Azure Gateways Architecture, Types, SKUs, Configuration Practices, Real World Usage, and Cost

Azure Gateways Architecture, Types, SKUs, Configuration Practices, Real World Usage, and Cost

In Microsoft Azure Networking Architecture, Gateways act as Controlled Entry and Exit Points for Traffic moving between Different Networks. These Networks can include Internet Clients, Azure Virtual Networks, on Premises Datacenters, Branch Offices, and Global Application Endpoints. Gateways enable organizations to Securely Route Traffic, Inspect Requests, Accelerate Application Delivery, and provide connectivity between Hybrid Environments.

Azure includes several different Gateway Services because Modern Cloud Environments require Multiple Types of Connectivity. Some Gateways provide Secure Hybrid Connectivity, others focus on Web Traffic Routing, some enable Outbound Internet Access for Private Workloads, and others Provide Global Traffic Acceleration.

Understanding the different Azure Gateway Types, their available SKUs, Configuration approaches, Operational Practices, and Cost Considerations is critical when Designing Enterprise Networking Architectures.

1.     Azure Gateway Types

Microsoft Azure provides Several Gateway Technologies that Address Different Networking Scenarios. Each Gateway Type is Optimized for a Specific Purpose within Cloud Networking Architecture.

Azure VPN Gateway

Azure VPN Gateway provides Encrypted Communication between Azure Virtual Networks and External Networks. These External Networks may include Corporate Datacenters, Branch Offices, or Remote Users connecting through Client VPN Software.

VPN Gateway uses IPsec and IKE Encryption Protocols to establish Secure Tunnels across the Public Internet. The Service is typically deployed in a dedicated Subnet Inside an Azure Virtual Network called the GatewaySubnet.

Three Primary Connection Models are Supported:

Site to Site connections allow an On-Premises Network to connect to Azure through a Secure IPsec Tunnel.

Point to Site connections allow Individual Remote Users to Connect Securely to Azure using VPN client software.

VNet to VNet connections allow separate Azure Virtual Networks to communicate Securely using Encrypted Tunnels.

VPN Gateway is widely used when Organizations begin adopting Hybrid Cloud Infrastructure and need Secure Communication between existing Datacenters and Azure Workloads.

Azure ExpressRoute Gateway

ExpressRoute Gateway provides Private Connectivity between On-Premises Infrastructure and Azure. Unlike VPN Gateway, ExpressRoute does not rely on the Public Internet. Instead, it uses a Private Circuit delivered by a connectivity provider through an MPLS Network.

ExpressRoute Provides Predictable Latency, Higher Bandwidth Capacity, and Improved Reliability. This makes it Ideal for Mission Critical Enterprise Workloads that require Consistent Performance.

Organizations frequently use ExpressRoute when Migrating Large Enterprise Applications such as SAP, SQL Server Clusters, or High-Volume Data Platforms to Azure.

Azure Application Gateway

Application Gateway is a Layer 7 Load Balancer designed specifically for Web Applications. Instead of simply Forwarding Packets, Application Gateway understands HTTP and HTTPS Traffic and can Route Requests based on Application-Level Information such as URL Paths, Cookies, or Host Headers.

Application Gateway performs several Functions Simultaneously. It distributes Web Traffic across Multiple Backend Servers, performs SSL Termination to reduce Encryption Overhead on Backend Systems, and can enforce Web Application Firewall Rules to Protect Against Common Web Attacks.

Because Application Gateway operates at the Application Layer, it is commonly deployed for Web Application Hosting Environments that require Intelligent Routing and Security Inspection.

Azure Front Door

Azure Front Door is a Globally Distributed Application Gateway that operates at Microsoft Edge Locations around the World. Instead of being deployed inside a Virtual Network, Front Door runs at the Edge of Microsoft’s Global Network and acts as the First Point of Entry for User Requests.

Front Door provides Global Load Balancing, Automatic Failover Across Regions, Edge Caching, and Application Level Security Controls. Because it operates Globally, it is capable of Routing Users to the closest Azure Region Based on Latency and Availability.

Front Door is commonly used by Global Web Applications, SaaS Platforms, and Services that need to provide Consistent Performance to Users Located in different Geographic Regions.

Azure NAT Gateway

NAT Gateway provides Outbound Internet Connectivity for Resources that are deployed in Private Subnets inside Azure Virtual Networks. Without NAT Gateway, Many Resources would require Individual Public IP Addresses to Access the Internet.

