Re: [CCAMP] I-D Action: draft-lee-ccamp-wson-impairment-yang-00.txt

"Beller, Dieter (Nokia - DE/Stuttgart)" <dieter.beller@nokia.com> Fri, 19 October 2018 15:51 UTC

Return-Path: <dieter.beller@nokia.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 7C891130F5F for <ccamp@ietfa.amsl.com>; Fri, 19 Oct 2018 08:51:12 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.953
X-Spam-Level:
X-Spam-Status: No, score=-1.953 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.064, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_PASS=-0.001, T_KAM_HTML_FONT_INVALID=0.01, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (1024-bit key) header.d=nokia.onmicrosoft.com
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 B2rC5i60Rh2N for <ccamp@ietfa.amsl.com>; Fri, 19 Oct 2018 08:51:08 -0700 (PDT)
Received: from EUR03-AM5-obe.outbound.protection.outlook.com (mail-eopbgr30093.outbound.protection.outlook.com [40.107.3.93]) (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 32106130F5E for <ccamp@ietf.org>; Fri, 19 Oct 2018 08:51:08 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nokia.onmicrosoft.com; s=selector1-nokia-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=A1FOHYHk1TY5o5Ri0tqC+9GVKAjiVdJw0AYZfH1dG6U=; b=PS5CjOCnSn17BmMoph8nYMAGU+6jzMfrJfONEO32pFN0O5gAdN+W7PTX+h58XytEjs/R+cGjFmsee3kMNtKPxrcZ1z18fidUsAKwF3SDuFDGr50kfJFn9gwj33FO8gP352mO3QI2SNm6r3Q6m8Roa87V89y8J/CVzS10/YTgu7Y=
Received: from AM5PR0701MB2433.eurprd07.prod.outlook.com (10.169.153.14) by AM5PR0701MB2546.eurprd07.prod.outlook.com (10.173.92.14) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.1250.18; Fri, 19 Oct 2018 15:51:05 +0000
Received: from AM5PR0701MB2433.eurprd07.prod.outlook.com ([fe80::e925:a4b6:284d:f76a]) by AM5PR0701MB2433.eurprd07.prod.outlook.com ([fe80::e925:a4b6:284d:f76a%3]) with mapi id 15.20.1250.028; Fri, 19 Oct 2018 15:51:05 +0000
From: "Beller, Dieter (Nokia - DE/Stuttgart)" <dieter.beller@nokia.com>
To: Leeyoung <leeyoung@huawei.com>, Jonas Mårtensson <jonas.martensson@ri.se>, "Zhenghaomian (Zhenghaomian, Optical &Microwave Technology Research Dept)" <zhenghaomian@huawei.com>
CC: "ccamp@ietf.org" <ccamp@ietf.org>
Thread-Topic: [CCAMP] I-D Action: draft-lee-ccamp-wson-impairment-yang-00.txt
Thread-Index: AQHUYf38AJHH9ZW/WE+VJQPmsLe0P6Ubp8IAgATQq4CAABVpgIAA8/AAgABI8oCAAJBpgIAEZ/aA
Date: Fri, 19 Oct 2018 15:51:05 +0000
Message-ID: <4f7eb2c3-4fd2-1f09-2dd0-3c9082df56ba@nokia.com>
References: <153577337941.29073.132620799131044718@ietfa.amsl.com> <3be83a17-85af-c425-5228-b4b28eb48598@nokia.com> <2034a3e97fd34423817dafc5bb0800f9@ri.se> <7AEB3D6833318045B4AE71C2C87E8E173D068BD0@sjceml521-mbx.china.huawei.com> <38f96492-312e-8c45-b52f-8a09096bbee9@nokia.com> <7AEB3D6833318045B4AE71C2C87E8E173D07A0E5@sjceml521-mbx.china.huawei.com> <fb323dd848714af683ed6ee88be7b4d0@ri.se> <4c14cb75-02e5-ef5a-3e15-4b74ed1063be@nokia.com> <7AEB3D6833318045B4AE71C2C87E8E173D07B6C6@sjceml521-mbx.china.huawei.com>
In-Reply-To: <7AEB3D6833318045B4AE71C2C87E8E173D07B6C6@sjceml521-mbx.china.huawei.com>
Accept-Language: en-US
Content-Language: en-US
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
x-originating-ip: [135.245.212.163]
user-agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1
x-clientproxiedby: AM6PR03CA0028.eurprd03.prod.outlook.com (2603:10a6:20b::41) To AM5PR0701MB2433.eurprd07.prod.outlook.com (2603:10a6:203:f::14)
authentication-results: spf=none (sender IP is ) smtp.mailfrom=dieter.beller@nokia.com;
x-ms-exchange-messagesentrepresentingtype: 1
x-ms-publictraffictype: Email
