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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) == Unused Reference: 'RFC5578' is defined on line 3117, but no explicit reference was found in the text ** Obsolete normative reference: RFC 5246 (Obsoleted by RFC 8446) -- Obsolete informational reference (is this intentional?): RFC 5226 (Obsoleted by RFC 8126) -- Obsolete informational reference (is this intentional?): RFC 7525 (Obsoleted by RFC 9325) Summary: 1 error (**), 0 flaws (~~), 4 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Mobile Ad hoc Networks Working Group S. Ratliff 3 Internet-Draft VT iDirect 4 Intended status: Standards Track S. Jury 5 Expires: September 29, 2017 Cisco Systems 6 D. Satterwhite 7 Broadcom 8 R. Taylor 9 Airbus Defence & Space 10 B. Berry 11 March 28, 2017 13 Dynamic Link Exchange Protocol (DLEP) 14 draft-ietf-manet-dlep-29 16 Abstract 18 When routing devices rely on modems to effect communications over 19 wireless links, they need timely and accurate knowledge of the 20 characteristics of the link (speed, state, etc.) in order to make 21 routing decisions. In mobile or other environments where these 22 characteristics change frequently, manual configurations or the 23 inference of state through routing or transport protocols does not 24 allow the router to make the best decisions. DLEP describes a new 25 protocol for a bidirectional, event-driven communication channel 26 between the router and the modem to facilitate communication of 27 changing link characteristics. 29 Status of This Memo 31 This Internet-Draft is submitted in full conformance with the 32 provisions of BCP 78 and BCP 79. 34 Internet-Drafts are working documents of the Internet Engineering 35 Task Force (IETF). Note that other groups may also distribute 36 working documents as Internet-Drafts. The list of current Internet- 37 Drafts is at http://datatracker.ietf.org/drafts/current/. 39 Internet-Drafts are draft documents valid for a maximum of six months 40 and may be updated, replaced, or obsoleted by other documents at any 41 time. It is inappropriate to use Internet-Drafts as reference 42 material or to cite them other than as "work in progress." 44 This Internet-Draft will expire on September 29, 2017. 46 Copyright Notice 48 Copyright (c) 2017 IETF Trust and the persons identified as the 49 document authors. All rights reserved. 51 This document is subject to BCP 78 and the IETF Trust's Legal 52 Provisions Relating to IETF Documents 53 (http://trustee.ietf.org/license-info) in effect on the date of 54 publication of this document. Please review these documents 55 carefully, as they describe your rights and restrictions with respect 56 to this document. Code Components extracted from this document must 57 include Simplified BSD License text as described in Section 4.e of 58 the Trust Legal Provisions and are provided without warranty as 59 described in the Simplified BSD License. 61 Table of Contents 63 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 64 2. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 7 65 2.1. Destinations . . . . . . . . . . . . . . . . . . . . . . 8 66 2.2. Conventions and Terminology . . . . . . . . . . . . . . . 9 67 3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 9 68 4. Implementation Scenarios . . . . . . . . . . . . . . . . . . 9 69 5. Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 10 70 6. Metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 71 7. DLEP Session Flow . . . . . . . . . . . . . . . . . . . . . . 12 72 7.1. Peer Discovery State . . . . . . . . . . . . . . . . . . 12 73 7.2. Session Initialization State . . . . . . . . . . . . . . 13 74 7.3. In-Session State . . . . . . . . . . . . . . . . . . . . 14 75 7.3.1. Heartbeats . . . . . . . . . . . . . . . . . . . . . 14 76 7.4. Session Termination State . . . . . . . . . . . . . . . . 15 77 7.5. Session Reset state . . . . . . . . . . . . . . . . . . . 15 78 7.5.1. Unexpected TCP connection termination . . . . . . . . 16 79 8. Transaction Model . . . . . . . . . . . . . . . . . . . . . . 16 80 9. Extensions . . . . . . . . . . . . . . . . . . . . . . . . . 17 81 9.1. Experiments . . . . . . . . . . . . . . . . . . . . . . . 17 82 10. Scalability . . . . . . . . . . . . . . . . . . . . . . . . . 18 83 11. DLEP Signal and Message Structure . . . . . . . . . . . . . . 18 84 11.1. DLEP Signal Header . . . . . . . . . . . . . . . . . . . 18 85 11.2. DLEP Message Header . . . . . . . . . . . . . . . . . . 19 86 11.3. DLEP Generic Data Item . . . . . . . . . . . . . . . . . 20 87 12. DLEP Signals and Messages . . . . . . . . . . . . . . . . . . 20 88 12.1. General Processing Rules . . . . . . . . . . . . . . . . 20 89 12.2. Status code processing . . . . . . . . . . . . . . . . . 21 90 12.3. Peer Discovery Signal . . . . . . . . . . . . . . . . . 22 91 12.4. Peer Offer Signal . . . . . . . . . . . . . . . . . . . 22 92 12.5. Session Initialization Message . . . . . . . . . . . . . 23 93 12.6. Session Initialization Response Message . . . . . . . . 24 94 12.7. Session Update Message . . . . . . . . . . . . . . . . . 25 95 12.8. Session Update Response Message . . . . . . . . . . . . 27 96 12.9. Session Termination Message . . . . . . . . . . . . . . 27 97 12.10. Session Termination Response Message . . . . . . . . . . 27 98 12.11. Destination Up Message . . . . . . . . . . . . . . . . . 28 99 12.12. Destination Up Response Message . . . . . . . . . . . . 29 100 12.13. Destination Announce Message . . . . . . . . . . . . . . 30 101 12.14. Destination Announce Response Message . . . . . . . . . 30 102 12.15. Destination Down Message . . . . . . . . . . . . . . . . 32 103 12.16. Destination Down Response Message . . . . . . . . . . . 32 104 12.17. Destination Update Message . . . . . . . . . . . . . . . 32 105 12.18. Link Characteristics Request Message . . . . . . . . . . 34 106 12.19. Link Characteristics Response Message . . . . . . . . . 34 107 12.20. Heartbeat Message . . . . . . . . . . . . . . . . . . . 35 108 13. DLEP Data Items . . . . . . . . . . . . . . . . . . . . . . . 36 109 13.1. Status . . . . . . . . . . . . . . . . . . . . . . . . . 37 110 13.2. IPv4 Connection Point . . . . . . . . . . . . . . . . . 39 111 13.3. IPv6 Connection Point . . . . . . . . . . . . . . . . . 40 112 13.4. Peer Type . . . . . . . . . . . . . . . . . . . . . . . 41 113 13.5. Heartbeat Interval . . . . . . . . . . . . . . . . . . . 42 114 13.6. Extensions Supported . . . . . . . . . . . . . . . . . . 43 115 13.7. MAC Address . . . . . . . . . . . . . . . . . . . . . . 44 116 13.8. IPv4 Address . . . . . . . . . . . . . . . . . . . . . . 44 117 13.8.1. IPv4 Address Processing . . . . . . . . . . . . . . 45 118 13.9. IPv6 Address . . . . . . . . . . . . . . . . . . . . . . 46 119 13.9.1. IPv6 Address Processing . . . . . . . . . . . . . . 47 120 13.10. IPv4 Attached Subnet . . . . . . . . . . . . . . . . . . 48 121 13.10.1. IPv4 Attached Subnet Processing . . . . . . . . . . 49 122 13.11. IPv6 Attached Subnet . . . . . . . . . . . . . . . . . . 50 123 13.11.1. IPv6 Attached Subnet Processing . . . . . . . . . . 51 124 13.12. Maximum Data Rate (Receive) . . . . . . . . . . . . . . 52 125 13.13. Maximum Data Rate (Transmit) . . . . . . . . . . . . . . 53 126 13.14. Current Data Rate (Receive) . . . . . . . . . . . . . . 54 127 13.15. Current Data Rate (Transmit) . . . . . . . . . . . . . . 54 128 13.16. Latency . . . . . . . . . . . . . . . . . . . . . . . . 55 129 13.17. Resources . . . . . . . . . . . . . . . . . . . . . . . 56 130 13.18. Relative Link Quality (Receive) . . . . . . . . . . . . 57 131 13.19. Relative Link Quality (Transmit) . . . . . . . . . . . . 57 132 13.20. Maximum Transmission Unit (MTU) . . . . . . . . . . . . 58 133 14. Security Considerations . . . . . . . . . . . . . . . . . . . 59 134 15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 60 135 15.1. Registrations . . . . . . . . . . . . . . . . . . . . . 60 136 15.2. Signal Type Registration . . . . . . . . . . . . . . . . 60 137 15.3. Message Type Registration . . . . . . . . . . . . . . . 61 138 15.4. DLEP Data Item Registrations . . . . . . . . . . . . . . 61 139 15.5. DLEP Status Code Registrations . . . . . . . . . . . . . 62 140 15.6. DLEP Extensions Registrations . . . . . . . . . . . . . 63 141 15.7. DLEP IPv4 Connection Point Flags . . . . . . . . . . . . 63 142 15.8. DLEP IPv6 Connection Point Flags . . . . . . . . . . . . 64 143 15.9. DLEP Peer Type Flag . . . . . . . . . . . . . . . . . . 64 144 15.10. DLEP IPv4 Address Flag . . . . . . . . . . . . . . . . . 64 145 15.11. DLEP IPv6 Address Flag . . . . . . . . . . . . . . . . . 65 146 15.12. DLEP IPv4 Attached Subnet Flag . . . . . . . . . . . . . 65 147 15.13. DLEP IPv6 Attached Subnet Flag . . . . . . . . . . . . . 65 148 15.14. DLEP Well-known Port . . . . . . . . . . . . . . . . . . 66 149 15.15. DLEP IPv4 Link-local Multicast Address . . . . . . . . . 66 150 15.16. DLEP IPv6 Link-local Multicast Address . . . . . . . . . 66 151 16. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 66 152 17. References . . . . . . . . . . . . . . . . . . . . . . . . . 66 153 17.1. Normative References . . . . . . . . . . . . . . . . . . 66 154 17.2. Informative References . . . . . . . . . . . . . . . . . 67 155 Appendix A. Discovery Signal Flows . . . . . . . . . . . . . . . 68 156 Appendix B. Peer Level Message Flows . . . . . . . . . . . . . . 68 157 B.1. Session Initialization . . . . . . . . . . . . . . . . . 68 158 B.2. Session Initialization - Refused . . . . . . . . . . . . 