Fact is that if you put two or more routers on a network and let them announce different prefixes, I have never seen a device that will not pick them up correctly. I have never seen a desktop OS that did not choose the correct address, do you have any documentation for that claim?
What address would you put in DNS if you were using NAT with multiple uplinks? Whatever your answer to that question I will say the same for the solution without NAT.
I am not sure why you want client computers to be in the DNS in the first place. But anyway, one possible answer is to put all the public IP addresses in the DNS. Some programs, like a web browser, knows to try the alternative IP if the first fails. Another answer is to put the private fd00:: addresses in DNS. This will work for anyone using VPN or similar to your network (ie. anyone that has a reason to communicating with your client machines using a DNS name).
If we are talking about servers the best option is PI. As would it be in a solution that includes NAT. But there is actually an alternative: You can use mobile IPv6. This has no overhead when your primary link is up.
In fact you can use mobile IPv6 or NEMO for the whole network if need to. Or you can use LISP.
Copyright © 2017, Eklektix, Inc.
Comments and public postings are copyrighted by their creators.
Linux is a registered trademark of Linus Torvalds