x-microsoft-exchange-diagnostics: 1; AM5PR0701MB2546; 6:80+3ImBD64huqFlPxipR1xttjsBkF3Xf/CJ4Z/ZiTSG2qN8+2u5NIPRnOcwOfarzZPQPbLH540oTBaeENPVMdrofkLdAZy34AoicmSaXQ1JCo89RPXXbIOkuCvQ/ou5/0RTmvvriItJkdAGD7el3yZ4kXvuodssvjJbZB+79fmRyldYTUtiQ6SsRiHmH9EdxWZzeAHd+Jl1ZIBoaUZchYk4pCJ3lR6jjq3AmXrzQbD22gJE4JWvGKl8pBsbrSID3gRwTWsHf93JMiL8LwTl/EPwvTMJKk2Raa/Wikpxnn23I2Nagki51ColnZvw28NjTtd+/qNkcSIAV3YqXdbXxIG1oJm36yhQPvuqq1MMZ4RXtqCEn6oDaDrBI1mWznfcCUg4G5LK9nGsPuLn5otKLJG6NmTZ8oPMfKhVc9V+1lRTp39QpvAntWMxQmqX3kEaiXRTkPN2dkDQ2z3eWZNQDdw==; 5:wlRNbNgIctWdSy2JdacXbuhsPIyuTXKvUB6a74zYILFzEAAST/XysX7JvA9J53C15X7tG4CL4oej9CnZNKcsXWNUUmBd0rErkrHiEkt2QQg9VYIyDwxtJftQf1OleDAcpktmIZVx9VOKg7VXXVTJTKhEi4vy4M/lJcP5EK2wCwY=; 7:47xKaJ7DOTFJZ7UDa7Uu08axzSgAFmLJ6wbOm01cVx+zkuf5JRVNXOikJLTPbg6ZR/KyzSicew7uM2F8vwMc+RVvJDlxRe45tTWi+4VQaFlsGzZgnYm7iYELEfTqaXb1e9vtANgxUAVfA+LoQOyGDbHyrhadn5c31t8MS5Mdwn3V5iBitCBIh8iZC08zh9Qcf/SDkyFJcjVUe/T7uQcNzK+TBUmk4h/u05XvlXHFiqooOo9rqQsi8/HAZhZbI6rT
x-ms-office365-filtering-correlation-id: 207b057e-3593-4ca4-a6d0-08d635daad96
x-ms-office365-filtering-ht: Tenant
x-microsoft-antispam: BCL:0; PCL:0; RULEID:(7020095)(4652040)(8989299)(5600074)(711020)(4618075)(4534185)(4627221)(201703031133081)(201702281549075)(8990200)(2017052603328)(7193020); SRVR:AM5PR0701MB2546;
x-ms-traffictypediagnostic: AM5PR0701MB2546:
x-microsoft-antispam-prvs: <AM5PR0701MB254608CAA42CC19E551D6156E2F90@AM5PR0701MB2546.eurprd07.prod.outlook.com>
x-exchange-antispam-report-test: UriScan:(109105607167333)(82608151540597)(195916259791689)(50582790962513)(166708455590820)(120809045254105);
x-ms-exchange-senderadcheck: 1
x-exchange-antispam-report-cfa-test: BCL:0; PCL:0; RULEID:(8211001083)(6040522)(2401047)(8121501046)(5005006)(3231355)(11241501184)(806099)(944501410)(4982022)(52105095)(93006095)(93001095)(10201501046)(3002001)(6055026)(148016)(149066)(150057)(6041310)(20161123560045)(20161123562045)(20161123564045)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(20161123558120)(201708071742011)(7699051)(76991095); SRVR:AM5PR0701MB2546; BCL:0; PCL:0; RULEID:; SRVR:AM5PR0701MB2546;
x-forefront-prvs: 0830866D19
x-forefront-antispam-report: SFV:NSPM; SFS:(10019020)(376002)(346002)(396003)(366004)(136003)(39860400002)(189003)(199004)(51444003)(6512007)(36756003)(5250100002)(6306002)(54896002)(236005)(99286004)(53936002)(53946003)(6436002)(478600001)(476003)(14454004)(606006)(229853002)(256004)(68736007)(86362001)(11346002)(446003)(6486002)(486006)(31696002)(6506007)(65956001)(386003)(102836004)(66066001)(4326008)(6246003)(65806001)(52116002)(76176011)(2900100001)(21615005)(14444005)(2616005)(25786009)(5024004)(790700001)(8936002)(6116002)(81156014)(81166006)(186003)(105586002)(3846002)(31686004)(53546011)(26005)(8676002)(106356001)(64126003)(966005)(97736004)(7736002)(66574009)(316002)(58126008)(93886005)(71200400001)(71190400001)(65826007)(110136005)(2906002)(5660300001); DIR:OUT; SFP:1102; SCL:1; SRVR:AM5PR0701MB2546; H:AM5PR0701MB2433.eurprd07.prod.outlook.com; FPR:; SPF:None; LANG:en; PTR:InfoNoRecords; MX:1; A:1;
received-spf: None (protection.outlook.com: nokia.com does not designate permitted sender hosts)
x-microsoft-antispam-message-info: 6KpfZQw3yH8179J2n70LyAtyzKdXzWdYSg8DBU8nEzH6yAmT5IijCka2RTdxIWAGqHA+jKiLobJBoNmLrw1pgOfPNcjrR3NOzrpWG8AOvH84Ph1Ikpo2/K+VWpE5P3EdgXgZ651K0wbeWYnk9G4MHVAuh+hkJepfJNLMSDBK2f2x4JdEY1iya/uImUV7WJD0Rz3MQL+HB1H97/BQlndfLJc+QAHeVI6LdB2w7eRZN9mdKpMDJXDh1WT7jrQP0vjjl8vpc0yVCrZCfGdePXq3SPebOCW+Bna81rr9pysoS7qS4ArO+307AOSX0u1P+F+qNjie9lw0CISRbkDC9MNxBY+eBVKrPBt4YxahxlC1W6UHbZSpcVJ55utDWnO9CV+9zXmmOt5U75l6Zvtw97qGtQ==
spamdiagnosticoutput: 1:99
spamdiagnosticmetadata: NSPM
Content-Type: multipart/alternative; boundary="_000_4f7eb2c34fd21f092dd03c9082df56banokiacom_"
MIME-Version: 1.0
X-OriginatorOrg: nokia.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 207b057e-3593-4ca4-a6d0-08d635daad96
X-MS-Exchange-CrossTenant-originalarrivaltime: 19 Oct 2018 15:51:05.3790 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 5d471751-9675-428d-917b-70f44f9630b0
X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM5PR0701MB2546
Archived-At: <https://mailarchive.ietf.org/arch/msg/ccamp/zbMYkdpb1IL4zYMwQq6gogvPx_4>
Subject: Re: [CCAMP] I-D Action: draft-lee-ccamp-wson-impairment-yang-00.txt
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: Fri, 19 Oct 2018 15:51:13 -0000

