Hybrid Cloud Networking Architecture

Hybrid Cloud Networking Architecture

A well-designed hybrid cloud network seamlessly connects on-premises data centers, AWS, and potentially other cloud providers. This reference architecture covers the networking, DNS, security, and operational patterns needed for production hybrid environments.

Reference Architecture

On-Premises Data Center
├── Core Network (172.16.0.0/12)
├── DNS Servers (Active Directory / BIND)
├── VPN Device / Router
└── Direct Connect Router

    ↕ IPsec VPN (backup) + Direct Connect (primary)

AWS Transit Gateway
├── Production VPC (10.0.0.0/16)
├── Staging VPC (10.1.0.0/16)
├── Shared Services VPC (10.3.0.0/16)
│   ├── Route 53 Resolver Endpoints
│   ├── Active Directory Connectors
│   └── Centralized NAT Gateways
└── Security VPC (10.4.0.0/16)
    ├── AWS Network Firewall
    └── VPC Flow Log Analysis

DNS Resolution: Split Horizon

The most critical hybrid networking challenge is DNS. Route 53 Resolver endpoints enable bidirectional DNS resolution:

# Inbound Endpoint - resolve AWS private zones from on-premises
aws route53resolver create-resolver-endpoint \
  --creator-request-id inbound-1 \
  --security-group-ids sg-xxx \
  --direction INBOUND \
  --ip-addresses SubnetId=subnet-xxx,Ip=10.3.0.10 SubnetId=subnet-yyy,Ip=10.3.1.10

# Outbound Endpoint - resolve on-premises domains from AWS
aws route53resolver create-resolver-endpoint \
  --creator-request-id outbound-1 \
  --security-group-ids sg-xxx \
  --direction OUTBOUND \
  --ip-addresses SubnetId=subnet-xxx SubnetId=subnet-yyy

# Forward on-premises domain queries
aws route53resolver create-resolver-rule \
  --creator-request-id fwd-corp \
  --domain-name corp.example.com \
  --rule-type FORWARD \
  --resolver-endpoint-id rslvr-out-xxx \
  --target-ips Ip=172.16.0.53 Ip=172.16.1.53

Network Segmentation

Use Transit Gateway route tables for network segmentation:

• Production route table — Can reach shared services and on-premises, not dev/staging
• Development route table — Can reach shared services only, isolated from production and on-premises
• Shared services route table — Can reach all VPCs (provides common services)

Security Architecture

1. Perimeter — AWS Network Firewall for traffic inspection between on-premises and AWS
2. Segmentation — Transit Gateway route tables isolate environments
3. Microsegmentation — Security Groups and Network Policies within VPCs
4. Encryption — All cross-network traffic encrypted (IPsec VPN, TLS for application traffic)
5. Monitoring — VPC Flow Logs and Traffic Mirroring for threat detection

Identity Integration

• AWS SSO + Active Directory — Federated access to AWS console and CLI
• AD Connector — Proxy AWS service authentication to on-premises AD
• SAML/OIDC — Application-level identity federation

Operational Considerations

• IP address management — Use a centralized IPAM tool to prevent CIDR conflicts
• Change management — Infrastructure as Code (Terraform) for all network resources
• Monitoring — Unified dashboard showing connectivity status across all paths
• DR planning — Test failover between Direct Connect and VPN quarterly

Eazy SaaS Tip: We deploy hybrid cloud networks using Terraform with a modular design: VPC module, Transit Gateway module, DNS module, and connectivity module. This makes the architecture reproducible, auditable, and easy to extend as your cloud footprint grows.