Evaluating VPC connectivity options is a critical skill for AWS Solutions Architects designing complex organizational architectures. When assessing connectivity solutions, architects must consider multiple factors including security requirements, bandwidth needs, latency tolerance, and cost optimiz…Evaluating VPC connectivity options is a critical skill for AWS Solutions Architects designing complex organizational architectures. When assessing connectivity solutions, architects must consider multiple factors including security requirements, bandwidth needs, latency tolerance, and cost optimization.
Key VPC connectivity options include:
**VPC Peering**: Enables private connectivity between two VPCs using AWS's network infrastructure. This option works well for connecting VPCs within the same or different AWS accounts and regions. Traffic stays on the AWS backbone, providing low latency and high bandwidth. However, peering relationships are non-transitive, meaning each VPC pair requires its own peering connection.
**AWS Transit Gateway**: Serves as a central hub that connects multiple VPCs and on-premises networks through a single gateway. This approach simplifies network architecture by reducing the number of connections needed, especially beneficial when managing numerous VPCs. Transit Gateway supports transitive routing and enables centralized network management.
**AWS PrivateLink**: Provides private connectivity to services across VPCs while keeping traffic within the AWS network. This option is ideal for exposing services to consumers securely, as it eliminates the need for internet gateways or NAT devices.
**VPN Connections**: Site-to-Site VPN establishes encrypted tunnels over the public internet, suitable for connecting on-premises data centers to AWS VPCs. Client VPN enables remote users to access AWS resources securely.
**AWS Direct Connect**: Offers dedicated private connectivity between on-premises infrastructure and AWS, providing consistent network performance and reduced bandwidth costs for high-volume data transfers.
When evaluating these options, architects should assess:
- Number of VPCs requiring connectivity
- Cross-region versus same-region requirements
- Bandwidth and latency requirements
- Security and compliance mandates
- Operational complexity and management overhead
- Total cost of ownership including data transfer charges
The optimal solution often combines multiple connectivity options to meet diverse organizational requirements while maintaining security and cost efficiency.
Evaluating VPC Connectivity Options
Why is This Important?
Understanding VPC connectivity options is critical for AWS Solutions Architects because it forms the foundation of secure, scalable, and cost-effective network architectures. Organizations often have complex requirements involving multiple VPCs, on-premises data centers, and third-party networks. Choosing the wrong connectivity option can lead to security vulnerabilities, performance bottlenecks, and unnecessary costs.
What are VPC Connectivity Options?
VPC connectivity options are the various methods AWS provides to connect Virtual Private Clouds to each other, to on-premises networks, and to the internet. The main options include:
1. VPC Peering - Point-to-point connection between two VPCs - Non-transitive (traffic cannot pass through to a third VPC) - Works across regions and accounts - No bandwidth bottleneck (uses AWS backbone) - No single point of failure
3. AWS PrivateLink - Exposes services privately to other VPCs - One-way access (consumer to provider) - Does not require VPC peering or public IPs - Ideal for SaaS and shared services
4. VPN Connections - Site-to-Site VPN over IPsec - Quick to set up - Uses public internet (encrypted) - Limited bandwidth (up to 1.25 Gbps per tunnel)
5. AWS Direct Connect - Dedicated private connection to AWS - Consistent network performance - Higher bandwidth options (up to 100 Gbps) - Lower data transfer costs for high volume
6. Direct Connect Gateway - Connects Direct Connect to multiple VPCs across regions - Does not support transitive routing between VPCs
How Does Each Option Work?
VPC Peering: Creates a networking connection using private IP addresses. Both VPCs must have non-overlapping CIDR blocks. Route tables in each VPC must be updated to direct traffic to the peering connection.
Transit Gateway: Acts as a cloud router where each connected network only needs to connect to the Transit Gateway rather than every other network. Uses route tables to control traffic flow and supports multiple route tables for network segmentation.
PrivateLink: Creates an interface endpoint (ENI) in the consumer VPC that provides private connectivity to services. Traffic never traverses the public internet.
Site-to-Site VPN: Establishes encrypted tunnels between your on-premises network and AWS. Requires a Virtual Private Gateway on the AWS side and a Customer Gateway on your side.
Direct Connect: Establishes a physical connection at an AWS Direct Connect location. Can be combined with VPN for encrypted traffic over the dedicated line.
Decision Criteria for Choosing Options
Consider these factors when evaluating connectivity: - Scale: Few VPCs favor peering; many VPCs favor Transit Gateway - Bandwidth requirements: High bandwidth needs favor Direct Connect - Cost sensitivity: VPN is cheaper but less reliable than Direct Connect - Security requirements: PrivateLink for service exposure; Direct Connect with VPN for encrypted dedicated lines - Latency requirements: Direct Connect provides consistent latency - Transitivity needs: Transit Gateway when traffic must flow between connected networks
Exam Tips: Answering Questions on Evaluating VPC Connectivity Options
1. Look for scale indicators: Questions mentioning hundreds of VPCs point toward Transit Gateway. A few VPCs with simple connectivity suggest VPC Peering.
2. Identify transitive routing requirements: If traffic needs to flow from VPC A through VPC B to VPC C, Transit Gateway is required since VPC Peering is non-transitive.
3. Watch for overlapping CIDR blocks: VPC Peering requires non-overlapping CIDRs. PrivateLink works with overlapping CIDRs.
4. Consider cost optimization scenarios: High data transfer volumes favor Direct Connect due to lower per-GB costs. Occasional or burst traffic may favor VPN.
5. Note latency and reliability requirements: Mission-critical applications with strict latency requirements point toward Direct Connect.
6. Recognize service exposure patterns: When a service needs to be shared across accounts or with partners, PrivateLink is the secure choice.
7. Understand hybrid scenarios: Questions involving on-premises connectivity with multiple VPCs suggest Transit Gateway combined with Direct Connect or VPN.
8. Remember bandwidth limits: Site-to-Site VPN maxes at 1.25 Gbps per tunnel. Scenarios requiring higher throughput need Direct Connect or multiple VPN connections with ECMP.
9. Multi-region considerations: Transit Gateway peering connects Transit Gateways across regions. Direct Connect Gateway provides multi-region access from a single Direct Connect connection.
10. Eliminate based on constraints: If the question mentions quick deployment, eliminate Direct Connect (takes weeks to provision). If it mentions high throughput, eliminate single VPN tunnels.