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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 7752 (ref. '2') (Obsoleted by RFC 9552) Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 IDR Working Group G. Van de Velde, Ed. 3 Internet-Draft W. Henderickx 4 Intended status: Standards Track M. Bocci 5 Expires: September 4, 2017 Nokia 6 March 3, 2017 8 Signalling RLD using BGP-LS 9 draft-vandevelde-idr-bgp-ls-segment-routing-rld-01 11 Abstract 13 This document defines the attribute to use for BGP-LS to expose a 14 node RLD "Readable Label Depth" to a centralised controller (PCE/ 15 SDN). 17 Requirements Language 19 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 20 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 21 document are to be interpreted as described in RFC 2119 [1]. 23 Status of This Memo 25 This Internet-Draft is submitted in full conformance with the 26 provisions of BCP 78 and BCP 79. 28 Internet-Drafts are working documents of the Internet Engineering 29 Task Force (IETF). Note that other groups may also distribute 30 working documents as Internet-Drafts. The list of current Internet- 31 Drafts is at http://datatracker.ietf.org/drafts/current/. 33 Internet-Drafts are draft documents valid for a maximum of six months 34 and may be updated, replaced, or obsoleted by other documents at any 35 time. It is inappropriate to use Internet-Drafts as reference 36 material or to cite them other than as "work in progress." 38 This Internet-Draft will expire on September 4, 2017. 40 Copyright Notice 42 Copyright (c) 2017 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents 47 (http://trustee.ietf.org/license-info) in effect on the date of 48 publication of this document. Please review these documents 49 carefully, as they describe your rights and restrictions with respect 50 to this document. Code Components extracted from this document must 51 include Simplified BSD License text as described in Section 4.e of 52 the Trust Legal Provisions and are provided without warranty as 53 described in the Simplified BSD License. 55 Table of Contents 57 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 58 2. Conventions used in this document . . . . . . . . . . . . . . 2 59 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2 60 3. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3 61 4. RLD support by a node . . . . . . . . . . . . . . . . . . . . 3 62 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4 63 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 64 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 65 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 66 8.1. Normative References . . . . . . . . . . . . . . . . . . 4 67 8.2. Informative References . . . . . . . . . . . . . . . . . 4 68 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 4 70 1. Introduction 72 When Segment Routing tunnels are computed by a centralised 73 controller, it is beneficial that the controller knows the RLD 74 "Readable Label Depth" of each node the computed tunnel traverses. 76 RLD awareness of each node will allow the network SDN controller to 77 influence the path used for each tunnel. The SDN controller may for 78 example only create tunnels with a label stack smaller or equal as 79 the RLD of each node on the path. This will allow the network to 80 behave accordingly (e.g. make use of Entropy Labels to improve ECMP) 81 upon the imposed Segment Routing labels on each packet. 83 This document describes how to use BGP-LS to expose the RLD of a 84 node. 86 2. Conventions used in this document 88 2.1. Terminology 90 BGP-LS: Distribution of Link-State and TE Information using Border 91 Gateway Protocol 93 RLD: Readable Label Depth 95 PCC: Path Computation Client 96 PCE: Path Computation Element 98 PCEP: Path Computation Element Protocol 100 SID: Segment Identifier 102 SR: Segment routing 104 3. Problem Statement 106 In existing technology both ISIS [4] and OSPF [3] have proposed 107 extensions to signal the Readable Label Depth of a node. However, if 108 a network SDN controller is connected to the network through a BGP-LS 109 session and not through ISIS or OSPF technology, then the RLD needs 110 to be conveyed in BGP-LS accordingly. This document describes the 111 extension BGP-LS requires to transport the RLD. 113 A network SDN controller having awareness of the Readable Label Depth 114 can for example use it as a constraint on path computation so that it 115 can make sure that high bandwidth LSPs are not placed on LAG links 116 with smaller member bandwidths if they know the Entropy Label cannot 117 be processed by the node at the ingress to the link. 119 4. RLD support by a node 121 Node RLD is encoded in a new Node Attribute TLV, as defined in 122 RFC7752 [2]. 124 0 1 2 3 125 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 126 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 127 | Type | Length | 128 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 129 | RLD | 130 +-+-+-+-+-+-+-+-+ 132 Figure 1 134 Type : A 2-octet field specifying code-point of the new TLV type. 135 Code-point: TBA from BGP-LS Node Descriptor, Link Descriptor, 136 Prefix Descriptor, and Attribute TLVs registry 138 Length: A 2-octet field that indicates the length of the value 139 portion 140 RLD: Node RLD is a number in the range of 0-254. The value of 0 141 represents lack of ability to read a label stack of any depth, any 142 other value represents the readable label depth of the node. 144 5. Security Considerations 146 This document does not introduce security issues beyond those 147 discussed in RFC7752 [2] 149 6. Acknowledgements 151 7. IANA Considerations 153 This document requests assigning 1 new code-points from the BGP-LS 154 Node Descriptor, Link Descriptor, Prefix Descriptor, and Attribute 155 TLVs registry as specified in sections 4. 157 8. References 159 8.1. Normative References 161 [1] Bradner, S., "Key words for use in RFCs to Indicate 162 Requirement Levels", BCP 14, RFC 2119, March 1997, 163 . 165 [2] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and 166 S. Ray, "North-Bound Distribution of Link-State and 167 Traffic Engineering (TE) Information Using BGP", RFC 7752, 168 DOI 10.17487/RFC7752, March 2016, 169 . 171 8.2. Informative References 173 [3] Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S. 174 Litkowski, "draft-ietf-ospf-mpls-elc", October 2016. 176 [4] Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S. 177 Litkowski, "draft-ietf-ospf-mpls-elc", October 2016. 179 Authors' Addresses 181 Gunter Van de Velde (editor) 182 Nokia 183 Antwerp 184 BE 186 Email: gunter.van_de_velde@nokia.com 187 Wim Henderickx 188 Nokia 189 Belgium 191 Email: wim.henderickx@nokia.com 193 Matthew Bocci 194 Nokia 195 Shoppenhangers Road 196 Maidenhead, Berks 197 UK 199 Email: matthew.bocci@nokia.com