Re: [Softwires] ietf-softwire: IPv4 + PSID primary key for lw4over6 binding

Andy Wingo <> Tue, 12 July 2016 12:48 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 655B412D813 for <>; Tue, 12 Jul 2016 05:48:55 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -1.121
X-Spam-Status: No, score=-1.121 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, SPF_NEUTRAL=0.779] autolearn=no autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (1024-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id i8gNIFKjrOfV for <>; Tue, 12 Jul 2016 05:48:53 -0700 (PDT)
Received: from ( []) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by (Postfix) with ESMTPS id C24AD12D80C for <>; Tue, 12 Jul 2016 05:48:53 -0700 (PDT)
Received: from (unknown []) by (Postfix) with ESMTP id 1582B2465A; Tue, 12 Jul 2016 08:48:53 -0400 (EDT)
DKIM-Signature: v=1; a=rsa-sha1; c=relaxed;; h=from:to:cc :subject:references:date:in-reply-to:message-id:mime-version :content-type; s=sasl; bh=Q/OSIC+Xclfn+jCzQc1jb1TIAVQ=; b=YqsSVQ BlTM7+17mOCauTQChMOwFBMd+ktTL9xvBD1U5bECWs94UCI3q6uwd4nn68m38jrC jZK3h3o6znoUC5kAAckPkpSznCxdQt24NSfFv6KVC2ikMsreXD3e2CFhRqp0U/2y THAizMz1Uijanh+9JhsTVA99/Ypyj1HDFpb30=
Received: from (unknown []) by (Postfix) with ESMTP id 0EF4524658; Tue, 12 Jul 2016 08:48:53 -0400 (EDT)
Received: from rusty (unknown []) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by (Postfix) with ESMTPSA id 6530924657; Tue, 12 Jul 2016 08:48:52 -0400 (EDT)
From: Andy Wingo <>
To: <>
References: <> <787AE7BB302AE849A7480A190F8B933008DE5EB3@OPEXCLILMA3.corporate.adroot.infra.ftgroup>
Date: Tue, 12 Jul 2016 14:48:49 +0200
In-Reply-To: <787AE7BB302AE849A7480A190F8B933008DE5EB3@OPEXCLILMA3.corporate.adroot.infra.ftgroup> (mohamed boucadair's message of "Tue, 12 Jul 2016 11:46:16 +0000")
Message-ID: <>
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux)
MIME-Version: 1.0
Content-Type: text/plain
X-Pobox-Relay-ID: FC9F033E-482E-11E6-94A4-C1836462E9F6-02397024!
Archived-At: <>
Cc: "" <>
Subject: Re: [Softwires] ietf-softwire: IPv4 + PSID primary key for lw4over6 binding
X-Mailman-Version: 2.1.17
Precedence: list
List-Id: softwires wg discussion list <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Tue, 12 Jul 2016 12:48:55 -0000

Hi Mohamed,

Thank you for your response.

On Tue 12 Jul 2016 13:46, <> writes:

> [Med] Actually, the data model allows to map a B4 to one or multiple
> softwires.
> The rationale for using binding-ipv6info as an index is to ease
> enforcing per-subscriber policies (e.g., limit the number of softwires
> per B4).

I am new to YANG; apologies in advance for making all of the beginner
mistakes.  My understanding of the specification

              list binding-entry {
                key "binding-ipv6info";
                description "binding entry";
                uses binding-entry;

was that "binding-ipv6info" uniquely identifies the B4 (because it's a
key within the binding-entry list).  Is that not the case?  If it is the
case, how is it possible for one B4 to have multiple softwires?

>> It seems to me that one CPE could very well have multiple slices of
>> IPv4 addresses.
> [Med] That's possible with the current data model: distinct binding
> entries that belong to the same B4 may have distinct IPv4
> addresses. Whether the same or distinct IPv4 addresses are bound to the
> same B4 is deployment-specific. IMHO, this should be considered with
> caution as it may lead to some applications failures e.g., RTP using
> IPv4@1 while companion RTCP flows are bound to another IPv4@2.

Indeed.  Happily for me though this complexity is on the B4 side of
things ;-)  By the time it gets to the AFTR I don't have any sort of
policy decisions to make there.  It is a very pleasant standard in that
regard :)