Re: [Idr] Robert Wilton's No Objection on draft-ietf-idr-ext-opt-param-11: (with COMMENT)

John Scudder <jgs@juniper.net> Wed, 21 April 2021 21:55 UTC

Return-Path: <jgs@juniper.net>
X-Original-To: idr@ietfa.amsl.com
Delivered-To: idr@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id A7C4B3A3876; Wed, 21 Apr 2021 14:55:03 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.098
X-Spam-Level:
X-Spam-Status: No, score=-2.098 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=juniper.net header.b=ksZdp2wA; dkim=pass (1024-bit key) header.d=juniper.net header.b=kEewt+ls
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 Rfm-4W-dd09V; Wed, 21 Apr 2021 14:54:59 -0700 (PDT)
Received: from mx0b-00273201.pphosted.com (mx0a-00273201.pphosted.com [208.84.65.16]) (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 D80223A3873; Wed, 21 Apr 2021 14:54:58 -0700 (PDT)
Received: from pps.filterd (m0108157.ppops.net [127.0.0.1]) by mx0a-00273201.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 13LLrjmB008632; Wed, 21 Apr 2021 14:54:56 -0700
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=juniper.net; h=from : to : cc : subject : date : message-id : references : in-reply-to : content-type : mime-version; s=PPS1017; bh=wUfpteFHsfj4prVxxa/QU8sheNiTYqRUnmxnIaok87c=; b=ksZdp2wAKCafwJ9WRP3ra37wl1C8mTg5QBgdDj5EWhTMeiO8YkEaVCIRLPMni4EB4PQR lD1P5C6iD+jjyvF8rRJqP1PMKk5+TkbG53Q91PB9p85De02KH11lq4F3orAtJ530eKk2 0WVClOI5HdhYHj8HJ0pG8TXrErO2VCkLbHqdTrR3nMHvMDk4p7fphKCBr+RRkuff2gPA JpcPIqTO9D6lb7vXaIayxBKBWpCHxDI1WVmm1oeKT6SXDZ7hRpvOaUaF/dqrcdWN6YZt jPilQ1Qxx/3UvsC9ZnIgTe3XQJMopKk1CPzPh1lzZB2P0oGqbTbOQezADqc4s74OGdXe fA==
Received: from nam12-dm6-obe.outbound.protection.outlook.com (mail-dm6nam12lp2170.outbound.protection.outlook.com [104.47.59.170]) by mx0a-00273201.pphosted.com with ESMTP id 382ac4j3cm-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 21 Apr 2021 14:54:56 -0700
ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=fmYVqGmuCJ1bresr6bxwzgTd4MIxYlB/mFI1rI2+VcYg43ijNf5IbD3Zt4OBZfa/a6zSgN7Q0gkt8+R5qIduiyYKumAAejr2ulQcEKSgMVQtoT/SXloqxniVIV9LmyAIJaRyPMKw35ubBgYjmUBkHbBjG4HsM+Y6uHahvKBUkDMkKpL3al1Eyw4LCk4cukDDSKl+GcaqV6xJ7j3+MVntjL2pc2j2rz5UDg1ll4/BgYCghZB5v9UUovqeS2F5TiiLfLouvqbQFtA5muw/f09bgWsgJhau1ROVaE2fp0ErPCb10dKMD1kcV306krI20jhtiQekMiRWrfSo/k63abfn6g==
ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=wUfpteFHsfj4prVxxa/QU8sheNiTYqRUnmxnIaok87c=; b=YbWtuIidAQZXXsCnqYTZTIL/kykmMgWkMxAZ0BwRHRfKXftOVDzkOs7ZuubMqQLirMvMF5z7o3gqamYHReCuk7Lk9lgmDFxfx0UsAUhgetMeDCuIAbz3y1U95DTkrP2Zeb5dLmTuRTsxfIEUok0V1BHywFMQp4KJT55ZZyiJ8jlytkztdtcLhdjZQkQKqx3HMxDzcVSZEpOvkeTnzVw2RGTrJZiVOSJhkLnqLl/GfsxYEjjxZHUJs8CNUqPrgAuDG7nz6YfEnqs9HNOcY3KDZLvrPtubVuq95y6lHV6+ZaWmWKVEPXHQobTMLBs2YEt939rwpzRTueSG7RbJnsmqSw==
ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=juniper.net; dmarc=pass action=none header.from=juniper.net; dkim=pass header.d=juniper.net; arc=none
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=juniper.net; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=wUfpteFHsfj4prVxxa/QU8sheNiTYqRUnmxnIaok87c=; b=kEewt+lsNbqDceFV/SlrER5KCv5btwvdKaW3j/8AuGHYXWAoqJWZ86y7bEHcEZL+rXGxCwAJyWfDXhbDun2xvSKsIy6Xs0dUwfXQYYpxX4gFNRY/q68rGYcXBA7kgFvxGI19b0P7LWQfFIRADzoZpQJes1q7edSBgVf17Rc5NbI=
Received: from BN8PR05MB6098.namprd05.prod.outlook.com (2603:10b6:408:45::29) by BN3PR05MB2772.namprd05.prod.outlook.com (2a01:111:e400:7bb7::24) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4065.6; Wed, 21 Apr 2021 21:54:54 +0000
Received: from BN8PR05MB6098.namprd05.prod.outlook.com ([fe80::4d47:2d3c:d3c5:2e14]) by BN8PR05MB6098.namprd05.prod.outlook.com ([fe80::4d47:2d3c:d3c5:2e14%3]) with mapi id 15.20.4065.021; Wed, 21 Apr 2021 21:54:54 +0000
From: John Scudder <jgs@juniper.net>
To: Robert Wilton <rwilton@cisco.com>
CC: The IESG <iesg@ietf.org>, "draft-ietf-idr-ext-opt-param@ietf.org" <draft-ietf-idr-ext-opt-param@ietf.org>, "idr-chairs@ietf.org" <idr-chairs@ietf.org>, "idr@ietf. org" <idr@ietf.org>, Hares Susan <shares@ndzh.com>, "aretana.ietf@gmail.com" <aretana.ietf@gmail.com>
Thread-Topic: Robert Wilton's No Objection on draft-ietf-idr-ext-opt-param-11: (with COMMENT)
Thread-Index: AQHXMpC08mMk9GSEe0KueMJz2OLtNqq/jMmA
Date: Wed, 21 Apr 2021 21:54:53 +0000
Message-ID: <19209EFB-262A-4D6B-8199-D21AE309CBB4@juniper.net>
References: <161855750520.19502.8074982121802045183@ietfa.amsl.com>
In-Reply-To: <161855750520.19502.8074982121802045183@ietfa.amsl.com>
Accept-Language: en-US
Content-Language: en-US
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
x-mailer: Apple Mail (2.3608.120.23.2.4)
authentication-results: cisco.com; dkim=none (message not signed) header.d=none;cisco.com; dmarc=none action=none header.from=juniper.net;
x-originating-ip: [163.116.133.117]
x-ms-publictraffictype: Email
x-ms-office365-filtering-correlation-id: 9e28df8e-d252-4a9b-1da4-08d9051018b5
x-ms-traffictypediagnostic: BN3PR05MB2772:
x-microsoft-antispam-prvs: <BN3PR05MB2772B787706E6D96DA56A8F7AA479@BN3PR05MB2772.namprd05.prod.outlook.com>
