Re: [v6ops] draft-ietf-6man-grand : saving lookups

Jen Linkova <> Sun, 09 August 2020 23:41 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 30EE93A0F6C; Sun, 9 Aug 2020 16:41:51 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -1.849
X-Spam-Status: No, score=-1.849 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_ENVFROM_END_DIGIT=0.25, FREEMAIL_FROM=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (2048-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id 1k-5vy39NTvd; Sun, 9 Aug 2020 16:41:50 -0700 (PDT)
Received: from ( [IPv6:2607:f8b0:4864:20::731]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by (Postfix) with ESMTPS id E7FFE3A0F56; Sun, 9 Aug 2020 16:41:49 -0700 (PDT)
Received: by with SMTP id m7so6855579qki.12; Sun, 09 Aug 2020 16:41:49 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=S+6TymZ+42EUoF45KaxBqQxSNBKtrjslpAJk4ZTm194=; b=qD3aYVPucmoT3YViAC0iNUZ8cM44omO9iVN+gvhyA6Jf2Alx1tCB4odxNvAl/3AFDh XaUos+N1B1rtrB+5RlCj/m6pbiU456a2hLIzlj2Nf/Q560RRStKwL/8SH7Xv4ca4FIJ+ iU7g5V5Jb5U6tG/cBfdc6GZHen5/fXbBrsy7QA1gJbfl25fOwslVIRigNp6AYggRWE3f AH2qY3NE8qNFM/G9XtbfLLbrcK2KVQ3ilRgaKDXvAPCmCYNKZT37pc24/b4/D1gV0DOD SseDJQbmyDRIQHrSetLitLeBa5N1ZLOB5vbZPeFwhLIyeU7HAFseNZf/aG51j0pxpQKk PZMQ==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=S+6TymZ+42EUoF45KaxBqQxSNBKtrjslpAJk4ZTm194=; b=Hmd/OzOwwmOrsxP5QJYAPbgVYkyRUQc6KwHoF0Atx4kwPtyWPJO628/DzVejoepmMx rKr22nLK9/nMCYMUhK5r4pLRLXx22ymiw5nzk02rb/yHVPeAcfMlZANE/5Cl4ZWIkFEk rJzsI5G2i1dd3wRWWa+OAUzXTO8bN2qv6jnKtNn0r+5jP5T0hMYj/iymfJF6bRa6nWtA aS2R0ZkWSclYyp2mA7Wpo7uW8HrPQhhIizR/OzATzLXMb1QF0gkKsjQpeq9346MwHVLk xx40LpvJXHBlUxfUosiGeqEeQAV0xNWkx1YIaWOA3qCz6HbyKCwCnW2szEzndfts4IXp tAUQ==
X-Gm-Message-State: AOAM5339fL4MazyhMpw8xrpeKnj07i80CaLgLM/9SepnmfWyw3h7gI6x RgoT/JgcMbWe3bljAIm7gzr2LAkNk46Tcb9pNQg=
X-Google-Smtp-Source: ABdhPJxDvJzHA1DXsTusGyMbEPNTqMdYom1Go5AAVjUaGh6yeKDcXIwWSA4ZPzNyK+wWghU97elvQaxfjPZatqiFsbs=
X-Received: by 2002:a37:9c4b:: with SMTP id f72mr24532926qke.332.1597016508926; Sun, 09 Aug 2020 16:41:48 -0700 (PDT)
MIME-Version: 1.0
References: <> <> <> <> <> <> <> <> <> <> <>
In-Reply-To: <>
From: Jen Linkova <>
Date: Mon, 10 Aug 2020 09:41:37 +1000
Message-ID: <>
To: Mark Smith <>
Cc: "Pascal Thubert (pthubert)" <>, 6man <>, IPv6 Operations <>, Jen Linkova <>
Content-Type: text/plain; charset="UTF-8"
Archived-At: <>
Subject: Re: [v6ops] draft-ietf-6man-grand : saving lookups
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: v6ops discussion list <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Sun, 09 Aug 2020 23:41:51 -0000

On Sun, Aug 9, 2020 at 7:40 PM Mark Smith <> wrote:
>> > Maybe the host should renew the NCE in the router periodically ?

>> I guess we can add to the very end of the Section 4.1.2 (the new text):
>> "A node MAY send unsolicited NAs for its preferred addresses
>> periodically to refresh the Neighbor Cache on the first hop routers."
>> On the other hand it might pollute the router NC with entries for
>> addresses which the node has configured but is not going to use.

> Won't NUD probes keep those entries current in the routers' cache, even though hosts may not be actively using them?

No, why would it? By the definition, for STALE entries no attempts are
made to verify the neighbor reachability. So if the node has not been
receiving traffic for that address, the STALE entry would stay there
until the router cleans it up.
So if we recommend sending periodic unsolicited NAs it might
re-populate the router cache with unused addresses which have been
cleaned up.
As sending periodic NAs would make sense for the very specific
scenario - the was sleeping, has woken up and is going to send some
traffic it might be a bit tricky to give guidance on that. In all
other cases I do not see much benefits...
Strictly speaking nothing described in this draft is prohibited in
RFC4861 anyway. So hosts can send unsolicited NAs anyway ;)

> I've thought that something like GRAND + NUD is starting to approach an address registration protocol, or at least, makes the routers' cache the "active addresses on a link" database.

I'd say 'most active addresses' as we can not guarantee that
unsolicited NAs reach routers.

SY, Jen Linkova aka Furry