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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references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 4971 (Obsoleted by RFC 7981) == Outdated reference: A later version (-25) exists of draft-ietf-isis-segment-routing-extensions-15 == Outdated reference: A later version (-12) exists of draft-ietf-mpls-spring-entropy-label-07 == Outdated reference: A later version (-22) exists of draft-ietf-spring-segment-routing-mpls-11 Summary: 1 error (**), 0 flaws (~~), 4 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 ISIS Working Group X. Xu 3 Internet-Draft Huawei 4 Intended status: Standards Track S. Kini 5 Expires: July 7, 2018 Ericsson 6 S. Sivabalan 7 C. Filsfils 8 Cisco 9 S. Litkowski 10 Orange 11 January 3, 2018 13 Signaling Entropy Label Capability and Readable Label-stack Depth Using 14 IS-IS 15 draft-ietf-isis-mpls-elc-03 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, referred to as Readable Label-stack Depth (RLD), 27 in the cases where stacked LSPs are used for whatever reasons. This 28 document defines mechanisms to signal these two capabilities using 29 OSPF. These mechanisms are useful when the label advertisement is 30 also done via IS-IS. 32 Requirements Language 34 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 35 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 36 document are to be interpreted as described in RFC 2119 [RFC2119]. 38 Status of This Memo 40 This Internet-Draft is submitted in full conformance with the 41 provisions of BCP 78 and BCP 79. 43 Internet-Drafts are working documents of the Internet Engineering 44 Task Force (IETF). Note that other groups may also distribute 45 working documents as Internet-Drafts. The list of current Internet- 46 Drafts is at https://datatracker.ietf.org/drafts/current/. 48 Internet-Drafts are draft documents valid for a maximum of six months 49 and may be updated, replaced, or obsoleted by other documents at any 50 time. It is inappropriate to use Internet-Drafts as reference 51 material or to cite them other than as "work in progress." 53 This Internet-Draft will expire on July 7, 2018. 55 Copyright Notice 57 Copyright (c) 2018 IETF Trust and the persons identified as the 58 document authors. All rights reserved. 60 This document is subject to BCP 78 and the IETF Trust's Legal 61 Provisions Relating to IETF Documents 62 (https://trustee.ietf.org/license-info) in effect on the date of 63 publication of this document. Please review these documents 64 carefully, as they describe your rights and restrictions with respect 65 to this document. Code Components extracted from this document must 66 include Simplified BSD License text as described in Section 4.e of 67 the Trust Legal Provisions and are provided without warranty as 68 described in the Simplified BSD License. 70 Table of Contents 72 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 73 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 74 3. Advertising ELC Using IS-IS . . . . . . . . . . . . . . . . . 3 75 4. Advertising RLD Using IS-IS . . . . . . . . . . . . . . . . . 3 76 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 77 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 78 7. Security Considerations . . . . . . . . . . . . . . . . . . . 4 79 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 80 8.1. Normative References . . . . . . . . . . . . . . . . . . 4 81 8.2. Informative References . . . . . . . . . . . . . . . . . 4 82 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 84 1. Introduction 86 [RFC6790] describes a method to load balance Multiprotocol Label 87 Switching (MPLS) traffic flows using Entropy Labels (EL). [RFC6790] 88 introduces the concept of Entropy Label Capability (ELC) and defines 89 the signalings of this capability via MPLS signaling protocols. 90 Recently, mechanisms are being defined to signal labels via link- 91 state Interior Gateway Protocols (IGP) such as IS-IS 92 [I-D.ietf-isis-segment-routing-extensions]. In such scenario, the 93 signaling mechanisms defined in [RFC6790] are inadequate. This draft 94 defines a mechanism to signal the ELC [RFC6790] using IS-IS. This 95 mechanism is useful when the label advertisement is also done via IS- 96 IS. In addition, in the cases where stacked LSPs are used for 97 whatever reasons (e.g., SPRING-MPLS 98 [I-D.ietf-spring-segment-routing-mpls]), it would be useful for 99 ingress LSRs to know each LSR's capability of reading the maximum 100 label stack depth. This capability, referred to as Readable Label- 101 stack Depth (RLD) may be used by ingress LSRs to determine whether 102 it's necessary to insert an EL for a given LSP of the stacked LSP 103 tunnel in the case where there has already been at least one EL in 104 the label stack [I-D.ietf-mpls-spring-entropy-label]. 