link-local needed w/static IP and gateway?

[Hiroki Sato]

Charles Sprickman <spork at bway.net> wrote
  in <4DF9ACCC.5070506 at bway.net>:

sp> >  LLA is a MUST for every IPv6-speaking interface, not for automatic
sp> >  router discovery only.  This is because ICMPv6 heavily depends on it.
sp> >  Without LLA some unexpected and/or inconsistent behaviors can happen,
sp> >  especially on a router as you experienced.
sp>
sp> I'm puzzled by why hosts with static IPv6 IPs could communicate with
sp> each other.  I noticed in some of my netstat output that even though the
sp> ff02 multicast network was in the table, it was only bound to the
sp> loopback.  However I still logged multicast to/from the box.  One of the
sp> RFCs also noted that multicast is limited in scope to the link-local
sp> address, so in theory, not even the host to host ND should have worked.
sp>  I guess that's what threw me.

 This is because an L3 address to an L2 address resolution in NDP
 works in the host-to-host case by chance; addresses in the NDP
 messages do not have to have a link-local scope and FreeBSD's
 implementation uses a GUA if it is configured.  The host-to-router
 case doesn't work properly because a router with no LLA never accepts
 multicast listener discovery messages.

 You can observe tcpdump output of the host-to-host case and the
 host-to-router case.  The primary difference will be that the
 unspecified address ("::") is used in MLD report messages in the
 latter.

-- Hiroki
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 196 bytes
Desc: not available
Url : http://lists.freebsd.org/pipermail/freebsd-net/attachments/20110616/e90b8656/attachment.pgp