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Berger, Ed. 5 Expires: April 30, 2017 LabN Consulting, L.L.C. 6 October 27, 2016 8 DLEP Multi-Hop Forwarding Extension 9 draft-cheng-manet-dlep-multi-hop-extension-00 11 Abstract 13 This document defines an extension to the DLEP protocol that enables 14 a the reporting and control of Multi-Hop Forwarding by DLEP capable 15 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 http://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 April 30, 2017. 34 Copyright Notice 36 Copyright (c) 2016 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 (http://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 . . . . . . . . . . . . . . . . . . . . . . 6 59 3.2.3. Direct Connection . . . . . . . . . . . . . . . . . . 6 60 3.2.4. Suppress Forwarding . . . . . . . . . . . . . . . . . 7 61 4. Security Considerations . . . . . . . . . . . . . . . . . . . 7 62 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 63 5.1. Extension Type Value . . . . . . . . . . . . . . . . . . 7 64 5.2. Data Item Values . . . . . . . . . . . . . . . . . . . . 8 65 5.3. Hop Control Actions Registry . . . . . . . . . . . . . . 8 66 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 67 6.1. Normative References . . . . . . . . . . . . . . . . . . 9 68 6.2. Informative References . . . . . . . . . . . . . . . . . 9 69 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 71 1. Introduction 73 The Dynamic Link Event Protocol (DLEP) is defined in 74 [I-D.ietf-manet-dlep]. It provides the exchange of link related 75 control information between DLEP peers. DLEP peers are comprised of 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 connectivity to destinations via 81 multi-hop forwarding. DLEP Destination messages can be used to 82 report such connectivity, see [I-D.ietf-manet-dlep], but do not 83 provide any information related to the number or capacity of the 84 hops. The extension defined in this document enables modems to 85 inform routers when multi-hop forwarding is being used, and routers 86 to request that modems change multi-hop forwarding behavior. The 87 extension defined in this document is referred to as "Multi-Hop 88 Forwarding". 90 This document defines a new DLEP Extension Type Value in Section 2 91 which is used to indicate the use of the extension, and three new 92 DLEP Data Items in Section 3. 94 1.1. Key Words 96 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 97 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 98 "OPTIONAL" in this document are to be interpreted as described in BCP 99 14, RFC 2119 [RFC2119]. 101 2. Extension Usage and Identification 103 The use of the Multi-Hop Forwarding Extension SHOULD be configurable. 104 To indicate that the extension is to be used, an implementation MUST 105 include the Multi-Hop Forwarding Extension Type Value in the 106 Extensions Supported Data Item. The Extensions Supported Data Item 107 is sent and processed according to [I-D.ietf-manet-dlep]. 109 The Multi-Hop Forwarding Extension Type Value is TBA1, see Section 5. 111 3. Extension Data Items 113 Three data items are defined by this extension. The Hop Count Data 114 Item is used by a modem to provide the number of network hops 115 traversed to reach a particular destination. The Hop Control Data 116 Item is used by a router to request that a modem alter connectivity 117 to a particular destination. The Suppress Forwarding Data Item is 118 used by a router to request that a modem disable multi-hop forwarding 119 on either a device or destination basis. 121 3.1. Hop Count 123 The Hop Count Data Item is used by a modem to indicate the number of 124 physical hops between the modem and a specific destination. In other 125 words, each hop represents a transmission and the number of hops is 126 equal to the number of transmissions required to go from a router 127 connected modem to the destination's connected modem. The minimum 128 number of hops is 1, which represents the router's locally connected 129 modem. 131 The data item also contains an indication of when a destination which 132 currently has a hop count of greater than one (1) could be made 133 direcly reachable by a modem, e.g., by re-aiming an antenna. 135 The Hop Count Data Item SHOULD be carried in the Destination Up, 136 Destination Update, Destination Announce Response, and Link 137 Characteristics Response Messages when the Hop Count to a destination 138 is greater than one (1). 140 A router receiving a Hop Count Data Item MAY use this information in 141 its forwarding and routing decisions, and specific use is out of 142 scope of this document. The absence of the Hop Count Data Item MUST 143 be interpreted by the router as a Hop Count value of one (1). 