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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-25) exists of draft-ietf-isis-segment-routing-extensions-19 == Outdated reference: A later version (-19) exists of draft-ietf-isis-segment-routing-msd-13 == Outdated reference: A later version (-22) exists of draft-ietf-spring-segment-routing-mpls-14 ** Obsolete normative reference: RFC 4971 (Obsoleted by RFC 7981) Summary: 1 error (**), 0 flaws (~~), 4 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group X. Xu 3 Internet-Draft Alibaba Inc 4 Intended status: Standards Track S. Kini 5 Expires: January 26, 2019 6 S. Sivabalan 7 C. Filsfils 8 Cisco 9 S. Litkowski 10 Orange 11 July 25, 2018 13 Signaling Entropy Label Capability and Entropy Readable Label Depth 14 Using IS-IS 15 draft-ietf-isis-mpls-elc-04 17 Abstract 19 Multiprotocol Label Switching (MPLS) has defined a mechanism to load 20 balance traffic flows using Entropy Labels (EL). An ingress Label 21 Switching Router (LSR) cannot insert ELs for packets going into a 22 given tunnel unless an egress LSR has indicated via signaling that it 23 has the capability of processing ELs, referred to as Entropy Label 24 Capability (ELC), on that tunnel. In addition, it would be useful 25 for ingress LSRs to know each LSR's capability of reading the maximum 26 label stack depth and performing EL-based load-balancing, referred to 27 as Entropy Readable Label Depth (ERLD), in the cases where stacked 28 LSPs are used for whatever reasons. This document defines mechanisms 29 to signal these two capabilities using IS-IS. These mechanisms are 30 useful when the label advertisement is also done via IS-IS. 32 Status of This Memo 34 This Internet-Draft is submitted in full conformance with the 35 provisions of BCP 78 and BCP 79. 37 Internet-Drafts are working documents of the Internet Engineering 38 Task Force (IETF). Note that other groups may also distribute 39 working documents as Internet-Drafts. The list of current Internet- 40 Drafts is at https://datatracker.ietf.org/drafts/current/. 42 Internet-Drafts are draft documents valid for a maximum of six months 43 and may be updated, replaced, or obsoleted by other documents at any 44 time. It is inappropriate to use Internet-Drafts as reference 45 material or to cite them other than as "work in progress." 47 This Internet-Draft will expire on January 26, 2019. 49 Copyright Notice 51 Copyright (c) 2018 IETF Trust and the persons identified as the 52 document authors. All rights reserved. 54 This document is subject to BCP 78 and the IETF Trust's Legal 55 Provisions Relating to IETF Documents 56 (https://trustee.ietf.org/license-info) in effect on the date of 57 publication of this document. Please review these documents 58 carefully, as they describe your rights and restrictions with respect 59 to this document. Code Components extracted from this document must 60 include Simplified BSD License text as described in Section 4.e of 61 the Trust Legal Provisions and are provided without warranty as 62 described in the Simplified BSD License. 64 Table of Contents 66 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 67 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 68 3. Advertising ELC Using IS-IS . . . . . . . . . . . . . . . . . 3 69 4. Advertising ERLD Using IS-IS . . . . . . . . . . . . . . . . 3 70 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 71 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 72 7. Security Considerations . . . . . . . . . . . . . . . . . . . 4 73 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 74 8.1. Normative References . . . . . . . . . . . . . . . . . . 4 75 8.2. Informative References . . . . . . . . . . . . . . . . . 5 76 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 78 1. Introduction 80 [RFC6790] describes a method to load balance Multiprotocol Label 81 Switching (MPLS) traffic flows using Entropy Labels (EL). [RFC6790] 82 introduces the concept of Entropy Label Capability (ELC) and defines 83 the signalings of this capability via MPLS signaling protocols. 84 Recently, mechanisms are being defined to signal labels via link- 85 state Interior Gateway Protocols (IGP) such as IS-IS 86 [I-D.ietf-isis-segment-routing-extensions]. In such scenario, the 87 signaling mechanisms defined in [RFC6790] are inadequate. This draft 88 defines a mechanism to signal the ELC [RFC6790] using IS-IS. This 89 mechanism is useful when the label advertisement is also done via IS- 90 IS. 92 In addition, in the cases where stacked LSPs are used for whatever 93 reasons (e.g., SR-MPLS [I-D.ietf-spring-segment-routing-mpls]), it 94 would be useful for ingress LSRs to know each intermediate LSR's 95 capability of reading the maximum label stack depth and performing 96 EL-based load-balancing. This capability, referred to as Entropy 97 Readable Label Depth (ERLD) as defined in 98 [I-D.ietf-mpls-spring-entropy-label] may be used by ingress LSRs to 99 determine whether it's necessary to insert an EL for a given LSP of 100 the stacked LSP tunnel in the case where there has already been at 101 least one EL in the label stack [I-D.ietf-mpls-spring-entropy-label]. 