* Stuart D Gathman > One situation that ought to work IMHO (although ~1/2 of IPv6 experts > disagree) is that DHCP6 should work in concert with routes that are > not /64.
Agreed. As it happens, NM recently gained support for such setups. > For instance, RA provides a 2001:db8:1:2:3::1/80 default > route, The default route, by definition, is ::/0. Do you mean a on-link prefix route? Also, 2001:db8:1:2:3::1/80 isn't a prefix you'd normally see in a RA, as the interface bits aren't all zeroes. Did you mean 2001:db8:1:2:3::/80? > sets the M bit, and DHCP6 provides the address > 2001:db8:1:2:3::1000. NM should be able to set the default route It's actually the kernel that will set the default route, as well as any on-link prefix routes, in response to receiving an RA, not NM. (However, NM will make a static copy of the default route set up by the kernel.) This has worked just fine for many many years. > *and* apply the /80 prefix length to the DHCP6 address. Why? > This could > get non-trivial when there are multiple routes provided by RA. NM > must then find the route that matches the DHCP6 address to determine > the correct prefix. An address assigned by DHCPv6 IA_NA is just that, a single address. DHCPv6 cannot provide a prefix length, or indeed any routes at all. The implicit prefix length if an IA_NA assignment, therefore, is always /128. This is what was recently fixed in NM. Before it used to believe the buggy ISC DHCPv6 client, which always explicitly advertised a false prefix length of /64. Now NM hard-codes /128 instead. See <http://cgit.freedesktop.org/NetworkManager/NetworkManager/commit/?id=eb460b70dad82d366d35fa5703c0e79a1389e4d1>. > Note: the experts that disagree feel that all LANs should be /64 > always forever, and prefixes should only be used in routers. I find > it quite handy to be able to subnet the /64 provided by the ISP, and > while I agree that ISPs should always forever allocate a minimum of > /64 to end users, nevertheless endusers should be able to subnet that > and still have workstations and devices work without manual > configuration. I think «the experts» generally have a more pragmatic view of the world than that (there are exceptions, of course). Using prefix lengths other than /64 is certainly not forbidden (see for example RFC 6164). What is true, however, is that if you want to use SLAAC, you'll have to use a /64, because that's the only prefix length for which an algorighm to automatically generate your own interface bits is defined. For that reason, *defaulting* to a /64 is sensible - especially in consumer-grade home routers and similar. For the same reason, the absolutely minimum an ISP should hand out to its subscribers, is a /64 - and in the RIPE NCC service area, the IPv6 address allocation and assignment policy explicitly forbids the assignment of smaller prefixes to end users. -- Tore Anderson _______________________________________________ networkmanager-list mailing list [email protected] https://mail.gnome.org/mailman/listinfo/networkmanager-list
