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Xu 3 Internet-Draft Alibaba Inc 4 Intended status: Standards Track S. Kini 5 Expires: March 29, 2019 6 S. Sivabalan 7 C. Filsfils 8 Cisco 9 S. Litkowski 10 Orange 11 September 25, 2018 13 Signaling Entropy Label Capability and Entropy Readable Label-stack 14 Depth Using OSPF 15 draft-ietf-ospf-mpls-elc-07 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 OSPF. These mechanisms are 30 useful when the label advertisement is also done via OSPF. In 31 addition, this document introduces the Non-IGP Functional 32 Capabilities TLV for advertising OSPF router's actual non-IGP 33 functional capabilities. ELC is one of such non-IGP functional 34 capabilities. 36 Requirements Language 38 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 39 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 40 document are to be interpreted as described in RFC 2119 [RFC2119]. 42 Status of This Memo 44 This Internet-Draft is submitted in full conformance with the 45 provisions of BCP 78 and BCP 79. 47 Internet-Drafts are working documents of the Internet Engineering 48 Task Force (IETF). Note that other groups may also distribute 49 working documents as Internet-Drafts. The list of current Internet- 50 Drafts is at https://datatracker.ietf.org/drafts/current/. 52 Internet-Drafts are draft documents valid for a maximum of six months 53 and may be updated, replaced, or obsoleted by other documents at any 54 time. It is inappropriate to use Internet-Drafts as reference 55 material or to cite them other than as "work in progress." 57 This Internet-Draft will expire on March 29, 2019. 59 Copyright Notice 61 Copyright (c) 2018 IETF Trust and the persons identified as the 62 document authors. All rights reserved. 64 This document is subject to BCP 78 and the IETF Trust's Legal 65 Provisions Relating to IETF Documents 66 (https://trustee.ietf.org/license-info) in effect on the date of 67 publication of this document. Please review these documents 68 carefully, as they describe your rights and restrictions with respect 69 to this document. Code Components extracted from this document must 70 include Simplified BSD License text as described in Section 4.e of 71 the Trust Legal Provisions and are provided without warranty as 72 described in the Simplified BSD License. 74 Table of Contents 76 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 77 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 78 3. Non-OSPF Functional Capabilities TLV . . . . . . . . . . . . 3 79 4. Advertising ELC Using OSPF . . . . . . . . . . . . . . . . . 4 80 5. Advertising ERLD Using OSPF . . . . . . . . . . . . . . . . . 4 81 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 82 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 83 8. Security Considerations . . . . . . . . . . . . . . . . . . . 5 84 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 85 9.1. Normative References . . . . . . . . . . . . . . . . . . 5 86 9.2. Informative References . . . . . . . . . . . . . . . . . 6 87 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 89 1. Introduction 91 [RFC6790] describes a method to load balance Multiprotocol Label 92 Switching (MPLS) traffic flows using Entropy Labels (EL). [RFC6790] 93 introduces the concept of Entropy Label Capability (ELC) and defines 94 the signalings of this capability via MPLS signaling protocols. 95 Recently, mechanisms are being defined to signal labels via link- 96 state Interior Gateway Protocols (IGP) such as OSPF 98 [I-D.ietf-ospf-segment-routing-extensions]. In such scenario, the 99 signaling mechanisms defined in [RFC6790] are inadequate. This draft 100 defines a mechanism to signal the ELC [RFC6790] using OSPF. This 101 mechanism is useful when the label advertisement is also done via 102 OSPF. 104 In addition, in the cases where stacked LSPs are used for whatever 105 reasons (e.g., SR-MPLS [I-D.ietf-spring-segment-routing-mpls]), it 106 would be useful for ingress LSRs to know each intermediate LSR's 107 capability of reading the maximum label stack depth and performing 108 EL-based load-balancing. This capability, referred to as Entropy 109 Readable Label Depth (ERLD) as defined in 110 [I-D.ietf-mpls-spring-entropy-label] may be used by ingress LSRs to 111 determine whether it's necessary to insert an EL for a given LSP of 112 the stacked LSP tunnel in the case where there has already been at 113 least one EL in the label stack [I-D.ietf-mpls-spring-entropy-label]. 115 2. Terminology 117 This memo makes use of the terms defined in [RFC6790] and [RFC7770]. 119 3. Non-OSPF Functional Capabilities TLV 121 This document defines the Router Non-IGP Functional Capabilities TLV 122 with TLV type code of TBD1 within the body of the OSPF Router 123 Information LSA. An OSPF router advertising an OSPF RI LSA MAY 124 include the Router Non-IGP Functional Capabilities TLV. If included, 125 it MUST be included in the first instance of the LSA. Additionally, 126 the TLV MUST reflect the advertising OSPF router's actual non-IGP 127 functional capabilities in the flooding scope of the containing OSPF 128 RI LSA. 130 The format of the Router Non-OSPF Functional Capabilities TLV is as 131 follows: 133 0 1 2 3 134 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 1 135 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 136 | Type=TBD1 | Length | 137 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 138 | Non-IGP Functional Capabilities | 139 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 140 Figure 1: Non-OSPF Functional Capabilities TLV Format 142 Type: TBD1. 