103 2. Terminology 105 This memo makes use of the terms defined in [RFC6790] and [RFC4971]. 107 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 108 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 109 document are to be interpreted as described in RFC 2119 [RFC2119]. 111 3. Advertising ELC Using IS-IS 113 The IS-IS Router CAPABILITY TLV as defined in [RFC4971] is used by 114 IS-IS routers to announce their capabilities. A new sub-TLV of this 115 TLV, called ELC sub-TLV is defined to advertise the capability of the 116 router to process the ELs. As shown in Figure 1, it is formatted as 117 described in [RFC5305] with a Type code to be assigned by IANA and a 118 Length of zero. The scope of the advertisement depends on the 119 application. If a router has multiple linecards, the router MUST NOT 120 advertise the ELC unless all of the linecards are capable of 121 processing ELs. 123 0 1 2 3 124 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 1 125 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 126 | Type=TBD1 | Length=0 | 127 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 128 Figure 1: ELC sub-TLV Format 130 4. Advertising ERLD Using IS-IS 132 A new MSD-type of the IS-IS Node MSD sub-TLV 133 [I-D.ietf-isis-segment-routing-msd], called ERLD is defined to 134 advertise the ERLD of a given router . As shown in Figure 2, it is 135 formatted as described in [I-D.ietf-isis-segment-routing-msd] with a 136 new MSD-Type code to be assigned by IANA (the type code of 2 is 137 desired) and the Value field is set to the ERLD in the range between 138 0 to 255. The scope of the advertisement depends on the application. 139 If a router has multiple linecards with different capabilities of 140 reading the maximum label stack deepth, the router MUST advertise the 141 smallest one. 143 0 1 2 3 144 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 1 145 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 146 | MSD-Type=TBD2 | ERLD | 147 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 148 Figure 2: ERLD MSD-Type Format 150 5. Acknowledgements 152 The authors would like to thank Yimin Shen, George Swallow, Acee 153 Lindem, Les Ginsberg, Ketan Talaulikar, Jeff Tantsura and Carlos 154 Pignataro for their valuable comments. 156 6. IANA Considerations 158 IANA is requested to allocate one sub-TLV type of the IS-IS Router 159 Capability TLV for ELC and a MSD type (the type code of 2 is desired) 160 from the "IGP MSD Types" registry for ERLD. 162 7. Security Considerations 164 The security considerations as described in [RFC4971] is applicable 165 to this document. This document does not introduce any new security 166 risk. 168 8. References 170 8.1. Normative References 172 [I-D.ietf-isis-segment-routing-extensions] 173 Previdi, S., Ginsberg, L., Filsfils, C., Bashandy, A., 174 Gredler, H., Litkowski, S., Decraene, B., and J. Tantsura, 175 "IS-IS Extensions for Segment Routing", draft-ietf-isis- 176 segment-routing-extensions-19 (work in progress), July 177 2018. 179 [I-D.ietf-isis-segment-routing-msd] 180 Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg, 181 "Signaling MSD (Maximum SID Depth) using IS-IS", draft- 182 ietf-isis-segment-routing-msd-13 (work in progress), July 183 2018. 185 [I-D.ietf-spring-segment-routing-mpls] 186 Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., 187 Litkowski, S., and R. Shakir, "Segment Routing with MPLS 188 data plane", draft-ietf-spring-segment-routing-mpls-14 189 (work in progress), June 2018. 191 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 192 Requirement Levels", BCP 14, RFC 2119, 193 DOI 10.17487/RFC2119, March 1997, 194 . 196 [RFC4971] Vasseur, JP., Ed., Shen, N., Ed., and R. Aggarwal, Ed., 197 "Intermediate System to Intermediate System (IS-IS) 198 Extensions for Advertising Router Information", RFC 4971, 199 DOI 10.17487/RFC4971, July 2007, 200 . 202 [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic 203 Engineering", RFC 5305, DOI 10.17487/RFC5305, October 204 2008, . 206 [RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and 207 L. Yong, "The Use of Entropy Labels in MPLS Forwarding", 208 RFC 6790, DOI 10.17487/RFC6790, November 2012, 209 . 211 8.2. Informative References 213 [I-D.ietf-mpls-spring-entropy-label] 214 Kini, S., Kompella, K., Sivabalan, S., Litkowski, S., 215 Shakir, R., and J. Tantsura, "Entropy label for SPRING 216 tunnels", draft-ietf-mpls-spring-entropy-label-12 (work in 217 progress), July 2018. 219 Authors' Addresses 221 Xiaohu Xu 222 Alibaba Inc 224 Email: xiaohu.xxh@alibabab-inc.com 226 Sriganesh Kini 228 Email: sriganeshkini@gmail.com 230 Siva Sivabalan 231 Cisco 233 Email: msiva@cisco.com 234 Clarence Filsfils 235 Cisco 237 Email: cfilsfil@cisco.com 239 Stephane Litkowski 240 Orange 242 Email: stephane.litkowski@orange.com