Hi Young, all,

I think that we need both, the G.698.2 application codes, which are standardized (standardized operational modes), and vendor-specific operational modes.

Operational modes represent optical transponder settings which have to be the same for the two optical transponders terminating a photonic tunnel or segment
in case the tunnel includes 3R regenerators.

The vendor-ID attribute should be of type string. We can further discuss this in Bangkok.


Thanks,
Dieter


On 16.10.2018 22:33, Leeyoung wrote:
Hi Dieter,

Thanks for providing good comments. Please see inline for my response.

Best regards,
Young

From: Beller, Dieter (Nokia - DE/Stuttgart) [mailto:dieter.beller@nokia.com]
Sent: Tuesday, October 16, 2018 6:57 AM
To: Jonas Mårtensson <jonas.martensson@ri.se><mailto:jonas.martensson@ri.se>; Leeyoung <leeyoung@huawei.com><mailto:leeyoung@huawei.com>; Zhenghaomian (Zhenghaomian, Optical &Microwave Technology Research Dept) <zhenghaomian@huawei.com><mailto:zhenghaomian@huawei.com>
Cc: ccamp@ietf.org<mailto:ccamp@ietf.org>
Subject: Re: [CCAMP] I-D Action: draft-lee-ccamp-wson-impairment-yang-00.txt