x-ms-oob-tlc-oobclassifiers: OLM:10000;
x-ms-exchange-senderadcheck: 1
x-microsoft-antispam: BCL:0;
x-microsoft-antispam-message-info: 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
x-forefront-antispam-report: CIP:255.255.255.255; CTRY:; LANG:en; SCL:1; SRV:; IPV:NLI; SFV:NSPM; H:BN8PR05MB6098.namprd05.prod.outlook.com; PTR:; CAT:NONE; SFS:(4636009)(39860400002)(366004)(136003)(346002)(376002)(396003)(8936002)(66446008)(71200400001)(66476007)(5660300002)(66556008)(64756008)(6916009)(83380400001)(76116006)(26005)(186003)(478600001)(6506007)(2616005)(4326008)(166002)(53546011)(91956017)(33656002)(66946007)(6486002)(2906002)(54906003)(38100700002)(122000001)(8676002)(316002)(6512007)(86362001)(36756003)(45980500001); DIR:OUT; SFP:1102;
x-ms-exchange-antispam-messagedata: =?utf-8?B?RVNPemdaNVFLTVpnNlhyL1R6c1JaVzZxTWpjei9tT2UwVzZFQklzREE1TVoy?= =?utf-8?B?dVlCS1B2N2lsOTZ4dDkwQ1d0TjFHSXlCbUZFSXlzbEkzcXRhdS9KMzI3Uk5a?= =?utf-8?B?TVU1QXB6NVJKdGR3RVN6NFNyMEI3OUZSYmlheE5qeS9MZmU3UExYZUsyRlRt?= =?utf-8?B?cEU3eVhYa0F2eDdxdzhuOEVaWXh5dFBNZmh6Y1dPRHhqdjQrMGNadXdDakFJ?= =?utf-8?B?S21IWDJmN2w2Q0d3UDF3OFdBdjNxOWZBc3VOT1ozRHkrdjdtQXV1bVB0Z01J?= =?utf-8?B?aDRkM3VKOWdoZEFMVmQvUFNpc2M2WXYreW1mdkIyNkQwVnlzeDc0TVlsSjVE?= =?utf-8?B?MVYzbDhZN1JpTWRETHZkSk96WXJUdEhYSVNRcllNSjF2NUYrKzczR3FWTmtx?= =?utf-8?B?VUZBckVhWUdHV2k1THRQOUVHUGVPSHJuZ0NMdHAwb1ViVHpHQTdVNWUxLytI?= =?utf-8?B?WXNnRjNXKzgwNzBNeTdZdjVwbE5ZYjdBaWdLMkpvR1BjdWJENHpXdzVBVUFB?= =?utf-8?B?RU83SlhWUnN2ZHVkNkhXeVo2aFFqMjR5VDZraTdKOU5ISnY2eWEycFREMGsx?= =?utf-8?B?d2htQWZ2NVNKaHcvR0dFOU9BOFZiU3NVM1U0eGJ2djVuVVM2Y0MzUnhGZWpO?= =?utf-8?B?Vm9LVjZzcUtRQmErYlhpczZVVU9GMllsSTRMM0t1cTJJRVBtUC91WGJNSjhr?= =?utf-8?B?OS9aT0Z5R0h5NUlEeFVhRDFmaGo1T053cnNJQ0VqdmE0WTRmeEkrM2VrcEtP?= =?utf-8?B?M1ZXMU1tdnNwN1hwN01sMUtWbE9aQ1B0UThrZHBCV1RsNDdRZFRlTDUraXlv?= =?utf-8?B?MlUrdUd5S1dGSUgrdTBhUVdERXlhK0Y1T2pjZVZsYUtLRzlLZUpsYmlnZ0E1?= =?utf-8?B?cFhlUU5Ub05CVWNtNTgrRENHS0dLRzNISERLb2xGd2V0YWg4b25hT2xPbTds?= =?utf-8?B?ditPaXhEMEREcVZaNHV2VVRmZkw0azhHdmlmNXhFR0dnMk52dkFxcGt1dkox?= =?utf-8?B?R2wzcUFmdEY3SThjb2tVQVVyRWxkS0d2M1pEUUJTZHZKMDBiRmtEOTI2TnBL?= =?utf-8?B?czJiT1BKTkNIRUx6ZEZHdmkxTXpoL1owMTE4UGxURDYwVmZ2T3ZrVWtRZlQ0?= =?utf-8?B?RHhOd1N5UDdFdTNoTlRXeFJVV2FYRnZveFVScGRZb3Y3WitFQXhjQnhzL3VY?= =?utf-8?B?SktudHpJOExkamJUbnFlMTdCbFAyN3NUUEFSVkxOa2tJbHhnYnEwamNBaXdz?= =?utf-8?B?Snd5QkR3QnAxNUd4cTl4OTZGRXY5NjIyVWdJZHVpOEp1U3VyM1pydS9iTGtq?= =?utf-8?B?ZndLSE0yNXBINlFpSU5ybmNYZGl6ZkI1RkI3TXdVbHYxR1ZVS0xNYW9NcElx?