145 The format of the Hop Count Data Item is: 147 0 1 2 3 148 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 1 149 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 150 | Data Item Type | Length | 151 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 152 | Hop Count |P| Reserved | 153 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 155 Data Item Type: TBA2 157 Length: 4 159 Hop Count: 161 An unsigned 8-bit integer indicating the number of network hops 162 required (i.e., number of times a packet will be transmitted) to 163 reach the destination indicated in the message. The special value 164 of 255 (0xFF) is used to indicate that the number of hops is an 165 unknown number greater than one (1). This field MUST contain a 166 value of at least one (1) if the associated destination is 167 reachable. 169 A value of zero (0) is used to indicated that processing of a Hop 170 Control action, see Section 3.2, has resulted in a destination no 171 longer being reachable. A zero value MUST NOT be used in any 172 message other then a Destination Announce Response Message. 174 P: 176 The P-bit indicates that a destination is potentially directly 177 reachable. When the P-bit is set, the router MAY request a direct 178 link to the associated destination using the Hop Control Data Item 179 described below. 181 Reserved: 183 MUST be set to zero by the sender (a modem) and ignored by the 184 receiver (a router). 186 3.2. Hop Control 188 The Hop Control Data Item is used by a router to request a change in 189 connectivity to a particular destination, or in multi-hop processing 190 on a device wide basis. A router can request multi-hop reachable 191 destination be changed to a single hop. A router can also indicate 192 that the modem terminate connectivity to a particular destination. 194 The Hop Control Data Item MAY be carried in the Session Update 195 Message or Destination Announce Message. 197 A router that receives the Hop Control in a Session Update Message 198 SHOULD attempt to make the change indicated by the data item for the 199 whole device. Results of any changes made are reflected in 200 Destination Down and Destination Update Messages. The modem MUST 201 notify the router of each destination that is no longer reachable via 202 a Destination Down Message. The modem MUST notify the router of any 203 changes in Hop Counts via Destination Update Messages. 205 A router that receives the Hop Control in a Destination Announce 206 Message SHOULD attempt to make the change indicated by the data item 207 for the associated destination MAC address. Once the change is made, 208 or fails or is rejected, the modem MUST respond with a Destination 209 Announce Response Message containing an updated Hop Count Data Item. 211 The format of the Hop Control Data Item is: 213 0 1 2 3 214 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 1 215 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 216 | Data Item Type | Length | 217 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 218 | Hop Control Actions | Reserved | 219 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 221 Data Item Type: TBA3 223 Length: 4 225 Hop Control Actions: 227 An unsigned 16-bit value with the following meaning: 229 +-------+---------------------+ 230 | Value | Action | 231 +-------+---------------------+ 232 | 0 | Reset | 233 | | | 234 | 1 | Terminate | 235 | | | 236 | 2 | Direct Connection | 237 | | | 238 | 3 | Suppress Forwarding | 239 +-------+---------------------+ 241 Table 1: Hop Control Actions Values 243 3.2.1. Reset 245 The Reset Action requests that the default behavior be restored. 246 When received in a Session Update Message message, a modem SHOULD 247 clear all control actions that have previously been processed on a 248 device wide basis, and revert to its configured behavior. When 249 received in a Destination Announce Message, a modem SHOULD clear all 250 control actions that have previously been processed for the 251 destination indicated in the message. 