Hub-spoke architecture in Azure Virtual WAN
Overview
The hub-spoke network topology is a widely used design pattern for network environments. Azure Virtual WAN simplifies the deployment and management of hub-spoke architectures at scale. In this model, a Virtual WAN hub acts as a central transit point, connecting various branch offices, remote sites, and on-premises networks through VPNs or ExpressRoute circuits. Multiple spokes, typically represented by Azure virtual networks (VNets), connect to this central hub. This design offers advantages in manageability, security, and connectivity.Azure Virtual WAN provides a managed, scalable, and highly available network infrastructure that allows you to connect and manage your Azure and on-premises resources. The hub-spoke model is a foundational concept within Virtual WAN, enabling efficient and secure network connectivity.
Key Components of a Hub-Spoke Architecture
1. Virtual WAN Hub
The Virtual WAN hub is the central transit point of the network. It's a Microsoft-managed service that aggregates connectivity from various sources. Key features include:
- Transit Routing: Enables communication between connected VNets and on-premises networks.
- Scalability: Automatically scales to meet demand.
- High Availability: Built-in redundancy for continuous operation.
- Integrated Services: Supports VPN gateways, ExpressRoute gateways, Azure Firewall, and Network Security Groups (NSGs).
2. Spoke Virtual Networks (VNets)
Spoke VNets are peered with the Virtual WAN hub. They host your cloud workloads and resources. Each spoke VNet typically represents a specific workload, department, or environment.
- Isolation: Provides network isolation for workloads within the VNet.
- Connectivity: Connects to the hub for access to other resources and on-premises locations.
- Resource Hosting: Contains virtual machines, PaaS services, and other Azure resources.
3. Connectivity Methods
Various methods can be used to connect to the Virtual WAN hub:
- Site-to-Site VPN: Connects your on-premises networks to the Virtual WAN hub.
- ExpressRoute: Provides a private, high-bandwidth connection between your on-premises environment and Azure.
- VNet Peering: Connects your spoke VNets to the Virtual WAN hub.
- User VPN: Enables remote users to connect to your Azure network.
Benefits of the Hub-Spoke Model with Virtual WAN
- Centralized Management: Simplifies network management by providing a single pane of glass for connectivity and policy enforcement.
- Improved Security: Allows for centralized security policies and inspection points (e.g., Azure Firewall) in the hub.
- Cost Efficiency: Reduces the number of complex routing configurations and hardware requirements.
- Scalability: Easily add new spokes or connections without reconfiguring the entire network.
- Reduced Latency: Optimized routing paths for inter-VNet and on-premises communication.
Example Scenario
Consider a large enterprise with multiple branch offices and several Azure VNets for different applications.
- A central Azure Virtual WAN hub is deployed in a region.
- VPN connections are established from each branch office to the hub.
- ExpressRoute is used to connect the main datacenter to the hub.
- Several VNets (e.g., for HR applications, development environments, production services) are peered with the hub.
In this setup, a user in a branch office can access resources in any of the spoke VNets, and vice-versa, all routed through the central Virtual WAN hub. The hub can also host Azure Firewall for deep packet inspection and threat protection for all traffic.
Diagram
(Imagine a diagram here illustrating the hub-spoke topology with a central hub connecting multiple spokes and on-premises sites.)
Considerations
- Region Selection: Choose a region for your hub that offers low latency to your connected resources and on-premises locations.
- Hub Size: Ensure the hub has sufficient capacity for your anticipated traffic volume.
- Security Policies: Define clear security rules and leverage Azure Firewall for centralized protection.
- Routing: Understand how routes are propagated between the hub and spokes, and how to manage them.
By implementing a hub-spoke architecture with Azure Virtual WAN, organizations can build robust, secure, and scalable network infrastructures in Azure.
Last updated: October 26, 2023