netdev - Re: [IPV6] ADDRCONF: Defer dad for global address until dad for linklocal is completed.

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Message-ID: <4832C579.2040800@miraclelinux.com>
Date:	Tue, 20 May 2008 21:35:05 +0900
From:	Toyo Abe <tabe@...aclelinux.com>
To:	YOSHIFUJI Hideaki / 吉藤英明 
	<yoshfuji@...ux-ipv6.org>
CC:	davem@...emloft.net, netdev@...r.kernel.org
Subject: Re: [IPV6] ADDRCONF: Defer dad for global address until dad for linklocal
 is completed.

Sorry for lack of explanation.

 > But then, many other test scenarios in TAHI test suite went to FAIL. 
It was because
 > the tester node send RA with prefix option to the host right after it 
receives DAD NS
 > from the host, which is obviously in autoconfiguration process for 
linklocal address.

And the tester node never accepts RS(es) from the host after sending the 
RA. The tester
node determine FAIL unless it doesn't receive DAD NS for corresponding 
global address
from the host.

-toyo

Toyo Abe wrote:
> Yoshifuji-san,
>
> Thanks for your response.
>
> > Why don't we just ignore RA until DAD for link-local
> > address has been successfully completed?
> I was also thinking so. And I tried it at first.
> But then, many other test scenarios in TAHI test suite went to FAIL. 
> It was because
> the tester node send RA with prefix option to the host right after it 
> receives DAD NS
> from the host, which is obviously in autoconfiguration process for 
> linklocal address.
>
> Besides, RFC4862 section 4(protocol overview) says;
> ---
> To speed the autoconfiguration process, a host may generate its link-
> local address (and verify its uniqueness) in parallel with waiting
> for a Router Advertisement. Because a router may delay responding to
> a Router Solicitation for a few seconds, the total time needed to
> complete autoconfiguration can be significantly longer if the two
> steps are done serially.
> ---
>
> The  text indicates that a host *may* accept RA including prefix 
> option even before
> completion of DAD for linklocal address.
> Since current addrconf code actually accepts RA including prefix 
> option while DAD for
> linklocal address is processing, changes of the behaviour looks like a 
> degradation for me.
> Hence, I chose to accept RA at that moment and defer sending DAD NS 
> for global addresses.
>
> Thanks,
> -toyo
>
> YOSHIFUJI Hideaki / 吉藤英明 wrote:
>> In article <48324792.5070309@...aclelinux.com> (at Tue, 20 May 2008 
>> 12:37:54 +0900), Toyo Abe <tabe@...aclelinux.com> says:
>>
>>> This patch fixes the problem by deferring DAD initiation for global 
>>> address until
>>> DAD for linklocal address is completed. Now the failed test 
>>> scenarios noted above
>>> are all passed.
>>
>> Why don't we just ignore RA until DAD for link-local
>> address has been successfully completed?
>>
>> --yoshfuji
>>
>>
>
>

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