Re: IPv4 traffic on "ietf-v6ONLY"

joel jaeggli <joelja@bogus.com> Fri, 17 November 2017 05:12 UTC

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Subject: Re: IPv4 traffic on "ietf-v6ONLY"
To: Alexandre Petrescu <alexandre.petrescu@gmail.com>, ipv6@ietf.org
References: <f9805855-68cf-a3e8-a13f-c6ac31b09058@gmail.com> <bbd4e1d2-047f-6758-76f8-fd591c51dad7@gmail.com> <D631CE54.8C0F5%lee@asgard.org> <m1eEvEP-0000G3C@stereo.hq.phicoh.net> <D75288D5-B571-46EB-A35E-0DBD79F930E5@google.com> <b05f3549-585f-f834-2df3-3b458f67ba2d@gmail.com>
From: joel jaeggli <joelja@bogus.com>
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Date: Fri, 17 Nov 2017 13:12:02 +0800
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On 11/17/17 12:50, Alexandre Petrescu wrote:
> 
> 
> Le 15/11/2017 à 20:15, james woodyatt a écrit :
>> On Nov 15, 2017, at 02:47, Philip Homburg
>> <pch-ipv6-ietf-4@u-1.phicoh.com
>> <mailto:pch-ipv6-ietf-4@u-1.phicoh.com>> wrote:
>>>
>>> The safest option to do that is a DHCPv4 option that says 'no IPv4
>>> service here, go away'.
>>
>> Better: extend ARP with a signal that says, “ARP is not welcome here."
> 
> During changes between the 3 SSIDs I noticed often the message "Windows
> detected an IP address conflict" popped up.  The explanation says that
> another computer on the network has the same address, contact the
> sysadmin, and more details are available.
> 
> This makes wonder whether someone put a computer there that responds to
> all ARP resolution requests for LLs 169, claiming them all.
> 
> It happens systematically when changing the ESSID from "ietf" to
> "ietf-v6ONLY".  If, prior to that change, I disable the IPv4 checkbox in
> interface Properties, the message does not pop up.

The arp / broadcast suppression proxy in the wireless controller is
responding afirmatively to the gratuitous arp that your client sends in
order to test  that it's auto-configured address is available. Roaming
rapidly between APs can achieve that. It thinks you're in two places at
one. sending any other kinda of packet first that would allow it to
update it's mac address table.


> However, this message appears also when changing attachment from SSID
> "ietf-v6ONLY" to "ietf".
> 
> Alex
> 
>>
>> --james woodyatt <jhw@google.com <mailto:jhw@google.com>>
>>
>>
>>
>>
>>
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