NAT Gateway Centralizes Outbound Connectivity and allows Multiple Virtual Machines or Services to Share a Controlled Set of Public IP Addresses. This Design improves Security because Workloads remain Private while still allowing them to Download Updates, access External APIs, or communicate with Internet Services.

NAT Gateway is often used in Container Platforms, Microservice Environments, and Application Servers that require Outbound Internet Communication but should not be Exposed Publicly.

Azure Virtual WAN Gateway

Azure Virtual WAN Gateway is used in Large Scale Global Networking Environments. Virtual WAN provides an Integrated Networking Hub that connects Branch Offices, Remote Users, Azure Workloads, and Private Connectivity Circuits.

Virtual WAN Gateways Simplify the Deployment of Large Enterprise Networks by automating Routing Configuration and Integrating Multiple Connectivity Services into a Centralized Architecture.

Organizations with Large Global Networks frequently use Virtual WAN to Manage thousands of Branch Locations and Distributed Workloads.

2.     Azure Gateway SKUs

Each Azure Gateway Service includes Multiple SKUs that Provide Different Levels of Performance, Scalability, and Features.

VPN Gateway SKUs

VPN Gateway SKUs determine the Maximum Throughput, Number of Tunnels, and Scalability of the Gateway Deployment. Basic SKU Provides Limited throughput and is typically used only in Test Environments. VpnGw1 Supports Moderate throughput and is appropriate for Small Hybrid Deployments. VpnGw2 and VpnGw3 provide Higher Bandwidth and are designed for Production Environments with Larger Traffic Volumes.

Higher end SKUs such as VpnGw4 and VpnGw5 provide Multi Gigabit throughput and support a Larger Number of concurrent tunnels. These SKUs are typically used in Enterprise Networks with many Branch Offices or Large Data Transfers between On-Premises Infrastructure and Azure.

Availability Zone enabled Versions of these SKUs provide improved Resiliency by distributing Gateway Instances across Multiple Datacenter Zones.

Application Gateway SKUs

Application Gateway is offered primarily in Two Modern SKUs known as Standard v2 and WAF v2. Standard v2 provides Application Layer Load Balancing with Autoscaling and Zone Redundancy. WAF v2 includes all Standard Capabilities Plus Integrated Web Application Firewall Protection.

The v2 Generation introduced Automatic Scaling, Improved Performance, and Better Integration with Azure Networking Services.

NAT Gateway SKUs

Azure NAT Gateway is available in Standard and Standard v2 SKUs. Standard v2 provides improved resiliency, Zone Redundancy, and enhanced throughput capabilities.

A NAT Gateway instance can Scale to support Extremely Large Numbers of Outbound Connections, making it suitable for High Scale Container or Microservice Environments.

Front Door SKUs

Azure Front Door provides Two Primary Tiers known as Standard and Premium. Standard supports Global Load Balancing and Basic Web Acceleration features. Premium includes Advanced Security capabilities such as Private Link integration and enhanced WAF Functionality.

ExpressRoute Gateway SKUs

ExpressRoute Gateway SKUs determine the Maximum Bandwidth Available for Private Connectivity. Standard SKUs Support Moderate Bandwidth requirements, while High Performance and Ultra Performance SKUs provide Multi Gigabit Connectivity suitable for Large Enterprise Workloads.

3.     Azure Gateway Configuration and Best Practices

Proper Gateway Configuration ensures High Availability, Performance, and Security.

VPN Gateway Configuration Practices

When deploying VPN Gateway, the Gateway Must be placed inside a dedicated GatewaySubnet within the Virtual Network. This Subnet is reserved exclusively for Gateway Services and should not contain other Resources.

For Enterprise Deployments, Active Active Gateway Configurations provide Improved Availability because Multiple Gateway instances Handle Traffic Simultaneously. Dynamic Routing using BGP should be enabled whenever possible because it simplifies Route Management between Azure and on Premises Networks.

Monitoring VPN Gateway Health and Tunnel Stability using Azure Monitoring Tools is also essential for maintaining Hybrid Connectivity.

Application Gateway Configuration Practices

Application Gateway should always be deployed in a dedicated Subnet to avoid interference with other Network Services. Backend Pools should include Multiple Application Servers to provide Load Balancing and Resiliency.

Autoscaling should be enabled to allow the Gateway to Automatically adjust Capacity based on Incoming Traffic Volume. When security is a priority, the WAF v2 SKU should be used so that Web Application Firewall Rules can protect Applications from common Attack Patterns.

