idnits 2.17.00 (12 Aug 2021) /tmp/idnits11184/draft-ietf-manet-dlep-multi-hop-extension-07.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (May 5, 2019) is 1105 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) No issues found here. Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group B. Cheng 3 Internet-Draft MIT Lincoln Laboratory 4 Intended status: Standards Track L. Berger, Ed. 5 Expires: November 6, 2019 LabN Consulting, L.L.C. 6 May 5, 2019 8 Dynamic Link Exchange Protocol (DLEP) Multi-Hop Forwarding Extension 9 draft-ietf-manet-dlep-multi-hop-extension-07 11 Abstract 13 This document defines an extension to the Dynamic Link Exchange 14 Protocol (DLEP) that enables the reporting and control of Multi-Hop 15 Forwarding by DLEP capable modems. 17 Status of This Memo 19 This Internet-Draft is submitted in full conformance with the 20 provisions of BCP 78 and BCP 79. 22 Internet-Drafts are working documents of the Internet Engineering 23 Task Force (IETF). Note that other groups may also distribute 24 working documents as Internet-Drafts. The list of current Internet- 25 Drafts is at https://datatracker.ietf.org/drafts/current/. 27 Internet-Drafts are draft documents valid for a maximum of six months 28 and may be updated, replaced, or obsoleted by other documents at any 29 time. It is inappropriate to use Internet-Drafts as reference 30 material or to cite them other than as "work in progress." 32 This Internet-Draft will expire on November 6, 2019. 34 Copyright Notice 36 Copyright (c) 2019 IETF Trust and the persons identified as the 37 document authors. All rights reserved. 39 This document is subject to BCP 78 and the IETF Trust's Legal 40 Provisions Relating to IETF Documents 41 (https://trustee.ietf.org/license-info) in effect on the date of 42 publication of this document. Please review these documents 43 carefully, as they describe your rights and restrictions with respect 44 to this document. Code Components extracted from this document must 45 include Simplified BSD License text as described in Section 4.e of 46 the Trust Legal Provisions and are provided without warranty as 47 described in the Simplified BSD License. 49 Table of Contents 51 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 52 1.1. Key Words . . . . . . . . . . . . . . . . . . . . . . . . 3 53 2. Extension Usage and Identification . . . . . . . . . . . . . 3 54 3. Extension Data Items . . . . . . . . . . . . . . . . . . . . 3 55 3.1. Hop Count . . . . . . . . . . . . . . . . . . . . . . . . 3 56 3.2. Hop Control . . . . . . . . . . . . . . . . . . . . . . . 5 57 3.2.1. Reset . . . . . . . . . . . . . . . . . . . . . . . . 6 58 3.2.2. Terminate . . . . . . . . . . . . . . . . . . . . . . 7 59 3.2.3. Direct Connection . . . . . . . . . . . . . . . . . . 7 60 3.2.4. Suppress Forwarding . . . . . . . . . . . . . . . . . 7 61 4. Security Considerations . . . . . . . . . . . . . . . . . . . 8 62 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 63 5.1. Extension Type Value . . . . . . . . . . . . . . . . . . 8 64 5.2. Data Item Values . . . . . . . . . . . . . . . . . . . . 9 65 5.3. Hop Control Actions Registry . . . . . . . . . . . . . . 9 66 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 67 6.1. Normative References . . . . . . . . . . . . . . . . . . 10 68 6.2. Informative References . . . . . . . . . . . . . . . . . 10 69 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 10 70 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 72 1. Introduction 74 The Dynamic Link Exchange Protocol (DLEP) is defined in [RFC8175]. 75 It provides the exchange of link related control information between 76 a modem and a router. DLEP defines a base set of mechanisms as well 77 as support for possible extensions. This document defines one such 78 extension. 80 Some modem technologies support mobile ad hoc network (MANET) 81 forwarding where connectivity to destinations is provided via 82 forwarding in intermediate modems. This document refers to 83 forwarding by intermediate modems as 'multi-hop forwarding'. DLEP 84 Destination messages can be used to report such reachable 85 destinations, see [RFC8175], but do not provide any information 86 related to the number or capacity of the hops. The extension defined 87 in this document enables modems to inform routers when multi-hop 88 forwarding is being used, and routers to request that modems change 89 multi-hop forwarding behavior. The extension defined in this 90 document is referred to as "Multi-Hop Forwarding", where each modem 91 that transmits/sends data to reach a particular destination is 92 counted as a hop. 94 It is important to note that the use of the hop control mechanism 95 defined in this document can result in connectivity changes and even 96 loss of the ability to reach one or more destinations. The defined 97 mechanism will report such connectivity changes, but the details of 98 what a router does or how it reacts to such are out scope of this 99 document. 101 This document defines a new DLEP Extension Type Value in Section 2 102 which is used to indicate the use of the extension, and three new 103 DLEP Data Items in Section 3. 