patch: bad ipv6 neighbor solicitation

Tue Dec 15 04:53:47 UTC 2009

Please find the more proper fix at

	http://people.freebsd.org/~qingli/nd6-patch.diff

I realized I was slightly off in my previous email after
I spent a bit more time looking through the problem. 
Both prefixes are present but one was marked off-link due
to the fact only a single prefix route was installed in
the routing table (non RADIX_MPATH system).

I evaluated various options to fixing this issue, however, 
due to the association between NDPRF_ONLINK and the route
installation, I decided to go with what I have here for
the time being.

I have verified the fix in my setup. Please apply the
patch and report back.

Thanks,

-- Qing

> -----Original Message-----
> From: owner-freebsd-net at freebsd.org [mailto:owner-freebsd-
> net at freebsd.org] On Behalf Of Li, Qing
> Sent: Monday, December 14, 2009 3:00 PM
> To: Dennis Glatting; JASSAL Aman
> Cc: freebsd-net at freebsd.org
> Subject: RE: Understanding multiple IPv6 interfaces under 8.0 (fwd)
> 
> 
> You don't need to perform all that route-foo. I believe the root cause
> of
> this issue may be due to a bit of regression in the IPv6 prefix
> management
> code, and I am in the process of putting together a permanent fix.
> 
> The issue as it stands today, is due to how the prefix was inserted in
> the first place. Since bce0 was configured first, the interface
> associated
> with the prefix is bce0. Later the reference count on the prefix is
> simply incremented when bce1 configures another IPv6 address of the
> same prefix.
> 
> When ND6 NS arrives for bce1, due to the interface mismatch of the
> prefix
> interface against the input interface, the NS packet was considered
> invalid and thus dropped.
> 
> Again, in case you didn't see my earlier reply, try the temporary hack
> at
>     http://people.freebsd.org/~qingli/nd6-ns.diff
> 
> until I commit a permanent patch. The problem was easily reproducible
> and
> I have verified with limited unit testing the patch works.
> 
> -- Qing
> 
> 
> -----Original Message-----
> From: owner-freebsd-net at freebsd.org on behalf of Dennis Glatting
> Sent: Mon 12/14/2009 2:03 PM
> To: JASSAL Aman
> Cc: freebsd-net at freebsd.org
> Subject: Re: Understanding multiple IPv6 interfaces under 8.0 (fwd)
> 
> 
> Thanks. Responses in-line.
> 
> 
> 
> On Mon, 14 Dec 2009, JASSAL Aman wrote:
> 
> > Hello Mr.Glatting,
> >
> > Not that I'm an IPv6 genius, but at first sight your problem seems
to
> be a
> > route-related. I've put comments in-line.
> >
> >
> > Le Dim 13 d?cembre 2009 22:58, Dennis Glatting a ?crit :
> >>
> >>
> >> Elmer# netstat -rn
> >> Routing tables
> >>
> >>
> >> Internet6:
> >> Destination                       Gateway
> Flags
> >> Netif Expire
> >> ::/96                             ::1
UGRS
> >> lo0  => default                           fd7c:3f2b:e791:1::1
> >> UGS        bce0
> >> ::1                               ::1                           UH
> >> lo0 ::ffff:0.0.0.0/96                 ::1
> UGRS
> >> lo0 fd7c:3f2b:e791:1::/64             link#1
> U
> >> bce0 fd7c:3f2b:e791:1::ac13:a0a        link#1
> UHS
> >> lo0 fd7c:3f2b:e791:1:0:1:ac13:a0a     link#2
> UHS
> >> lo0 fe80::/10                         ::1
> UGRS
> >> lo0 fe80::%bce0/64                    link#1
> U
> >> bce0 fe80::213:72ff:fe60:ac52%bce0     link#1
> UHS
> >> lo0 fe80::%bce1/64                    link#2
> U
> >> bce1 fe80::213:72ff:fe60:ac50%bce1     link#2
> UHS
> >> lo0 fe80::%lo0/64                     link#3
> U
> >> lo0 fe80::1%lo0                       link#3
> UHS
> >> lo0 ff01:1::/32                       fe80::213:72ff:fe60:ac52%bce0
> U
> >> bce0 ff01:2::/32
fd7c:3f2b:e791:1:0:1:ac13:a0a
> U
> >> bce1 ff01:3::/32                       ::1
> U
> >> lo0 ff02::/16                         ::1
