Trouble with ipv6 routing through interface,Re: Trouble with ipv6 routing through interface

[Hiroki Sato]

"Andrey V. Elsukov" <ae at FreeBSD.org> wrote
  in <c5400b5d-a391-c688-f569-d2f129925a89 at FreeBSD.org>,<c5400b5d-a391-c688-f569-d2f129925a89 at FreeBSD.org>:

ae> On 16.12.2016 03:24, Anderson Soares Ferreira wrote:
ae> > I have a freebsd 11 box running as my network gateway and I’m having
ae> > some trouble trying to route ipv6 packets through an interface with
ae> > only linklocal address. In short, what I’m doing is:
ae> >
ae> > My freebsd gateway has one global scope address on lo0 interface,
ae> > each other interface has only a link local address fe80::1. Static
ae> > routes for the global scope subnets have been created, Each route was
ae> > created using the command:
ae> >
ae> > # route -6 add -net <net address>/64 -interface <dev>
ae> >
ae> > The clients on each subnet have a global scope address and fe80::1 as
ae> > default gateway.
ae> >
ae> > What is happening with this approach is that my gateway can’t reach
ae> > the clients on the subnets. Ping tests from the gateway to the client
ae> > return the error "ping6: sendmsg: No buffer space available”. On the
ae>
ae> Hi,
ae>
ae> this ENOBUFS error is returned from ND6 code. Due to the lack of
ae> prefixes, layer2 doesn't consider that destination address is a
ae> neighbor.
ae>
ae> > other hand, when I try to do a ping from client to gateway, the
ae> > packets from the client are received by the gateway but no response
ae> > is sent. In my tests using a linux gateway with the same approach,
ae> > everything worked fine .
ae>
ae> I'm not sure how this should be fixed.

 A FreeBSD router box must have an IPv6 address on each interface if
 you want to reach the router from a client (and vice versa).
 Currently FreeBSD does not properly support an IPv6 GUA on an
 interface and a route of the GUA's prefix on another interface
 without an GUA at the same time, which is often seen on a dedicated
 router box like Cisco.  This is partly because FreeBSD's NDP and
 routing table assume that an on-link prefix is interface-local, not
 node-local across multiple interfaces.

 A practical workaround is using an LLA (i.e. fe80::1 or something)
 for communication between the router and the clients.

-- Hiroki
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