105 1.1. Key Words 107 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 108 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 109 "OPTIONAL" in this document are to be interpreted as described in BCP 110 14 [RFC2119] [RFC8174] when, and only when, they appear in all 111 capitals, as shown here. 113 2. Extension Usage and Identification 115 The use of the Multi-Hop Forwarding Extension SHOULD be configurable. 116 Per [RFC8175], to indicate that the extension is to be used, an 117 implementation includes the Multi-Hop Forwarding Extension Type Value 118 in the Extensions Supported Data Item. The Extensions Supported Data 119 Item is sent and processed according to [RFC8175]. 121 The Multi-Hop Forwarding Extension Type Value is TBA1, see Section 5. 123 3. Extension Data Items 125 Three data items are defined by this extension. The Hop Count Data 126 Item is used by a modem to provide the number of modem hops traversed 127 to reach a particular destination. The Hop Control Data Item is used 128 by a router to request that a modem alter connectivity to a 129 particular destination. The Suppress Forwarding Data Item is used by 130 a router to request that a modem disable multi-hop forwarding on 131 either a device or destination basis. 133 3.1. Hop Count 135 The Hop Count Data Item is used by a modem to indicate the number of 136 modems that transmit/send data to reach a particular destination, 137 i.e., hops, between the modem and a specific destination. In other 138 words, each hop represents a transmission and the number of hops is 139 equal to the number of transmissions required to go from a router 140 connected modem to the destination's connected modem. The minimum 141 number of hops is 1, which represents transmission to destinations 142 that are directly reachable via the router's locally connected modem. 144 The data item also contains an indication of when a destination which 145 currently has a hop count of greater than one (1) could be made 146 directly reachable by a modem, e.g., by re-aiming an antenna. 148 The Hop Count Data Item SHOULD be carried in the Destination Up, 149 Destination Update, Destination Announce Response, and Link 150 Characteristics Response Messages when the Hop Count to a destination 151 is greater than one (1). 153 A router receiving a Hop Count Data Item can use this information in 154 its forwarding and routing decisions, and specific use is out of 155 scope of this document. When using this extension, the absence of 156 the Hop Count Data Item MUST be interpreted by the router as a Hop 157 Count value of one (1). 159 The format of the Hop Count Data Item is: 161 0 1 2 3 162 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 1 163 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 164 | Data Item Type | Length | 165 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 166 |P| Reserved | Hop Count | 167 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 169 Data Item Type: TBA2 171 Length: 2 173 P: 175 The P-bit indicates that a destination is potentially directly 176 reachable. When the P-bit is set, the router MAY request a direct 177 link to the associated destination using the Hop Control Data Item 178 described below. This field MUST be ignored when the value 179 contained in the Hop Count field is one (1). 181 Reserved: 183 MUST be set to zero by the sender (a modem) and ignored by the 184 receiver (a router). 186 Hop Count: 188 An unsigned 8-bit integer indicating the number of modem hops 189 required (i.e., number of times a packet will be transmitted) to 190 reach the destination indicated in the message. The special value 191 of 255 (0xFF) is used to indicate that the number of hops is an 192 unknown number greater than one (1). This field MUST contain a 193 value of at least one (1) if the associated destination is 194 reachable. 196 A value of zero (0) is used to indicate that processing of a Hop 197 Control action, see Section 3.2, has resulted in the destination 198 no longer being reachable. A zero value MUST NOT be used in any 199 message other than a Link Characteristics Response Message. 201 3.2. Hop Control 203 The Hop Control Data Item is used by a router to request a change in 204 connectivity to a particular destination, or in multi-hop processing 205 on a device wide basis. A router can request that a multi-hop 206 reachable destination be changed to a single hop. A router can also 207 indicate that the modem terminates a previous direct connectivity 208 request to a particular destination. 210 The Hop Control Data Item MAY be carried in a Session Update Message 211 sent by a router when the control applies to the whole device, or a 212 Link Characteristics Request Message when the control applies to a 213 particular destination. 