Identify possible IPv4 in IPv6 approaches

* [ ] identify possible IPv4 in IPv6 approaches
* [ ] identify which are being commercially used
* [ ] identify local configuration scenarios - which make sense (i.e does presence of IPv4 negate need for this translation?)
* [ ] identify approach for embedding into code - is this an address translation at "discovery" time an/or an address translation at "use" time?
* [ ] identify testing requirements - including how can this be tested in CI (does a suitable VM testing environment exist? Would one need to be created)