netdev - Re: [PATCH] IPv6: Implement RFC 4429 Optimistic Duplicate Address Detection

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Date:	Fri, 26 Jan 2007 16:42:41 -0500
From:	Vlad Yasevich <vladislav.yasevich@...com>
To:	Neil Horman <nhorman@...driver.com>
Cc:	YOSHIFUJI Hideaki / 吉藤英明 
	<yoshfuji@...ux-ipv6.org>, sri@...ibm.com, davem@...emloft.net,
	kuznet@....inr.ac.ru, pekkas@...core.fi, jmorris@...ei.org,
	kaber@...eworks.de, netdev@...r.kernel.org
Subject: Re: [PATCH] IPv6: Implement RFC 4429 Optimistic Duplicate Address
 Detection

Neil Horman wrote:
> On Fri, Jan 26, 2007 at 03:28:40PM -0500, Vlad Yasevich wrote:
>> Hi Neil
>>
>> Neil Horman wrote:
>>> On Fri, Jan 26, 2007 at 09:13:31AM +0900, YOSHIFUJI Hideaki / 吉藤英明 wrote:
>>>> In article <20070125194500.GB8891@...reliant.homelinux.net> (at Thu, 25 Jan 2007 14:45:00 -0500), Neil Horman <nhorman@...driver.com> says:
>>>
>>> New patch attached with most of your suggestions incorporated.  I've a few
>>> comments mixed in for some of the suggestions that I think need further
>>> discussion
>>>
>>>> If optimistic_dad is disabled, flags should be IFA_F_TEMPORARY,
>>>> not IFA_F_TEMPORARY|IFA_F_OPTIMISTIC.
>>>>
>>>> Another idea is to use IFA_F_OPTIMISTIC not
>>>> IFA_F_OPTIMISTIC|IFA_F_TENTATIVE until the DAD has been finished.
>>>>
>>> I'm currently setting the OPTIMISTIC flag in every location that its possibly
>>> needed, and then clearing it in addrconf_dad_start if that interface is not
>>> participating in optimistic dad.  I do this because the RFC in section 3.1
>>> indicates that manually configured addresses should not set the optimistic flag.
>>> If I removed the OPTIMISTIC flag from the locations it gets set in the patch and
>>> then only set it for participating interfaces in addrconf_dad_start, I would
>>> need to have some way to tell if the address in question was manually configured
>>> (to avoid setting it in that case).  At present I see no clear way to do that,
>>> but if you have a suggestion, I'll happily change this around.
>> One suggestiong/question:
>>
>> Instead of clearing the OPTIMISTIC flag in addrconf_dad_start(), wouldn't it be better
>> to simply not set the flag in ipv6_add_addr()?  Just mask that flag from the 'flags'
>> argument passed to that function when conditions are right.
>>
> Doh!  Sometimes I don't just think straight.  Yes, as long as ipv6_add_addr is
> only for adding static addresses (which it pretty clearly is), that would work
> much better.  I'll fix it up and repost on monday.
> 
> Don't suppose you have any thoughts on how to solve the "send to default router"
> problem, do you?
> 

Still trying to figure how the routing side works. sorry....

-vlad
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