Re: [Idr] Mail regarding draft-ietf-idr-segment-routing-te-policy

"Ketan Talaulikar (ketant)" <ketant@cisco.com> Wed, 08 May 2019 10:28 UTC

Return-Path: <ketant@cisco.com>
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 77D1D12003E for <idr@ietfa.amsl.com>; Wed, 8 May 2019 03:28:34 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -14.499
X-Spam-Level:
X-Spam-Status: No, score=-14.499 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, RCVD_IN_DNSWL_HI=-5, SPF_PASS=-0.001, URIBL_BLOCKED=0.001, USER_IN_DEF_DKIM_WL=-7.5] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (1024-bit key) header.d=cisco.com header.b=R76nrg/o; dkim=pass (1024-bit key) header.d=cisco.onmicrosoft.com header.b=KGNFdhOz
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 ZSmpL6H0QyxM for <idr@ietfa.amsl.com>; Wed, 8 May 2019 03:28:32 -0700 (PDT)
Received: from alln-iport-5.cisco.com (alln-iport-5.cisco.com [173.37.142.92]) (using TLSv1.2 with cipher DHE-RSA-SEED-SHA (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 3898812000E for <idr@ietf.org>; Wed, 8 May 2019 03:28:32 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=cisco.com; i=@cisco.com; l=23048; q=dns/txt; s=iport; t=1557311312; x=1558520912; h=from:to:cc:subject:date:message-id:references: in-reply-to:mime-version; bh=ZQ8rpedppRecVRhRtwCG4+ixIjDCG+bMc+lOj1Y6hII=; b=R76nrg/oBn39iFWB4nUwfXdVBx7IJrnNwkkiPgQPjWtrkUyKXAAMPoIp Jh0Z9rnHZV9+Hsg92pfnNLu764QVMehjLmZMFOE9EiRTh+gQWsraqThxd OxG7QqRGqjV0/T0+xKsl17Q47mAZTagG7gRiUaSxm1TRUA9sy1ZS52pLc Q=;
IronPort-PHdr: =?us-ascii?q?9a23=3AeebBGhYqLQFp8nL93vDZSeD/LSx94ef9IxIV55?= =?us-ascii?q?w7irlHbqWk+dH4MVfC4el20Q6bRp3VvvRDjeee87vtX2AN+96giDgDa9QNMn?= =?us-ascii?q?1NksAKh0olCc+BB1f8KavpYjAzGthqX15+9Hb9Ok9QS47z?=
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: =?us-ascii?q?A0AIAABXrtJc/5JdJa1kGgEBAQEBAgE?= =?us-ascii?q?BAQEHAgEBAQGBUQUBAQEBCwGBDi8pJwNpVSAECyiEEINHA4RSijKCV36WJoE?= =?us-ascii?q?ugSQDVAkHAQEjCgKEPwIXgXAjNAkOAQMBAQQBAQIBBG0cDIVKAQEBAQMSEQo?= =?us-ascii?q?TAQE3AQ8CAQgRBAEBKAMCAgIwFAkIAQEEDgUIDA6DAYEdTQMdAQIMoX8CgTW?= =?us-ascii?q?IX3GBL4J5AQEFgTYCg0kYgg4DBoEyAYtNF4FAP4ERRoIXNT6CYQEBA4E+AQE?= =?us-ascii?q?gKwmCVDKCJo1ahE2ICY0WCQKCCYYdjE2CEIZEi0GBQo1FhSyOKQIEAgQFAg4?= =?us-ascii?q?BAQWBTzgogS5wFTuCbIIPDBeBAQEIgkKFFIU/coEpjiSCQwEB?=
X-IronPort-AV: E=Sophos;i="5.60,445,1549929600"; d="scan'208,217";a="270225731"
Received: from rcdn-core-10.cisco.com ([173.37.93.146]) by alln-iport-5.cisco.com with ESMTP/TLS/DHE-RSA-SEED-SHA; 08 May 2019 10:28:30 +0000
Received: from XCH-ALN-013.cisco.com (xch-aln-013.cisco.com [173.36.7.23]) by rcdn-core-10.cisco.com (8.15.2/8.15.2) with ESMTPS id x48ASUnv022505 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=FAIL); Wed, 8 May 2019 10:28:30 GMT
Received: from xhs-rcd-002.cisco.com (173.37.227.247) by XCH-ALN-013.cisco.com (173.36.7.23) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Wed, 8 May 2019 05:28:30 -0500
Received: from xhs-rcd-003.cisco.com (173.37.227.248) by xhs-rcd-002.cisco.com (173.37.227.247) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Wed, 8 May 2019 05:28:29 -0500
Received: from NAM05-BY2-obe.outbound.protection.outlook.com (72.163.14.9) by xhs-rcd-003.cisco.com (173.37.227.248) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Wed, 8 May 2019 05:28:29 -0500
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cisco.onmicrosoft.com; s=selector1-cisco-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=ZQ8rpedppRecVRhRtwCG4+ixIjDCG+bMc+lOj1Y6hII=; b=KGNFdhOzJW7wyPFTvNudQp7LbucjQ8J9BuHcz7R0uizF04OtYiLh949Nnie97zb6DJ/YNtrBqaGiBma+bua+FHk2JCTV6HHxMgSqsm9mlL+GPcEdwCKFABDn1IOJ5brQdI2NSeKTAfLoC2bCBohCz6jXKWC76Td0OgVXUvH74aE=
Received: from SN6PR11MB2845.namprd11.prod.outlook.com (52.135.93.24) by SN6PR11MB2749.namprd11.prod.outlook.com (52.135.92.28) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.1878.20; Wed, 8 May 2019 10:28:28 +0000
