Forum Discussion
Best Practices for Designing a Hub-and-Spoke Architecture in Azure
A Hub-and-Spoke architecture is a widely used networking topology in Azure that helps organizations centralize network management, enhance security, and optimize connectivity. However, designing an efficient Hub-and-Spoke model requires careful planning regarding network security, scalability, and cost optimization.
What are the core components of a Hub-and-Spoke architecture in Azure?
What factors should be considered when designing the hub (e.g., Virtual Network Gateway, Firewall, Security controls)?
What are the key challenges you've encountered while implementing a Hub-and-Spoke architecture in Azure, and how have you addressed them?
Components
Hub
- Subscriptions – Typically, one for the hub and multiple for the spokes.
- Hub vNet
- Virtual Networks (vNets)
- Subnets
- Network Security Groups (NSGs) per subnet
- User Defined Routes (UDRs) per subnet
- Peering with spoke networks
- Virtual Network Gateway (VPN or ExpressRoute)
- Network Virtual Appliances (NVAs) such as Azure Firewall or third-party solutions
- Azure Bastion or VM jump hosts
- Application Gateway with Web Application Firewall (WAF)
- If VMs are used, core infrastructure resources are typically placed in the hub rather than relying on on-premises traffic, including:
- Domain controllers (DCs) and DNS
- Upstream update servers for third-party endpoint protection or other on-premises core infra dependencies
Spoke
- Spoke vNet
- Virtual Networks (vNets)
- Subnets
- Network Security Groups (NSGs) per subnet
- User Defined Routes (UDRs) per subnet
- Peering with the hub
- Requirements for private links and service endpoints
Key Challenges Encountered
Complex Routing with network segmentation- Segmentation & NVAs – When strict segmentation is required, all traffic between subnets must pass through an NVA, even within the same vNet.
- On-Premises Connectivity – Ensuring seamless traffic flow to on-premises networks via BGP, making all known network ranges accessible.
- Internet Traffic Management – Deciding whether Azure should handle inbound/outbound internet traffic or route it through on-premises.
ExpressRoute Deployment
If ExpressRoute is required, the process of ordering, physical installation by the ISP, and configuration can be time-consuming.IP Addressing Strategy
- Carefully plan the IP addressing scheme based on expected workloads:
- Some PaaS services with service endpoints cannot share subnets with other resources.
- AKS requires a large subnet range for scalability, which must be accounted for upfront.
Role-Based Access Control (RBAC) & Resource Management
- Clearly define who will manage what early on to:
- Properly plan resource placement
- Ensure RBAC roles are set up efficiently
Detection and monitoring
- Ensure that log collection is set up, but be mindful that if not managed efficiently, it can become a costly component. Implement proper log retention policies and optimization to avoid unnecessary costs.
I think all the items that petevern are great! To add on a few things, the detection and monitoring section which are typically part of Governance and Security I would add a proper naming policy for resources in Azure along with a proper tagging strategy. Also Azure Policy to help with governance and security. Let's not forget a proper backup strategy as well as a disaster recovery strategy for your Azure environment. Along with all this you should determine and document deployment process, whether clickopsing throught the portal or utilizing a proper DevOps methodology process and procedures should be created to assist with not only deploying your Azure environment but also allowing you to scale it as needs change and grow.