253 3.2.2. Terminate 255 The Terminate Action is only valid on a per destination basis and 256 MUST NOT be sent in a Session Update Message message. It indicates 257 that the modem SHOULD attempt to terminate communication with the 258 destination identified in the message. This request has no impact 259 for multi-hop destinations and may fail even in a single hop case, 260 i.e. MAY result in the Hop Count to the destination not being 261 impacted by the processing of the request 263 3.2.3. Direct Connection 265 The Direct Connection is only valid on a per destination basis and 266 MUST NOT be sent in a Session Update Message message. It indicates 267 that the modem SHOULD attempt to establish a direct connection with 268 the destination identified in the message. This action SHOULD only 269 be sent for destinations for which the Hop Count is greater than 1 270 and has the P-Bit set in the previously received Hop Count Data Item. 271 Results of the request for the destination identified in the message 272 are provided as described above. If any other destination is 273 impacted in the processing of this action, the modem MUST send a 274 Destination Update Message for each impacted destination. 276 3.2.4. Suppress Forwarding 278 The Suppress Forwarding Action is used by a router to indicate to its 279 peer that multi-hop forwarding is to be suppressed. A router may 280 request that multi-hop forwarding may be suppressed on a device wide 281 or destination specific basis. 283 A modem which receives the Suppress Forwarding Data Item in a Session 284 Update Message MUST suppress multi-hop forwarding on a device wide 285 basis. Impact to destination hop counts are provided to the router 286 by the modem as described above. 288 A modem which receives the Suppress Forwarding Data Item in a 289 Destination Announce Message MUST suppress multi-hop forwarding for 290 only the destination indicated in the message. Results are provided 291 as described above. 293 4. Security Considerations 295 The extension introduces a new mechanism for flow control between a 296 router and modem using the DLEP protocol. The extension does not 297 inherently introduce any additional threats above those documented in 298 [I-D.ietf-manet-dlep]. The approach taken to Security in that 299 document applies equally when running the extension defined in this 300 document. 302 5. IANA Considerations 304 This document requests the assignment of 3 values by IANA. All 305 assignments are to registries defined by [I-D.ietf-manet-dlep]. It 306 also requests creation of one new registry. 308 5.1. Extension Type Value 310 This document requests 1 new assignment to the DLEP Extensions 311 Registry named "Extension Tyoe Values" in the range with the 312 "Specification Required" policy. The requested value is as follows: 314 +------+----------------------+ 315 | Code | Description | 316 +------+----------------------+ 317 | TBA1 | Multi-Hop Forwarding | 318 +------+----------------------+ 320 Table 2: Requested Extension Type Value 322 5.2. Data Item Values 324 This document requests 2 new assignments to the DLEP Data Item 325 Registry named "Data Item Values" in the range with the 326 "Specification Required" policy. The requested values are as 327 follows: 329 +-----------+-------------+ 330 | Type Code | Description | 331 +-----------+-------------+ 332 | TBA2 | Hop Count | 333 | | | 334 | TBA3 | Hop Control | 335 +-----------+-------------+ 337 Table 3: Requested Data Item Values 339 5.3. Hop Control Actions Registry 341 Upon approval of this document, IANA is requested to create a new 342 DLEP registry, named "Hop Control Actions Values". The following 343 table provides initial registry values and the [RFC5226]. defined 344 policies that should apply to the registry: 346 +-------------+------------------------+ 347 | Value | Action/Policy | 348 +-------------+------------------------+ 349 | 0 | Reset | 350 | | | 351 | 1 | Terminate | 352 | | | 353 | 2 | Direct Connection | 354 | | | 355 | 3 | Suppress Forwarding | 356 | | | 357 | 4-65519 | Specification Required | 358 | | | 359 | 65520-65534 | Private Use | 360 | | | 361 | 65535 | Reserved | 362 +-------------+------------------------+ 364 Table 4: Hop Control Actions Values 366 6. References 368 6.1. Normative References 370 [I-D.ietf-manet-dlep] 371 Ratliff, S., Jury, S., Satterwhite, D., Taylor, R., and (. 372 (Unknown), "Dynamic Link Exchange Protocol (DLEP)", draft- 373 ietf-manet-dlep-24 (work in progress), July 2016. 375 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 376 Requirement Levels", BCP 14, RFC 2119, 377 DOI 10.17487/RFC2119, March 1997, 378 . 380 6.2. Informative References 382 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 383 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 384 DOI 10.17487/RFC5226, May 2008, 385 . 387 Authors' Addresses 389 Bow-Nan Cheng 390 Lincoln Laboratory 391 Massachusetts Institute of Technology 392 244 Wood Street 393 Lexington, MA 02420-9108 395 Email: bcheng@ll.mit.edu 397 Lou Berger (editor) 398 LabN Consulting, L.L.C. 400 Email: lberger@labn.net