215 A modem that receives the Hop Control Data Item in a Link 216 Characteristics Request Message SHOULD take whatever actions are 217 needed to make the change indicated by the data item for the 218 associated destination MAC address. Once the change is made, fails 219 or is rejected, the modem MUST respond with a Link Characteristics 220 Response Message containing an updated Hop Count Data Item. Note 221 that other destinations can be impacted as a result of the change and 222 such changes are reported in Destination Down and Destination Update 223 Messages. The modem MUST notify the router of each destination that 224 is not identified in the Link Characteristics Response Message and is 225 no longer reachable via a Destination Down Message. The modem MUST 226 also notify the router of each impacted destination that is not 227 identified in the Link Characteristics Response Message via a 228 Destination Update Message. 230 Failures may occur for multiple reasons, for example, the 231 transmission characteristics of the link don't support the one-hop 232 connection at the time of the request. Requests can be rejected by 233 local policy. 235 A modem that receives the Hop Control Data Item in a Session Update 236 Message SHOULD take whatever actions are needed to make the change 237 indicated by the data item for all known destinations. Once the 238 change is made, or fails or is rejected, the modem MUST respond with 239 a Session Update Response Message with an appropriate Status Code. 241 Destination specific impact resulting from the processing of a Hop 242 Control Data Item in a Session Update Message is provided via 243 Destination Down and Destination Update Messages. The modem MUST 244 notify the router of each destination that is no longer reachable via 245 a Destination Down Message. The modem MUST notify the router of any 246 changes in Hop Counts via Destination Update Messages. 248 The format of the Hop Control Data Item is: 250 0 1 2 3 251 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 1 252 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 253 | Data Item Type | Length | 254 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 255 | Hop Control Actions | 256 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 258 Data Item Type: TBA3 260 Length: 2 262 Hop Control Actions: 264 An unsigned 16-bit value with the following meaning: 266 +-------+---------------------+ 267 | Value | Action | 268 +-------+---------------------+ 269 | 0 | Reset | 270 | | | 271 | 1 | Terminate | 272 | | | 273 | 2 | Direct Connection | 274 | | | 275 | 3 | Suppress Forwarding | 276 +-------+---------------------+ 278 Table 1: Hop Control Actions Values 280 3.2.1. Reset 282 The Reset Action requests that the default behavior be restored. 283 When received in a Session Update Message message, a modem MUST clear 284 all control actions that have previously been processed on a device 285 wide basis, and revert to its configured behavior. When received in 286 a Link Characteristics Request Message, a modem MUST clear all 287 control actions that have previously been processed for the 288 destination indicated in the message. 290 3.2.2. Terminate 292 The Terminate Action is only valid on a per destination basis and 293 MUST NOT be sent in a Session Update Message message. It indicates 294 that a direct connection is no longer needed with the destination 295 identified in the message. This request has no impact for multi-hop 296 destinations and may fail even in a single hop case, i.e. can result 297 in the Hop Count to the destination not being impacted by the 298 processing of the request. 300 3.2.3. Direct Connection 302 The Direct Connection Action is only valid on a per destination basis 303 and MUST NOT be sent in a Session Update Message message. It 304 indicates that the modem SHOULD attempt to establish a direct 305 connection with the destination identified in the message. This 306 action SHOULD only be sent for destinations for which the Hop Count 307 is greater than 1 and has the P-Bit set in the previously received 308 Hop Count Data Item. Results of the request for the destination 309 identified in the message are provided as described above. 311 3.2.4. Suppress Forwarding 313 The Suppress Forwarding Action is used by a router to indicate to its 314 peer that multi-hop forwarding performed by the modem is to be 315 suppressed. A router can request that multi-hop forwarding may be 316 suppressed on a device wide or destination specific basis. 318 A modem that receives the Suppress Forwarding Data Item in a Session 319 Update Message MUST suppress multi-hop forwarding on a device wide 320 basis. This means that data traffic originating from the modem's 321 peer router SHALL only be sent by the modem to destinations that are 322 one modem hop away, and that any data traffic received by the modem 323 from another modem that is not destined to the peer router SHALL be 324 dropped. Impact to destination hop counts are provided to the router 325 by the modem as described above. 327 A modem that receives the Suppress Forwarding Data Item in a Link 328 Characteristics Request Message MUST suppress multi-hop forwarding 329 for only the destination indicated in the message. This means that 330 data traffic originating from the modem's peer router SHALL be sent 331 by the modem to the destination indicated in the Link Characteristics 332 Request Message only when it is one modem hop away. Notably, data 333 traffic received by the modem from another modem can be forwarded by 334 the modem per its normal processing. Results are provided as 335 described above. 