69 159 B.3. Router Changes IP Addresses . . . . . . . . . . . . . . . 70 160 B.4. Modem Changes Session-wide Metrics . . . . . . . . . . . 70 161 B.5. Router Terminates Session . . . . . . . . . . . . . . . . 70 162 B.6. Modem Terminates Session . . . . . . . . . . . . . . . . 71 163 B.7. Session Heartbeats . . . . . . . . . . . . . . . . . . . 71 164 B.8. Router Detects a Heartbeat timeout . . . . . . . . . . . 72 165 B.9. Modem Detects a Heartbeat timeout . . . . . . . . . . . . 73 166 Appendix C. Destination Specific Message Flows . . . . . . . . . 73 167 C.1. Common Destination Notification . . . . . . . . . . . . . 73 168 C.2. Multicast Destination Notification . . . . . . . . . . . 74 169 C.3. Link Characteristics Request . . . . . . . . . . . . . . 75 170 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 76 172 1. Introduction 174 There exist today a collection of modem devices that control links of 175 variable datarate and quality. Examples of these types of links 176 include line-of-sight (LOS) terrestrial radios, satellite terminals, 177 and broadband modems. Fluctuations in speed and quality of these 178 links can occur due to configuration, or on a moment-to-moment basis, 179 due to physical phenomena like multipath interference, obstructions, 180 rain fade, etc. It is also quite possible that link quality and 181 datarate vary with respect to individual destinations on a link, and 182 with the type of traffic being sent. As an example, consider the 183 case of an IEEE 802.11 access point, serving two associated laptop 184 computers. In this environment, the answer to the question "What is 185 the datarate on the 802.11 link?" is "It depends on which associated 186 laptop we're talking about, and on what kind of traffic is being 187 sent." While the first laptop, being physically close to the access 188 point, may have a datarate of 54Mbps for unicast traffic, the other 189 laptop, being relatively far away, or obstructed by some object, can 190 simultaneously have a datarate of only 32Mbps for unicast. However, 191 for multicast traffic sent from the access point, all traffic is sent 192 at the base transmission rate (which is configurable, but depending 193 on the model of the access point, is usually 24Mbps or less). 195 In addition to utilizing variable datarate links, mobile networks are 196 challenged by the notion that link connectivity will come and go over 197 time, without an effect on a router's interface state (Up or Down). 198 Effectively utilizing a relatively short-lived connection is 199 problematic in IP routed networks, as IP routing protocols tend to 200 rely on interface state and independent timers to maintain network 201 convergence (e.g., HELLO messages and/or recognition of DEAD routing 202 adjacencies). These dynamic connections can be better utilized with 203 an event-driven paradigm, where acquisition of a new neighbor (or 204 loss of an existing one) is signaled, as opposed to a paradigm driven 205 by timers and/or interface state. DLEP not only implements such an 206 event-driven paradigm, but does so over a local (1 hop) TCP session, 207 which guarantees delivery of the event messages. 209 Another complicating factor for mobile networks are the different 210 methods of physically connecting the modem devices to the router. 211 Modems can be deployed as an interface card in a router's chassis, or 212 as a standalone device connected to the router via Ethernet or serial 213 link. In the case of Ethernet attachment, with existing protocols 214 and techniques, routing software cannot be aware of convergence 215 events occurring on the radio link (e.g., acquisition or loss of a 216 potential routing neighbor), nor can the router be aware of the 217 actual capacity of the link. This lack of awareness, along with the 218 variability in datarate, leads to a situation where finding the 219 (current) best route through the network to a given node is difficult 220 to establish and properly maintain. This is especially true of 221 demand-based access schemes such as Demand Assigned Multiple Access 222 (DAMA) implementations used on some satellite systems. With a DAMA- 223 based system, additional datarate may be available, but will not be 224 used unless the network devices emit traffic at a rate higher than 225 the currently established rate. Increasing the traffic rate does not 226 guarantee additional datarate will be allocated; rather, it may 227 result in data loss and additional retransmissions on the link. 229 Addressing the challenges listed above, the Dynamic Link Exchange 230 Protocol, or DLEP, has been developed. The DLEP protocol runs 231 between a router and its attached modem devices, allowing the modem 232 to communicate link characteristics as they change, and convergence 233 events (acquisition and loss of potential routing next-hops). The 234 following diagrams are used to illustrate the scope of DLEP packets. 236 |-------Local Node-------| |-------Remote Node------| 237 | | | | 238 +--------+ +-------+ +-------+ +--------+ 239 | Router |=======| Modem |{~~~~~~~~}| Modem |=======| Router | 240 | | | Device| | Device| | | 241 +--------+ +-------+ +-------+ +--------+ 242 | | | Link | | | 243 |-DLEP--| | Protocol | |-DLEP--| 244 | | | (e.g. | | | 245 | | | 802.11) | | | 247 Figure 1: DLEP Network 249 In Figure 1, when the local modem detects the presence of a remote 250 node, it (the local modem) sends a message to its router via the DLEP 251 protocol. The message consists of an indication of what change has 252 occurred on the link (e.g., presence of a remote node detected), 253 along with a collection of DLEP-defined data items that further 254 describe the change. Upon receipt of the message, the local router 255 may take whatever action it deems appropriate, such as initiating 256 discovery protocols, and/or issuing HELLO messages to converge the 257 network. On a continuing, as-needed basis, the modem devices use 258 DLEP to report any characteristics of the link (datarate, latency, 259 etc.) that have changed. DLEP is independent of the link type and 260 topology supported by the modem. Note that the DLEP protocol is 261 specified to run only on the local link between router and modem. 262 Some over the air signaling may be necessary between the local and 263 remote modem in order to provide some parameters in DLEP messages 264 between the local modem and local router, but DLEP does not specify 265 how such over the air signaling is carried out. Over the air 266 signaling is purely a matter for the modem implementer. 268 Figure 2 shows how DLEP can support a configuration where routers are 269 connected with different link types. In this example, Modem A 270 implements a point-to-point link, and Modem B is connected via a 271 shared medium. In both cases, the DLEP protocol is used to report 272 the characteristics of the link (datarate, latency, etc.) to routers. 273 The modem is also able to use the DLEP session to notify the router 274 when the remote node is lost, shortening the time required to re- 275 converge the network. 277 +--------+ +--------+ 278 +----+ Modem | | Modem +---+ 279 | | Device | | Device | 280 | | Type A | <===== // ======> | Type A | | 281 | +--------+ P-2-P Link +--------+ | 282 +---+----+ +---+----+ 283 | Router | | Router | 284 | | | | 285 +---+----+ +---+----+ 286 | +--------+ +--------+ | 287 +-----+ Modem | | Modem | | 288 | Device | o o o o o o o o | Device +--+ 289 | Type B | o Shared o | Type B | 290 +--------+ o Medium o +--------+ 291 o o 292 o o 293 o o 294 o 295 +--------+ 296 | Modem | 297 | Device | 298 | Type B | 299 +---+----+ 300 | 301 | 302 +---+----+ 303 | Router | 304 | | 305 +--------+ 307 Figure 2: DLEP Network with Multiple Modem Devices 309 2. Protocol Overview 311 DLEP defines a set of Messages used by modems and their attached 312 routers to communicate events that occur on the physical link(s) 313 managed by the modem: for example, a remote node entering or leaving 314 the network, or that the link has changed. Associated with these 315 Messages are a set of Data Items - information that describes the 316 remote node (e.g., address information), and/or the characteristics 317 of the link to the remote node. Throughout this document, we refer 318 to a modems/routers participating in a DLEP session as 'DLEP 319 Participants', unless a specific distinction (e.g. modem or router) 320 is required. 322 DLEP uses a session-oriented paradigm between the modem device and 323 its associated router. If multiple modem devices are attached to a 324 router (as in Figure 2), or the modem supports multiple connections 325 (via multiple logical or physical interfaces), then separate DLEP 326 sessions exist for each modem or connection. A router and modem form 327 a session by completing the discovery and initialization process. 328 This router-modem session persists unless or until it either (1) 329 times out, based on the absence of DLEP traffic (including 330 heartbeats), or (2) is explicitly torn down by one of the DLEP 331 participants. 333 While this document represents the best efforts of the working group 334 to be functionally complete, it is recognized that extensions to DLEP 335 will in all likelihood be necessary as more link types are used. 336 Such extensions are defined as additional Messages, Data Items and/or 337 status codes, and associated rules of behavior, that are not defined 338 in this document. DLEP contains a standard mechanism for router and 339 modem implementations to negotiate the available extensions to use on 340 a per-session basis. 