144 Length: Indicates the length of the value portion in octets and 145 will be a multiple of 4 octets dependent on the number of 146 capabilities advertised. Initially, the length will be 4, 147 denoting 4 octets of Non-IGP Functional Capabilities Bits as 148 defined in [I-D.ietf-isis-mpls-elc]. 150 Value: contains the Non-IGP Functional Capabilities Bits as 151 defined in [I-D.ietf-isis-mpls-elc]. 153 The Non-IGP Functional Capabilities TLV MAY be followed by optional 154 TLVs that further specify a non-OSPF functional capability. In 155 contrast to the OSPF Router Functional Capabilities TLV, the non-OSPF 156 functional capabilities advertised in this TLV have no impact on the 157 OSPF protocol operation. The specifications for non-IGP functional 158 capabilities advertised in this TLV MUST describe protocol behavior 159 and address backwards compatibility. 161 4. Advertising ELC Using OSPF 163 One bit of the Non-IGP Functional Capability Bits for is used to 164 indicate the ELC. 166 Assignment of a Non-IGP Functional Capability Bit for the ELC is 167 defined in [I-D.ietf-isis-mpls-elc]. 169 If a router has multiple line cards, the router MUST NOT announce the 170 ELC [RFC6790] unless all of its linecards are capable of processing 171 ELs. 173 How to apply the ELC advertisement to the inter-area, inter-AS and 174 inter-protocol scenarios is outside the scope of this document. 176 5. Advertising ERLD Using OSPF 178 A new MSD-type of the Node MSD sub-TLV 179 [I-D.ietf-isis-segment-routing-msd], called ERLD is defined to 180 advertise the ERLD of a given router. The scope of the advertisement 181 depends on the application. 183 Assignment of a MSD-Type for ERLD is defined in 184 [I-D.ietf-isis-mpls-elc]. 186 If a router has multiple linecards with different capabilities of 187 reading the maximum label stack deepth, the router MUST advertise the 188 smallest one. 190 6. Acknowledgements 192 The authors would like to thank Yimin Shen, George Swallow, Acee 193 Lindem, Les Ginsberg, Ketan Talaulikar, Jeff Tantsura , Bruno 194 Decraene and Carlos Pignataro for their valuable comments. 196 7. IANA Considerations 198 This document requests IANA to allocate one TLV type from the OSPF RI 199 TLVs registry for the Non-IGP Functional CapabilitiesTLV. 201 8. Security Considerations 203 The security considerations as described in [RFC7770] is applicable 204 to this document. This document does not introduce any new security 205 risk. 207 9. References 209 9.1. Normative References 211 [I-D.ietf-isis-mpls-elc] 212 Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S. 213 Litkowski, "Signaling Entropy Label Capability and Entropy 214 Readable Label Depth Using IS-IS", draft-ietf-isis-mpls- 215 elc-05 (work in progress), July 2018. 217 [I-D.ietf-isis-segment-routing-msd] 218 Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg, 219 "Signaling MSD (Maximum SID Depth) using IS-IS", draft- 220 ietf-isis-segment-routing-msd-16 (work in progress), 221 September 2018. 223 [I-D.ietf-ospf-segment-routing-extensions] 224 Psenak, P., Previdi, S., Filsfils, C., Gredler, H., 225 Shakir, R., Henderickx, W., and J. Tantsura, "OSPF 226 Extensions for Segment Routing", draft-ietf-ospf-segment- 227 routing-extensions-25 (work in progress), April 2018. 229 [I-D.ietf-spring-segment-routing-mpls] 230 Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., 231 Litkowski, S., and R. Shakir, "Segment Routing with MPLS 232 data plane", draft-ietf-spring-segment-routing-mpls-14 233 (work in progress), June 2018. 235 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 236 Requirement Levels", BCP 14, RFC 2119, 237 DOI 10.17487/RFC2119, March 1997, 238 . 240 [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic 241 Engineering", RFC 5305, DOI 10.17487/RFC5305, October 242 2008, . 244 [RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and 245 L. Yong, "The Use of Entropy Labels in MPLS Forwarding", 246 RFC 6790, DOI 10.17487/RFC6790, November 2012, 247 . 249 [RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and 250 S. Shaffer, "Extensions to OSPF for Advertising Optional 251 Router Capabilities", RFC 7770, DOI 10.17487/RFC7770, 252 February 2016, . 254 9.2. Informative References 256 [I-D.ietf-mpls-spring-entropy-label] 257 Kini, S., Kompella, K., Sivabalan, S., Litkowski, S., 258 Shakir, R., and J. Tantsura, "Entropy label for SPRING 259 tunnels", draft-ietf-mpls-spring-entropy-label-12 (work in 260 progress), July 2018. 262 Authors' Addresses 264 Xiaohu Xu 265 Alibaba Inc 267 Email: xiaohu.xxh@alibaba-inc.com 269 Sriganesh Kini 271 Email: sriganeshkini@gmail.com 273 Siva Sivabalan 274 Cisco 276 Email: msiva@cisco.com 277 Clarence Filsfils 278 Cisco 280 Email: cfilsfil@cisco.com 282 Stephane Litkowski 283 Orange 285 Email: stephane.litkowski@orange.com