Re: RFC4861 question - short prefixes in PIOs

[Michael Richardson <[e-mail]>]

Templin (US), Fred L <[e-mail]> wrote:
    > 3) If the PIO instead has L=0, does it mean that 2001:db8::/32 is
    > “associated” with the link but not necessarily “on-link”?

As others have said, and I find the RFC rather obtuse in this way, I think
that only thing one can say is that if L=1, then devices in that indicated
PIO can be found using ND (appropriately multicast).

I think that when it is associated with the link, one can use SLAAC to assign
interfaces, but can't use ND to find neighbours.

Hairpin'ing all traffic through the advertising router when L=0 seems like
the only general solution.  But, I can imagine many situations where if a
Neighbour Cache entry somehow existed, then it could be used.

I think that hairpin'ing all traffic has many interesting uses when it comes
to providing firewalling (such as RFC8520) between devices.

    > 4) If yes to 3), does it mean that 2001:db8::/32 should be added to the
    > IPv6 forwarding table
    > as a “route-to-interface” with the receiving interface as the next hop?

I don't think so.
That would imply it was on-link, and L=0 means it isn't.

--
Michael Richardson <[e-mail]>, Sandelman Software Works
 -= IPv6 IoT consulting =-