342 2.1. Destinations 344 The router/modem session provides a carrier for information exchange 345 concerning 'destinations' that are available via the modem device. 346 Destinations can be identified by either the router or the modem, and 347 represent a specific, addressable location that can be reached via 348 the link(s) managed by the modem. 350 The DLEP Messages concerning destinations thus become the way for 351 routers and modems to maintain, and notify each other about, an 352 information base representing the physical and logical destinations 353 accessible via the modem device, as well as the link characteristics 354 to those destinations. 356 A destination can be either physical or logical. The example of a 357 physical destination would be that of a remote, far-end router 358 attached via the variable-quality network. It should be noted that 359 for physical destinations the MAC address is the address of the far- 360 end router, not the modem. 362 The example of a logical destination is Multicast. Multicast traffic 363 destined for the variable-quality network (the network accessed via 364 the modem) is handled in IP networks by deriving a Layer 2 MAC 365 address based on the Layer 3 address. Leveraging on this scheme, 366 multicast traffic is supported in DLEP simply by treating the derived 367 MAC address as any other destination in the network. 369 To support these logical destinations, one of the DLEP participants 370 (typically, the router) informs the other as to the existence of the 371 logical destination. The modem, once it is aware of the existence of 372 this logical destination, reports link characteristics just as it 373 would for any other destination in the network. The specific 374 algorithms a modem would use to derive metrics on logical 375 destinations are outside the scope of this specification, and is left 376 to specific implementations to decide. 378 In all cases, when this specification uses the term destination, it 379 refers to the addressable locations, either logical or physical, that 380 are accessible by the radio link(s). 382 2.2. Conventions and Terminology 384 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 385 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 386 "OPTIONAL" in this document are to be interpreted as described in BCP 387 14, RFC 2119 [RFC2119]. 389 3. Requirements 391 DLEP MUST be implemented on a single Layer 2 domain. The protocol 392 identifies next-hop destinations by using the MAC address for 393 delivering data traffic. No manipulation or substitution is 394 performed; the MAC address supplied in all DLEP Messages is used as 395 the Destination MAC address for frames emitted by the participating 396 router. MAC addresses MUST be unique within the context of router- 397 modem session. 399 To enforce the single Layer 2 domain, implementations MUST support 400 The Generalized TTL Security Mechanism [RFC5082], and implementations 401 MUST adhere to this specification for all DLEP Messages. 403 DLEP specifies UDP multicast for single-hop discovery signaling, and 404 TCP for transport of the Messages. Modems and routers participating 405 in DLEP sessions MUST have topologically consistent IP addresses 406 assigned. It is RECOMMENDED that DLEP implementations utilize IPv6 407 link-local addresses to reduce the administrative burden of address 408 assignment. 410 DLEP relies on the guaranteed delivery of its Messages between router 411 and modem, once the 1 hop discovery process is complete, hence, the 412 specification of TCP to carry the Messages. Other reliable 413 transports for the protocol are possible, but are outside the scope 414 of this document. 416 4. Implementation Scenarios 418 During development of this specification, two types of deployments 419 were discussed. 421 The first can be viewed as a "dedicated deployment". In this mode, 422 DLEP routers and modems are either directly connected (e.g., using 423 cross-over cables to connect interfaces), or are connected to a 424 dedicated switch. An example of this type of deployment would be a 425 router with a line-of- sight radio connected into one interface, with 426 a satellite modem connected into another interface. In mobile 427 environments, the router and the connected modem(s) are placed into a 428 mobile platform (e.g., a vehicle, boat, or airplane). In this mode, 429 when a switch is used, it is possible that a small number of 430 ancillary devices (e.g., a laptop) are also plugged into the switch. 431 But in either event, the resulting network segment is constrained to 432 a small number of devices, and is not generally accessible from 433 anywhere else in the network. 435 The other type of deployment envisioned can be viewed as a "networked 436 deployment". In this type of scenario, the DLEP router and modem(s) 437 are placed on a segment that is accessible from other points in the 438 network. In this scenario, not only are the DLEP router and modem(s) 439 accessible from other points in the network; the router and a given 440 modem could be multiple physical hops away from each other. This 441 scenario necessitates the use of Layer 2 tunneling technology to 442 enforce the single-hop requirement of DLEP. 444 5. Assumptions 446 DLEP assumes that a signaling protocol exists between modems 447 participating in a network. The specification does not define the 448 character or behavior of this over-the-air signaling, but does expect 449 some information to be carried (or derived) by the signaling, such as 450 the arrival and departure of modems from this network, and the 451 variation of the link characteristics between modems. This 452 information is then assumed to be used by the modem to implement the 453 DLEP protocol. 455 The specification assumes that the link between router and modem is 456 static with respect to datarate and latency, and that this link is 457 not likely to be the cause of a performance bottleneck. In 458 deployments where the router and modem are physically separated by 459 multiple network hops, served by Layer 2 tunneling technology, DLEP 460 statistics on the RF links could be insufficient for routing 461 protocols to make appropriate routing decisions. This would 462 especially become an issue in cases where the Layer 2 tunnel between 463 router and modem is itself served in part (or in total) with a 464 wireless back-haul link. 466 6. Metrics 468 DLEP includes the ability for the router and modem to communicate 469 metrics that reflect the characteristics (e.g., datarate, latency) of 470 the variable-quality link in use. DLEP does not specify how a given 471 metric value is to be calculated, rather, the protocol assumes that 472 metrics have been calculated by a 'best effort', incorporating all 473 pertinent data that is available to the modem device. Metrics based 474 on large enough sample sizes will preclude short traffic bursts from 475 adversely skewing reported values. 477 DLEP allows for metrics to be sent within two contexts - metrics for 478 a specific destination within the network (e.g., a specific router), 479 and per-session (those that apply to all destinations accessed via 480 the modem). Most metrics can be further subdivided into transmit and 481 receive metrics. In cases where metrics are provided at session 482 level, the router propagates the metrics to all entries in its 483 information base for destinations that are accessed via the modem. 485 DLEP modems announce all metric Data Items that will be reported 486 during the session, and provide default values for those metrics, in 487 the Session Initialization Response Message (Section 12.6). In order 488 to use a metric type that was not included in the Session 489 Initialization Response Message, modem implementations terminate the 490 session with the router (via the Session Terminate Message 491 (Section 12.9)), and establish a new session. 493 A DLEP modem can send metrics both in a session context, via the 494 Session Update Message (Section 12.7), and a specific destination 495 context, via the Destination Update Message (Section 12.17), at any 496 time. The most recently received metric value takes precedence over 497 any earlier value, regardless of context - that is: 499 1. If the router receives metrics in a specific destination context 500 (via the Destination Update Message), then the specific 501 destination is updated with the new metric. 503 2. If the router receives metrics in a session-wide context (via the 504 Session Update Message), then the metrics for all destinations 505 accessed via the modem are updated with the new metric. 507 It is left to implementations to choose sensible default values based 508 on their specific characteristics. Modems having static (non- 509 changing) link metric characteristics can report metrics only once 510 for a given destination (or once on a session-wide basis, if all 511 connections via the modem are of this static nature). 513 In addition to communicating existing metrics about the link, DLEP 514 provides a Message allowing a router to request a different datarate 515 or latency from the modem. This Message is the Link Characteristics 516 Request Message (Section 12.18), and gives the router the ability to 517 deal with requisite increases (or decreases) of allocated datarate/ 518 latency in demand-based schemes in a more deterministic manner. 