Hi Young, Jonas, all,

I checked again the YANG tree<https://github.com/younglee-ietf/actn-wson-flexi-grid/blob/master/ietf-optical-impairment-topology%402018-10-08.tree#L75> (ietf-optical-impairment-topology@2018-10-08.tree<mailto:ietf-optical-impairment-topology@2018-10-08.tree>) and particularly looked at the following augmentation:

  augment /nw:networks/nw:network/nw:node/tet:te/tet:tunnel-termination-point:
    +--rw transponder-id?         uint32
    +--ro available-modulation*   identityref
    +--rw modulation-enabled?     boolean
    +--rw modulation-type?        identityref
    +--ro available-FEC*          identityref
    +--rw FEC-enabled?            boolean
    +--rw FEC-type?               identityref
    +--ro FEC-code-rate?          decimal64
    +--rw FEC-threshold?          decimal64
    +--ro power?                  int32
    +--ro power-min?              int32
    +--ro power-max?              int32

these are clearly optical transponder attributes and I am wondering why the following grouping wson-ttp-attributes<https://github.com/younglee-ietf/actn-wson-flexi-grid/blob/master/ietf-optical-impairment-topology%402018-10-09.yang#L410> is not used:

  grouping wson-ttp-attributes {
     description
       "WSON tunnel termination point (e.g.tranponder) attributes";
        leaf-list available-operational-mode {
          type te-wson-types:operational-mode;
          description "List of all vendor-specific supported
          mode identifiers";
        }
        leaf operational-mode {
          type te-wson-types:operational-mode;
          description "Vendor-specific mode identifier";
        }
  }

This would make the optical transponder configuration attributes related to modulation and FEC obsolete.
YL>> Yes, we are discussing if the application codes are going to be used or not. If we are limited to application code usage, then you are correct.

A vendor-ID attribute has to be added because the operational modes vcan only be interpreted properly in the scope of a specific vendor.
YL>> Can you provide some idea as to vendor-ID attribute?

More discussion is also needed regarding power attributes.

YL>> Agree.

Thanks,
Dieter

On 16.10.2018 09:35, Jonas Mårtensson wrote:
Hi Young,

I had a look at the model in the github and I have some questions:

About modulation: You have DP_ (Dual Polarization) variants for QPSK and QAM16 but not for QAM8. Is that just an oversight? Also you have DC_ (Dual Carrier?) only for DP_QAM16. Why not for the others?

About link (fiber) attributes: since you added a number of attributes in the latest version (e.g. cd and pmd) why not also add loss and distance?

Specifically about link attribute “power”: The description now says “Total Input Power Level at the line port of the link”. In the previous version it said "Input Power Level of the receiver side of the link". So which side of the link does the attribute refer to? Why not include power level both at the transmit and receive sides? On the other hand, how is this attribute supposed to be used for path computation since the power level anyway does not represent the new connection (not yet setup) for which path computation is performed.

How are the “path” attributes (BER, etc.) meant to be used for path computation?

About transponder attributes: Why is the exact FEC-type needed for path computation? Would it not be sufficient to know the FEC-threshold? Another transponder attribute that could be useful to have is required OSNR (per modulation-type).

/Jonas

From: Leeyoung <leeyoung@huawei.com><mailto:leeyoung@huawei.com>
Sent: den 15 oktober 2018 19:03
To: Dieter Beller <Dieter.Beller@nokia.com><mailto:Dieter.Beller@nokia.com>; Jonas Mårtensson <jonas.martensson@ri.se><mailto:jonas.martensson@ri.se>; Zhenghaomian (Zhenghaomian, Optical &Microwave Technology Research Dept) <zhenghaomian@huawei.com><mailto:zhenghaomian@huawei.com>
Cc: ccamp@ietf.org<mailto:ccamp@ietf.org>
Subject: RE: [CCAMP] I-D Action: draft-lee-ccamp-wson-impairment-yang-00.txt

Hi Dieter,

What I meant a new scope of this draft is to combine flexi-grid with WSON (fixed-grid) as we discussed in the last week’s meeting. In regards to your point on separating the topology and the tunnel model, I agree. We haven’t got to the tunnel model yet. Please check the latest model in the github: https://github.com/younglee-ietf/actn-wson-flexi-grid

Please find the latest model per our meeting:
https://github.com/younglee-ietf/actn-wson-flexi-grid/blob/master/ietf-optical-impairment-topology%402018-10-09.yang

and its tree:
https://github.com/younglee-ietf/actn-wson-flexi-grid/blob/master/ietf-optical-impairment-topology%402018-10-08.tree

Thanks.
Young

From: Dieter Beller [mailto:Dieter.Beller@nokia.com]
Sent: Monday, October 15, 2018 10:46 AM
To: Leeyoung <leeyoung@huawei.com<mailto:leeyoung@huawei.com>>; Jonas Mårtensson <jonas.martensson@ri.se<mailto:jonas.martensson@ri.se>>; Zhenghaomian (Zhenghaomian, Optical &Microwave Technology Research Dept) <zhenghaomian@huawei.com<mailto:zhenghaomian@huawei.com>>
Cc: ccamp@ietf.org<mailto:ccamp@ietf.org>
Subject: Re: [CCAMP] I-D Action: draft-lee-ccamp-wson-impairment-yang-00.txt

Hi Young, all,

it would be great if you could share the new scope on the list before you submit the new version. This will allow folks to send comments to the list.

