《POINT》
・① To let virtual machines communicate with each other, you need to create a “virtual network.”
・② Different virtual networks cannot communicate by default.
・③ A virtual network must have at least one subnet.
What Computers Need to Communicate
At school, people need hallways and classrooms to talk with friends, right?
Computers also need a “path” to send and receive data with each other.
That path is called a network.
For example, companies often connect many computers together instead of using just one.
By doing this, computers can send and receive data with one another.
Computers Have a “Cable Port”
Normal computers have a part called a NIC (Network Interface Card).
This is the part where you plug in a LAN cable.
It is similar to connecting to a home Wi-Fi router.
Computers also use something called an IP address.
What Is an IP Address?
It is like a “home address” on a network.
For example:
Mr. Tanaka’s house
Ms. Suzuki’s house
Letters can be delivered because each house has an address.
In the same way, computers can send data because they each have an IP address.
In the Cloud, We Use “Virtual” Networks
In cloud services like Azure, computers exist somewhere on the internet.
Because of this, we cannot plug in real LAN cables or place real switches and routers there.
So instead, we use something called a:
“Virtual Network”
This is not a physical network, but it works like a real one.
In Azure, you can:
create a virtual network
connect virtual machines to it
assign IP addresses
By doing this, virtual machines can communicate with each other.
What Is a Virtual Network (VNet)?
A virtual network is the most basic network component in Azure.
You can imagine it as:
“A group connected by the same LAN cable”
Virtual machines inside the same virtual network can communicate freely.
You Can Create Multiple Virtual Networks
Azure allows you to create many virtual networks.
For example:
Production VNet (the real environment people use)
Test VNet (for testing)
Development VNet (for building systems)
By separating them:
mistakes in testing will not affect production
development work can be done safely
Different Virtual Networks Cannot Communicate
This is important.
Machines inside the same VNet can communicate, but:
Production VNet
Test VNet
cannot communicate with each other by default.
You can think of them as:
“Separate islands”
What Is a Subnet?
A virtual network can be divided into smaller sections.
These smaller sections are called:
“Subnets”
Let’s Imagine It
Suppose the entire school is the “virtual network.”
Inside the school, there are:
Class 1-A
Class 1-B
Class 1-C
Each classroom is like a “subnet.”
Virtual Machines Connect to Subnets
Actually, virtual machines do not connect directly to the VNet itself.
They connect to:
“A subnet inside the VNet”
Because of this, every virtual network must have at least one subnet.
You Can Create Multiple Subnets
Inside one VNet, you can create:
Subnet A
Subnet B
Subnet C
and more.
Inside the same VNet:
a virtual machine in Subnet A
a virtual machine in Subnet B
can still communicate with each other.