Re: [CCAMP] Magnus Westerlund's Discuss on draft-ietf-ccamp-rsvp-te-bandwidth-availability-14: (with DISCUSS)

"Yemin (Amy)" <amy.yemin@huawei.com> Thu, 11 April 2019 15:03 UTC

Return-Path: <amy.yemin@huawei.com>
X-Original-To: ccamp@ietfa.amsl.com
Delivered-To: ccamp@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 2E9591206AE; Thu, 11 Apr 2019 08:03:25 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -4.2
X-Spam-Level:
X-Spam-Status: No, score=-4.2 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] 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 QyTUTagMqI3y; Thu, 11 Apr 2019 08:03:23 -0700 (PDT)
Received: from huawei.com (lhrrgout.huawei.com [185.176.76.210]) (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 DBA831203A4; Thu, 11 Apr 2019 08:03:21 -0700 (PDT)
Received: from LHREML714-CAH.china.huawei.com (unknown [172.18.7.107]) by Forcepoint Email with ESMTP id D9D6EA652E17F4F8A760; Thu, 11 Apr 2019 16:03:19 +0100 (IST)
Received: from lhreml703-chm.china.huawei.com (10.201.108.52) by LHREML714-CAH.china.huawei.com (10.201.108.37) with Microsoft SMTP Server (TLS) id 14.3.408.0; Thu, 11 Apr 2019 16:03:19 +0100
Received: from lhreml703-chm.china.huawei.com (10.201.108.52) by lhreml703-chm.china.huawei.com (10.201.108.52) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1713.5; Thu, 11 Apr 2019 16:03:19 +0100
Received: from DGGEMM424-HUB.china.huawei.com (10.1.198.41) by lhreml703-chm.china.huawei.com (10.201.108.52) with Microsoft SMTP Server (version=TLS1_0, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA_P256) id 15.1.1713.5 via Frontend Transport; Thu, 11 Apr 2019 16:03:18 +0100
Received: from DGGEMM528-MBX.china.huawei.com ([169.254.8.72]) by dggemm424-hub.china.huawei.com ([10.1.198.41]) with mapi id 14.03.0415.000; Thu, 11 Apr 2019 23:03:12 +0800
From: "Yemin (Amy)" <amy.yemin@huawei.com>
To: Magnus Westerlund <magnus.westerlund@ericsson.com>, The IESG <iesg@ietf.org>
CC: "draft-ietf-ccamp-rsvp-te-bandwidth-availability@ietf.org" <draft-ietf-ccamp-rsvp-te-bandwidth-availability@ietf.org>, "Daniele Ceccarelli" <daniele.ceccarelli@ericsson.com>, "ccamp-chairs@ietf.org" <ccamp-chairs@ietf.org>, "ccamp@ietf.org" <ccamp@ietf.org>
Thread-Topic: Magnus Westerlund's Discuss on draft-ietf-ccamp-rsvp-te-bandwidth-availability-14: (with DISCUSS)
Thread-Index: AQHU7fO86dSEr/UGs0ayq4z5V/xqkaY26NxP
Date: Thu, 11 Apr 2019 15:03:12 +0000
Message-ID: <9C5FD3EFA72E1740A3D41BADDE0B461FCFBDC2AE@DGGEMM528-MBX.china.huawei.com>
References: <155471841105.6393.10821256003431720439.idtracker@ietfa.amsl.com>
In-Reply-To: <155471841105.6393.10821256003431720439.idtracker@ietfa.amsl.com>
Accept-Language: zh-CN, en-US
Content-Language: zh-CN
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
x-originating-ip: [10.203.246.156]
Content-Type: text/plain; charset="gb2312"
Content-Transfer-Encoding: base64
MIME-Version: 1.0
X-CFilter-Loop: Reflected
Archived-At: <https://mailarchive.ietf.org/arch/msg/ccamp/NYHny6MKzt_TnmeJO2RDrq06udk>
Subject: Re: [CCAMP] Magnus Westerlund's Discuss on draft-ietf-ccamp-rsvp-te-bandwidth-availability-14: (with DISCUSS)
X-BeenThere: ccamp@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Discussion list for the CCAMP working group <ccamp.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/ccamp>, <mailto:ccamp-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/ccamp/>
List-Post: <mailto:ccamp@ietf.org>
List-Help: <mailto:ccamp-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/ccamp>, <mailto:ccamp-request@ietf.org?subject=subscribe>
X-List-Received-Date: Thu, 11 Apr 2019 15:03:27 -0000

Hi Magnus, 

Thanks for the comments, please see reply inline below. 

BR,
Amy
________________________________________
发件人: Magnus Westerlund via Datatracker [noreply@ietf.org]
发送时间: 2019年4月8日 18:13
收件人: The IESG
抄送: draft-ietf-ccamp-rsvp-te-bandwidth-availability@ietf.org; Daniele Ceccarelli; ccamp-chairs@ietf.org; daniele.ceccarelli@ericsson.com; ccamp@ietf.org
主题: Magnus Westerlund's Discuss on draft-ietf-ccamp-rsvp-te-bandwidth-availability-14: (with DISCUSS)

Magnus Westerlund has entered the following ballot position for
draft-ietf-ccamp-rsvp-te-bandwidth-availability-14: Discuss

When responding, please keep the subject line intact and reply to all
email addresses included in the To and CC lines. (Feel free to cut this
introductory paragraph, however.)


Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html
for more information about IESG DISCUSS and COMMENT positions.


The document, along with other ballot positions, can be found here:
https://datatracker.ietf.org/doc/draft-ietf-ccamp-rsvp-te-bandwidth-availability/



----------------------------------------------------------------------
DISCUSS:
----------------------------------------------------------------------

Section 3.1:

      Availability (4 octets): a 32-bit floating point number describes
      the decimal value of availability requirement for this bandwidth
      request. The value MUST be less than 1and is usually expressed in
      the value of 0.99/0.999/0.9999/0.99999.

It appears that this format has some very clear limitations when it comes to
store availability numbers. Assuming that this 32-bit float is an IEEE-754
representation which should be explicitly stated.

In that case representing availabilities higher than 0.999999 starts to
introduce significant errors in relation to intended precision. Intended value
Error                                             Actual value 0.999999
 -1.3278961181640625E-8              0.999998986721038818359375 0.9999999
 -1.920928955078125E-8                0.99999988079071044921875 0.99999999
1E-8                                                   1 (Which is not allowed)

So at a minimal the limitations for what is practical to express needs to be
provided. Secondly, are this range sufficient in all cases?
[Amy] The floating point number may not be the perfect unit. But since the OSPF extension RFC8330 use the floating-point number, we would like to continue using it. 
Regarding the range, normally five 9s 0.99999 is highest value in telecom network, that's 5 minutes outage in a year.
So floating point is capable to represent this range.