Subject: Re: ROAM/CONNECT event with PORT_AUTHORIZED
To: Ben Greear <greearb@candelatech.com>,
        Johannes Berg <johannes@sipsolutions.net>,
        Arend van Spriel <arend.vanspriel@broadcom.com>,
        Arend van Spriel <arend@broadcom.com>,
        Jouni Malinen <j@w1.fi>
Cc: Avraham Stern <avraham.stern@intel.com>,
        linux-wireless <linux-wireless@vger.kernel.org>
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From: Denis Kenzior <denkenz@gmail.com>
Message-ID: <756be45c-fd13-56a7-b8d4-129c4fd07dc8@gmail.com> (sfid-20170914_223511_343312_52A23F96)
Date: Thu, 14 Sep 2017 15:35:05 -0500
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In-Reply-To: <8a26a838-adde-08f1-5f64-c98e1d947675@candelatech.com>
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Sender: linux-wireless-owner@vger.kernel.org

Hi Ben,

On 09/14/2017 03:29 PM, Ben Greear wrote:
> On 09/14/2017 01:26 PM, Denis Kenzior wrote:
>> Hi Ben,
>>>
>>> How do you re-confirm them?  There are definitely cases where 
>>> SSID/Security is the same but each
>>> AP has its own DHCP server and roaming between them will require 
>>> getting a new DHCP address (on
>>> the same (NAT'd) subnet and with same gateway, likely as not).
>>>
>>
>> Using DHCPREQUEST to verify obtained parameters, or the DHCPv6 
>> equivalent Confirm message.  This obviously requires some integration 
>> between the dhcp daemon and
>> the supplicant.
> 
> Do you want to allow the just-now-roamed station to use its old IP 
> address(es) while you are
> confirming?

I think it is sane to assume that the IP address _should_ be the same. 
The 802.11 spec expects this even.  This is to handle bizarre networks 
that don't do this properly.

> 
> If not, how is this different from just re-doing DHCP like normal?
> 

You get to use your old IP address.  So e.g. your VoIP call doesn't 
disappear if you decide to switch access points.

> And if so, you will in some cases be allowing duplicate IP addresses on
> a network?
> 

Life is never perfect ;)

Regards,
-Denis