Re: [spring] We don't seem to be following our processes (Re: Network Programming - Penultimate Segment Popping)

Robert Raszuk <robert@raszuk.net> Sat, 07 December 2019 11:47 UTC

Return-Path: <robert@raszuk.net>
X-Original-To: spring@ietfa.amsl.com
Delivered-To: spring@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 467CE120227 for <spring@ietfa.amsl.com>; Sat, 7 Dec 2019 03:47:16 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.999
X-Spam-Level:
X-Spam-Status: No, score=-1.999 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HTML_MESSAGE=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=raszuk.net
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id QT4WDfo9oQ_I for <spring@ietfa.amsl.com>; Sat, 7 Dec 2019 03:47:14 -0800 (PST)
Received: from mail-qv1-xf35.google.com (mail-qv1-xf35.google.com [IPv6:2607:f8b0:4864:20::f35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 885CA120220 for <spring@ietf.org>; Sat, 7 Dec 2019 03:47:14 -0800 (PST)
Received: by mail-qv1-xf35.google.com with SMTP id t7so936349qve.4 for <spring@ietf.org>; Sat, 07 Dec 2019 03:47:14 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=raszuk.net; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=h/8mRijPVRPN2uUYgPA0jDTqogU3n+bWTeUui94yFmw=; b=dcDYMVqlR7mABnGp9wyAXug3XDqk7bt5ZjZ8RPYW7Y4gqiLIgqAaXitgX5d2lSmFFL jb3809Xf+fj/EAAxKNX5FW8xSVwJbfUjujXNuTDlbU48h6M8v4O/+2EpN6SslgnqPw1Z jo+h4WDF2XjBhe/Vn/Go0ASJstaHIUJcHaiVliGv7T3cDl74ttw0PP5eQ61CbYHGSlk6 zID5TWzi1WgD7GM9JdvczP4lHovAeYYlMH3xSDPgjC9RK65E5D2h7vqHmgMCN/E/n/Fb HI+rXTN0Eriqy+quZ5rjWjqzAvoUYLkZ8HgF1jeNznGwaDMkRMtnpmRDC8FqeRm/AntQ GKZg==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=h/8mRijPVRPN2uUYgPA0jDTqogU3n+bWTeUui94yFmw=; b=JD2gQgMZOlCCIVgklUgVlL3OVwxmGWz16A0nAUIti4TZDjTSqKOfjRnkU5i2j4IK+V GiLQ7B6JGig1d3EVtuieOyuhxuaR1HcqpWatjmc/q5H5ad4W7S5hjaLUNEKjsKoLuW30 fwuLR+8tAuXx0rkmBgsmpomYolhgJsI/JMDfoD7mlngf0GQmVkUSD6WfJBIzI2x81+1i QXRYpaeOxjposw2agUdrb2EK8XadWbrG8dNp1aSpyQljg6gAW5F+vToloAIwVfGeIYwX UTWfcS8OwKBFDPD2kU8VF2CxG9aopkqij+kJ6CTAieqRohceg9SOrFX24cldQa9DqM1m sSPA==
X-Gm-Message-State: APjAAAXewF2HcmpGfsl8GVW70Wf5DLm2aXfxsW5wsfx7BK65ryExhy5k frf6dSoCikHiqkYEsW0V7kPux7gDyCRYn+zpZniabg==
X-Google-Smtp-Source: APXvYqzH+uyqovV4YsU0/rAH/HK+q75U2RJXpfz62D3Oo0hCbGgaVLDxfEcz5HaLsO8CWcdCitmDjiQuFLm71aqPaLg=
X-Received: by 2002:a0c:8a31:: with SMTP id 46mr17073470qvt.8.1575719233222; Sat, 07 Dec 2019 03:47:13 -0800 (PST)
MIME-Version: 1.0
References: <f2a0ad13-0eba-6f5a-1d3c-e45e2780f201@si6networks.com> <D666EA6E-E8E9-439A-9CDE-20857F03CB65@employees.org> <4255AD3B-379C-45BF-96E1-D3D9141A684F@liquidtelecom.com> <d59de54e-c7f8-be67-1e77-b051735d40a6@gmail.com> <3bce7b18-ea45-d29f-5dfb-1d3258b07d1e@si6networks.com> <c6e1f690-b0bf-9f45-8fa7-92ed182c5b04@gmail.com> <a2cc5cbd-ac06-e193-307c-3ffe5b21b0b1@si6networks.com>
In-Reply-To: <a2cc5cbd-ac06-e193-307c-3ffe5b21b0b1@si6networks.com>
From: Robert Raszuk <robert@raszuk.net>
Date: Sat, 7 Dec 2019 12:47:05 +0100
Message-ID: <CAOj+MMGaSooQbsRzJC2yCrFeHYFvbQgLY=merdwzjBFNXAj17g@mail.gmail.com>
To: Fernando Gont <fgont@si6networks.com>
Cc: Brian E Carpenter <brian.e.carpenter@gmail.com>, Andrew Alston <Andrew.Alston@liquidtelecom.com>, Ole Troan <otroan@employees.org>, Ron Bonica <rbonica=40juniper.net@dmarc.ietf.org>, SPRING WG <spring@ietf.org>, 6man <6man@ietf.org>, "int-ads@ietf.org" <int-ads@ietf.org>, rtg-ads <rtg-ads@ietf.org>, Bob Hinden <bob.hinden@gmail.com>
Content-Type: multipart/alternative; boundary="000000000000298f1305991bb9da"
Archived-At: <https://mailarchive.ietf.org/arch/msg/spring/i0faTfqB-NduzI2VyMyQ6R60dQw>
Subject: Re: [spring] We don't seem to be following our processes (Re: Network Programming - Penultimate Segment Popping)
X-BeenThere: spring@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: "Source Packet Routing in NetworkinG \(SPRING\)" <spring.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/spring>, <mailto:spring-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/spring/>
List-Post: <mailto:spring@ietf.org>
List-Help: <mailto:spring-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/spring>, <mailto:spring-request@ietf.org?subject=subscribe>
X-List-Received-Date: Sat, 07 Dec 2019 11:47:16 -0000