Received: from SN6PR11MB2845.namprd11.prod.outlook.com ([fe80::5c42:5f15:d194:98f]) by SN6PR11MB2845.namprd11.prod.outlook.com ([fe80::5c42:5f15:d194:98f%5]) with mapi id 15.20.1878.019; Wed, 8 May 2019 10:28:28 +0000
From: "Ketan Talaulikar (ketant)" <ketant@cisco.com>
To: Gurusiddesh Nidasesi <gurusiddesh.nidasesi@ipinfusion.com>
CC: Chaitanya Varma <chaitanya.varma@ipinfusion.com>, "idr@ietf.org" <idr@ietf.org>
Thread-Topic: [Idr] Mail regarding draft-ietf-idr-segment-routing-te-policy
Thread-Index: AdT/KtjPP6BADXj+R+K+v5ydxRQvuQA+pdWgASkO/wAAL5Y2QA==
Date: Wed, 8 May 2019 10:28:28 +0000
Message-ID: <SN6PR11MB28451163BCFFD7E2A2DFBFA9C1320@SN6PR11MB2845.namprd11.prod.outlook.com>
References: <993db9e45983acc9769af61bf786a6d6@mail.gmail.com> <SN6PR11MB284516BC1430BFFA5E494C0EC13B0@SN6PR11MB2845.namprd11.prod.outlook.com> <CAHhGMfGRgdDTam97sb5dYZQHBLLHpTj85yJ7oL5w7wrB3+q3jA@mail.gmail.com>
In-Reply-To: <CAHhGMfGRgdDTam97sb5dYZQHBLLHpTj85yJ7oL5w7wrB3+q3jA@mail.gmail.com>
Accept-Language: en-US
Content-Language: en-US
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
authentication-results: spf=none (sender IP is ) smtp.mailfrom=ketant@cisco.com;
x-originating-ip: [2001:420:54fe:180::33ac]
x-ms-publictraffictype: Email
x-ms-office365-filtering-correlation-id: 79d3a40d-d1b5-49a2-b9d9-08d6d39fe906
x-microsoft-antispam: BCL:0; PCL:0; RULEID:(2390118)(7020095)(4652040)(8989299)(4534185)(4627221)(201703031133081)(201702281549075)(8990200)(5600141)(711020)(4605104)(2017052603328)(7193020); SRVR:SN6PR11MB2749;
x-ms-traffictypediagnostic: SN6PR11MB2749:
x-ms-exchange-purlcount: 3
x-microsoft-antispam-prvs: <SN6PR11MB27497D5D2ED083C708840ABCC1320@SN6PR11MB2749.namprd11.prod.outlook.com>
x-ms-oob-tlc-oobclassifiers: OLM:10000;
x-forefront-prvs: 0031A0FFAF
x-forefront-antispam-report: SFV:NSPM; SFS:(10009020)(366004)(39860400002)(136003)(396003)(376002)(346002)(51914003)(189003)(199004)(53936002)(4326008)(6916009)(478600001)(5660300002)(6246003)(2906002)(74316002)(966005)(256004)(14454004)(52536014)(25786009)(5024004)(71190400001)(71200400001)(66574012)(14444005)(76116006)(66556008)(99286004)(66446008)(64756008)(66476007)(73956011)(66946007)(86362001)(33656002)(8936002)(6116002)(46003)(9326002)(446003)(486006)(476003)(6506007)(606006)(53546011)(790700001)(229853002)(7696005)(11346002)(76176011)(7736002)(236005)(9686003)(81156014)(54896002)(102836004)(6306002)(316002)(8676002)(6436002)(54906003)(68736007)(186003)(81166006)(55016002); DIR:OUT; SFP:1101; SCL:1; SRVR:SN6PR11MB2749; H:SN6PR11MB2845.namprd11.prod.outlook.com; FPR:; SPF:None; LANG:en; PTR:InfoNoRecords; MX:1; A:1;
received-spf: None (protection.outlook.com: cisco.com does not designate permitted sender hosts)
x-ms-exchange-senderadcheck: 1
x-microsoft-antispam-message-info: 93O+ISmiAKBfDnnIYR3IA8OrsojW/2Kgwjc1WZ8Oxa1ybpuA4h+Ps90TQIdwqo1oaTyJ8NUW6teghJIxbkgK0d5c3jfwtNWVDVBGVZpBgvPsXc1ZynOkQwJfymc/iNpzC+KhY3VXOLkOtVksKhDlrNB9hOUCGpMDIop/4XG9QkI5ymopc19qP1WSlg7omQjmGspNW54zS/YsG73Is38PwILX8bVs3e2/QKoywqkS2NjuJBIOt9leWRry179cqvHKeSIqjyTTQlkG8tJnm8mIIKq5yuiVdkhai/yo7S6jMtAfygD/BYvCeHxNPAPYsdD5oNkjOJ1s+SSQTl3VHDscOtbbKfKi+hfYtRetR5Vbgg0jBTIfTMZ8sH0YJvCvoKXOHQhYyTDl/Yr4JvW9O/+N2mfoMVlr246cefcxbgUbagc=
Content-Type: multipart/alternative; boundary="_000_SN6PR11MB28451163BCFFD7E2A2DFBFA9C1320SN6PR11MB2845namp_"
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-Network-Message-Id: 79d3a40d-d1b5-49a2-b9d9-08d6d39fe906
X-MS-Exchange-CrossTenant-originalarrivaltime: 08 May 2019 10:28:28.0995 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 5ae1af62-9505-4097-a69a-c1553ef7840e
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN6PR11MB2749
X-OriginatorOrg: cisco.com
X-Outbound-SMTP-Client: 173.36.7.23, xch-aln-013.cisco.com
X-Outbound-Node: rcdn-core-10.cisco.com
Archived-At: <https://mailarchive.ietf.org/arch/msg/idr/7TTLQh80vJ29wIn4eb9bgiELqik>
Subject: Re: [Idr] Mail regarding draft-ietf-idr-segment-routing-te-policy
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, 08 May 2019 10:28:35 -0000

