🔥 Hybrid Networking 101: Linking On-Prem to Azure 🔥

Many organizations seek to extend their networks to include subnets and virtual machines (VMs) hosted on Azure. The goal is to enable seamless connectivity between on-premises computers in a data center and Azure-based virtual machines.

🔹 Common Use Cases for Hybrid Networking:

# Application Connectivity: You have an Azure-hosted application that needs access to your on-premises database servers.

# Branch Office Integration: Your business operates retail stores worldwide and requires a single centralized service to connect all locations.

# Remote Access: You need secure remote access to your Azure VMs and applications.

# Data Synchronization: You want to connect on-premises servers with Azure servers for real-time synchronization and data transfer.

# To address these scenarios, Azure provides four key networking solutions: 

✅ Point-to-Site VPN (P2S) ✅ Site-to-Site VPN (S2S) ✅ ExpressRoute ✅ Azure Virtual WAN

One essential component that supports all these solutions is Azure VPN Gateway. Let's explore its capabilities! 🔍

🚀 Azure VPN Gateway 🚀 

# Secure Connectivity Between Azure & On-Premises by encrypting data while transferring it between Azure VNets and on-premises servers over the internet.

# Multiple connections can be established using a single VPN Gateway, sharing available bandwidth across all VPN tunnels.

# The gateway consists of Azure-managed VMs, automatically deployed and configured in a GatewaySubnet with a CIDR size of /27. 

# There are two types of gateways: 

🔹 VPN Gateway (for encrypted connections)           🔹 ExpressRoute Gateway (for dedicated high-speed connectivity)

💡 Gateway SKUs define performance characteristics, including:

# Supported tunnel types (S2S, P2S, VNet-to-VNet)

# Maximum aggregate throughput

# BGP (Border Gateway Protocol) support

# Scalability options (resize within the same generation and family via Azure Portal or PowerShell)

🚀 VPN Gateway Types:

# Route-Based VPN: Supports S2S & P2S connections—widely used in hybrid networking.

# Policy-Based VPN: Limited to Basic SKUs and allows only S2S connections (not ideal for Remote Access).

🔹 Local Network Gateway: Represents your on-premises router or firewall, enabling Azure to recognize your internal network's public IP and subnets for connectivity via IPSec IKEv1/2. 

🔹 Azure Availability Zones can be leveraged for high availability and service continuity.

📌 Point-to-Site VPN (P2S) 📌 

🔹 Secure access for individual users connecting remotely to Azure VNets. 
🔹 Supported protocols:

OpenVPN® (SSL/TLS-based; compatible with Windows, Mac, Linux, Android, iOS)
SSTP (TLS-based; Windows-only)
IKEv2 (IPsec VPN solution; Mac-supported)

🔹 Authentication Methods: 
(1) Certificate Authentication (requires client certificates issued from a trusted root certificate).
(2) Azure AD Authentication (available for OpenVPN clients).
(3) Active Directory Domain Server Authentication (via RADIUS server integration).

📌 Site-to-Site VPN (S2S) 📌

🔹 Enables on-premises data centers to connect with Azure VNets via IPSec IKEv1/2. 
🔹 Supports VNet-to-VNet connections over Microsoft's backbone network. 
🔹 Compatible with hardware devices from vendors such as Cisco, Fortinet, Barracuda, Check Point. 
🔹 Supports software VPN devices, including Microsoft RRAS and Linux Openswan. 
🔹 Enables dynamic routing via BGP to propagate network changes automatically.

📌 ExpressRoute 📌

🔹 Dedicated high-speed connectivity to Microsoft Cloud (Azure, Microsoft 365). 
🔹 Up to 100 Gbps speeds with low latency, ideal for business-critical applications. 
🔹 Layer 3 connectivity, using BGP for seamless route exchange between on-premises and Azure networks.

📌 Azure Virtual WAN 📌 

🔹 A scalable networking service integrating VPN, ExpressRoute, and SD-WAN solutions. 
🔹 Provides branch connectivity using site-to-site VPN or private ExpressRoute connections. 
🔹 Supports remote user VPN (P2S) for secure external access. 
🔹 Follows hub-and-spoke architecture, ensuring full mesh connectivity across Azure regions.

If you found this valuable, consider sharing so more professionals can benefit. Let's keep the conversation growing! 🚀