can monitor your routing table with CloudWatch Metrics to ensure that your routes are functioning correctly. You can use metrics like PacketsForwarded and PacketsRejected to monitor traffic flow in your routing table.

Internet Gateways design best practices

Internet Gateway

Designing internet gateways in your VPC requires careful planning and design to ensure optimal performance and security. Here are some technical best practices to consider when designing internet gateways in your VPC:

1. Internet Gateway Configuration: An internet gateway is required to enable communication between resources in your VPC and the public internet. When designing your internet gateway, you must configure it properly to ensure that traffic is routed correctly between your VPC and the public internet.
2. Route Table Configuration: To direct traffic to your internet gateway, you must configure your VPC’s route table properly. Specifically, you must create a default route that directs traffic to the internet gateway. Proper routing ensures that traffic is routed to the appropriate resources and that internet access is available to all required resources.
3. Security Considerations: Security is a critical concern when designing your internet gateway. To reduce the risk of unauthorized access, it is essential to implement security controls such as security groups and NACLs to restrict access to your internet gateway. These controls allow you to control access to your resources and ensure that only authorized traffic is allowed.
4. Cost Optimization: When designing your internet gateway, you must also consider cost optimization. Internet gateways have an associated cost, so it’s important to minimize costs by using a smaller instance size and only attaching the internet gateway to subnets that require internet connectivity. Careful cost optimization can help you maximize the value of your VPC resources.
5. High Availability: High availability is crucial to ensure that your resources remain accessible in the event of a failure. To achieve high availability, you can attach your internet gateway to multiple subnets in different availability zones. This configuration ensures that your resources are accessible, even if a failure occurs in one availability zone.
6. Private Subnet Access: To enable internet access for resources in private subnets, you can use a NAT gateway. NAT gateways allow instances in private subnets to access the internet while maintaining security by hiding their private IP addresses.
7. Troubleshooting: To troubleshoot connectivity issues with your internet gateway, you can use VPC flow logs to monitor network traffic and identify issues. You can also use the AWS Trusted Advisor to identify and resolve common issues with your internet gateway configuration.

Security groups design best practices

Designing security groups is a critical aspect of setting up your AWS VPC. Security groups serve as virtual firewalls that regulate inbound and outbound traffic for your resources. Here are some essential best practices for designing security groups in VPC:

1. Establish a Security Group: When setting up an instance in your VPC, you must create a security group that governs inbound and outbound traffic. To allow traffic to and from your resources, you’ll need to add rules.
2. Rule Creation: It’s crucial to consider the type of traffic that you need to allow or block when creating security group rules. Establish rules that allow traffic from trustworthy sources and restrict the number of open ports to the minimum necessary for your resources.
3. Security Group Composition: To more efficiently manage security rules, you can create multiple security groups for your resources. It’s best to group resources with similar security requirements in the same security group.
4. Security Group Interoperability: You can design security groups that cross multiple VPCs, granting you access control for resources across VPCs. Additionally, you can establish security group rules that reference other security groups, providing access control between resources in different security groups.
5. Review Security Group Rules: It’s vital to regularly assess security group rules to ensure that they are necessary and suitable. Eliminate any unused rules, close unnecessary ports, and block traffic that isn’t needed for your resources.
6. Dynamic IP Addresses: Security groups can control access for resources with dynamic IP addresses. For example, you can permit access to an application only from an IP address that fits a specific pattern.
7. Security Group Testing: Testing your security group configuration is crucial to ensuring it’s functioning correctly. AWS provides tools like Security Group Analyzer that can test your security group configuration and identify any potential issues.

