Useful when migrating from CMS to SP
After your go live (congratulations) if you made the mistake I made and wanted to replace the namespace of your cms with your service portal you will likely have an issue where old links from past emails, bookmarks and 3rd party sources link to the cms pages.
When I sought out help for this after the fact the responses I got were not very helpful.
Don't use the same name space
So what I did to correct what I could was the following;
This page you can toss a HTML redirect to the appropriate Service Portal page.
<?xml version="1.0" encoding="utf-8" ?>
window.location.href = '/cms'