IP in IP is an unusual mechanism: not only does it use two network layers, it uses the same protocol on both.

How many tabs are open in your Web browser?

If Thy indulgent Care / Had not preven'd, among unbody'd Shades / I now had wander'd

LOL. I know it well enough to teach it in Colleges around the world. Maybe that's causing some of our worldly problems. What exactly do you teach? Nazism/witchism! Regards, BB