Azure Load Balancer - MSDN Documentation

Overview of Azure Load Balancer

Azure Load Balancer is a high-performance, highly available load balancer that you can use to distribute incoming traffic across a pool of backend resources. This can include virtual machines, virtual machine scale sets, and even services hosted outside of Azure.

It operates at Layer 4 (TCP/UDP) of the OSI model, providing direct access to your applications and services. Azure Load Balancer is a fully managed service, meaning Microsoft handles the underlying infrastructure, ensuring high availability and scalability without manual intervention.

Key Benefits

High Availability: Ensures your application remains accessible even if one or more backend instances fail.
Scalability: Distributes traffic to handle increased demand, allowing you to scale your application horizontally.
Performance: Offers low latency and high throughput for your network traffic.
Cost-Effective: A managed service that eliminates the need for dedicated hardware.
Security: Integrates with Azure Network Security Groups (NSGs) for fine-grained access control.

How it Works

Azure Load Balancer functions by receiving incoming network traffic and then distributing it to healthy instances in a backend pool. This distribution is based on configured load-balancing rules and health probes. If a backend instance is unresponsive, the load balancer will automatically stop sending traffic to it until it becomes healthy again.

Did you know? Azure Load Balancer supports both public and internal (private) IP addresses, allowing you to load balance both internet-facing and internal-only applications.

Common Use Cases

Distributing traffic to web servers or application servers.
Ensuring high availability for databases or other critical services.
Providing a single point of access for a scalable application.
Load balancing traffic across multiple availability zones for disaster recovery.

Getting Started

To start using Azure Load Balancer, you'll typically create a load balancer resource in the Azure portal or via the Azure CLI. You'll then define:

Frontend IP configuration: The public or private IP address that clients connect to.
Backend pools: The set of resources (e.g., VMs) that will receive the traffic.
Health probes: How the load balancer checks the health of backend instances.
Load-balancing rules: How traffic is directed to the backend pool.

For a more detailed guide, please refer to the Configuration Guide section.

                    
# Example CLI command to create a basic load balancer (simplified)
az network lb create \
    --name myLoadBalancer \
    --resource-group myResourceGroup \
    --frontend-ip-name myFrontend \
    --sku Standard
                    
                

This documentation provides comprehensive details, concepts, configuration instructions, and best practices for effectively using Azure Load Balancer to enhance the availability and performance of your applications.