In this article, we will learn how to create a Virtual Network VNet using Azure Management Portal.

Introduction

As a Software engineer, within our organization, while working on a workstation, we need to be connected to multiple resources like Web Servers, Database servers, Printers, Active Directory servers, Centralized File Servers etc. In order to be connected to all those multiple resources, our work stations need to be connected to Networks (ex: LAN, WAN). In the similar way, our production environment, each Virtual Machine need to connect to multiple resources (like IP Address, other Virtual Machine, etc.). In order to connect to any other resource, the Virtual Machine should be first connected to a Virtual Network. Like how we work in our Local Area Network (LAN), we can also create network on Cloud called as Virtual Network (VNet). Think about VNet as a network of resources that could communicate each other. I hope you have now got a brief idea on why and what is a Virtual Network.

In this article, we will learn how to create a VNet using Azure Management Portal. We will also learn about the basic attributes of a VNet that are required while creating the same.

Create a Virtual Network

After logging into the Azure Management Portal, as shown in the below screen capture, select the Virtual Network to navigate to the blade to create a new VNet.

In the next step, you will need to choose the deployment model.

As shown in the above screen capture, we have chosen “Resource Manager” as the deployment model where everything (ex: VNet, Subnet, NSG, NIC, IPAddress) is treated as a separate component or entity.

After clicking on the “Create” button, you will be taken the following blade where you can provide all the VNet related attributes.

Let’s try to understand each of the attributes in detail.

• Address Space – Range of the IPAddress that could be assigned to the devices (it’s actually NIC’s to which an IPAddress could be assigned) within the network.
• CIDR Notation (Classless Inter Domain Routing) – The notation using which the IP Address is assigned.
  • In the above example, the address space (which is comprised of 32 bits) of our network is 10.1.0.0/24. In this notation, “/24” denotes that the first 24 bits are used for Network address and the rest of 8 bits are for IP Address which also means that we can have 255 addresses within our network. Read more about CIDR and other basics of Networks here at Understanding IP Addresses, Subnets, and CIDR Notation for Networking (https://www.digitalocean.com/community/tutorials/understanding-ip-addresses-subnets-and-cidr-notation-for-networking )
• Subnet – It’s nothing but a segmentation of a Virtual Network. You can have multiple Subnets in a given VNet. Below are examples on the considerations while creating your Cloud production environments.
  • You could create a Subnet (10.1.0.0/25) for hosting all your Web Servers
  • You could create a Subnet (10.2.0.0/25) for hosting all your Database servers

By default, a VNet must have a subnet to contain any devices within the VNet.

Once you provide all the mandatory fields, click on “Create” button to create the Virtual Network as shown below.

Other important points to remember

• The smallest subnet that Azure support is a /29 and the largest is a /8 (using CIDR notation).
• Azure reserves some IP addresses within each subnet. The first and last IP addresses of the subnets are reserved for protocol conformance, along with 3 more addresses (2^nd, 3^rd and 4^th) used for Azure services. As shown below, the Azure management portal shows that we can create 128 addresses in a given subnet based on the address range.
• 

However, when I navigate to the Subnet’s blade of the “demo-web-snet” I can see that we can just create 123 addresses.

Summary: In this article, we have learned what is VNet and Subnet and also few of the basics of Networking like CIDR notation.

Hope you enjoyed the article. Your feedback is appreciated.