ietf-nat64 gives IPv4 address conflict message

[brian.e.carpenter@…]

A bit odd this. When I connect to ietf-nat64, Windows 7 shows up an IPv4 address conflict... IPv6 seems to work though, but I haven't spent much time looking for NAT64 issues yet.

Screen shot of the error msg attached. FYI here's what Windows believes:

Wireless LAN adapter Wireless Network Connection:

Connection-specific DNS Suffix . : meeting.ietf.org
Description . . . . . . . . . . . : Intel(R) Centrino(R) Advanced-N 6230
Physical Address. . . . . . . . . : 88-53-2E-B9-56-22
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IPv6 Address. . . . . . . . . . . : 2001:67c:370:1998:28cc:dc4c:9703:6781(Preferred)
Link-local IPv6 Address . . . . . : fe80::28cc:dc4c:9703:6781%12(Preferred)
Autoconfiguration IPv4 Address. . : 169.254.103.129(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.0.0
Default Gateway . . . . . . . . . : fe80::1998:1%12
DHCPv6 IAID . . . . . . . . . . . : 310924078
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-18-3B-A2-69-E8-03-9A-3C-67-7A
DNS Servers . . . . . . . . . . . : 2001:67c:370:229::7

2001:67c:370:229::6

NetBIOS over Tcpip. . . . . . . . : Enabled
Connection-specific DNS Suffix Search List :

meeting.ietf.org

[llynch@…]

Thanks for trying the NAT64 network (SSID ietf-nat64) and reporting
your experience. As far as we can tell, the issue you reported is
either an issue of the NAT64 implementation's handling of that
specific traffic or the given application vendor's implementation.
We're collecting all the issues that come up and will pass the
reports back to the vendor at the end of the week. Hopefully this
will lead to better implementations and greater functionality for
the next meeting. If you're curious about other known issues,
please see https://tickets.meeting.ietf.org/wiki/nat64

If you have additional input on this issue please update the ticket,
if you see new issues please open additional tickets.

Thanks -

[panda@…]

Thank you for reporting the issue.

We don't run DHCP services on the NAT64 segment. Your IPv4 address is assigned by your operating system from /16 link local address block. IPv4 link-local addresses possibly conflict with low probability. Therefore, we suspect your self-assigned link-local address conflicts with the other's and your operating system detected . However, it is very low probability then it could be happened by another reason if you encounter this issue again.

I'm closing this ticket but feel free to reopen if this issue occurs again.

Thank you.
Hirochika Asai

[brian.e.carpenter@…]

I think I see what happens. When I switch from ietf to ietf-nat64 or vice versa, this error message appears. So I assume that my address is already in my own ARP cache and Windows 7 does not clear it. Something like that, anyway.