= =?utf-8?B?UjlqdjZ2RXBmS05wQk9yV1ZKU3krQ0hzUHVHM0cvd3RHbmxTY3FrVUpPZmMz?= =?utf-8?B?RHV4WjY2WklNRmNyQTBHTE9SRjVCZ1JMYWlNTi9Gak4zanF3WHBod3NrbTY2?= =?utf-8?B?cXNTSHorN3hQcWlkZUs2eE5EOElBbktHNTQvRGtWbTlRRDVnS0luOURTUWFj?= =?utf-8?B?VFpyNDJTQkhBemRPMDhPUUs3bVJYc29QdHNJczh0NEUzc1N3QXFkMUFrNVBy?= =?utf-8?B?cE4yeWk5clNIZ0xHWWZCL29WMnRJekt4eldEdVBPL1NmNHg3MXA4dDhjQ29y?= =?utf-8?B?TlU1cGFPbFpacFhQQXo2UW9KdnVBbGpIb0NyQkJTS2ppMGZMbXpoN1l6ZDE3?= =?utf-8?B?T1h4bzhsR2pwZWhCTDRERCt1NTZ4OHQrK2NlMWZNdHV6NlBpbW5hUnc2OGZl?= =?utf-8?B?WWJUNDZKZGJFd2ZONmpYUT09?=
x-ms-exchange-transport-forked: True
Content-Type: multipart/alternative; boundary="_000_19209EFB262A4D6B8199D21AE309CBB4junipernet_"
MIME-Version: 1.0
X-OriginatorOrg: juniper.net
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-AuthSource: BN8PR05MB6098.namprd05.prod.outlook.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 9e28df8e-d252-4a9b-1da4-08d9051018b5
X-MS-Exchange-CrossTenant-originalarrivaltime: 21 Apr 2021 21:54:53.9785 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: bea78b3c-4cdb-4130-854a-1d193232e5f4
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: mbqOi+EB4/7aDZB06i/EMVp2wuxycoxcXKoppwMzV/QF3fvgdhwOOHhfHzJKmLVD
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN3PR05MB2772
X-Proofpoint-GUID: GFC53Q3dS9zazX6L7SU3yJF9_4UwwfY5
X-Proofpoint-ORIG-GUID: GFC53Q3dS9zazX6L7SU3yJF9_4UwwfY5
X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391, 18.0.761 definitions=2021-04-21_06:2021-04-21, 2021-04-21 signatures=0
X-Proofpoint-Spam-Details: rule=outbound_spam_notspam policy=outbound_spam score=0 mlxscore=0 suspectscore=0 phishscore=0 mlxlogscore=948 clxscore=1011 adultscore=0 impostorscore=0 spamscore=0 bulkscore=0 lowpriorityscore=0 priorityscore=1501 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104060000 definitions=main-2104210144
Archived-At: <https://mailarchive.ietf.org/arch/msg/idr/LOB9rjIqtZ9A23Q1qqxD9i9iTvI>
Subject: Re: [Idr] Robert Wilton's No Objection on draft-ietf-idr-ext-opt-param-11: (with COMMENT)
X-BeenThere: idr@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Inter-Domain Routing <idr.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/idr>, <mailto:idr-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/idr/>
List-Post: <mailto:idr@ietf.org>
List-Help: <mailto:idr-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/idr>, <mailto:idr-request@ietf.org?subject=subscribe>
X-List-Received-Date: Wed, 21 Apr 2021 21:55:04 -0000