520 7. DLEP Session Flow 522 All DLEP participants of a session transition through a number of 523 distinct states during the lifetime of a DLEP session: 525 o Peer Discovery 527 o Session Initialization 529 o In-Session 531 o Session Termination 533 o Session Reset 535 Modems, and routers supporting DLEP discovery, transition through all 536 five (5) of the above states. Routers that rely on preconfigured TCP 537 address/port information start in the Session Initialization state. 539 Modems MUST support the Peer Discovery state. 541 7.1. Peer Discovery State 543 Modems MUST support DLEP Peer Discovery; routers MAY support the 544 discovery signals, or rely on a priori configuration to locate 545 modems. If a router chooses to support DLEP discovery, all signals 546 MUST be supported. 548 In the Peer Discovery state, routers that support DLEP discovery MUST 549 send Peer Discovery Signals (Section 12.3) to initiate modem 550 discovery. 552 The router implementation then waits for a Peer Offer Signal 553 (Section 12.4) response from a potential DLEP modem. While in the 554 Peer Discovery state, Peer Discovery Signals MUST be sent repeatedly 555 by a DLEP router, at regular intervals. It is RECOMMENDED that this 556 interval be set to 60 seconds. The interval MUST be a minimum of one 557 second; it SHOULD be a configurable parameter. Note that this 558 operation (sending Peer Discovery and waiting for Peer Offer) is 559 outside the DLEP Transaction Model (Section 8), as the Transaction 560 Model only describes Messages on a TCP session. 562 Routers receiving a Peer Offer Signal MUST use one of the modem 563 address/port combinations from the Peer Offer Signal to establish a 564 TCP connection to the modem, even if a priori configuration exists. 565 If multiple connection point Data Items exist in the received Peer 566 Offer Signal, routers SHOULD prioritize IPv6 connection points over 567 IPv4 connection points. If multiple connection points exist with the 568 same transport (e.g. IPv6 or IPv4), implementations MAY use their 569 own heuristics to determine the order in which they are tried. If a 570 TCP connection cannot be achieved using any of the address/port 571 combinations and the Discovery mechanism is in use, then the router 572 SHOULD resume issuing Peer Discovery Signals. If no Connection Point 573 Data Items are included in the Peer Offer Signal, the router MUST use 574 the source address of the UDP packet containing the Peer Offer Signal 575 as the IP address, and the DLEP well-known port number. 577 In the Peer Discovery state, the modem implementation MUST listen for 578 incoming Peer Discovery Signals on the DLEP well-known IPv6 and/or 579 IPv4 link-local multicast address and port. On receipt of a valid 580 Peer Discovery Signal, it MUST reply with a Peer Offer Signal. 582 Modems MUST be prepared to accept a TCP connection from a router that 583 is not using the Discovery mechanism, i.e. a connection attempt that 584 occurs without a preceding Peer Discovery Signal. 586 Implementations of DLEP SHOULD implement, and use, TLS [RFC5246] to 587 protect the TCP session. The "dedicated deployments" discussed in 588 Implementation Scenarios (Section 4) MAY consider use of DLEP without 589 TLS. For all "networked deployments" (again, discussed in 590 Implementation Scenarios), implementation and use of TLS is STRONGLY 591 RECOMMENDED. If TLS is to be used then the TLS session MUST be 592 established before any Messages are passed between peers. Routers 593 supporting TLS MUST prioritize connection points using TLS over those 594 that do not. 596 Upon establishment of a TCP connection, and TLS session if TLS is in 597 use, both modem and router enter the Session Initialization state. 598 It is up to the router implementation if Peer Discovery Signals 599 continue to be sent after the device has transitioned to the Session 600 Initialization state. Modem implementations MUST silently ignore 601 Peer Discovery Signals from a router with which it already has a TCP 602 connection. 604 7.2. Session Initialization State 606 On entering the Session Initialization state, the router MUST send a 607 Session Initialization Message (Section 12.5) to the modem. The 608 router MUST then wait for receipt of a Session Initialization 609 Response Message (Section 12.6) from the modem. Receipt of the 610 Session Initialization Response Message containing a Status Data Item 611 (Section 13.1) with status code set to 0 'Success', see Table 2, 612 indicates that the modem has received and processed the Session 613 Initialization Message, and the router MUST transition to the In- 614 Session state. 616 On entering the Session Initialization state, the modem MUST wait for 617 receipt of a Session Initialization Message from the router. Upon 618 receipt of a Session Initialization Message, the modem MUST send a 619 Session Initialization Response Message, and the session MUST 620 transition to the In-Session state. If the modem receives any 621 Message other than Session Initialization, or it fails to parse the 622 received Message, it MUST NOT send any Message, and MUST terminate 623 the TCP connection and transition to the Session Reset state. 625 DLEP provides an extension negotiation capability to be used in the 626 Session Initialization state, see Section 9. Extensions supported by 627 an implementation MUST be declared to potential DLEP participants 628 using the Extensions Supported Data Item (Section 13.6). Once both 629 DLEP participants have exchanged initialization Messages, an 630 implementation MUST NOT emit any Message, Signal, Data Item or status 631 code associated with an extension that was not specified in the 632 received initialization Message from its peer. 634 7.3. In-Session State 636 In the In-Session state, Messages can flow in both directions between 637 DLEP participants, indicating changes to the session state, the 638 arrival or departure of reachable destinations, or changes of the 639 state of the links to the destinations. 641 The In-Session state is maintained until one of the following 642 conditions occur: 644 o The implementation terminates the session by sending a Session 645 Termination Message (Section 12.9), or, 647 o Its peer terminates the session, indicated by receiving a Session 648 Termination Message. 650 The implementation MUST then transition to the Session Termination 651 state. 653 7.3.1. Heartbeats 655 In order to maintain the In-Session state, periodic Heartbeat 656 Messages (Section 12.20) MUST be exchanged between router and modem. 657 These Messages are intended to keep the session alive, and to verify 658 bidirectional connectivity between the two DLEP participants. It is 659 RECOMMENDED that the interval timer between heartbeat messages be set 660 to 60 seconds. The interval MUST be a minimum of one second; it 661 SHOULD be a configurable parameter. 663 Each DLEP participant is responsible for the creation of Heartbeat 664 Messages. 666 Receipt of any valid DLEP Message MUST reset the heartbeat interval 667 timer (i.e., valid DLEP Messages take the place of, and obviate the 668 need for, additional Heartbeat Messages). 670 Implementations MUST allow a minimum of two (2) heartbeat intervals 671 to expire with no Messages from its peer before terminating the 672 session. When terminating the session, a Session Termination Message 673 containing a Status Data Item (Section 13.1) with status code set to 674 132 'Timed Out', see Table 2, MUST be sent, and then the 675 implementation MUST transition to the Session Termination state. 677 7.4. Session Termination State 679 When an implementation enters the Session Termination state after 680 sending a Session Termination Message (Section 12.9) as the result of 681 an invalid Message or error, it MUST wait for a Session Termination 682 Response Message (Section 12.10) from its peer. Senders SHOULD allow 683 four (4) heartbeat intervals to expire before assuming that its peer 684 is unresponsive, and continuing with session termination. Any other 685 Message received while waiting MUST be silently ignored. 687 When the sender of the Session Termination Message receives a Session 688 Termination Response Message from its peer, or times out, it MUST 689 transition to the Session Reset state. 691 When an implementation receives a Session Termination Message from 692 its peer, it enters the Session Termination state and then it MUST 693 immediately send a Session Termination Response and transition to the 694 Session Reset state. 696 7.5. Session Reset state 698 In the Session Reset state the implementation MUST perform the 699 following actions: 701 o Release all resources allocated for the session. 703 o Eliminate all destinations in the information base represented by 704 the session. Destination Down Messages (Section 12.15) MUST NOT 705 be sent. 707 o Terminate the TCP connection. 709 Having completed these actions the implementation SHOULD return to 710 the relevant initial state: Peer Discovery for modems; either Peer 711 Discovery or Session Initialization for routers, depending on 712 configuration. 714 7.5.1. Unexpected TCP connection termination 716 If the TCP connection between DLEP participants is terminated when an 717 implementation is not in the Session Reset state, the implementation 718 MUST immediately transition to the Session Reset state. 