Increasing Fault Tolerance for AWS Direct Connect in SecureCart’s Multi-VPC Network

🔹 Company Setup: SecureCart operates two VPCs connected via VPC Peering: ✔ VPC-1 (Private Subnets) – Contains databases and internal services. ✔ VPC-2 (Public Subnets) – Hosts internet-facing applications.

🔹 Current AWS Networking Setup: ✔ SecureCart has a Direct Connect (DX) connection with a private virtual interface linking the on-premises data center to VPC-1. ✔ All on-premises traffic routes through Direct Connect to reach AWS resources.

🔹 Business Requirement: SecureCart wants to increase the fault tolerance of its Direct Connect link to AWS.

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📌 Recommended Fault Tolerance Solutions

To ensure high availability and redundancy, SecureCart should implement two strategies:

✅ Solution 1: Add Another Direct Connect Connection (Option A)

✔ Why? ✔ Multiple DX connections in the same AWS region provide redundancy in case the primary connection fails. ✔ AWS Direct Connect Resiliency Recommendations suggest at least two connections for fault tolerance.

✔ Implementation Steps: 1️⃣ Order a second Direct Connect connection in the same region as VPC-1. 2️⃣ Create a new private virtual interface linked to SecureCart’s AWS account. 3️⃣ Configure BGP routing with Active/Passive or Active/Active failover.

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✅ Solution 2: Establish a Backup VPN (Option B)

✔ Why? ✔ A site-to-site VPN over the internet acts as a backup path if Direct Connect fails. ✔ AWS recommends using VPN tunnels as backup links for Direct Connect failures.

✔ Implementation Steps: 1️⃣ Create a VPN connection between SecureCart’s on-premises network and VPC-1. 2️⃣ Attach the VPN to the Virtual Private Gateway (VGW) in VPC-1. 3️⃣ Update routing tables to prefer Direct Connect but fail over to VPN in case of failure.

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📌 Why Are Other Options Incorrect?

Option	Explanation
❌ Option C (DX to VPC-2)	Direct Connect should be connected to VPC-1 where private workloads exist, not to VPC-2, which only has public subnets.
❌ Option D (VPN to VPC-2)	VPN traffic would need to traverse VPC Peering to reach VPC-1, introducing latency and potential routing issues.
❌ Option E (VPN CloudHub)	AWS VPN CloudHub is for multiple remote sites connecting to AWS, not a backup strategy for a single VPC.

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📌 Updated SecureCart Architecture for Fault Tolerance

✅ Primary Path: Direct Connect (DX) - Primary private interface to VPC-1 ✅ Secondary Path: Backup Site-to-Site VPN over the Internet to VPC-1

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📌 Best Practices for SecureCart’s Network Resiliency

✔ Deploy multiple Direct Connect connections in different AWS Direct Connect locations. ✔ Configure Active/Passive failover using BGP between DX and VPN. ✔ Enable CloudWatch monitoring for Direct Connect link failures. ✔ Use AWS Transit Gateway for scalable connectivity between VPCs and on-prem.

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📌 Summary

🚀 SecureCart’s improved fault-tolerant network includes: ✔ Two Direct Connect links for redundancy. ✔ A site-to-site VPN backup for automatic failover. ✔ Optimized BGP routing for automatic failover between DX & VPN.