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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references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 4971 (Obsoleted by RFC 7981) == Outdated reference: A later version (-25) exists of draft-ietf-isis-segment-routing-extensions-03 == Outdated reference: A later version (-12) exists of draft-ietf-mpls-spring-entropy-label-00 == Outdated reference: A later version (-22) exists of draft-ietf-spring-segment-routing-mpls-00 Summary: 1 error (**), 0 flaws (~~), 4 warnings (==), 1 comment (--).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 Huawei 4 Intended status: Standards Track S. Kini 5 Expires: October 22, 2015 Ericsson 6 S. Sivabalan 7 C. Filsfils 8 Cisco 9 S. Litkowski 10 Orange 11 April 20, 2015 13 Signaling Entropy Label Capability Using IS-IS 14 draft-xu-isis-mpls-elc-02 16 Abstract 18 Multi Protocol Label Switching (MPLS) has defined a mechanism to load 19 balance traffic flows using Entropy Labels (EL). An ingress LSR 20 cannot insert ELs for packets going into a given tunnel unless an 21 egress LSR has indicated that it can process ELs for that tunnel. 22 This draft defines a mechanism to signal that capability using IS-IS. 23 This mechanism is useful when the label advertisement is also done 24 via IS-IS. 26 Status of This Memo 28 This Internet-Draft is submitted in full conformance with the 29 provisions of BCP 78 and BCP 79. 31 Internet-Drafts are working documents of the Internet Engineering 32 Task Force (IETF). Note that other groups may also distribute 33 working documents as Internet-Drafts. The list of current Internet- 34 Drafts is at http://datatracker.ietf.org/drafts/current/. 36 Internet-Drafts are draft documents valid for a maximum of six months 37 and may be updated, replaced, or obsoleted by other documents at any 38 time. It is inappropriate to use Internet-Drafts as reference 39 material or to cite them other than as "work in progress." 41 This Internet-Draft will expire on October 22, 2015. 43 Copyright Notice 45 Copyright (c) 2015 IETF Trust and the persons identified as the 46 document authors. All rights reserved. 48 This document is subject to BCP 78 and the IETF Trust's Legal 49 Provisions Relating to IETF Documents 50 (http://trustee.ietf.org/license-info) in effect on the date of 51 publication of this document. Please review these documents 52 carefully, as they describe your rights and restrictions with respect 53 to this document. Code Components extracted from this document must 54 include Simplified BSD License text as described in Section 4.e of 55 the Trust Legal Provisions and are provided without warranty as 56 described in the Simplified BSD License. 58 Table of Contents 60 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 61 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 62 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 63 3. Advertising ELC using IS-IS . . . . . . . . . . . . . . . . . 3 64 4. Advertising RLSDC using IS-IS . . . . . . . . . . . . . . . . 3 65 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 3 66 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 67 7. Security Considerations . . . . . . . . . . . . . . . . . . . 4 68 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 69 8.1. Normative References . . . . . . . . . . . . . . . . . . 4 70 8.2. Informative References . . . . . . . . . . . . . . . . . 4 71 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 73 1. Introduction 75 Multi Protocol Label Switching (MPLS) has defined a method in 76 [RFC6790] to load balance traffic flows using Entropy Labels (EL). 77 An ingress LSR cannot insert ELs for packets going into a given 78 tunnel unless an egress LSR has indicated that it can process ELs for 79 that tunnel. [RFC6790] defines the signaling of this capability 80 (a.k.a Entropy Label Capability - ELC) via signaling protocols. 