Re: [mpls] Ben's Comments on draft-ietf-mpls-sr-over-ip

"Adrian Farrel" <adrian@olddog.co.uk> Sun, 28 April 2019 20:37 UTC

Return-Path: <adrian@olddog.co.uk>
X-Original-To: mpls@ietfa.amsl.com
Delivered-To: mpls@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 8ECA61200FE; Sun, 28 Apr 2019 13:37:57 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.6
X-Spam-Level:
X-Spam-Status: No, score=-2.6 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_LOW=-0.7] autolearn=ham autolearn_force=no
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 gUHKKKZg9FOZ; Sun, 28 Apr 2019 13:37:55 -0700 (PDT)
Received: from mta5.iomartmail.com (mta5.iomartmail.com [62.128.193.155]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 11E5D120089; Sun, 28 Apr 2019 13:37:54 -0700 (PDT)
Received: from vs1.iomartmail.com (vs1.iomartmail.com [10.12.10.121]) by mta5.iomartmail.com (8.14.4/8.14.4) with ESMTP id x3SKblx8015489; Sun, 28 Apr 2019 21:37:52 +0100
Received: from vs1.iomartmail.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 63D972203C; Sun, 28 Apr 2019 21:37:52 +0100 (BST)
Received: from asmtp2.iomartmail.com (unknown [10.12.10.249]) by vs1.iomartmail.com (Postfix) with ESMTPS id 4EB282203A; Sun, 28 Apr 2019 21:37:52 +0100 (BST)
Received: from LAPTOPK7AS653V ([87.112.228.68]) (authenticated bits=0) by asmtp2.iomartmail.com (8.14.4/8.14.4) with ESMTP id x3SKbonw006724 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Sun, 28 Apr 2019 21:37:51 +0100
Reply-To: <adrian@olddog.co.uk>
From: "Adrian Farrel" <adrian@olddog.co.uk>
To: "'Benjamin Kaduk'" <kaduk@mit.edu>
Cc: <mpls@ietf.org>, <draft-ietf-mpls-sr-over-ip@ietf.org>, "'The IESG'" <iesg@ietf.org>
References: <07cc01d4f232$19436200$4bca2600$@olddog.co.uk> <20190420062140.GU51586@kduck.mit.edu>
In-Reply-To: <20190420062140.GU51586@kduck.mit.edu>
Date: Sun, 28 Apr 2019 21:37:50 +0100
Organization: Old Dog Consulting
Message-ID: <016701d4fe02$3fd3c5a0$bf7b50e0$@olddog.co.uk>
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: quoted-printable
X-Mailer: Microsoft Outlook 16.0
Thread-Index: AQJM5a1+ZtGjTh+JuRSQYSOhF4nciwIvuO3FpVCOHeA=
Content-Language: en-gb
X-Originating-IP: 87.112.228.68
X-Thinkmail-Auth: adrian@olddog.co.uk
X-TM-AS-GCONF: 00
X-TM-AS-Product-Ver: IMSVA-9.0.0.1623-8.2.0.1013-24580.002
X-TM-AS-Result: No--2.342-10.0-31-10
X-imss-scan-details: No--2.342-10.0-31-10
X-TMASE-Version: IMSVA-9.0.0.1623-8.2.1013-24580.002
X-TMASE-Result: 10--2.341700-10.000000
X-TMASE-MatchedRID: oTBA/+sdKabxIbpQ8BhdbPHkpkyUphL9f6/Md8Lb2l+IDxaki6CTmOaN 0ZrIlpD2EIySkWAxpKpbr1chLToaD3XZ29PKwetsnhHKNOYbLL6vzXNI4No01UJqedX9vt/Ztx6 Lm/haEDwFpt9nAr6Q+a4Wv5s6vlQf3XkI6jWXY3StxpVfAE2l79ZKsq3DGpalT8iIY3QZ4pdb2X fqc6ksXxvMVWzt3AmLBRxbqCB9WeuqPs53eDBzubu9iqQJLR0vfS0Ip2eEHnwa2S8rkvtFcbDsz p3K5gqDjoczmuoPCq0CoGxQy/O2vkjZ2E8SUSL4gYmiyD2ka/xPyvIHDhMoIGTwbNFDoDdu/K+z LM5d+O9Acpvv65tU9VH8LIbsffKLGJPB7neDaqsl4nVYwIRGQa1+3JijYrAOMqmhG/M0o4/0MHw zu2JowBZt/2+KOWzz
X-TMASE-SNAP-Result: 1.821001.0001-0-1-12:0,22:0,33:0,34:0-0
Archived-At: <https://mailarchive.ietf.org/arch/msg/mpls/1omfJr12bDjIBJLjF4h_SIHwF3s>
Subject: Re: [mpls] Ben's Comments on draft-ietf-mpls-sr-over-ip
X-BeenThere: mpls@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Multi-Protocol Label Switching WG <mpls.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/mpls>, <mailto:mpls-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/mpls/>
List-Post: <mailto:mpls@ietf.org>
List-Help: <mailto:mpls-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/mpls>, <mailto:mpls-request@ietf.org?subject=subscribe>
X-List-Received-Date: Sun, 28 Apr 2019 20:37:58 -0000

Hey Ben,

>>>   IP Header Fields:  When encapsulating an MPLS packet in UDP, the
>>>      resulting packet is further encapsulated in IP for transmission.
>>>      IPv4 or IPv6 may be used according to the capabilities of the
>>>      network.  The address fields are set as described in Section 2.
>>>
>>> (Does Section 2 say how to set the source address?)
>> 
>> Sure does.
>>       The tunnel selected MUST have its
>>       remote end point (destination) address equal to the address of the
>>       next SR-MPLS capable node along the path (i.e., the egress of the
>>       active node segment).
>
> I might still be missing it.  Is the idea that once you've selected a
> specific tunnel, that naturally will have a record of the source address
> corresponding to that tunnel?  (I only see a literal "remote end point
> (destination) address" in the quoted text, i.e., "source" or "local" do not
> appear.)

Sorry, I completely missed "source" in your question. Stupid of me.

That needs clarifying in the document, you're quite right.
The source address is set to an address of the encapsulating node. 7510 gives further advice when the UDP zero-checksum mode is used. 

This will show up in the next revision.

Best,
Adrian