linux-kernel - [Discuss]ipv6: send ns packet while dad

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Message-ID: <20250402121205.305919-1-gaoxingwang1@huawei.com>
Date: Wed, 2 Apr 2025 20:12:05 +0800
From: gaoxingwang <gaoxingwang1@...wei.com>
To: <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<davem@...emloft.net>, <kuznet@....inr.ac.ru>, <yoshfuji@...ux-ipv6.org>
CC: <kuba@...nel.org>, <yanan@...wei.com>
Subject: [Discuss]ipv6: send ns packet while dad

Hello, everyone:

I have an RFC-related question when using ipv6.

Configure an IPv6 address on network adapter A. The IP address is being used for DAD and is unavailable.
In this case, the application sends an NS packet to resolve the tentative IP address. The target address
in the multicast packet contains the tentative IP address, and the source address is set to the link-local address.
Is this allowed to be sent? Does it contradict the following description in the RFC 4862?
(https://datatracker.ietf.org/doc/html/rfc4862#section-5.4)

>Other packets addressed to the
>tentative address should be silently discarded.  Note that the "other
>packets" include Neighbor Solicitation and Advertisement messages
>that have the tentative (i.e., unicast) address as the IP destination
>address and contain the tentative address in the Target Address field.

Or is this description just for receiving packets?

The actual problem I encountered was that when proxy ND was enabled
on the switch, the reply ND packet would cause the dad to fail. 
So I'm not sure if it's the NS sending problem.
Thank you very much, if anyone can reply!