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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Internet Engineering Task Force H. Chen 3 Internet-Draft Futurewei 4 Intended status: Standards Track 25 August 2021 5 Expires: 26 February 2022 7 OSPF Abnormal State Information 8 draft-chen-ospf-abnormal-state-info-06 10 Abstract 12 This document describes a couple of options for an OSPF router to 13 advertise its abnormal state information in a routing domain. 15 Status of This Memo 17 This Internet-Draft is submitted in full conformance with the 18 provisions of BCP 78 and BCP 79. 20 Internet-Drafts are working documents of the Internet Engineering 21 Task Force (IETF). Note that other groups may also distribute 22 working documents as Internet-Drafts. The list of current Internet- 23 Drafts is at https://datatracker.ietf.org/drafts/current/. 25 Internet-Drafts are draft documents valid for a maximum of six months 26 and may be updated, replaced, or obsoleted by other documents at any 27 time. It is inappropriate to use Internet-Drafts as reference 28 material or to cite them other than as "work in progress." 30 This Internet-Draft will expire on 26 February 2022. 32 Copyright Notice 34 Copyright (c) 2021 IETF Trust and the persons identified as the 35 document authors. All rights reserved. 37 This document is subject to BCP 78 and the IETF Trust's Legal 38 Provisions Relating to IETF Documents (https://trustee.ietf.org/ 39 license-info) in effect on the date of publication of this document. 40 Please review these documents carefully, as they describe your rights 41 and restrictions with respect to this document. Code Components 42 extracted from this document must include Simplified BSD License text 43 as described in Section 4.e of the Trust Legal Provisions and are 44 provided without warranty as described in the Simplified BSD License. 46 Table of Contents 48 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 49 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2 50 3. Conventions Used in This Document . . . . . . . . . . . . . . 3 51 4. OSPF Router State Information LSA . . . . . . . . . . . . . . 3 52 4.1. OSPFv2 Router State Information (RSI) Opaque LSA . . . . 3 53 4.2. OSPFv3 Router State Information (RSI) Opaque LSA . . . . 4 54 4.3. OSPF Router State Information (RSI) TLV . . . . . . . . . 4 55 5. Attach RSI TLV to Router Inforamtion LSA . . . . . . . . . . 6 56 6. Notify Other Systems . . . . . . . . . . . . . . . . . . . . 6 57 7. Security Considerations . . . . . . . . . . . . . . . . . . . 6 58 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 59 9. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 6 60 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 61 10.1. Normative References . . . . . . . . . . . . . . . . . . 6 62 10.2. Informative References . . . . . . . . . . . . . . . . . 7 63 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7 65 1. Introduction 67 There may be some states that are not normal in an OSPF router, which 68 include the state that a link state advertisement (LSA) stays in a 69 retransmission list on the router for more than a given time period 70 such as more than hello dead interval, and may include the state that 71 a database description (DD) packet does not get acknowledged for a 72 given period of time. 74 If a link state advertisement (LSA) with a topology change in a 75 router can not get through over an OSPF interface for a given time 76 period, some of the routers in the routing domain may have different 77 view of the real network topology, thus routing loops may occur and 78 some traffic may get dropped. 80 It is useful for an OSPF router in a routing domain to advertise its 81 abnormal state information to other routers, or notify some systems 82 such as an event management or monitoring system for its abnormal 83 state. 85 This document describes a couple of options for an OSPF router to 86 advertise its abnormal state information in a routing domain. 88 2. Terminology 90 This document uses terminologies defined in RFC 4970, RFC 2328, and 91 RFC 2740. 93 3. Conventions Used in This Document 95 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 96 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 97 document are to be interpreted as described in RFC 2119. 99 4. OSPF Router State Information LSA 101 OSPF routers MAY advertise their state information in a area-scoped 102 or AS-scoped router state information LSA with a router state 103 informatioin TLV. 105 4.1. OSPFv2 Router State Information (RSI) Opaque LSA 107 OSPFv2 routers will advertise an area-scoped or AS-scoped Router 108 State Information Opaque-LSA [RFC 2370], which has an Opaque type of 109 5 and Opaque ID of 0. 111 The RSI LSA will be originated initially by an OSPF router when an 112 OSPF instance is created and re-originated in every refresh interval 113 (LSRefreshTime) with the current state information of the router. 114 When the current state information changes, the RSI LSA will also be 115 originated. 