Detailed logging and Performance Monitoring should be enabled to analyze request patterns and troubleshoot potential Application Issues.

NAT Gateway Configuration Practices

NAT Gateway should be attached to Subnets that require Outbound Internet Connectivity. Multiple Public IP Addresses can be assigned to increase the Available Number of Outbound Connections.

Using NAT Gateway alongside Azure Firewall provides both outbound connectivity and outbound traffic inspection. This combination is commonly used in Enterprise Security Architectures.

Front Door Configuration Practices

Front Door should be used as the Global Entry Point for Applications that Operate Across Multiple Azure Regions. Backend Services should be configured with Health Probes so that Front Door can Automatically Detect Failures and Redirect Traffic to Healthy Regions.

Caching should be enabled for Static Content to improve Performance and Reduce Backend Load. Web Application Firewall Policies should also be configured to protect Internet Facing Applications.

4.     Real World Azure Gateway Usage Examples

Hybrid Enterprise Infrastructure

A large enterprise may deploy VPN Gateway or ExpressRoute Gateway to connect its Corporate Datacenter to Azure. Internal Applications Hosted in Azure can communicate securely with Systems running inside the company Datacenter. Employees inside the Corporate Network can access Azure Hosted Applications without exposing them Publicly to the Internet.

Secure Web Application Hosting

A typical enterprise Web Architecture may include Azure Front Door as the Global Entry Point, followed by Application Gateway within each Azure region. Front Door Routes Users to the closest Region, while Application Gateway distributes requests to Backend Web Servers and applies Web Application Firewall Protections.

Secure Outbound Internet Access

Organizations often deploy NAT Gateway for Workloads that require Outbound Internet Connectivity but should not have Inbound Public exposure. Virtual Machines and Application Services inside Private Subnets can Download Updates or communicate with External APIs while remaining Protected from Inbound Traffic.

Global SaaS Platform

Software as Service providers commonly deploy Front Door to deliver Applications to Users Worldwide. The platform may run in multiple Azure Regions, and Front Door Directs Users to the Closest Available Region while providing Global Failover if one Region becomes unavailable.

5.     Azure Gateway Cost Considerations

Azure Gateway Pricing varies depending on the Gateway Service used, the selected SKU, and the amount of Traffic Processed.

VPN Gateway Cost Factors

VPN Gateway Costs Primarily depend on the Gateway SKU and the duration the Gateway Runs. Higher SKUs Cost more but provide Greater Bandwidth and connection limits. Data Transfer Leaving Azure may also incur Additional Charges.

Application Gateway Cost Factors

Application Gateway pricing includes instance hours and capacity consumption. When Autoscaling is enabled, Costs Increase during High Traffic periods because Additional Instances are provisioned automatically. WAF enabled deployments also include additional security processing costs.

NAT Gateway Cost Factors

NAT Gateway Pricing is based on Hourly Gateway Operation and the Volume of Outbound Data processed. Additional Costs may apply for Public IP Addresses assigned to the Gateway.

Front Door Cost Factors

Front Door Pricing depends on the Number of Incoming Requests, the Volume of Data Transferred, and optional Security Features such as Web Application Firewall Policies.

6.     Azure Gateway Architecture Strategy

Enterprise Cloud Architectures frequently combine Multiple Gateway Services to create Layered Security and Connectivity Designs.

A typical Architecture may use Front Door as the Global Entry Point, Application Gateway to protect Regional Web Applications, VPN Gateway or ExpressRoute for Hybrid Connectivity with On Premises Infrastructure, and NAT Gateway to control Outbound Internet Access for Private Workloads.

This layered Gateway Architecture provides Global Traffic Distribution, secure Hybrid Connectivity, Application Layer Protection, and Controlled Outbound Connectivity.

Conclusion

Azure Gateways form the Foundation of Secure and Scalable Cloud Networking. Each Gateway Service Addresses a different aspect of connectivity, Traffic Routing, or Application Delivery.

VPN Gateway enables Secure Hybrid Networking over the Internet. ExpressRoute Gateway Provides Private Enterprise Connectivity. Application Gateway delivers Application Level Routing and Security. Front Door Accelerates Global Application delivery. NAT Gateway Enables Secure Outbound Internet Connectivity for Private Workloads.

By selecting the correct Gateway Types, SKUs, and deployment Architecture, Organizations can Build Resilient, Scalable, and Secure Networking Environments that Support Modern Cloud Applications and Hybrid Infrastructure.