106 2. Terminology 108 This memo makes use of the terms defined in [RFC6790] and [RFC4971]. 110 3. Advertising ELC Using IS-IS 112 The IS-IS Router CAPABILITY TLV as defined in [RFC4971] is used by 113 IS-IS routers to announce their capabilities. A new sub-TLV of this 114 TLV, called ELC sub-TLV is defined to advertise the capability of the 115 router to process the ELs. As shown in Figure 1, it is formatted as 116 described in [RFC5305] with a Type code to be assigned by IANA and a 117 Length of zero. The scope of the advertisement depends on the 118 application but it is RECOMMENDED that it SHOULD be domain-wide. If 119 a router has multiple linecards, the router MUST NOT advertise the 120 ELC unless all of the linecards are capable of processing ELs. 122 0 1 2 3 123 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 1 124 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 125 | Type=TBD1 | Length=0 | 126 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 127 Figure 1: ELC sub-TLV Format 129 4. Advertising RLD Using IS-IS 131 A new sub-TLV of the IS-IS Router CAPABILITY TLV, called RLD sub-TLV 132 is defined to advertise the capability of the router to read the 133 maximum label stack depth. As shown in Figure 2, it is formatted as 134 described in [RFC5305] with a Type code to be assigned by IANA and a 135 Length of one. The Value field is set to the maximum readable label 136 stack deepth in the range between 1 to 255. The scope of the 137 advertisement depends on the application but it is RECOMMENDED that 138 it SHOULD be domain-wide. If a router has multiple linecards with 139 different capabilities of reading the maximum label stack deepth, the 140 router MUST advertise the smallest one in the RLDC sub-TLV. 142 0 1 2 3 143 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 1 144 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 145 | Type=TBD2 | Length=1 | RLD | 146 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 147 Figure 2: RLD sub-TLV Format 149 5. Acknowledgements 151 The authors would like to thank Yimin Shen, George Swallow, Acee 152 Lindem and Carlos Pignataro for their valuable comments. 154 6. IANA Considerations 156 This memo includes a request to IANA to allocate two sub-TLV types 157 within the IS-IS Router Capability TLV. 159 7. Security Considerations 161 The security considerations as described in [RFC4971] is applicable 162 to this document. This document does not introduce any new security 163 risk. 165 8. References 167 8.1. Normative References 169 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 170 Requirement Levels", BCP 14, RFC 2119, 171 DOI 10.17487/RFC2119, March 1997, 172 . 174 [RFC4971] Vasseur, JP., Ed., Shen, N., Ed., and R. Aggarwal, Ed., 175 "Intermediate System to Intermediate System (IS-IS) 176 Extensions for Advertising Router Information", RFC 4971, 177 DOI 10.17487/RFC4971, July 2007, 178 . 180 8.2. Informative References 182 [I-D.ietf-isis-segment-routing-extensions] 183 Previdi, S., Ginsberg, L., Filsfils, C., Bashandy, A., 184 Gredler, H., Litkowski, S., Decraene, B., and J. Tantsura, 185 "IS-IS Extensions for Segment Routing", draft-ietf-isis- 186 segment-routing-extensions-15 (work in progress), December 187 2017. 189 [I-D.ietf-mpls-spring-entropy-label] 190 Kini, S., Kompella, K., Sivabalan, S., Litkowski, S., 191 Shakir, R., and J. Tantsura, "Entropy label for SPRING 192 tunnels", draft-ietf-mpls-spring-entropy-label-07 (work in 193 progress), October 2017. 195 [I-D.ietf-spring-segment-routing-mpls] 196 Filsfils, C., Previdi, S., Bashandy, A., Decraene, B., 197 Litkowski, S., and R. Shakir, "Segment Routing with MPLS 198 data plane", draft-ietf-spring-segment-routing-mpls-11 199 (work in progress), October 2017. 201 [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic 202 Engineering", RFC 5305, DOI 10.17487/RFC5305, October 203 2008, . 205 [RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and 206 L. Yong, "The Use of Entropy Labels in MPLS Forwarding", 207 RFC 6790, DOI 10.17487/RFC6790, November 2012, 208 . 210 Authors' Addresses 212 Xiaohu Xu 213 Huawei 215 Email: xuxh.mail@gmail.com 217 Sriganesh Kini 218 Ericsson 220 Email: sriganesh.kini@ericsson.com 222 Siva Sivabalan 223 Cisco 225 Email: msiva@cisco.com 227 Clarence Filsfils 228 Cisco 230 Email: cfilsfil@cisco.com 231 Stephane Litkowski 232 Orange 234 Email: stephane.litkowski@orange.com