Hi everyone,
I’m running a dual-homed IPv6-mostly LAN where two on-link routers advertise distinct global Provider-Assigned prefixes (one per ISP). On Linux, the host stack appears to follow RFC 8028. It keeps one default route per prefix, and packets appear to leave through a router that recognises their source address and pass ISP BCP 38 (https://datatracker.ietf.org/doc/bcp38/) checks.
On macOS Sequoia, I'm only seeing a single un-scoped default route. As a result, traffic sourced from prefix B often exits via router A and is dropped upstream.
Questions:
- 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?
- Does the kernel perform any hidden next-hop selection that isn’t reflected in netstat -rn output?
- Are there any road-map items for fully adopting RFC 8028 in macOS?
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).
The Apple Developer Forums are primarily focused on developer topics, like the the APIs in Apple’s various platform SDKs. AFAICT this question is about the on-the-wire behaviour of macOS. Given that, I’m gonna recommend that you ask it over in the Apple Support Community, run by Apple Support.
Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
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