720 8. Transaction Model 722 DLEP defines a simple Message transaction model: Only one request per 723 destination may be in progress at a time per session. A Message 724 transaction is considered complete when a response matching a 725 previously issued request is received. If a DLEP participant 726 receives a request for a destination for which there is already an 727 outstanding request, the implementation MUST terminate the session by 728 issuing a Session Termination Message (Section 12.9) containing a 729 Status Data Item (Section 13.1) with status code set to 129 730 'Unexpected Message', see Table 2, and transition to the Session 731 Termination state. There is no restriction to the total number of 732 Message transactions in progress at a time, as long as each 733 transaction refers to a different destination. 735 It should be noted that some requests may take a considerable amount 736 of time for some DLEP participants to complete, for example, a modem 737 handling a multicast destination up request may have to perform a 738 complex network reconfiguration. A sending implementation MUST be 739 able to handle such long running transactions gracefully. 741 Additionally, only one session request, e.g. a Session Initialization 742 Message (Section 12.5), may be in progress at a time per session. As 743 above, a session transaction is considered complete when a response 744 matching a previously issued request is received. If a DLEP 745 participant receives a session request while there is already a 746 session request in progress, it MUST terminate the session by issuing 747 a Session Termination Message containing a Status Data Item with 748 status code set to 129 'Unexpected Message', and transition to the 749 Session Termination state. Only the Session Termination Message may 750 be issued when a session transaction is in progress. Heartbeat 751 Messages (Section 12.20) MUST NOT be considered part of a session 752 transaction. 754 DLEP transactions do not time out and are not cancellable, except for 755 transactions in-flight when the DLEP session is reset. If the 756 session is terminated, canceling transactions in progress MUST be 757 performed as part of resetting the state machine. An implementation 758 can detect if its peer has failed in some way by use of the session 759 heartbeat mechanism during the In-Session state, see Section 7.3. 761 9. Extensions 763 Extensions MUST be negotiated on a per-session basis during session 764 initialization via the Extensions Supported mechanism. 765 Implementations are not required to support any extension in order to 766 be considered DLEP compliant. 768 If interoperable protocol extensions are required, they will need to 769 be standardized either as an update to this document, or as an 770 additional stand-alone specification. The requests for IANA- 771 controlled registries in this document contain sufficient Reserved 772 space for DLEP Signals, Messages, Data Items and status codes to 773 accommodate future extensions to the protocol. 775 As multiple protocol extensions MAY be announced during session 776 initialization, authors of protocol extensions need to consider the 777 interaction of their extension with other published extensions, and 778 specify any incompatibilities. 780 9.1. Experiments 782 This document requests Private Use numbering space in the DLEP 783 Signal, Message, Data Item and status code registries for 784 experimental extensions. The intent is to allow for experimentation 785 with new Signals, Messages, Data Items, and/or status codes, while 786 still retaining the documented DLEP behavior. 788 Use of the Private Use Signals, Messages, Data Items, status codes, 789 or behaviors MUST be announced as DLEP Extensions, during session 790 initialization, using extension identifiers from the Private Use 791 space in the Extensions Supported registry (Table 3), with a value 792 agreed upon (a priori) between the participants. DLEP extensions 793 using the Private Use numbering space are commonly referred to as 794 Experiments. 796 Multiple experiments MAY be announced in the Session Initialization 797 Messages. However, use of multiple experiments in a single session 798 could lead to interoperability issues or unexpected results (e.g., 799 clashes of experimental Signals, Messages, Data Items and/or status 800 code types), and is therefore discouraged. It is left to 801 implementations to determine the correct processing path (e.g., a 802 decision on whether to terminate the session, or to establish a 803 precedence of the conflicting definitions) if such conflicts arise. 805 10. Scalability 807 The protocol is intended to support thousands of destinations on a 808 given modem/router pair. At large scale, implementations should 809 consider employing techniques to prevent flooding its peer with a 810 large number of Messages in a short time. For example, a dampening 811 algorithm could be employed to prevent a flapping device from 812 generating a large number of Destination Up/Destination Down 813 Messages. 815 Also, use of techniques such as a hysteresis can lessen the impact of 816 rapid, minor fluctuations in link quality. The specific algorithms 817 for handling flapping destinations and minor changes in link quality 818 are outside the scope of this specification. 820 11. DLEP Signal and Message Structure 822 DLEP defines two protocol units used in two different ways: Signals 823 and Messages. Signals are only used in the Discovery mechanism and 824 are carried in UDP datagrams. Messages are used bidirectionally over 825 a TCP connection between the participants, in the Session 826 Initialization, In-Session and Session Termination states. 828 Both Signals and Messages consist of a Header followed by an 829 unordered list of Data Items. Headers consist of Type and Length 830 information, while Data Items are encoded as TLV (Type-Length-Value) 831 structures. In this document, the Data Items following a Signal or 832 Message Header are described as being 'contained in' the Signal or 833 Message. 835 There is no restriction on the order of Data Items following a 836 Header, and the acceptability of duplicate Data Items is defined by 837 the definition of the Signal or Message declared by the type in the 838 Header. 840 All integers in Header fields and values MUST be in network byte- 841 order. 843 11.1. DLEP Signal Header 845 The DLEP Signal Header contains the following fields: 847 0 1 2 3 848 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 1 849 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 850 | 'D' | 'L' | 'E' | 'P' | 851 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 852 | Signal Type | Length | 853 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 855 Figure 3: DLEP Signal Header 857 "DLEP": Every Signal MUST start with the characters: U+0044, U+004C, 858 U+0045, U+0050. 860 Signal Type: A 16-bit unsigned integer containing one of the DLEP 861 Signal Type values defined in this document. 863 Length: The length in octets, expressed as a 16-bit unsigned 864 integer, of all of the DLEP Data Items contained in this Signal. 865 This length MUST NOT include the length of the Signal Header 866 itself. 868 The DLEP Signal Header is immediately followed by zero or more DLEP 869 Data Items, encoded in TLVs, as defined in this document. 871 11.2. DLEP Message Header 873 The DLEP Message Header contains the following fields: 875 0 1 2 3 876 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 1 877 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 878 | Message Type | Length | 879 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 881 Figure 4: DLEP Message Header 883 Message Type: A 16-bit unsigned integer containing one of the DLEP 884 Message Type values defined in this document. 886 Length: The length in octets, expressed as a 16-bit unsigned 887 integer, of all of the DLEP Data Items contained in this Message. 888 This length MUST NOT include the length of the Message Header 889 itself. 891 The DLEP Message Header is immediately followed by zero or more DLEP 892 Data Items, encoded in TLVs, as defined in this document. 894 11.3. DLEP Generic Data Item 896 All DLEP Data Items contain the following fields: 898 0 1 2 3 899 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 1 900 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 901 | Data Item Type | Length | 902 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 903 | Value... : 904 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 906 Figure 5: DLEP Generic Data Item 908 Data Item Type: A 16-bit unsigned integer field specifying the type 909 of Data Item being sent. 911 Length: The length in octets, expressed as a 16-bit unsigned 912 integer, of the Value field of the Data Item. This length MUST 913 NOT include the length of the Data Item Type and Length fields. 915 Value: A field of octets, which contains data specific to a 916 particular Data Item. 918 12. DLEP Signals and Messages 920 12.1. General Processing Rules 922 If an unrecognized, or unexpected Signal is received, or a received 923 Signal contains unrecognized, invalid, or disallowed duplicate Data 924 Items, the receiving implementation MUST ignore the Signal. 926 If a Signal is received with a TTL value that is NOT equal to 255, 927 the receiving implementation MUST ignore the Signal. 929 If an unrecognized Message is received, the receiving implementation 930 MUST issue a Session Termination Message (Section 12.9) containing a 931 Status Data Item (Section 13.1) with status code set to 128 'Unknown 932 Message', see Table 2, and transition to the Session Termination 933 state. 935 If an unexpected Message is received, the receiving implementation 936 MUST issue a Session Termination Message containing a Status Data 937 Item with status code set to 129 'Unexpected Message', and transition 938 to the Session Termination state. 