Hybrid Cloud Architecture — On-Prem to Cloud Connectivity, VPN, Direct Connect & Strategies

In this tutorial, you'll learn about Hybrid Cloud Architecture. We cover key concepts, practical examples, and best practices to help you understand and apply this topic effectively.

Hybrid cloud architecture connects on-premises data centers with public cloud infrastructure, enabling workloads to run in the most appropriate environment while sharing data and applications seamlessly.

What You'll Learn

You'll learn how to design hybrid cloud connectivity using VPN and Direct Connect, extend on-premises networks to the cloud, migrate workloads in phases, and implement consistent security across environments.

Why It Matters

Most enterprises run hybrid environments during cloud Migration and for workloads that cannot move to the cloud due to latency, Compliance, or legacy constraints. Cloud Migration strategies depend on hybrid connectivity. Durga Antivirus Pro processes sensitive threat data on-premises while using cloud for analytics.

Real-World Use

A financial services company keeps customer Transaction processing on-premises for regulatory Compliance but uses AWS for big data analytics and ML training, connected via Direct Connect with automatic failover over VPN.

Connectivity Options

Site-to-Site VPN

IPsec VPN tunnels connect on-premises routers to virtual private gateways in the cloud.

# AWS: Create a virtual private gateway and attach to VPC
aws ec2 create-vpn-gateway --type ipsec.1
aws ec2 attach-vpn-gateway \
  --vpn-gateway-id vgw-0abcd1234 \
  --vpc-id vpc-0efgh5678

# Create a VPN connection with customer gateway
aws ec2 create-vpn-connection \
  --type ipsec.1 \
  --customer-gateway-id cgw-0a1b2c3d \
  --vpn-gateway-id vgw-0abcd1234

Expected behavior: Two IPsec tunnels are created. AWS provides configuration files for popular on-premises routers (Cisco, Juniper, pfSense).

flowchart LR
  A[On-Prem Router] -->|IPsec Tunnel 1| B[AWS VPN Endpoint 1]
  A -->|IPsec Tunnel 2| C[AWS VPN Endpoint 2]
  B --> D[Virtual Private Gateway]
  C --> D
  D --> E["VPC: 10.0.0.0/16"]
  style A fill:#48f,color:#fff
  style E fill:#4a4,color:#fff

Direct Connect

AWS Direct Connect provides dedicated private connectivity from your data center to AWS.

# Simulate Direct Connect capacity planning
def estimate_dx_capacity(
    daily_data_gb: int,
    peak_factor: float = 2.0,
    utilization_target: float = 0.7
) -> str:
    peak_gbps = (daily_data_gb * 8 * peak_factor) / (24 * 3600)
    required = peak_gbps / utilization_target

    options = [0.05, 0.1, 0.5, 1, 10, 100]  # Gbps
    for opt in options:
        if opt >= required:
            return f"{opt} Gbps (peak: {peak_gbps:.2f} Gbps)"

    return f"100+ Gbps (consider multiple connections, peak: {peak_gbps:.2f} Gbps)"

print(estimate_dx_capacity(5000))  # 5 TB daily

Expected output:

1 Gbps (peak: 0.38 Gbps)

Hybrid DNS and Name Resolution

Hybrid environments need DNS resolution across on-premises and cloud networks. Route 53 Resolver or Azure DNS Private Resolver handles this.

# Route 53 Resolver: forward on-prem DNS queries to cloud
aws route53resolver create-resolver-rule \
  --creator-request-id "on-prem-to-cloud" \
  --rule-type FORWARD \
  --domain-name "dodatech.internal" \
  --target-ips Ip=10.0.1.10,Port=53 \
  --name "on-prem-dns-forward"

Expected behavior: On-premises resources can resolve cloud private DNS names and cloud resources can resolve on-premises DNS names through bidirectional forwarding.

Migration Strategies for Hybrid Architectures

Common Errors

1. Routing conflicts: On-premises and cloud VPC CIDR ranges overlap. Plan non-overlapping IP space before starting the connection.
2. Single tunnel without redundancy: A single VPN tunnel is a single point of failure. Always configure two tunnels on different AWS endpoints.
3. MTU issues: Direct Connect supports 1500 or 9001 MTU. On-premises routers must match the MTU or packet fragmentation causes performance degradation.
4. No monitoring: Without BGP session monitoring, a failed tunnel goes undetected. Set up CloudWatch alarms on VPN tunnel status.
5. Ignoring data transfer costs: Data transfer over Direct Connect is more predictable but not free. Egress from AWS to on-premises is not charged, but ingress is.
6. Security group overlap: The same security rules that work in the cloud might not apply on-premises. Maintain independent security policies in each environment.

Practice Questions

1. What is the difference between VPN and Direct Connect? VPN uses the public internet with IPsec encryption. Direct Connect uses a dedicated private circuit for consistent performance.
2. Can you use multiple Direct Connect connections? Yes, multiple connections in different locations provide high availability and can be combined with BGP for traffic Load Balancing.
3. How does hybrid DNS work across environments? Route 53 Resolver forwards DNS queries between on-premises and cloud, enabling name resolution across both environments.
4. What is a transit gateway in hybrid architecture? A network transit hub that connects VPCs, VPN, and Direct Connect in a single gateway, simplifying routing.
5. Challenge: A company with two data centers (NYC and London) needs to connect to AWS in us-east-1 and eu-west-2. Each data center runs critical applications that cannot lose connectivity. Design a resilient hybrid network.

Mini Project

Build a hybrid cloud network connecting on-premises to AWS:

• Set up a simulated on-premises network using Cisco Cloud Services Router (CSR) or VyOS in a separate VPC
• Create a VPC with public and private subnets
• Establish a site-to-site VPN with two tunnels
• Configure route propagation between the VPN and VPC subnets
• Set up Route 53 Resolver for DNS resolution across environments
• Test connectivity by pinging a private EC2 instance from the simulated on-premises network
• Add a Direct Connect (simulated) and configure failover from VPN to Direct Connect
• Monitor BGP session status with CloudWatch

Built by the developers of Doda Browser, DodaZIP, and Durga Antivirus Pro.