Azure Virtual Network Overview

Azure Virtual Network (VNet) is the foundational building block for your private network in Azure. It enables many types of Azure resources, such as Azure Virtual Machines (VMs), to securely communicate with each other, with the internet, and with on-premises networks. VNet is a logical representation of your network in Azure, and it provides a variety of networking capabilities to connect your resources.

What is Azure Virtual Network?

An Azure Virtual Network is a virtual representation of a traditional network that you would own in your own data center. However, it is hosted in Azure's infrastructure. A VNet is the fundamental component that enables you to create a private space in Azure. This private space allows you to:

Isolate resources: Create a private network for your Azure resources, preventing unauthorized access from external networks.
Connect to on-premises networks: Establish secure connections between your VNet and your on-premises data centers using VPN Gateway or ExpressRoute.
Communicate between Azure resources: Enable seamless communication between different Azure services and virtual machines within the same or different VNets.
Control traffic: Implement network security groups (NSGs) and Azure Firewall to control inbound and outbound traffic to your resources.
Segment networks: Divide your VNet into subnets to organize and secure your resources logically.

Key Concepts of Azure Virtual Network

IP Addressing

Every VNet and subnet is defined by a private IP address space. You can specify a private IP address range for your VNet. This address space can be broken down into smaller subnets, each with its own IP address range. Azure assigns IP addresses to resources within these subnets. You can choose from RFC 1918 private IP address spaces.

Note: Ensure that your VNet address space does not overlap with your on-premises network address space if you plan to connect them.

Subnets

Subnets are divisions of your virtual network's IP address range. Each subnet can contain Azure resources. Subnets enable you to segment your VNet into smaller, manageable network segments. You can apply network security groups (NSGs) to subnets to control traffic flow between them.

Network Security Groups (NSGs)

NSGs are virtual firewalls that you can associate with NICs (network interface cards) of VMs or subnets. They allow you to filter network traffic by defining security rules that permit or deny inbound and outbound traffic based on source/destination IP address, port, and protocol.

            # Example NSG Rule (Conceptual)
            {
                "name": "AllowHTTPS",
                "properties": {
                    "priority": 100,
                    "direction": "Inbound",
                    "access": "Allow",
                    "protocol": "*",
                    "sourceAddressPrefix": "*",
                    "sourcePortRange": "*",
                    "destinationAddressPrefix": "*",
                    "destinationPortRange": "443"
                }
            }
            

Routing

Azure automatically routes traffic between subnets within a VNet. You can also customize routing by creating user-defined routes (UDRs) to direct traffic through network appliances or to control traffic flow to specific destinations.

Service Endpoints and Private Endpoints

Service Endpoints extend your VNet's private address space and identity to Azure services over the Azure backbone, allowing resources to connect to Azure services securely. Private Endpoints provide a way to access Azure PaaS services (like Azure Storage or Azure SQL Database) from your VNet using a private IP address, rather than going over the public internet.

Benefits of Azure Virtual Network

Enhanced Security: Isolate your resources and control traffic with NSGs and Azure Firewall.
Hybrid Connectivity: Seamlessly connect your cloud and on-premises networks.
Scalability and Flexibility: Easily scale your network as your needs grow.
Global Reach: Deploy your VNets in multiple Azure regions around the world.
Cost-Effectiveness: Leverage Azure's global infrastructure and reduce the need for on-premises hardware.

Learn More: For detailed configuration steps and advanced features, refer to the official Azure Virtual Network documentation.

Azure Virtual Network is a core service for building robust, secure, and scalable cloud solutions. Understanding its components and capabilities is crucial for any Azure deployment.