Thanks for your comments, Rob.

On Apr 16, 2021, at 3:18 AM, Robert Wilton via Datatracker <noreply@ietf.org<mailto:noreply@ietf.org>> wrote:
...
----------------------------------------------------------------------
COMMENT:
----------------------------------------------------------------------

Hi,

Thanks for this document, I found it relatively easy to read and understand
even though I'm not particularly familiar with BGP.

There were a couple of areas of the document that I found slightly confusing,
or inconsistent.  However, I do not feel strongly on these and will leave it to
the authors/WG to decide how to handle these:

1. I found it slightly inconsistent that section 2 states:

  In the event that the length of Optional Parameters in the BGP OPEN
  message does not exceed 255, the encodings of the base BGP
  specification [RFC4271] MUST be used without alteration.

and at the same time, section 3 states:

  It is not considered an error to receive an OPEN message whose
  Extended Optional Parameters Length value is less than or equal to
  255.

To me, I think this means that it would be better as a SHOULD rather than a
MUST, or perhaps change section 3 to indicate that it a non-conformant
encoding, but one that should be handled anyway.

It’s a MUST and not a SHOULD because I couldn’t think of any guidance for when an implementor should violate it (I can’t think of a MAY clause to add). The stuff in §3 is more-or-less a statement of Postel’s Law [*] and further, is there to potentially enable a future deprecation of the RFC 4271 length encoding as I mentioned in my reply to Warren’s DISCUSS. Now that I’m reviewing the text for the first time in a while, I notice that the quoted sentence in §3 is redundant with this from §2:


   In the event that the length of Optional Parameters in the BGP OPEN
   message does not exceed 255, the encodings of the base BGP
   specification [RFC4271<https://datatracker.ietf.org/doc/html/rfc4271>] MUST be used without alteration.  (However,
   an implementation MUST accept an OPEN message that uses the encoding
   of this specification even if the length of Optional Parameters is
   255 or less.)


The sentence in parentheses, that is. I don’t think it does any harm to repeat the admonition, though, so I’m going to leave it as written.

2.
  In parsing an OPEN message, if the one-octet "Optional Parameters
  Length" field is non-zero, a BGP speaker MUST use the value of the
  octet following the one-octet "Optional Parameters Length" field to
  determine both the encoding of the Optional Parameters length and the
  size of the "Parameter Length" field of individual Optional
  Parameters.  If the value of this field is 255, then the encoding
  described above is used for the Optional Parameters length.
  Otherwise the encoding defined in [RFC4271] is used.

I wasn't really sure what this paragraph was stating beyond what had already
been stated previously in section 2, hence I'm wondering if it is required at
all.

It’s arguably redundant, but I’m not completely sure myself (the preceding text talks about encoding, this paragraph talks about parsing), so I’d like to leave it in. I do agree it can be made clearer though.

If it does remain then I found the reference to "Optional Parameters
Length" is perhaps not as clear as it could be, and perhaps it would be better
to refer to the "Non-Ext OP Len" field (as per the diagram), and perhaps to the
"Non-Ext OP Type" field rather than the 'octet following the one-octet
"Optional Parameters Length" field'.

Good point, that text always was a little tortured. It now says:


   In parsing an OPEN message, if the one-octet "Optional Parameters
   Length" field (labeled "Non-Ext OP Len." in Figure 1) is non-zero, a
   BGP speaker MUST use the value of the octet following the one-octet
   "Optional Parameters Length" field (labeled "Non-Ext OP Type" in
   Figure 1) to determine both the encoding of the Optional Parameters
   length and the size of the "Parameter Length" field of individual
   Optional Parameters.  If the value of the "Non-Ext OP Type" field is
   255, then the encoding described above is used for the Optional
   Parameters length.  Otherwise the encoding defined in [RFC4271] is
   used.


Regards,
Rob

Thanks,

—John

[*] Yes, I realize some people have strong feelings about what Postel did, and didn’t, intend by it.