Hey Fernando,

(pop when you are the destination but SL!=0 is essentially 'in the
> network removal')


I was trying to stay out of this but I have one fundamental question or
observation this entire debate seems to be about.

In the context of SRv6 there are two parallel discussions

*Discussion #1* - It is about inserting, modifying or deleting SRH by nodes
which are not in the outer IPv6 header of the packet

*Discussion #2* - It is about RFC8200 compliance when the node doing
insertion of SRH is *the* destination of the packet as read verbatim from
the outer IPv6 header.

*Discussion #3* - It is about RFC8200 compliance when the node doing
modification or removal of SRH is *the* destination of the packet as read
verbatim from the outer IPv6 header.

First let's observe that RFC8200 is only defining the behaviour regarding
EH processing in the context of destination address of the IPv6 outer
header: "identified in the Destination Address field of the IPv6
header.identified in the Destination Address field of the IPv6 header. "

Therefore stating that SL value before local decrement matters in this in
respect to being compliant to the IPv6 RFC is at best just an individual
interpretation. Besides the pseudocode says it black and white "S14.1.   If
(updated SL == 0) {". We do all sort of processing decision after
decrementing the values ... think TTL :)

So back to reality ...

*Discussion #1* - I think we all agree that to accomplish that RFC8200
would need to be updated.

*Discussion #2* - I think we also all agree here that to accomplish this
RFC8200 would need to be updated as it does says clearly that "Each
extension header should occur at most once, ..."

*Discussion #3* - It seems clearly that there is no issue with compliance
with RFC8200 and that if penultimate segment midpoint decides or is
instructed to pop SRH it sure can and still be 100% compliant with current
wording of RFC8200.

So other then so much foam what is this debate all about ?

Cheers,
Robert.