Hi Gurusiddesh,

Please check inline below

From: Gurusiddesh Nidasesi <gurusiddesh.nidasesi@ipinfusion.com>
Sent: 07 May 2019 17:11
To: Ketan Talaulikar (ketant) <ketant@cisco.com>
Cc: Chaitanya Varma <chaitanya.varma@ipinfusion.com>; idr@ietf.org
Subject: Re: [Idr] Mail regarding draft-ietf-idr-segment-routing-te-policy

Hi Ketan,

Thanks for the quick response.
Additionally, we have more queries as follows

"Alternatively, a router (i.e., a BGP egress router) advertises SR
   Policies representing paths to itself.  In this case, it is possible
   to send the policy to each head-end over a BGP session to that head-
  end, without requiring any further propagation of the policy."

How does an egress router advertise SR policies representing paths to itself?
[KT] By setting endpoint to it’s own router-id in the NLRI and setting the ingress router’s router-id in the router-target extended community.
Is it done through BGP configuration or any other trigger?
[KT] This would be implementation specific based on the use-case/workflow.

In the above case how ERO (SID-List) is calculated?
[KT] This is again implementation specific. It could be done by some TE module on the egress BGP router that has topology visibility from the ingress router to itself. It would be kind of reverse of how a headend computes a path from itself to an endpoint – this is the endpoint computing path to itself from some headend.
Thanks,
Ketan

Regards
Gurusiddesh V N

On Wed, May 1, 2019 at 7:34 PM Ketan Talaulikar (ketant) <ketant@cisco.com<mailto:ketant@cisco.com>> wrote:
Hi Chaitanya,

Please check inline below.

From: Idr <idr-bounces@ietf.org<mailto:idr-bounces@ietf.org>> On Behalf Of Chaitanya Varma
Sent: 30 April 2019 13:34
To: idr@ietf.org<mailto:idr@ietf.org>
Cc: Gurusiddesh Nidasesi <gurusiddesh.nidasesi@ipinfusion.com<mailto:gurusiddesh.nidasesi@ipinfusion.com>>
Subject: [Idr] Mail regarding draft-ietf-idr-segment-routing-te-policy

Hi,

I have couple of queries from the below draft.

https://tools.ietf.org/html/draft-ietf-idr-segment-routing-te-policy-05

  “ Typically, a controller defines the set of policies and advertise
   them to policy head-end routers (typically ingress routers).”

How do we communicate SR policies from controller? Is it through BGP-SR session or PCEP session.
[KT] This draft is all about using BGP for signalling SR Policies from a controller to the head-end routers. So yes (b) below.

a. If it is through PCEP session what happens if the PCC is non-headend?
b. If it is through BGP-SR what is the role for PCEP between PCE and PCC?
[KT] PCEP is another flavour for instantiation of SR Policies. Yet another option is using netconf/yang or another method for provisioning. This draft is about using BGP and PCEP is not required.


  “ Moreover, one or more route-target SHOULD be attached to the
   advertisement”

How Route-target should be attached to a SR-NLRI update?
[KT] As Route Target Extended Communities attribute – ref sec 1 of the draft.

Is it done through local configuration or picked up based on some dynamic parameter?
[KT] It is done by the controller and may be done via local config – either along with the SR Policy or route policy or even dynamically based on the head-end address. This would be implementation specific.

Thanks,
Ketan

Appreciate if you can help here.


Regards,
Chaitanya


..


--
Thanks,
Gurusiddesh V N

.