How to add loopback interfaces on Windows with PowerShell

One of the most frequent issues I encounter when customers are setting up a loopback adapter on Windows as part of their DR mode deployment is the confusion over which commands to enter. The other hurdle is the frustration caused by having to do this for each server (albeit once) — especially when you have 20 real servers in your cluster!

So, after 4 customers came to me with similar issues in a week, I decided to write a little PowerShell script to ease the workload slightly....

When do you need to set up a loopback adapter on Windows with your DR mode deployment?

Previously we've blogged about how much we love DR mode and how amazing it is. Unfortunately, it isn't always that easy to configure.

When setting up DR mode, there can be some tricky wizardry that you have to apply on your real servers, and this gets especially tricky when trying to do it on Windows. Whilst our deployment guides have in-depth detail on how to do this, it still catches some people out, so I decided to put together some automation to try and make like just that little bit easier.

How to add a loopback interface on Windows with PowerShell

This is my first attempt at PowerShell, so it may not be perfect! However, it does seem to reduce the general error rate and frustration levels.

Just download it onto a Windows server and run it in a PowerShell window as Administrator with the necessary parameters.

The full script can be found in our general repository of useful scripts.

addLoopback.ps1

In order to run this script you may receive a warning about the script not being digitally signed. To overcome this, execute the following command before running the script:

Set-ExecutionPolicy -Scope Process -ExecutionPolicy Bypass

This command sets the execution policy to bypass only the current PowerShell session after the window is closed, the next PowerShell session will open running with the default execution policy. “Bypass” means nothing is blocked and no warnings, prompts, or messages will be displayed.

This script also makes use of NuGet tools and may require an automatic library installation when the script is run for the first time if the Microsoft NuGet libraries aren't found.

command line options

Here are the parameters to call the script and control the functions within:

As always, this is provided as is, for free with no warranty.  Your comments and feedback are always welcomed.

Alternatively, here's the manual version of how to solve the ARP problem on Windows using a loopback adapter!