Support for Multi-Homed IPv6 Networks, esp. RFC 8028

bshacklett wrote:

Is the single-default-per-interface model in macOS an intentional design choice or simply legacy behaviour that has not yet been updated to RFC 8028?

No one outside Apple knows the answer and no one inside Apple ever would answer.

• Does the kernel perform any hidden next-hop selection that isn’t reflected in netstat -rn output?

See above.

• Are there any road-map items for fully adopting RFC 8028 in macOS?

Apple doesn't do "road maps", except in the Maps app.

As a bonus, I'd be very interested in any info you might be able to provide on the status of implementation/support for https://datatracker.ietf.org/doc/html/rfc8978 (Reaction of IPv6 Stateless Address Autoconfiguration (SLAAC) to Flash-Renumbering Events).

Modern Apple computers are simply souped-up iPhones, in terms of both hardware and software. In that light, your questions about IPv6 multi-hoping and obscure networking RFCs pretty much answer themselves. Those features that work on a Mac are those features that demonstrably work on a Mac. Those features that don't work on a Mac might work one day in the future, or might not. Those features that currently do work on a Mac might not work one day in the future. There is no documentation of any system behaviour at this level. Apple virtually never makes any road maps or promises regarding future features. The few times they do, they're often wrong.

I asked in the developer forums and was specifically directed here.

I'm not surprised.

If you are participating in the Apple Developer program, I'm a bit surprised that they would refer you to the Apple Support Communities to address your questions. As Barney-15E has already mentioned, none of us here would have any insights on what Apple will, or will not, implement. Even if we did, we wouldn't be able to share them in a open public forum.

So, as far as, where should these questions be raised, if you are not already, I suggest you consider joining the Apple Developer program ... or, at least, contact Apple Support directly for guidance for where you could possibly get answers to your questions.

The following ignores any “futures” or “roadmap” questions, as those are not something anybody here can address.

This isn’t an app-development question, so these support communities are the “best” spot for this question.

While this is the appropriate spot in the Apple Community forums, this IPv6 networking question is sufficiently obscure that’d not expect an answer around here. Maybe Apple Support can help (I’m doubtful), but I’d expect to be using external gear to manage this configuration, and maybe implementing your own IPv6 address range.

One potential option is using OpenWRT, and Ubiquiti and other vendors offer WAN failover.

I’d probably try asking this question again over in /r/IPv6 subreddit, or such.

https://www.reddit.com/r/ipv6/comments/1h2ve8x/routing_through_multiple_v6_isps/

And yeah, macOS makes a rotten router.

Try creating a 2nd network interface. I used to do this with IPv4

Tesserax wrote:

If you are participating in the Apple Developer program, I'm a bit surprised that they would refer you to the Apple Support Communities to address your questions.

I'm not. The best description I could come up with for the Apple Developer forums would be "hot mess".

Nobody here works for Apple nor have any knowledge of what Apple is or will be doing.

Did you create a 2nd macOS network interface, and setup that interface for the 2nd IPv6 address/subnet?