I can't seem to get a straight answer to this quesion. Wikipedia says "IPsec is an integral part of the base protocol suite in IPv6," but does that mean that ALL communications are always encrypted, or does it mean that encryption is optional, but devices must be able to understand it (should it be used)?
If encryption is optional, is it the operating system that decides whether to use encryption, or is it the application? Do popular operating systems and software generally enable encryption?
I would investigate this myself, but I lack IPv6 connectivity.
Update: Ok, so it's optional. My follow-up question: typically, is it the application that defines whether to use encryption, or is it the operating system?
A specific example: Imagine I have a recent version of Windows with native ipv6 support, and I search for something on ipv6.google.com using Mozilla Firefox. Would it be encrypted?