940 If a received Message contains unrecognized, invalid, or disallowed 941 duplicate Data Items, the receiving implementation MUST issue a 942 Session Termination Message containing a Status Data Item with status 943 code set to 130 'Invalid Data', and transition to the Session 944 Termination state. 946 If a packet in the TCP stream is received with a TTL value other than 947 255, the receiving implementation MUST immediately transition to the 948 Session Reset state. 950 Prior to the exchange of Destination Up (Section 12.11) and 951 Destination Up Response (Section 12.12) Messages, or Destination 952 Announce (Section 12.13) and Destination Announce Response 953 (Section 12.14) Messages, no Messages concerning a destination may be 954 sent. An implementation receiving any Message with such an 955 unannounced destination MUST terminate the session by issuing a 956 Session Termination Message containing a Status Data Item with status 957 code set to 131 'Invalid Destination', and transition to the Session 958 Termination state. 960 After exchanging Destination Down (Section 12.15) and Destination 961 Down Response (Section 12.16) Messages, no Messages concerning a 962 destination may be a sent until a new Destination Up or Destination 963 Announce Message is sent. An implementation receiving a Message 964 about a destination previously announced as 'down' MUST terminate the 965 session by issuing a Session Termination Message containing a Status 966 Data Item with status code set to 131 'Invalid Destination', and 967 transition to the Session Termination state. 969 12.2. Status code processing 971 The behavior of a DLEP participant receiving a Message containing a 972 Status Data Item (Section 13.1) is defined by the failure mode 973 associated with the value of the status code field, see Table 2. All 974 status code values less than 100 have a failure mode of 'Continue', 975 all other status codes have a failure mode of 'Terminate'. 977 A DLEP participant receiving any Message apart from Session 978 Termination Message (Section 12.9) containing a Status Data Item with 979 a status code value with failure mode 'Terminate' MUST immediately 980 issue a Session Termination Message echoing the received Status Data 981 Item, and then transition to the Session Termination state. 983 A DLEP participant receiving a Message containing a Status Data Item 984 with a status code value with failure mode 'Continue' can continue 985 normal operation of the session. 987 12.3. Peer Discovery Signal 989 A Peer Discovery Signal SHOULD be sent by a DLEP router to discover 990 DLEP modems in the network, see Section 7.1. 992 A Peer Discovery Signal MUST be encoded within a UDP packet. The 993 destination MUST be set to the DLEP well-known address and port 994 number. For routers supporting both IPv4 and IPv6 DLEP operation, it 995 is RECOMMENDED that IPv6 be selected as the transport. The source IP 996 address MUST be set to the router IP address associated with the DLEP 997 interface. There is no DLEP-specific restriction on source port. 999 To construct a Peer Discovery Signal, the Signal Type value in the 1000 Signal Header is set to 1 (see Signal Type Registration 1001 (Section 15.2)). 1003 The Peer Discovery Signal MAY contain a Peer Type Data Item 1004 (Section 13.4). 1006 12.4. Peer Offer Signal 1008 A Peer Offer Signal MUST be sent by a DLEP modem in response to a 1009 properly formatted and addressed Peer Discovery Signal 1010 (Section 12.3). 1012 A Peer Offer Signal MUST be encoded within a UDP packet. The IP 1013 source and destination fields in the packet MUST be set by swapping 1014 the values received in the Peer Discovery Signal. The Peer Offer 1015 Signal completes the discovery process, see Section 7.1. 1017 To construct a Peer Offer Signal, the Signal Type value in the Signal 1018 Header is set to 2 (see Signal Type Registration (Section 15.2)). 1020 The Peer Offer Signal MAY contain a Peer Type Data Item 1021 (Section 13.4). 1023 The Peer Offer Signal MAY contain one or more of any of the following 1024 Data Items, with different values: 1026 o IPv4 Connection Point (Section 13.2) 1028 o IPv6 Connection Point (Section 13.3) 1030 The IP Connection Point Data Items indicate the unicast address the 1031 router MUST use when connecting the DLEP TCP session. 1033 12.5. Session Initialization Message 1035 A Session Initialization Message MUST be sent by a DLEP router as the 1036 first Message of the DLEP TCP session. It is sent by the router 1037 after a TCP connect to an address/port combination that was obtained 1038 either via receipt of a Peer Offer, or from a priori configuration. 1040 To construct a Session Initialization Message, the Message Type value 1041 in the Message Header is set to 1 (see Message Type Registration 1042 (Section 15.3)). 1044 The Session Initialization Message MUST contain one of each of the 1045 following Data Items: 1047 o Heartbeat Interval Data Item (Section 13.5) 1049 o Peer Type (Section 13.4) 1051 The Session Initialization Message MUST contain an Extensions 1052 Supported Data Item (Section 13.6), if DLEP extensions are supported. 1054 The Session Initialization Message MAY contain one or more of each of 1055 the following Data Items, with different values, and the data item 1056 Add flag set to 1: 1058 o IPv4 Address (Section 13.8) 1060 o IPv6 Address (Section 13.9) 1062 o IPv4 Attached Subnet (Section 13.10) 1064 o IPv6 Attached Subnet (Section 13.11) 1066 If any optional extensions are supported by the implementation, they 1067 MUST be enumerated in the Extensions Supported Data Item. If an 1068 Extensions Supported Data Item does not exist in a Session 1069 Initialization Message, the modem MUST conclude that there is no 1070 support for extensions in the router. 1072 DLEP Heartbeats are not started until receipt of the Session 1073 Initialization Response Message (Section 12.6), and therefore 1074 implementations MUST use their own timeout heuristics for this 1075 Message. 1077 As an exception to the general rule governing an implementation 1078 receiving an unrecognized Data Item in a Message, see Section 12.1, 1079 if a Session Initialization Message contains one or more Extension 1080 Supported Data Items announcing support for extensions that the 1081 implementation does not recognize, then the implementation MAY ignore 1082 Data Items it does not recognize. 1084 12.6. Session Initialization Response Message 1086 A Session Initialization Response Message MUST be sent by a DLEP 1087 modem in response to a received Session Initialization Message 1088 (Section 12.5). 1090 To construct a Session Initialization Response Message, the Message 1091 Type value in the Message Header is set to 2 (see Message Type 1092 Registration (Section 15.3)). 1094 The Session Initialization Response Message MUST contain one of each 1095 of the following Data Items: 1097 o Status (Section 13.1) 1099 o Peer Type (Section 13.4) 1101 o Heartbeat Interval (Section 13.5) 1103 o Maximum Data Rate (Receive) (Section 13.12) 1105 o Maximum Data Rate (Transmit) (Section 13.13) 1107 o Current Data Rate (Receive) (Section 13.14) 1109 o Current Data Rate (Transmit) (Section 13.15) 1111 o Latency (Section 13.16) 1113 The Session Initialization Response Message MUST contain one of each 1114 of the following Data Items, if the Data Item will be used during the 1115 lifetime of the session: 1117 o Resources (Section 13.17) 1119 o Relative Link Quality (Receive) (Section 13.18) 1121 o Relative Link Quality (Transmit) (Section 13.19) 1123 o Maximum Transmission Unit (MTU) (Section 13.20) 1125 The Session Initialization Response Message MUST contain an 1126 Extensions Supported Data Item (Section 13.6), if DLEP extensions are 1127 supported. 1129 The Session Initialization Response Message MAY contain one or more 1130 of each of the following Data Items, with different values, and the 1131 data item Add flag set to 1: 1133 o IPv4 Address (Section 13.8) 1135 o IPv6 Address (Section 13.9) 1137 o IPv4 Attached Subnet (Section 13.10) 1139 o IPv6 Attached Subnet (Section 13.11) 1141 The Session Initialization Response Message completes the DLEP 1142 session establishment; the modem should transition to the In-Session 1143 state when the Message is sent, and the router should transition to 1144 the In-Session state upon receipt of an acceptable Session 1145 Initialization Response Message. 1147 All supported metric Data Items MUST be included in the Session 1148 Initialization Response Message, with default values to be used on a 1149 session-wide basis. This can be viewed as the modem 'declaring' all 1150 supported metrics at DLEP session initialization. Receipt of any 1151 further DLEP Message containing a metric Data Item not included in 1152 the Session Initialization Response Message MUST be treated as an 1153 error, resulting in the termination of the DLEP session between 1154 router and modem. 1156 If any optional extensions are supported by the modem, they MUST be 1157 enumerated in the Extensions Supported Data Item. If an Extensions 1158 Supported Data Item does not exist in a Session Initialization 1159 Response Message, the router MUST conclude that there is no support 1160 for extensions in the modem. 1162 After the Session Initialization/Session Initialization Response 1163 Messages have been successfully exchanged, implementations MUST only 1164 use extensions that are supported by both DLEP participants, see 1165 Section 7.2. 1167 12.7. Session Update Message 1169 A Session Update Message MAY be sent by a DLEP participant to 1170 indicate local Layer 3 address changes, or metric changes on a 1171 session-wide basis. 