Re: John Scudder's No Objection on draft-ietf-6man-grand-05: (with COMMENT)

Jen Linkova <> Thu, 01 July 2021 05:13 UTC

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From: Jen Linkova <>
Date: Thu, 01 Jul 2021 15:12:29 +1000
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Subject: Re: John Scudder's No Objection on draft-ietf-6man-grand-05: (with COMMENT)
To: John Scudder <>
Cc: The IESG <>, Bob Hinden <>,, 6man <>, 6man Chairs <>
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Hi John,

Thank you for your review and comments!

On Thu, Jul 1, 2021 at 11:34 AM John Scudder via Datatracker
<> wrote:
> 1. Section 5.2
>               The
>    only potential impact would be for packets arriving to the router
>    after the unsolicited NA from the host but before the rightful owner
>    responded with the solicited NA.  Those packets would be sent to the
>    host with the optimistic address instead of its rightful owner.
>    However most likely those packets would have been dropped anyway:
>    creating the INCOMPLETE entry is usually triggered by traffic, so the
>    router probably has some packets in the buffer already, dropping
>    subsequent packets received before the address resolution is
>    completed.
> Wouldn’t the buffered packets (received before the unsolicited NA) be
> misdelivered to the optimistic host? The quoted paragraph restricts itself to
> packets arriving after the unsolicited NA.

Yeah, that's been pointed out already, -06 has this section
re-written, please take a look:

> 2. Section 5.3.1
> Couldn’t step 4 (host detects duplication) complete sometime after step 7
> (router sends NS to host)? (This might also apply to 5.3.2.) If that's possible
> the analysis would be a little less rosy, right?

You are right. I've updated the text to clarify:

7. As the host has detected the address conflict already it does not
respond to the unicast NSes. (It is unlikely that the host has not
completed the DAD process at this stage, as DELAY_FIRST_PROBE_TIME (5
seconds) is much higher than the DAD duration
(DupAddrDetectTransmits*RetransTimer*1000 + MAX_RTR_SOLICITATION_DELAY
secs, section 5.4 of [RFC4862]). The default value for the DAD process
would be 1*1*1000 + 1 = 2 secs, [RFC4861]. If the host has completed
DAD but did not detect the address conflict then there are two hosts
with the same address in the Preferred state and the disruption is
inevitable anyway.

Also, -06 now has the text explaining that all those scenarios could
be easily avoided if the rightful owner also sends unsolicited NAs.

> 3. Section 5.3.1
>         However the same
>    behaviour would be observed if changes proposed in this document are
>    implemented
> Do you mean “are *not* implemented”?

Indeed I do, fixed.

> 4. Section 8.4
> Please add SLLAO to terminology section or expand on first use.


SY, Jen Linkova aka Furry