81 Recently, mechanisms are being defined to signal labels via link 82 state Interior Gateway Protocols (IGP) such as IS-IS 83 [I-D.ietf-isis-segment-routing-extensions]. In such scenario the 84 signaling mechanisms defined in [RFC6790] are inadequate. This draft 85 defines a mechanism to signal the ELC using IS-IS. This mechanism is 86 useful when the label advertisement is also done via IS-IS. In 87 addition, in the cases where stacked LSPs are used for whatever 88 reasons (e.g., SPRING-MPLS [I-D.ietf-spring-segment-routing-mpls]), 89 it would be useful for ingress LSRs to know each LSR's capability of 90 reading the maximum label stack deepth. This capability, referred to 91 as Readable Label Stack Deepth Capability (RLSDC) can be used by 92 ingress LSRs to determine whether it's necessary to insert an EL for 93 a given LSP tunnel in the case where there has already been at least 94 one EL in the label stack [I-D.ietf-mpls-spring-entropy-label] . Of 95 course, even it has been determined that it's neccessary to insert an 96 EL for a given LSP tunnel, if the egress LSR of that LSP tunnel has 97 not yet indicated that it can process ELs for that tunnel, the 98 ingress LSR MUST NOT include an entropy label for that tunnel as 99 well. 101 1.1. Requirements Language 103 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 104 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 105 document are to be interpreted as described in RFC 2119 [RFC2119]. 107 2. Terminology 109 This memo makes use of the terms defined in [RFC6790] and [RFC4971]. 111 3. Advertising ELC using IS-IS 113 The IS-IS Router CAPABILITY TLV defined in [RFC4971] is used by IS-IS 114 routers to announce their capabilities. A new sub-TLV of this TLV, 115 called ELC sub-TLV is defined to advertise the capability of the 116 router to process the ELs. It is formatted as described in [RFC5305] 117 with a Type code to be assigned by IANA and a Length of zero. The 118 scope of the advertisement depends on the application but it is 119 RECOMMENDED that it SHOULD be domain-wide. If a router has multiple 120 linecards, the router MUST NOT advertise the ELC unless all of the 121 linecards are capable of processing ELs. 123 4. Advertising RLSDC using IS-IS 125 A new sub-TLV of the IS-IS Router CAPABILITY TLV, called RLSDC sub- 126 TLV is defined to advertise the capability of the router to read the 127 maximum label stack depth. It is formatted as described in [RFC5305] 128 with a Type code to be assigned by IANA and a Length of one. The 129 Value field is set to the maximum readable label stack deepth in the 130 range between 1 to 255. The scope of the advertisement depends on 131 the application but it is RECOMMENDED that it SHOULD be domain-wide. 132 If a router has multiple linecards with different capabilities of 133 reading the maximum label stack deepth, the router MUST advertise the 134 smallest one in the RLSDC sub-TLV. 136 5. Acknowledgements 138 The authors would like to thank Yimin Shen and George Swallow for 139 their valuable comments on the draft. 141 6. IANA Considerations 143 This memo includes a request to IANA to allocate two sub-TLV types 144 within the IS-IS Router Capability TLV. 146 7. Security Considerations 148 This document does not introduce any new security risk. 150 8. References 152 8.1. Normative References 154 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 155 Requirement Levels", BCP 14, RFC 2119, March 1997. 157 [RFC4971] Vasseur, JP., Shen, N., and R. Aggarwal, "Intermediate 158 System to Intermediate System (IS-IS) Extensions for 159 Advertising Router Information", RFC 4971, July 2007. 161 [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic 162 Engineering", RFC 5305, October 2008. 164 8.2. Informative References 166 [I-D.ietf-isis-segment-routing-extensions] 167 Previdi, S., Filsfils, C., Bashandy, A., Gredler, H., 168 Litkowski, S., Decraene, B., and J. Tantsura, "IS-IS 169 Extensions for Segment Routing", draft-ietf-isis-segment- 170 routing-extensions-03 (work in progress), October 2014. 172 [I-D.ietf-mpls-spring-entropy-label] 173 Kini, S., Kompella, K., Sivabalan, S., Litkowski, S., 174 Shakir, R., Xu, X., Henderickx, W., and J. Tantsura, 175 "Entropy labels for source routed stacked tunnels", draft- 176 ietf-mpls-spring-entropy-label-00 (work in progress), 177 March 2015. 179 [I-D.ietf-spring-segment-routing-mpls] 180 Filsfils, C., Previdi, S., Bashandy, A., Decraene, B., 181 Litkowski, S., Horneffer, M., Shakir, R., Tantsura, J., 182 and E. Crabbe, "Segment Routing with MPLS data plane", 183 draft-ietf-spring-segment-routing-mpls-00 (work in 184 progress), December 2014. 186 [RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and 187 L. Yong, "The Use of Entropy Labels in MPLS Forwarding", 188 RFC 6790, November 2012. 190 Authors' Addresses 192 Xiaohu Xu 193 Huawei 195 Email: xuxiaohu@huawei.com 197 Sriganesh Kini 198 Ericsson 200 Email: sriganesh.kini@ericsson.com 202 Siva Sivabalan 203 Cisco 205 Email: msiva@cisco.com 207 Clarence Filsfils 208 Cisco 210 Email: cfilsfil@cisco.com 212 Stephane Litkowski 213 Orange 215 Email: stephane.litkowski@orange.com