1173 To construct a Session Update Message, the Message Type value in the 1174 Message Header is set to 3 (see Message Type Registration 1175 (Section 15.3)). 1177 The Session Update Message MAY contain one or more of each of the 1178 following Data Items, with different values: 1180 o IPv4 Address (Section 13.8) 1182 o IPv6 Address (Section 13.9) 1184 o IPv4 Attached Subnet (Section 13.10) 1186 o IPv6 Attached Subnet (Section 13.11) 1188 When sent by a modem, the Session Update Message MAY contain one of 1189 each of the following Data Items: 1191 o Maximum Data Rate (Receive) (Section 13.12) 1193 o Maximum Data Rate (Transmit) (Section 13.13) 1195 o Current Data Rate (Receive) (Section 13.14) 1197 o Current Data Rate (Transmit) (Section 13.15) 1199 o Latency (Section 13.16) 1201 When sent by a modem, the Session Update Message MAY contain one of 1202 each of the following Data Items, if the Data Item is in use by the 1203 session: 1205 o Resources (Section 13.17) 1207 o Relative Link Quality (Receive) (Section 13.18) 1209 o Relative Link Quality (Transmit) (Section 13.19) 1211 o Maximum Transmission Unit (MTU) (Section 13.20) 1213 If metrics are supplied with the Session Update Message (e.g., 1214 Maximum Data Rate), these metrics are considered to be session-wide, 1215 and therefore MUST be applied to all destinations in the information 1216 base associated with the DLEP session. This includes destinations 1217 for which metrics may have been stored based on received Destination 1218 Update messages. 1220 It should be noted that Session Update Messages can be sent by both 1221 routers and modems. For example, addition of an IPv4 address on the 1222 router MAY prompt a Session Update Message to its attached modems. 1223 Also, for example, a modem that changes its Maximum Data Rate 1224 (Receive) for all destinations MAY reflect that change via a Session 1225 Update Message to its attached router(s). 1227 Concerning Layer 3 addresses and subnets: If the modem is capable of 1228 understanding and forwarding this information (via mechanisms not 1229 defined by DLEP), the update would prompt any remote DLEP-enabled 1230 modems to issue a Destination Update Message (Section 12.17) to their 1231 local routers with the new (or deleted) addresses and subnets. 1233 12.8. Session Update Response Message 1235 A Session Update Response Message MUST be sent by a DLEP participant 1236 when a Session Update Message (Section 12.7) is received. 1238 To construct a Session Update Response Message, the Message Type 1239 value in the Message Header is set to 4 (see Message Type 1240 Registration (Section 15.3)). 1242 The Session Update Response Message MUST contain a Status Data Item 1243 (Section 13.1). 1245 12.9. Session Termination Message 1247 When a DLEP participant determines the DLEP session needs to be 1248 terminated, the participant MUST send (or attempt to send) a Session 1249 Termination Message. 1251 To construct a Session Termination Message, the Message Type value in 1252 the Message Header is set to 5 (see Message Type Registration 1253 (Section 15.3)). 1255 The Session Termination Message MUST contain Status Data Item 1256 (Section 13.1). 1258 It should be noted that Session Termination Messages can be sent by 1259 both routers and modems. 1261 12.10. Session Termination Response Message 1263 A Session Termination Response Message MUST be sent by a DLEP 1264 participant when a Session Termination Message (Section 12.9) is 1265 received. 1267 To construct a Session Termination Response Message, the Message Type 1268 value in the Message Header is set to 6 (see Message Type 1269 Registration (Section 15.3)). 1271 There are no valid Data Items for the Session Termination Response 1272 Message. 1274 Receipt of a Session Termination Response Message completes the tear- 1275 down of the DLEP session, see Section 7.4. 1277 12.11. Destination Up Message 1279 Destination Up Messages MAY be sent by a modem to inform its attached 1280 router of the presence of a new reachable destination. 1282 To construct a Destination Up Message, the Message Type value in the 1283 Message Header is set to 7 (see Message Type Registration 1284 (Section 15.3)). 1286 The Destination Up Message MUST contain a MAC Address Data Item 1287 (Section 13.7). 1289 The Destination Up Message SHOULD contain one or more of each of the 1290 following Data Items, with different values: 1292 o IPv4 Address (Section 13.8) 1294 o IPv6 Address (Section 13.9) 1296 The Destination Up Message MAY contain one of each of the following 1297 Data Items: 1299 o Maximum Data Rate (Receive) (Section 13.12) 1301 o Maximum Data Rate (Transmit) (Section 13.13) 1303 o Current Data Rate (Receive) (Section 13.14) 1305 o Current Data Rate (Transmit) (Section 13.15) 1307 o Latency (Section 13.16) 1309 The Destination Up Message MAY contain one of each of the following 1310 Data Items, if the Data Item is in use by the session: 1312 o Resources (Section 13.17) 1314 o Relative Link Quality (Receive) (Section 13.18) 1316 o Relative Link Quality (Transmit) (Section 13.19) 1318 o Maximum Transmission Unit (MTU) (Section 13.20) 1319 The Destination Up Message MAY contain one or more of each of the 1320 following Data Items, with different values: 1322 o IPv4 Attached Subnet (Section 13.10) 1324 o IPv6 Attached Subnet (Section 13.11) 1326 A router receiving a Destination Up Message allocates the necessary 1327 resources, creating an entry in the information base with the 1328 specifics (MAC Address, Latency, Data Rate, etc.) of the destination. 1329 The information about this destination will persist in the router's 1330 information base until a Destination Down Message (Section 12.15) is 1331 received, indicating that the modem has lost contact with the remote 1332 node, or the implementation transitions to the Session Termination 1333 state. 1335 12.12. Destination Up Response Message 1337 A router MUST send a Destination Up Response Message when a 1338 Destination Up Message (Section 12.11) is received. 1340 To construct a Destination Up Response Message, the Message Type 1341 value in the Message Header is set to 8 (see Message Type 1342 Registration (Section 15.3)). 1344 The Destination Up Response Message MUST contain one of each of the 1345 following Data Items: 1347 o MAC Address (Section 13.7) 1349 o Status (Section 13.1) 1351 A router that wishes to receive further information concerning the 1352 destination identified in the corresponding Destination Up Message 1353 MUST set the status code of the included Status Data Item to 0 1354 'Success', see Table 2. 1356 If the router has no interest in the destination identified in the 1357 corresponding Destination Up Message, then it MAY set the status code 1358 of the included Status Data Item to 1 'Not Interested'. 1360 A modem receiving a Destination Up Response Message containing a 1361 Status Data Item with status code of any value other than 0 'Success' 1362 MUST NOT send further Destination messages about the destination, 1363 e.g. Destination Down (Section 12.15) or Destination Update 1364 (Section 12.17) with the same MAC address. 1366 12.13. Destination Announce Message 1368 Usually a modem will discover the presence of one or more remote 1369 router/modem pairs and announce each destination's arrival by sending 1370 a corresponding Destination Up Message (Section 12.11) to the router. 1371 However, there may be times when a router wishes to express an 1372 interest in a destination that has yet to be announced, typically a 1373 multicast destination. Destination Announce Messages MAY be sent by 1374 a router to announce such an interest. 1376 A Destination Announce Message MAY also be sent by a router to 1377 request information concerning a destination in which it has 1378 previously declined interest, via the 1 'Not Interested' status code 1379 in a Destination Up Response Message (Section 12.12), see Table 2, or 1380 declared as 'down', via the Destination Down Message (Section 12.15). 1382 To construct a Destination Announce Message, the Message Type value 1383 in the Message Header is set to 9 (see Message Type Registration 1384 (Section 15.3)). 1386 The Destination Announce Message MUST contain a MAC Address Data Item 1387 (Section 13.7). 1389 The Destination Announce Message MAY contain zero or more of the 1390 following Data Items, with different values: 1392 o IPv4 Address (Section 13.8) 1394 o IPv6 Address (Section 13.9) 1396 One of the advantages of implementing DLEP is to leverage the modem's 1397 knowledge of the links between remote destinations allowing routers 1398 to avoid using probed neighbor discovery techniques, therefore modem 1399 implementations SHOULD announce available destinations via the 1400 Destination Up Message, rather than relying on Destination Announce 1401 Messages. 1403 12.14. Destination Announce Response Message 1405 A modem MUST send a Destination Announce Response Message when a 1406 Destination Announce Message (Section 12.13) is received. 1408 To construct a Destination Announce Response Message, the Message 1409 Type value in the Message Header is set to 10 (see Message Type 1410 Registration (Section 15.3)). 