IFT_L2VLAN and IPv6 link-local addresses

[John Hay]

Hi Hiroki,

On Tue, Dec 21, 2010 at 12:54:58AM +0900, Hiroki Sato wrote:
> John Baldwin <jhb at freebsd.org> wrote
>   in <201012200807.57670.jhb at freebsd.org>:
> 
> jh> On Monday, December 20, 2010 1:10:57 am John Hay wrote:
> jh> > Hi,
> jh> >
> jh> > I see that on FreeBSD-8 if you use IPv6 inside vlans, the local part of
> jh> > the address (bottom 64 bits) is based on the MAC address of the first
> jh> > ethernet interface on the system. It was not like this in my old -7,
> jh> > machine, so I looked around a bit. It looks like it is because vlans were
> jh> > changed to report their type as IFT_L2VLAN. So I made this patch to the
> jh> > IPv6 code that fix it for me:
> jh> >
> jh> > Index: sys/netinet6/in6_ifattach.c
> jh> > ===================================================================
> jh> > RCS file: /home/ncvs/src/sys/netinet6/in6_ifattach.c,v
> jh> > retrieving revision 1.74.2.3
> jh> > diff -u -U 5 -r1.74.2.3 in6_ifattach.c
> jh> > --- sys/netinet6/in6_ifattach.c	6 May 2010 06:44:19 -0000	1.74.2.3
> jh> > +++ sys/netinet6/in6_ifattach.c	15 Dec 2010 18:33:45 -0000
> jh> > @@ -265,10 +265,11 @@
> jh> >  	addrlen = sdl->sdl_alen;
> jh> >
> jh> >  	/* get EUI64 */
> jh> >  	switch (ifp->if_type) {
> jh> >  	case IFT_ETHER:
> jh> > +	case IFT_L2VLAN:
> jh> >  	case IFT_FDDI:
> jh> >  	case IFT_ISO88025:
> jh> >  	case IFT_ATM:
> jh> >  	case IFT_IEEE1394:
> jh> >  #ifdef IFT_IEEE80211
> jh> >
> jh> > Anything against me committing it? Am I missing something? Should it be
> jh> > sorted differently? Should it also be merged?
> jh>
> jh> This looks correct.  Please fix and MFC.  I haven't merged the kernel changes
> jh> to change the type of IFT_ for vlan's yet as I was worried about applications
> jh> such as this needing to be updated (such as dhcpd for example).  I had thought
> jh> that I had not merged the kernel change to 8 though, that it was just in 9?
> 
>  Agreed with the fix, but I think both 7.X and 8.X pick the first IF's
>  address anyway.  Which log message did you get, "borrow interface
>  identifier from..."  or "...got interface identifier from itself"
>  when net.inet6.icmp6.nd6_debug=1 on 7.X and 8.X, respectively?

You are correct. I forgot that in the 7.x network layout, the ipv6
networks were not in vlans. I just tried it on my old 7.2-PRE box:

sysctl net.inet6.icmp6.nd6_debug=1
ifconfig vlan0 create vlandev em2 vlan 1200
ifconfig vlan0 up
ifconfig vlan0
vlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        options=3<RXCSUM,TXCSUM>
        ether 00:11:43:dc:fd:78
        inet6 fe80::21b:21ff:fe13:2650%vlan0 prefixlen 64 tentative scopeid 0x6 
        media: Ethernet autoselect (1000baseTX <full-duplex>)
        status: active
        vlan: 1200 parent interface: em2

The last part of dmesg:
vlan0: borrow interface identifier from em0
vlan0: ifid: 02:1b:21:ff:fe:13:26:50
vlan0: starting DAD for fe80:6::21b:21ff:fe13:2650
vlan0: DAD complete for fe80:6::21b:21ff:fe13:2650 - no duplicates found

I also had a better look at if_vlan.c. John's IFT_L2VLAN changes has not
been merged, as he remembered. :-) 

The line

ifp->if_type = IFT_L2VLAN;

has been there for a long time and his changes only change sdl->sdl_type
in any case.

John
-- 
John Hay -- jhay at meraka.csir.co.za / jhay at FreeBSD.org