Azure Virtual Network (VNet) is the fundamental building block for your private cloud in Azure. VNet enables you to securely connect Azure resources to each other, to the internet, and to your on-premises networks. Think of it as your own network in the cloud, with the benefits of Azure's scalability, availability, and security.
What is Azure Virtual Network?
An Azure Virtual Network is a logical representation of your network in the cloud. It provides:
- Isolation and Segmentation: VNet allows you to create isolated private IP address spaces for your Azure resources. You can segment your network into subnets, enabling granular control over traffic flow and security policies.
- Connectivity: It enables seamless connectivity between Azure resources (like Virtual Machines, App Services, etc.) within the same VNet, and also allows you to connect to other Azure VNets, your on-premises networks via VPN or Azure ExpressRoute, and the internet.
- Security: VNet is the foundation for applying Azure's extensive security services, such as Network Security Groups (NSGs), Azure Firewall, and private endpoints, to protect your resources.
- Scalability and High Availability: VNet integrates with Azure's global infrastructure, ensuring your network can scale with your applications and remain highly available.
Key Components of Azure Virtual Network
Understanding the core components will help you design and manage your virtual network effectively:
Subnets
A subnet is a range of IP addresses within your virtual network. You can divide your VNet into multiple subnets, which can help you organize and secure your resources. For example, you might create separate subnets for your web servers, application servers, and database servers.
Best Practice
Allocate IP address spaces for subnets carefully to allow for future growth and to accommodate services like Azure Load Balancer or VPN Gateway deployments that require dedicated subnets.
IP Addressing
Azure VNet supports both private IP addresses (RFC 1918) and public IP addresses. Resources within a VNet communicate using private IP addresses. You can optionally assign public IP addresses to resources to make them accessible from the internet.
Network Security Groups (NSGs)
NSGs are stateful packet filtering firewalls that you can associate with network interfaces (NICs) or subnets. They allow you to control inbound and outbound traffic to and from Azure resources based on security rules.
Route Tables
Route tables allow you to define custom routes for network traffic. This is useful for scenarios like forcing all traffic through a network virtual appliance (NVA) for advanced inspection or routing traffic to specific destinations.
Gateways
Azure provides several types of gateways to extend your network:
- VPN Gateway: Connects your on-premises networks to Azure VNets over an encrypted connection (IPsec tunnel).
- ExpressRoute Gateway: Provides a high-bandwidth, low-latency connection between your on-premises network and Azure via a private connection from a connectivity provider.
- Virtual Network Gateway: A general term encompassing both VPN and ExpressRoute gateways.
Common Scenarios
Azure Virtual Network is essential for a wide range of cloud scenarios:
Connecting Azure Resources
Easily create private networks for your VMs, containers, and PaaS services, allowing them to communicate securely.
Hybrid Cloud Connectivity
Seamlessly extend your on-premises datacenter to Azure using VPN Gateway or ExpressRoute for a hybrid cloud solution.
Securing Network Traffic
Implement robust security policies using NSGs, Azure Firewall, and other network security services to protect your cloud deployments.
Example: Simple Web App Deployment
A typical setup might involve a VNet with two subnets: one for the public-facing web servers (accessible via a public IP and load balancer) and another for the backend database servers, which are only accessible from the application subnet.
What's Next?
Now that you have a foundational understanding of Azure Virtual Network, you can explore more advanced topics such as:
- VNet Peering for connecting VNets
- Network Security Groups for traffic filtering
- VPN Gateway for hybrid connectivity
- Azure Firewall for centralized network security
Dive deeper into the Azure documentation to design, deploy, and manage your robust and secure virtual networks.