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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references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 4970 (Obsoleted by RFC 7770) == Outdated reference: A later version (-12) exists of draft-ietf-mpls-spring-entropy-label-03 == Outdated reference: A later version (-27) exists of draft-ietf-ospf-segment-routing-extensions-08 == Outdated reference: A later version (-22) exists of draft-ietf-spring-segment-routing-mpls-04 Summary: 1 error (**), 0 flaws (~~), 4 warnings (==), 1 comment (--).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: November 4, 2016 Ericsson 6 S. Sivabalan 7 C. Filsfils 8 Cisco 9 S. Litkowski 10 Orange 11 May 3, 2016 13 Signaling Entropy Label Capability Using OSPF 14 draft-ietf-ospf-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 via signaling that it can process ELs on 22 that tunnel. This draft defines a mechanism to signal that 23 capability using OSPF. This mechanism is useful when the label 24 advertisement is also done via OSPF. 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 November 4, 2016. 43 Copyright Notice 45 Copyright (c) 2016 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 OSPF . . . . . . . . . . . . . . . . . 3 64 4. Advertising RLDC Using OSPF . . . . . . . . . . . . . . . . . 3 65 5. Usage and Applicability . . . . . . . . . . . . . . . . . . . 4 66 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 67 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 68 8. Security Considerations . . . . . . . . . . . . . . . . . . . 4 69 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 70 9.1. Normative References . . . . . . . . . . . . . . . . . . 4 71 9.2. Informative References . . . . . . . . . . . . . . . . . 5 72 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 74 1. Introduction 76 Multi Protocol Label Switching (MPLS) has defined a method in 77 [RFC6790] to load balance traffic flows using Entropy Labels (EL). 78 An ingress LSR cannot insert ELs for packets going into a given 79 tunnel unless an egress LSR has indicated that it can process ELs on 80 that tunnel. [RFC6790] defines the signaling of this capability 81 (a.k.a Entropy Label Capability - ELC) via signaling protocols. 82 Recently, mechanisms are being defined to signal labels via link 83 state Interior Gateway Protocols (IGP) such as OSPF 84 [I-D.ietf-ospf-segment-routing-extensions] . In such scenario the 85 signaling mechanisms defined in [RFC6790] are inadequate. This draft 86 defines a mechanism to signal the ELC using OSPF. This mechanism is 87 useful when the label advertisement is also done via OSPF. In 88 addition, in the cases where stacked LSPs are used for whatever 89 reasons (e.g., SPRING-MPLS [I-D.ietf-spring-segment-routing-mpls]), 90 it would be useful for ingress LSRs to know each LSR's capability of 91 reading the maximum label stack deepth. This capability, referred to 92 as Readable Label Deepth Capability (RLDC) can be used by ingress 93 LSRs to determine whether it's necessary to insert an EL for a given 94 LSP tunnel in the case where there has already been at least one EL 95 in the label stack [I-D.ietf-mpls-spring-entropy-label] . Of course, 96 even it has been determined that it's neccessary to insert an EL for 97 a given LSP tunnel, if the egress LSR of that LSP tunnel has not yet 98 indicated that it can process ELs for that tunnel, the ingress LSR 99 MUST NOT include an entropy label for that tunnel as 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 [RFC4970]. 111 3. Advertising ELC Using OSPF 113 The OSPF Router Information (RI) Opaque LSA defined in [RFC4970] is 114 used by OSPF routers to announce their capabilities. A new TLV 115 within the body of this LSA, called ELC TLV is defined to advertise 116 the capability of the router to process the ELs. As showed in 117 Figure 1, it is formatted as described in Section 2.1 of [RFC4970]. 118 The Type for the ELC TLV needs to be assigned by IANA and it has a 119 Length of zero. The scope of the advertisement depends on the 120 application but it is recommended that it SHOULD be AS-scoped. If a 121 router has multiple linecards, the router MUST NOT announce the ELC 122 unless all of its linecards are capable of processing ELs. This TLV 123 is applicable to both OSPFv2 and OSPFv3. 