idnits 2.17.1 draft-ietf-idr-bgp-ls-segment-routing-rld-05.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (August 20, 2019) is 1709 days in the past. Is this intentional? 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) -- Possible downref: Non-RFC (?) normative reference: ref. '5' Summary: 1 error (**), 0 flaws (~~), 1 warning (==), 2 comments (--). 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: February 21, 2020 Nokia 6 K. Patel 7 Arrcus 8 August 20, 2019 10 Signalling ERLD using BGP-LS 11 draft-ietf-idr-bgp-ls-segment-routing-rld-05 13 Abstract 15 This document defines the attribute encoding to use for BGP-LS to 16 expose ERLD "Entropy capable Readable Label Depth" from a node to a 17 centralised controller (PCE/SDN). 19 Requirements Language 21 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 22 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 23 document are to be interpreted as described in RFC 2119 [1]. 25 Status of This Memo 27 This Internet-Draft is submitted in full conformance with the 28 provisions of BCP 78 and BCP 79. 30 Internet-Drafts are working documents of the Internet Engineering 31 Task Force (IETF). Note that other groups may also distribute 32 working documents as Internet-Drafts. The list of current Internet- 33 Drafts is at https://datatracker.ietf.org/drafts/current/. 35 Internet-Drafts are draft documents valid for a maximum of six months 36 and may be updated, replaced, or obsoleted by other documents at any 37 time. It is inappropriate to use Internet-Drafts as reference 38 material or to cite them other than as "work in progress." 40 This Internet-Draft will expire on February 21, 2020. 42 Copyright Notice 44 Copyright (c) 2019 IETF Trust and the persons identified as the 45 document authors. All rights reserved. 47 This document is subject to BCP 78 and the IETF Trust's Legal 48 Provisions Relating to IETF Documents 49 (https://trustee.ietf.org/license-info) in effect on the date of 50 publication of this document. Please review these documents 51 carefully, as they describe your rights and restrictions with respect 52 to this document. Code Components extracted from this document must 53 include Simplified BSD License text as described in Section 4.e of 54 the Trust Legal Provisions and are provided without warranty as 55 described in the Simplified BSD License. 57 Table of Contents 59 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 60 2. Conventions used in this document . . . . . . . . . . . . . . 2 61 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 62 3. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3 63 4. Advertising of ERLD in BGP-LS . . . . . . . . . . . . . . . . 3 64 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4 65 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 66 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 67 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 68 8.1. Normative References . . . . . . . . . . . . . . . . . . 4 69 8.2. Informative References . . . . . . . . . . . . . . . . . 5 70 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 72 1. Introduction 74 When Segment Routing tunnels are computed by a centralised 75 controller, it is beneficial that the controller knows the ERLD 76 (Entropy Readable Label Depth) of each node or link a tunnel 77 traverses. A network node signalling an ERLD MUST support the 78 ability to read the signalled number of labels before any action is 79 done upon the packet and SHOULD support entropy awareness found 80 within the signalled ERLD depth. 82 ERLD awareness of each node will allow a network SDN controller to 83 influence the path used for each tunnel. The SDN controller may for 84 example only create tunnels with a label stack smaller or equal as 85 the ERLD of each node on the path. This will allow the network to 86 behave accordingly (e.g. make use of Entropy Labels to improve ECMP) 87 upon the imposed Segment Routing label stack on each packet. 