Azure Load Balancer Components

Azure Load Balancer Components

Azure Load Balancer includes some key components and these components can be configured in your subscription through Azure portal , Azure CLI , Azure powerShell , Resource Manager Template. 

Front IP Configuration 

The IP address on your Azure Load Balancer and these IP address can be either: 

• Public IP Address 
• Private IP Address 

The Nature of IP address determines the type of the load Balancer created. 

Public Load Balancer: 

• It has Public IP address as Front end IP Configuration 
• It maps the Public IP and port of incoming traffic to the private IP and port of the VM. 
• SKU Supported : Basic and Standard. 

Internal Load Balancer:

• It has a private IP address as Front End IP Configuration. 
• It distributes traffic to resources that are inside a Virtual network . Front End IP address and Virtual Network are never exposed to Internet Endpoints and hence cannot accept incoming traffic from the internet.
• SKU Supported : Basic and Standard  

Backend Pool : 

It is the Group of Virtual Machine , or instances in a virtual machine scale set that is serving incoming request. 

Load balancer automatically reconfigures when you scale instances UP and Down, Add or Remove from backend pools. Backend pools support addition of instances via Network interfaces or IP address . 

Health Probes:

A Health Probe is used to determine the status of the instances in the backend pool. This probe determines if an instance is healthy and can receive traffic or not.

When a health Probe fails to respond , load balancer stops sending new connections to unhealthy instances, but does not affect existing connections. The connection continues until Applications:

• Ends the Flow 
• Idle timeout Occurs 
• VM Shuts down. 

 Load Balancer provides different health probe types for Endpoints: TCP , HTTP, and HTTPS. Basic Load Balancer does not support HTTPS probe. 

Load balancer Rules: 

It is a rule that defines how incoming traffic is distributed to all instances within the backend pool. 

Below figure demonstrate how Load Balancer rule is used to redistribute traffic 

High Availability Ports: 

A Load Balancer rule configured with protocol - all and port - 0 is said to be HA port rule. It enables a single rule to load balance all TCP and UDP flows that arrive on all ports of an internal Standard Load balancer.