Azure Load Balancing Solution - Application Gateway or Azure Load Balancer

2
votes

Note: I'm still in learning phase.

Question: For the scenario described below, in the Load Balancing Settings for the two VMs for the FrontEnd subnet should I choose Application Gateway or Azure Load Balancer?

In Azure portal, when I create the VMs for FrontEnd, the Networking tab of the wizard, gives me two choices shown below:

enter image description here

Why the confusion:

For Load Balancing Internet Traffic to VMs, this tutorial does not choose Application Gateway. But the 5th bullet of the following scenario seems to indicate I should choose Application Gateway

Scenario

This tutorial from official Azure team describes designing an infrastructure for a simple online store as follows:

enter image description here

The above configuration incorporates:

  • A cloud-only virtual network with two subnets (FrontEnd and BackEnd)
  • Azure Managed Disks with both Standard and Premium disks
  • Four availability sets, one for each tier of the online store
  • The virtual machines for the four tiers
  • An external load balanced set for HTTPS-based web traffic from the Internet to the web servers
  • An internal load balanced set for unencrypted web traffic from the web servers to the application servers A single resource group
1
azureazure-virtual-machineazure-virtual-networkazure-application-gateway
You may be right based on how application gateways operate. In case of above diagram where web servers are accepting external application traffic, I believe Application gateway is the right choice where you would want to use those features like https load balancing, Session persistence as application gateways operate at application layer while load balancer operate at transport layer. For your main question regarding load balancing VM traffic, load balancer is correct choice. - Rahul Ruikar
@RahulRuikar Thank you for sharing your thoughts. I chose your suggestion from the last line of your above comments. Reason: I'm doing this scenario for my own practice and, as user 4c74356b41 mentioned, Gateway will be more costly - and since I'm in a learning phase on Azure, the Gateway being clunky may not be worth taking a risk for a novice like me in this area. - nam

1 Answers

7
votes

you can use both, its a matter of your needs. load balancer just forwards traffic to your vms, while application gateway can do path based routing, ssl offloading, has WAF capabilities, and so on. But it costs a lot more and is clunky.

Looking at the bullet points you've listed, your case will work with both of these solutions.

ps. Like Rahul mentioned, load balancer works on level 4 and is not HTTP aware, Application Gateway is a level 7 load balancer.