One of my comments was that the current 00-draft is defining augmentations, which are TE-topology related, and other augmentations that are tunnel-related
not aligned with the current scope.

I would clearly prefer separate drafts for these 2 different categories.


Thanks,
Dieter
On 12.10.2018 16:14, Leeyoung wrote:
Hi Jonas,

Thanks for your comment. We are updating the draft including the change of the names and the scope. As Haomiana and Gabriele shared their view, we are trying to harmonize with other impairment-related work for GMPLS/WSON.

Thanks.
Young

From: Jonas Mårtensson [mailto:jonas.martensson@ri.se]
Sent: Friday, October 12, 2018 2:34 AM
To: Leeyoung <leeyoung@huawei.com><mailto:leeyoung@huawei.com>; Zhenghaomian (Zhenghaomian, Optical &Microwave Technology Research Dept) <zhenghaomian@huawei.com><mailto:zhenghaomian@huawei.com>
Cc: ccamp@ietf.org<mailto:ccamp@ietf.org>
Subject: RE: [CCAMP] I-D Action: draft-lee-ccamp-wson-impairment-yang-00.txt

Hi Young and Haomian,

Interesting draft. What is the relation to other WSON impairment drafts (wson-iv-info and wson-iv-encode)? Are you proposing a completely different approach here since you do not refer to those drafts?

/Jonas

On 01.09.2018 05:42, internet-drafts@ietf.org<mailto:internet-drafts@ietf.org> wrote:

A New Internet-Draft is available from the on-line Internet-Drafts directories.





        Title           : A Yang Data Model for Impairment-Aware WSON Optical Networks

        Authors         : Young Lee

                          Haomian Zheng

  Filename        : draft-lee-ccamp-wson-impairment-yang-00.txt

  Pages           : 18

  Date            : 2018-08-31



Abstract:

   This document provides a YANG data model for the impairment-aware TE

   topology in wavelength switched optical networks (WSONs).









The IETF datatracker status page for this draft is:

https://datatracker.ietf.org/doc/draft-lee-ccamp-wson-impairment-yang/



There are also htmlized versions available at:

https://tools.ietf.org/html/draft-lee-ccamp-wson-impairment-yang-00

https://datatracker.ietf.org/doc/html/draft-lee-ccamp-wson-impairment-yang-00





Please note that it may take a couple of minutes from the time of submission

until the htmlized version and diff are available at tools.ietf.org.



Internet-Drafts are also available by anonymous FTP at:

ftp://ftp.ietf.org/internet-drafts/



_______________________________________________

I-D-Announce mailing list

I-D-Announce@ietf.org<mailto:I-D-Announce@ietf.org>

https://www.ietf.org/mailman/listinfo/i-d-announce

Internet-Draft directories: http://www.ietf.org/shadow.html

or ftp://ftp.ietf.org/ietf/1shadow-sites.txt






_______________________________________________

CCAMP mailing list

CCAMP@ietf.org<mailto:CCAMP@ietf.org>

https://www.ietf.org/mailman/listinfo/ccamp



--

Dieter Beller
Open Agent & Routing Project Manager
IP/Optical Networks, Optics, Nokia

m : +49 175 7266874 | j: 8831186<ciscotel://8831186>
Dieter.Beller@nokia.com<mailto:Dieter.Beller@nokia.com>

Nokia Solutions and Networks GmbH & Co. KG
Lorenzstr. 10, 70435 Stuttgart
Sitz der Gesellschaft: München / Registered office: Munich
Registergericht: München / Commercial registry: Munich, HRA 88537
WEEE-Reg.-Nr.: DE 52984304
Persönlich haftende Gesellschafterin / General Partner: Nokia Solutions and Networks Management GmbH
Geschäftsleitung / Board of Directors: Dr. Wolfgang Hackenberg, Nils-Peter Daetz, Wilhelm Dresselhaus
Vorsitzender des Aufsichtsrats / Chairman of supervisory board: Hans-Jürgen Bill
Sitz der Gesellschaft: München / Registered office: Munich
Registergericht: München / Commercial registry: Munich, HRB 163416

This e-mail and its attachments, if any, may contain confidential information.
If you have received this e-mail in error, please notify us and delete or destroy the e-mail and its attachments, if any, immediately.
If you have received this e-mail in error, you must not forward or make use of the e-mail and its attachments, if any.