125 0 1 2 3 126 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 1 127 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 128 | Type=TBD1 | Length=0 | 129 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 130 Figure 1: ELC TLV Format. 132 4. Advertising RLDC Using OSPF 134 A new TLV within the body of the OSPF RI LSA, called RLDC TLV is 135 defined to advertise the capability of the router to read the maximum 136 label stack depth. As showed in Figure 2, it is formatted as 137 described in Section 2.1 of [RFC4970] with a Type code to be assigned 138 by IANA and a Length of one. The Value field is set to the maximum 139 readable label stack depth in the range between 1 to 255. The scope 140 of the advertisement depends on the application but it is RECOMMENDED 141 that it SHOULD be domain-wide. If a router has multiple linecards 142 with different capabilities of reading the maximum label stack 143 deepth, the router MUST advertise the smallest one in the RLDC TLV. 144 This TLV is applicable to both OSPFv2 and OSPFv3. 146 0 1 2 3 147 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 1 148 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 149 | Type=TBD2 | Length | 150 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 151 | RLD | 152 +-+-+-+-+-+-+-+-+ 153 Figure 2: RLDC TLV Format 155 5. Usage and Applicability 157 The EL capability is used by ingress LSRs to determine whether an EL 158 could be inserted into a given LSP tunnel. The RLD capability is 159 used by ingress LSRs to determine whether it's necessary to insert an 160 EL for a given LSP tunnel in the case where there has already been at 161 least one EL in the label stack. This document only describes how to 162 signal the EL capability and RLD capability using OSPF. As for how 163 to apply those capabilities when inserting EL(s) into LSP tunnel(s), 164 it's outside the scope of this document and accordingly would be 165 described in [I-D.ietf-mpls-spring-entropy-label]. 167 6. Acknowledgements 169 The authors would like to thank Yimin Shen, George Swallow, Acee 170 Lindem and Carlos Pignataro for their valuable comments. 172 7. IANA Considerations 174 This memo includes a request to IANA to allocate two TLV types from 175 the OSPF RI TLVs registry. 177 8. Security Considerations 179 The security considerations as described in [RFC4970] is appliable to 180 this document. This document does not introduce any new security 181 risk. 183 9. References 185 9.1. Normative References 187 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 188 Requirement Levels", BCP 14, RFC 2119, 189 DOI 10.17487/RFC2119, March 1997, 190 . 192 [RFC4970] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and 193 S. Shaffer, "Extensions to OSPF for Advertising Optional 194 Router Capabilities", RFC 4970, DOI 10.17487/RFC4970, July 195 2007, . 197 9.2. Informative References 199 [I-D.ietf-mpls-spring-entropy-label] 200 Kini, S., Kompella, K., Sivabalan, S., Litkowski, S., 201 Shakir, R., and j. jefftant@gmail.com, "Entropy labels for 202 source routed tunnels with label stacks", draft-ietf-mpls- 203 spring-entropy-label-03 (work in progress), April 2016. 205 [I-D.ietf-ospf-segment-routing-extensions] 206 Psenak, P., Previdi, S., Filsfils, C., Gredler, H., 207 Shakir, R., Henderickx, W., and J. Tantsura, "OSPF 208 Extensions for Segment Routing", draft-ietf-ospf-segment- 209 routing-extensions-08 (work in progress), April 2016. 211 [I-D.ietf-spring-segment-routing-mpls] 212 Filsfils, C., Previdi, S., Bashandy, A., Decraene, B., 213 Litkowski, S., Horneffer, M., Shakir, R., Tantsura, J., 214 and E. Crabbe, "Segment Routing with MPLS data plane", 215 draft-ietf-spring-segment-routing-mpls-04 (work in 216 progress), March 2016. 218 [RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and 219 L. Yong, "The Use of Entropy Labels in MPLS Forwarding", 220 RFC 6790, DOI 10.17487/RFC6790, November 2012, 221 . 223 Authors' Addresses 225 Xiaohu Xu 226 Huawei 228 Email: xuxiaohu@huawei.com 230 Sriganesh Kini 231 Ericsson 233 Email: sriganesh.kini@ericsson.com 234 Siva Sivabalan 235 Cisco 237 Email: msiva@cisco.com 239 Clarence Filsfils 240 Cisco 242 Email: cfilsfil@cisco.com 244 Stephane Litkowski 245 Orange 247 Email: stephane.litkowski@orange.com