What is Azure Load Balancer and How to implement it?
Let's start with the basics of Azure load balancer
It is a load-balancing service provided by Microsoft. The Load balancer works on layer 4 of the OSI model. It is used to route the traffic to the backed VMs or resources based on the rules defined. It can route traffic from the Internet or can be internal.
The public load balancer will need a public IP assigned where the users will connect. Instead of connecting directly to the VMs or resources, the user will connect to the Load balancer public IP or the DNS name.
🌍 Internet
│
▼
☁️ Public IP
│
▼
🔄 Azure Load Balancer
│
┌───┴───┐
🖥 🖥 (Backend Servers)
An internal load balancer can provide connectivity to the services from the on-prem network.
Load Balancer SKUs
Azure LB offers 2 SKUs – Basic and Standard.
Basic SKU – MS is retiring this SKU in September 2025. It is free to use. If you are using a basic Load balancer then now is the time to upgrade to Standard.
Standard SKU – This is a paid SKU and will be the only option after September 2025. Pricing details can be found here - Pricing—Load Balancer | Microsoft Azure
Implementation
Pre-requisites
1. Public IP (if service is published externally)
2. Backend Pool – It can VMs, Containerised apps, Webapps etc.
3. Health Probes - monitor the status of the backend resources.
4. Routing rules – determine how traffic is routed
Implementing Public Azure Load Balancer for VMs
1. Create a public IP Address
a. Click Create a Resource
b. Search for Public IP address. (remember to remove any Public IPs assigned to the VMs)
c. Create a Basic or Standard IP SKU. I would recommend Standard IP for production environments.
d. Create the Static IP for production environments
2. Create a 2nd resource – Azure Load Balancer
a. Click Create a Resource
b. Search for Microsoft Load Balancer
c. Create the resource and follow the on-screen wizard
i. Resource Group – Same as the Public IP
ii. SKU – Choose Standard for production
iii. Type – Public
d. Add the Frontend IP address on the next screen. This is the public IP you have created above.
e. Add the Backend pool and Rules now or later.
f. To configure the rest of the settings later, click Review & Create the resource.
3. Configure the Load Balancer
a. Go to the load balancer resource (created above).
b. Click on the backend pool
c. Click on Add and add the Name of the pool, VNet, and Associate to Virtual Machines.
d. Scroll down choose IPv4 and Add the virtual machines. Then click on Add at the bottom of the page to add the pool.
P.S. VMs need to be in Availability Sets for Basic LB SKU.
e. Create a Health Probe > Click Add
f. Add the parameters accordingly and click Add
i. Protocol – TCP or HTTP
ii. Port – as per the Application port, for example 80
iii. Interval – After how many secs the probe is sent to check the VMs or application availability
g. Add Load Balancing Rule
h. Click Add to create a rule with the relevant information
And you have configured the Basic load balancer to load balance the VMs.
Azure Load Balancer Implementation