117 0 1 2 3 118 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 1 119 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 120 | LS age | Options | 10/11 | 121 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 122 | 5 | 0 | 123 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 124 | Advertising Router | 125 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 126 | LS sequence number | 127 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 128 | LS checksum | length | 129 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 130 | | 131 +- TLVs -+ 132 | ... | 134 Figure 1: OSPFv2 Router State Information Opaque LSA 136 The format of the TLVs within the body of a RSI LSA is the same as 137 the format used by the Traffic Engineering Extensions to OSPF [RFC 138 3630]. The LSA payload consists of one or more nested Type/Length/ 139 Value (TLV) triplets. The format of each TLV is: 141 0 1 2 3 142 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 1 143 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 144 | Type | Length | 145 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 146 | Value... | 147 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 149 Figure 2: TLV Format 151 The Length field defines the length of the value portion in octets 152 (thus a TLV with no value portion would have a length of 0). The TLV 153 is padded to 4-octet alignment; padding is not included in the length 154 field (so a 3-octet value would have a length of 3, but the total 155 size of the TLV would be 8 octets). Nested TLVs are also 32-bit 156 aligned. For example, a 1-byte value would have the length field set 157 to 1, and 3 octets of padding would be added to the end of the value 158 portion of the TLV. Unrecognized types are ignored. 160 4.2. OSPFv3 Router State Information (RSI) Opaque LSA 162 TBD. 164 4.3. OSPF Router State Information (RSI) TLV 166 A router advertising a RSI LSA MAY include the Router State 167 Information TLV. If included, it MUST be the first TLV in the LSA. 168 Additionally, the TLV MUST accurately reflect the OSPF router's state 169 information in the scope advertised. 171 The format of the Router State Information TLV is as follows: 173 0 1 2 3 174 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 1 175 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 176 | Type (1) | Length | 177 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 178 | State Information sub-TLVs | 179 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 181 Figure 3: Router State Information TLV 183 Type: A 2-octet field set to 1. 185 Length: A 2-octet field that indicates the length of the value 186 portion in octets and will be the total number of octets that 187 state information sub-TLVs use. 189 Value: A variable length sequence of router state information sub- 190 TLVs. 192 The format of the Router State Information LSA retranmission time 193 sub-TLV is as follows: 195 0 1 2 3 196 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 1 197 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 198 | Type (1) | Length (2) | 199 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 200 | Max LSA retransmission time | Padding | 201 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 203 Figure 4: Retranmission Time Sub-TLV 205 Type: A 2-octet field set to 1. 207 Length: A 2-octet field that indicates the length of the value 208 portion in octets and will be 2. 210 Value: A 2-octet field set to the current maximum time (in seconds) 211 that an LSA stays in a retransmission list in a router. 213 The format of the sub-TLV for the maximum time that a Database 214 Description packet is not acknowledged is illustrated below. 216 0 1 2 3 217 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 1 218 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 219 | Type (2) | Length (2) | 220 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 221 | Max time DD not acked | Padding | 222 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 224 Figure 5: Maximum DD Time Sub-TLV 226 Type: A 2-octet field set to 2. 228 Length: A 2-octet field that indicates the length of the value 229 portion in octets and will be 2. 231 Value: A 2-octet field set to the current maximum time (in seconds) 232 for which a DD packet is not acknowledged in a router. 234 5. Attach RSI TLV to Router Inforamtion LSA 236 Instead of using a Router State Information LSA to advertise the 237 abnormal state information for a router, we may use the existing 238 Router Information LSA defined in RFC 4970 to advertise the state 239 information through adding the Router State Information (RSI) TLV 240 into the Router Inforamtion LSA. 242 When a Router State Information (RSI) TLV is put into a Router 243 Information LSA, the type of the TLV may be different from the one 244 mentioned in the section above. 246 6. Notify Other Systems 248 An OSPF router may also notify other systems such as an event 249 management system about its abnormal state when the abnormal state 250 occurs in the router. 252 7. Security Considerations 254 The mechanism described in this document does not raise any new 255 security issues for the OSPF protocols. 257 8. IANA Considerations 259 tb 261 9. Acknowledgement 263 The author would like to thank people for their valuable comments on 264 this draft. 266 10. References 268 10.1. Normative References 270 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 271 Requirement Levels", BCP 14, RFC 2119, 272 DOI 10.17487/RFC2119, March 1997, 273 . 275 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, 276 DOI 10.17487/RFC2328, April 1998, 277 . 279 [RFC2370] Coltun, R., "The OSPF Opaque LSA Option", RFC 2370, 280 DOI 10.17487/RFC2370, July 1998, 281 . 283 [RFC2740] Coltun, R., Ferguson, D., and J. Moy, "OSPF for IPv6", 284 RFC 2740, DOI 10.17487/RFC2740, December 1999, 285 . 287 [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering 288 (TE) Extensions to OSPF Version 2", RFC 3630, 289 DOI 10.17487/RFC3630, September 2003, 290 . 292 [RFC4970] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and 293 S. Shaffer, "Extensions to OSPF for Advertising Optional 294 Router Capabilities", RFC 4970, DOI 10.17487/RFC4970, July 295 2007, . 297 10.2. Informative References 299 [RFC5250] Berger, L., Bryskin, I., Zinin, A., and R. Coltun, "The 300 OSPF Opaque LSA Option", RFC 5250, DOI 10.17487/RFC5250, 301 July 2008, . 303 Author's Address 305 Huaimo Chen 306 Futurewei 307 Boston, MA, 308 United States of America 310 Email: Huaimo.chen@futurewei.com