89 This document describes how to use BGP-LS to expose the ERLD of a 90 node. 92 2. Conventions used in this document 93 2.1. Terminology 95 BGP-LS: Distribution of Link-State and TE Information using Border 96 Gateway Protocol 98 ERLD: Entropy capable Readable Label Depth 100 ELC: Entropy Label Capability 102 MSD: Maximum SID Depth 104 SID: Segment Identifier 106 3. Problem Statement 108 For Segment Routing technology both ISIS [7] and OSPF [6] have 109 proposed extensions to signal the ERLD (Entropy Readable Label Depth) 110 and ELC (Entropy Label Capability) of a node. However, if a network 111 SDN controller is connected to the network through a BGP-LS session 112 and not through either ISIS or OSPF technology, then both ERLD and 113 ELC needs to be signalled using BGP-LS encoding. This document 114 describes the extension BGP-LS requires to signal ERLD. 116 A network SDN controller having awareness of the ERLD can for example 117 use it as a constraint on path computation to make sure that high 118 bandwidth LSPs are not placed on LAG (Link Aggregation Group), 119 containing links with smaller member bandwidth, if they know the 120 entropy label cannot be processed by the node at the ingress to the 121 link. 123 4. Advertising of ERLD in BGP-LS 125 Both ISIS [7] and OSPF [6] have proposed extensions to signal the 126 ERLD (Entropy Readable Label Depth) and ELC (Entropy Label 127 Capability) using new MSD-type of the Node MSD sub-Type TLV RFC8491 128 [4] or RFC8476 [3]. 130 This document defines a new node BGP MSD sub-type TLV from draft- 131 ietf-idr-bgp-ls-segment-routing-msd [5] to signal the ERLD. 133 A BGP-LS router exporting the IGP LSDB, MUST NOT encode the IGP ERLD 134 value in an BGP-LS ERLD attribute, if the associated ELC is not 135 signalled. 137 0 1 2 3 138 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 1 139 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 140 | MSD-Type=TBD | ERLD-Value | 141 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 143 Figure 1 145 The BGP-LS ERLD is encoded as a node MSD sub-type defined in the IANA 146 registry titled "IGP MSD-Types" under the "Interior Gateway Protocol 147 (IGP) Parameters" registry created by RFC8491 [4]. 149 The ERLD-Value field in the range between 0 to 255 is set to the BGP- 150 LS imported IGP ERLD. The value of 0 represents lack of ability to 151 read a label stack of any depth, any other value represents the 152 readable label depth of the node. 154 5. Security Considerations 156 This document does not introduce security issues beyond those 157 discussed in RFC7752 [2] 159 6. Acknowledgements 161 Thanks to discussions with Acee Lindem, Jeff Tantsura, Stephane 162 Litkowski, Bruno Decraene, Kireeti Kompella, John E. Drake and 163 Carlos Pignataro to bring the concept of combining ELC and RLD into a 164 single ERLD signalled parameter more suitable for SDN controller 165 based networks. 167 7. IANA Considerations 169 This document requests assigning new BGP MSD sub-TLV code-points as 170 described in section 4. 172 Note: placeholder IANA request 174 8. References 176 8.1. Normative References 178 [1] Bradner, S., "Key words for use in RFCs to Indicate 179 Requirement Levels", BCP 14, RFC 2119, March 1997, 180 . 182 [2] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and 183 S. Ray, "North-Bound Distribution of Link-State and 184 Traffic Engineering (TE) Information Using BGP", RFC 7752, 185 DOI 10.17487/RFC7752, March 2016, 186 . 188 [3] Tantsura, J., Chunduri, U., Aldrin, S., and P. Psenak, 189 "Signaling Maximum SID Depth (MSD) Using OSPF", RFC 8476, 190 DOI 10.17487/RFC8476, December 2018, 191 . 193 [4] Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg, 194 "Signaling Maximum SID Depth (MSD) Using IS-IS", RFC 8491, 195 DOI 10.17487/RFC8491, November 2018, 196 . 198 [5] Tantsura, J., Chunduri, U., Talaulikar, K., Mirsky, G., 199 and N. Triantafillis, "draft-ietf-idr-bgp-ls-segment- 200 routing-msd", June 2019. 202 8.2. Informative References 204 [6] Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S. 205 Litkowski, "draft-ietf-ospf-mpls-elc", May 2019. 207 [7] Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S. 208 Litkowski, "draft-ietf-isis-mpls-elc", May 2019. 210 Authors' Addresses 212 Gunter Van de Velde (editor) 213 Nokia 214 Antwerp 215 BE 217 Email: gunter.van_de_velde@nokia.com 219 Wim Henderickx 220 Nokia 221 Belgium 223 Email: wim.henderickx@nokia.com 224 Matthew Bocci 225 Nokia 226 Shoppenhangers Road 227 Maidenhead, Berks 228 UK 230 Email: matthew.bocci@nokia.com 232 Keyur Patel 233 Arrcus 234 USA 236 Email: keyur@arrcus.com