VPC Endpoint design best practices

VPC Endpoint

VPC endpoints are essential components for enabling secure communication between your resources in your AWS VPC and external services. Here are some technical best practices to consider when designing VPC endpoints for your VPC:

1. Endpoint Types: Your VPC endpoints can be Gateway endpoints or Interface endpoints, and the type of endpoint you use depends on the AWS services or PrivateLink partners you need to access.
2. PrivateLink: PrivateLink is a powerful feature that allows you to access AWS services privately, thereby minimizing the amount of traffic that goes over the public internet.
3. Security: Use security groups and NACLs to control inbound and outbound traffic for your VPC endpoints, limiting access only to authorized traffic and enhancing the security of your VPC resources.
4. High Availability: Designing VPC endpoints in multiple availability zones is essential to increase their availability and ensure that your resources remain accessible, even in the event of a failure in one availability zone.
5. Monitoring: Leveraging VPC flow logs to monitor traffic flowing through your VPC endpoints allows you to identify connectivity issues and troubleshoot problems quickly.
6. Endpoint Policy: With endpoint policies, you can define fine-grained access controls for resources connected to the endpoint, ensuring that only authorized actions are performed.
7. Endpoint Access: To further enhance the security of your VPC endpoints, you can limit access by only allowing specific source IP addresses to connect to the endpoint.
8. Endpoint Configuration: Configuring your endpoint to use the appropriate protocol and port for the service you are connecting to ensures that traffic is correctly routed to and from your endpoint.

NAT Endpoints design best practices

NAT Instance

Designing NAT gateways is a critical aspect of ensuring that your AWS VPC has secure, reliable, and optimized internet access. Here are some sophisticated best practices to consider when designing NAT gateways in your VPC:

1. Instance Size: The size of the NAT instance must be selected based on the traffic requirements of your VPC. Choose an instance that is large enough to handle the expected traffic load.
2. Auto-Scaling: Enabling auto-scaling for your NAT gateway can ensure that it has sufficient capacity to handle peak traffic.
3. Elastic IP Address: You should assign an elastic IP address to your NAT gateway to ensure that it maintains a static public IP address.
4. Cost Optimization: Sizing your NAT gateway appropriately and creating NAT gateways only in subnets that require access to the internet can optimize costs.
5. High Availability: Creating your NAT gateway in multiple availability zones can increase its availability and ensure that your resources remain accessible, even in the event of a failure in one availability zone.
6. Security: Use security groups and NACLs to control inbound and outbound traffic for your NAT gateway. Limit access to only the necessary ports and protocols.
7. Monitoring: CloudWatch can be used to monitor your NAT gateway and set up alarms to notify you of any issues.

Elastic Network Interfaces (ENIs):

Elastic Network Interfaces (ENIs) are used in the Virtual Private Cloud (VPC) to provide a networking interface for Amazon Elastic Compute Cloud (EC2) instances. Here are some best practice design practices for using Elastic Network Interfaces (ENIs) in the Virtual Private Cloud (VPC):

1. Use ENIs for different network topologies: ENIs can be used to create different network topologies for your EC2 instances, such as public-facing, private-facing, or hybrid-facing. It is recommended to use separate ENIs for different topologies to improve security and provide more flexibility.
2. Use ENIs for load balancing: ENIs can be used to create highly available architectures by attaching multiple network interfaces to an instance in different Availability Zones. This provides redundancy and helps ensure that network traffic can be automatically redirected to a new instance if one fails.
3. Use ENIs for attaching network interfaces to instances: It is recommended to use ENIs to attach and detach network interfaces to EC2 instances as needed, instead of using the Amazon EC2 API to modify the instance’s attributes directly.
4. Use ENIs for IP address management: ENIs allow you to assign multiple IP addresses to an instance and create network interfaces that span multiple subnets. This makes it possible to customize the network configuration of your EC2 instances in the VPC and create more complex networking setups.
5. Use ENIs for network security: ENIs can be used to control the traffic flow to and from an EC2 instance in a VPC, which makes it possible to implement security controls at the network interface level. You can also use security groups to control the traffic flow between different ENIs and instances.
6. Monitor ENI performance: It is important to monitor ENI performance to ensure that they are performing optimally and that there are no bottlenecks in the network traffic flow. You can use Amazon CloudWatch metrics to monitor ENI performance and identify any issues that need to be addressed.

Conclusion

AWS VPC is a powerful tool that can be used to create an isolated network in the AWS cloud infrastructure for a variety of use cases. By using VPC, you can achieve higher levels of security, scalability, flexibility, and cost-effectiveness for your applications and resources. By adhering to these technical best practices for designing you can create a robust and secure network that meets your specific requirements. Proper planning and design can help optimize network performance and ensure reliability, while also minimizing costs.