337 4. Security Considerations 339 The extension enables the reporting and control of forwarding 340 information by DLEP capable modems. The extension does not 341 inherently introduce any additional vulnerabilities above those 342 documented in [RFC8175]. The approach taken to Security in that 343 document applies equally when running the extension defined in this 344 document. 346 This extension does define one mechanism that is worth particular 347 note. This extension includes a Hop Control mechanism, see 348 Section 3.2, that is similar to the Link Characteristics Request 349 Message defined in [RFC8175] in that it can impact the set of 350 destinations reported as reachable. With the Link Characteristics 351 Request Message, this risk is implicit. With the Hop Control 352 mechanism defined in this document it is more likely. From a 353 security perspective, implementations should be aware of this 354 increased risk and may choose to implement additional configuration 355 control mechanisms to ensure that the Hop Control mechanism is only 356 used under conditions intended by the network operator. 358 Implementations of the extension defined in this document MUST 359 support configuration of TLS usage, as describe in [RFC8175], in 360 order to protect configurations where injection attacks are possible, 361 i.e., when the link between a modem and router is not otherwise 362 protected. 364 Note that this extension does allow a compromised or impersonating 365 modem to suppress transmission by the router or a switch that 366 interconnects the modem and router. Similar attacks are generally 367 possible base DLEP, for example an impersonating modem may cause a 368 session reset or a compromised modem simply can drop all traffic 369 destined to, or sent by a router. [RFC8175] defines the use of TLS 370 to protect against the impersonating attacker. 372 5. IANA Considerations 374 This document requests the assignment of 3 values by IANA. All 375 assignments are to registries defined by [RFC8175]. It also requests 376 creation of one new registry. 378 5.1. Extension Type Value 380 This document requests 1 new assignment to the DLEP Extensions 381 Registry named "Extension Type Values" in the range with the 382 "Specification Required" policy. The requested value is as follows: 384 +------+----------------------+ 385 | Code | Description | 386 +------+----------------------+ 387 | TBA1 | Multi-Hop Forwarding | 388 +------+----------------------+ 390 Table 2: Requested Extension Type Value 392 5.2. Data Item Values 394 This document requests 2 new assignments to the DLEP Data Item 395 Registry named "Data Item Type Values" in the range with the 396 "Specification Required" policy. The requested values are as 397 follows: 399 +-----------+-------------+ 400 | Type Code | Description | 401 +-----------+-------------+ 402 | TBA2 | Hop Count | 403 | | | 404 | TBA3 | Hop Control | 405 +-----------+-------------+ 407 Table 3: Requested Data Item Values 409 5.3. Hop Control Actions Registry 411 Upon approval of this document, IANA is requested to create a new 412 DLEP registry, named "Hop Control Actions Values". The following 413 table provides initial registry values and the [RFC8126] defined 414 policies that should apply to the registry: 416 +-------------+------------------------+ 417 | Value | Action/Policy | 418 +-------------+------------------------+ 419 | 0 | Reset | 420 | | | 421 | 1 | Terminate | 422 | | | 423 | 2 | Direct Connection | 424 | | | 425 | 3 | Suppress Forwarding | 426 | | | 427 | 4-65519 | Specification Required | 428 | | | 429 | 65520-65534 | Private Use | 430 | | | 431 | 65535 | Reserved | 432 +-------------+------------------------+ 434 Table 4: Hop Control Actions Values 436 6. References 438 6.1. Normative References 440 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 441 Requirement Levels", BCP 14, RFC 2119, 442 DOI 10.17487/RFC2119, March 1997, 443 . 445 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 446 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 447 May 2017, . 449 [RFC8175] Ratliff, S., Jury, S., Satterwhite, D., Taylor, R., and B. 450 Berry, "Dynamic Link Exchange Protocol (DLEP)", RFC 8175, 451 DOI 10.17487/RFC8175, June 2017, 452 . 454 6.2. Informative References 456 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 457 Writing an IANA Considerations Section in RFCs", BCP 26, 458 RFC 8126, DOI 10.17487/RFC8126, June 2017, 459 . 461 Appendix A. Acknowledgments 462 Helpful comments were received from members of the MANET working 463 grouping, including Henning Rogge, Victoria Pritchard and David 464 Wiggins. 466 Authors' Addresses 468 Bow-Nan Cheng 469 MIT Lincoln Laboratory 470 Massachusetts Institute of Technology 471 244 Wood Street 472 Lexington, MA 02421-6426 474 Email: bcheng@ll.mit.edu 476 Lou Berger (editor) 477 LabN Consulting, L.L.C. 479 Email: lberger@labn.net