Hybrid Cloud Networking

Purpose

When to Use

• Connect on-premises to cloud
• Extend datacenter to cloud
• Implement hybrid active-active setups
• Meet compliance requirements
• Migrate to cloud gradually

Connection Options

AWS Connectivity

1. Site-to-Site VPN

• IPSec VPN over internet
• Up to 1.25 Gbps per tunnel
• Cost-effective for moderate bandwidth
• Higher latency, internet-dependent

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resource "aws_vpn_gateway" "main" {
  vpc_id = aws_vpc.main.id
  tags = {
    Name = "main-vpn-gateway"
  }
}

resource "aws_customer_gateway" "main" {
  bgp_asn    = 65000
  ip_address = "203.0.113.1"
  type       = "ipsec.1"
}

resource "aws_vpn_connection" "main" {
  vpn_gateway_id      = aws_vpn_gateway.main.id
  customer_gateway_id = aws_customer_gateway.main.id
  type                = "ipsec.1"
  static_routes_only  = false
}

2. AWS Direct Connect

• Dedicated network connection
• 1 Gbps to 100 Gbps
• Lower latency, consistent bandwidth
• More expensive, setup time required

Azure Connectivity

1. Site-to-Site VPN

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resource "azurerm_virtual_network_gateway" "vpn" {
  name                = "vpn-gateway"
  location            = azurerm_resource_group.main.location
  resource_group_name = azurerm_resource_group.main.name

  type     = "Vpn"
  vpn_type = "RouteBased"
  sku      = "VpnGw1"

  ip_configuration {
    name                          = "vnetGatewayConfig"
    public_ip_address_id          = azurerm_public_ip.vpn.id
    private_ip_address_allocation = "Dynamic"
    subnet_id                     = azurerm_subnet.gateway.id
  }
}

2. Azure ExpressRoute

• Private connection via connectivity provider
• Up to 100 Gbps
• Low latency, high reliability
• Premium for global connectivity

GCP Connectivity

1. Cloud VPN

• IPSec VPN (Classic or HA VPN)
• HA VPN: 99.99% SLA
• Up to 3 Gbps per tunnel

2. Cloud Interconnect

• Dedicated (10 Gbps, 100 Gbps)
• Partner (50 Mbps to 50 Gbps)
• Lower latency than VPN

Hybrid Network Patterns

Pattern 1: Hub-and-Spoke

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On-Premises Datacenter
         ↓
    VPN/Direct Connect
         ↓
    Transit Gateway (AWS) / vWAN (Azure)
         ↓
    ├─ Production VPC/VNet
    ├─ Staging VPC/VNet
    └─ Development VPC/VNet
`### Pattern 2: Multi-Region Hybrid`
On-Premises
    ├─ Direct Connect → us-east-1
    └─ Direct Connect → us-west-2
            ↓
        Cross-Region Peering
`### Pattern 3: Multi-Cloud Hybrid`
On-Premises Datacenter
    ├─ Direct Connect → AWS
    ├─ ExpressRoute → Azure
    └─ Interconnect → GCP

Routing Configuration

BGP Configuration

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On-Premises Router:
- AS Number: 65000
- Advertise: 10.0.0.0/8

Cloud Router:
- AS Number: 64512 (AWS), 65515 (Azure)
- Advertise: Cloud VPC/VNet CIDRs

Route Propagation

• Enable route propagation on route tables
• Use BGP for dynamic routing
• Implement route filtering
• Monitor route advertisements

Security Best Practices

1. Use private connectivity (Direct Connect/ExpressRoute)
2. Implement encryption for VPN tunnels
3. Use VPC endpoints to avoid internet routing
4. Configure network ACLs and security groups
5. Enable VPC Flow Logs for monitoring
6. Implement DDoS protection
7. Use PrivateLink/Private Endpoints
8. Monitor connections with CloudWatch/Monitor
9. Implement redundancy (dual tunnels)
10. Regular security audits

High Availability

Dual VPN Tunnels

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resource "aws_vpn_connection" "primary" {
  vpn_gateway_id      = aws_vpn_gateway.main.id
  customer_gateway_id = aws_customer_gateway.primary.id
  type                = "ipsec.1"
}

resource "aws_vpn_connection" "secondary" {
  vpn_gateway_id      = aws_vpn_gateway.main.id
  customer_gateway_id = aws_customer_gateway.secondary.id
  type                = "ipsec.1"
}

Active-Active Configuration

• Multiple connections from different locations
• BGP for automatic failover
• Equal-cost multi-path (ECMP) routing
• Monitor health of all connections

Monitoring and Troubleshooting

Key Metrics

• Tunnel status (up/down)
• Bytes in/out
• Packet loss
• Latency
• BGP session status

Troubleshooting

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# AWS VPN
aws ec2 describe-vpn-connections
aws ec2 get-vpn-connection-telemetry

# Azure VPN
az network vpn-connection show
az network vpn-connection show-device-config-script

Cost Optimization

1. Right-size connections based on traffic
2. Use VPN for low-bandwidth workloads
3. Consolidate traffic through fewer connections
4. Minimize data transfer costs
5. Use Direct Connect for high bandwidth
6. Implement caching to reduce traffic

Reference Files

• references/vpn-setup.md - VPN configuration guide
• references/direct-connect.md - Direct Connect setup

Related Skills

• multi-cloud-architecture - For architecture decisions
• terraform-module-library - For IaC implementation