> UGRS
> >> lo0 ff02::%bce0/32                    fe80::213:72ff:fe60:ac52%bce0
> U
> >> bce0 ff02::%bce1/32
fd7c:3f2b:e791:1:0:1:ac13:a0a
> U
> >> bce1 ff02::%lo0/32                     ::1
> U
> >> lo0
> >>
> >
> > Hmm, the entry for fd7c:3f2b:e791:1:0:1:ac13:a0a looks suspect. I
was
> > expecting bce1 rather than lo0, I suppose you were as well :) If I'm
> not
> > mistaken, the packets emanating from bce1 go to the loopback
> interface,
> > thus not really going out. You can try specifying the route manually
> > with "route add *your parameters*" or even set it in /etc/rc.conf so
> > that it's loaded at boot-time. There's no reason why among 2
physical
> > interfaces sharing the same fabric, one can ship packets out and the
> > other can't.
> >
> 
> I was wondering about the route however I haven't figured out the
trick
> to
> get what I want. For example:
> 
> Elmer# route delete -inet6 fd7c:3f2b:e791:1:0:1:ac13:a0a
> delete host fd7c:3f2b:e791:1:0:1:ac13:a0a
> 
> Elmer# route add
> -inet6 fd7c:3f2b:e791:1:0:1:ac13:a0a/64 -iface bce1
> route: writing to routing socket: File exists
> add net fd7c:3f2b:e791:1:0:1:ac13:a0a/64: gateway bce1: route already
> in table
> 
> I did delete the lo0 route before I exected the above command. Also, I
> haven't been able to specify a higher metric (e.g., -metric 2). That
is
> rejected too. However, I can say:
> 
> Elmer# route delete -inet6 fd7c:3f2b:e791:1:0:1:ac13:a0a
> delete host fd7c:3f2b:e791:1:0:1:ac13:a0a
> 
> Elmer# route add -inet6 fd7c:3f2b:e791:1:0:1:ac13:a0a -iface bce1
> add host fd7c:3f2b:e791:1:0:1:ac13:a0a: gateway bce1
> 
> Elmer# netstat -rn
> (snip)
> fd7c:3f2b:e791:1:0:1:ac13:a0a     00:13:72:60:ac:50             UHS
> bce1
> 
> I don't think that is what I want. WHat I think I just said is "host
X"
> is
> out that door, rather than route net. If, however, I say Docs is out
> that
> door, I get:
> 
> Elmer# route add -inet6 docs.dco.penx.com -iface bce1
> add host docs.dco.penx.com: gateway bce1
> 
> Elmer# ping6
> docs.penx.com
> PING6(56=40+8+8 bytes) fd7c:3f2b:e791:1:0:1:ac13:a0a -->
> fd7c:3f2b:e791:1::ac13:a15
> ping6: sendmsg: Operation not permitted
> ping6: wrote docs.dco.penx.com 16 chars, ret=-1
> 
> 
> >>
> >> Elmer's rc.config:
> >>
> >>
> >> ipv6_enable="YES" ipv6_network_interfaces="bce0 bce1"
> >> ipv6_ifconfig_bce0="FD7C:3F2B:E791:0001::0:172.19.10.10 prefixlen
> 64"
> >> ipv6_ifconfig_bce1="FD7C:3F2B:E791:0001::1:172.19.10.10 prefixlen
64
> mtu
> >> 8192"
> >> ipv6_defaultrouter="FD7C:3F2B:E791:0001::1"
> >>
> >
> > Erm... You're using IPv4 addresses encapsulated in IPv6 ? I've never
> used
> > this myself so I can't really comment, and I can't say if there
> aren't any
> > sort of "interferences" with what you're trying to do.
> >
> 
> I hope what I am specifying is to use the 32 bit IPv4 address as the
> last
> 32 bits of the IPv6 address, at least that is how it works out
> numerically. My numbering scheme for fixed assets is the last 32 bits
> of
> the 128 bit IPv6 address is the same as its IPv4 address.
> 
> 
> >>
> >>
> >> The router (cisco):
> >>
> >>
> >> interface GigabitEthernet0/0 ipv6 address FD7C:3F2B:E791:1::1/64
> ipv6
> >> enable ipv6 nd prefix FD7C:3F2B:E791:1::/64 (etc)
> >>
> >
> > Just a side-note, I'm not sure if it will be really useful to you,
> but you
> > could give it a try if you want to. Have you tried using your Cisco
> router
> > as a Router Advertisement Daemon ? That way, addresses would be
built
> > automatically and you could see how both interfaces react to such
> > advertisements.
> >
> > I hope this helps.
> >
> > ------------
> > Aman Jassal
> >
> > Wisdom comes from experience.
> > Experience comes from a lack of wisdom.
> >
> >
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