1412 The Destination Announce Response Message MUST contain one of each of 1413 the following Data Items: 1415 o MAC Address (Section 13.7) 1417 o Status (Section 13.1) 1419 The Destination Announce Response Message MAY contain one or more of 1420 each of the following Data Items, with different values: 1422 o IPv4 Address (Section 13.8) 1424 o IPv6 Address (Section 13.9) 1426 o IPv4 Attached Subnet (Section 13.10) 1428 o IPv6 Attached Subnet (Section 13.11) 1430 The Destination Announce Response Message MAY contain one of each of 1431 the following Data Items: 1433 o Maximum Data Rate (Receive) (Section 13.12) 1435 o Maximum Data Rate (Transmit) (Section 13.13) 1437 o Current Data Rate (Receive) (Section 13.14) 1439 o Current Data Rate (Transmit) (Section 13.15) 1441 o Latency (Section 13.16) 1443 The Destination Announce Response Message MAY contain one of each of 1444 the following Data Items, if the Data Item is in use by the session: 1446 o Resources (Section 13.17) 1448 o Relative Link Quality (Receive) (Section 13.18) 1450 o Relative Link Quality (Transmit) (Section 13.19) 1452 o Maximum Transmission Unit (MTU) (Section 13.20) 1454 If a modem is unable to report information immediately about the 1455 requested information, if the destination is not currently reachable, 1456 for example, the status code in the Status Data Item MUST be set to 2 1457 'Request Denied', see Table 2. 1459 After sending a Destination Announce Response Message containing a 1460 Status Data Item with status code of 0 'Success', a modem then 1461 announces changes to the link to the destination via Destination 1462 Update Messages. 1464 When a successful Destination Announce Response Message is received, 1465 the router should add knowledge of the available destination to its 1466 information base. 1468 12.15. Destination Down Message 1470 A modem MUST send a Destination Down Message to report when a 1471 destination (a remote node or a multicast group) is no longer 1472 reachable. 1474 A router MAY send a Destination Down Message to report when it no 1475 longer requires information concerning a destination. 1477 To construct a Destination Down Message, the Message Type value in 1478 the Message Header is set to 11 (see Message Type Registration 1479 (Section 15.3)). 1481 The Destination Down Message MUST contain a MAC Address Data Item 1482 (Section 13.7). 1484 It should be noted that both modem and router may send a Destination 1485 Down Message to their peer, regardless of which participant initially 1486 indicated the destination to be 'up'. 1488 12.16. Destination Down Response Message 1490 A Destination Down Response MUST be sent by the recipient of a 1491 Destination Down Message (Section 12.15) to confirm that the relevant 1492 data concerning the destination has been removed from the information 1493 base. 1495 To construct a Destination Down Response Message, the Message Type 1496 value in the Message Header is set to 12 (see Message Type 1497 Registration (Section 15.3)). 1499 The Destination Down Response Message MUST contain one of each of the 1500 following Data Items: 1502 o MAC Address (Section 13.7) 1504 o Status (Section 13.1) 1506 12.17. Destination Update Message 1508 A modem SHOULD send the Destination Update Message when it detects 1509 some change in the information base for a given destination (remote 1510 node or multicast group). Some examples of changes that would prompt 1511 a Destination Update Message are: 1513 o Change in link metrics (e.g., Data Rates) 1515 o Layer 3 addressing change 1517 To construct a Destination Update Message, the Message Type value in 1518 the Message Header is set to 13 (see Message Type Registration 1519 (Section 15.3)). 1521 The Destination Update Message MUST contain a MAC Address Data Item 1522 (Section 13.7). 1524 The Destination Update Message MAY contain one of each of the 1525 following Data Items: 1527 o Maximum Data Rate (Receive) (Section 13.12) 1529 o Maximum Data Rate (Transmit) (Section 13.13) 1531 o Current Data Rate (Receive) (Section 13.14) 1533 o Current Data Rate (Transmit) (Section 13.15) 1535 o Latency (Section 13.16) 1537 The Destination Update Message MAY contain one of each of the 1538 following Data Items, if the Data Item is in use by the session: 1540 o Resources (Section 13.17) 1542 o Relative Link Quality (Receive) (Section 13.18) 1544 o Relative Link Quality (Transmit) (Section 13.19) 1546 o Maximum Transmission Unit (MTU) (Section 13.20) 1548 The Destination Update Message MAY contain one or more of each of the 1549 following Data Items, with different values: 1551 o IPv4 Address (Section 13.8) 1553 o IPv6 Address (Section 13.9) 1555 o IPv4 Attached Subnet (Section 13.10) 1557 o IPv6 Attached Subnet (Section 13.11) 1559 Metrics supplied in this message overwrite metrics provided in a 1560 previously received Session or Destination Up Messages. 1562 It should be noted that this Message has no corresponding response. 1564 12.18. Link Characteristics Request Message 1566 The Link Characteristics Request Message MAY be sent by a router to 1567 request that the modem initiate changes for specific characteristics 1568 of the link. The request can reference either a real destination 1569 (e.g., a remote node), or a logical destination (e.g., a multicast 1570 group) within the network. 1572 To construct a Link Characteristics Request Message, the Message Type 1573 value in the Message Header is set to 14 (see Message Type 1574 Registration (Section 15.3)). 1576 The Link Characteristics Request Message MUST contain one of the 1577 following Data Items: 1579 o MAC Address (Section 13.7) 1581 The Link Characteristics Request Message MUST contain at least one of 1582 each of the following Data Items: 1584 o Current Data Rate (Receive) (Section 13.14) 1586 o Current Data Rate (Transmit) (Section 13.15) 1588 o Latency (Section 13.16) 1590 The Link Characteristics Request Message MAY contain either a Current 1591 Data Rate (CDRR or CDRT) Data Item to request a different datarate 1592 than is currently allocated, a Latency Data Item to request that 1593 traffic delay on the link not exceed the specified value, or both. 1595 The router sending a Link Characteristics Request Message should be 1596 aware that a request may take an extended period of time to complete. 1598 12.19. Link Characteristics Response Message 1600 A modem MUST send a Link Characteristics Response Message when a Link 1601 Characteristics Request Message (Section 12.18) is received. 1603 To construct a Link Characteristics Response Message, the Message 1604 Type value in the Message Header is set to 15 (see Message Type 1605 Registration (Section 15.3)). 1607 The Link Characteristics Response Message MUST contain one of each of 1608 the following Data Items: 1610 o MAC Address (Section 13.7) 1612 o Status (Section 13.1) 1614 The Link Characteristics Response Message SHOULD contain one of each 1615 of the following Data Items: 1617 o Maximum Data Rate (Receive) (Section 13.12) 1619 o Maximum Data Rate (Transmit) (Section 13.13) 1621 o Current Data Rate (Receive) (Section 13.14) 1623 o Current Data Rate (Transmit) (Section 13.15) 1625 o Latency (Section 13.16) 1627 The Link Characteristics Response Message MAY contain one of each of 1628 the following Data Items, if the Data Item is in use by the session: 1630 o Resources (Section 13.17) 1632 o Relative Link Quality (Receive) (Section 13.18) 1634 o Relative Link Quality (Transmit) (Section 13.19) 1636 o Maximum Transmission Unit (MTU) (Section 13.20) 1638 The Link Characteristics Response Message MUST contain a complete set 1639 of metric Data Items, referencing all metrics declared in the Session 1640 Initialization Response Message (Section 12.6). The values in the 1641 metric Data Items in the Link Characteristics Response Message MUST 1642 reflect the link characteristics after the request has been 1643 processed. 1645 If an implementation is not able to alter the characteristics of the 1646 link in the manner requested, then the status code of the Status Data 1647 Item MUST be set to 2 'Request Denied', see Table 2. 1649 12.20. Heartbeat Message 1651 A Heartbeat Message MUST be sent by a DLEP participant every N 1652 milliseconds, where N is defined in the Heartbeat Interval Data Item 1653 (Section 13.5) of the Session Initialization Message (Section 12.5) 1654 or Session Initialization Response Message (Section 12.6). 1656 To construct a Heartbeat Message, the Message Type value in the 1657 Message Header is set to 16 (see Message Type Registration 1658 (Section 15.3)). 1660 There are no valid Data Items for the Heartbeat Message. 1662 The Message is used by DLEP participants to detect when a DLEP 1663 session peer (either the modem or the router) is no longer 1664 communicating, see Section 7.3.1. 1666 13. DLEP Data Items 1668 The core DLEP Data Items are: 1670 +-------------+-----------------------------------------------------+ 1671 | Type Code | Description | 1672 +-------------+-----------------------------------------------------+ 1673 | 0 | Reserved | 1674 | 1 | Status (Section 13.1) | 1675 | 2 | IPv4 Connection Point (Section 13.2) | 1676 | 3 | IPv6 Connection Point (Section 13.3) | 1677 | 4 | Peer Type (Section 13.4) | 1678 | 5 | Heartbeat Interval (Section 13.5) | 1679 | 6 | Extensions Supported (Section 13.6) | 1680 | 7 | MAC Address (Section 13.7) | 1681 | 8 | IPv4 Address (Section 13.8) | 1682 | 9 | IPv6 Address (Section 13.9) | 1683 | 10 | IPv4 Attached Subnet (Section 13.10) | 1684 | 11 | IPv6 Attached Subnet (Section 13.11) | 1685 | 12 | Maximum Data Rate (Receive) (MDRR) (Section 13.12) | 1686 | 13 | Maximum Data Rate (Transmit) (MDRT) (Section 13.13) | 1687 | 14 | Current Data Rate (Receive) (CDRR) (Section 13.14) | 1688 | 15 | Current Data Rate (Transmit) (CDRT) (Section 13.15) | 1689 | 16 | Latency (Section 13.16) | 1690 | 17 | Resources (RES) (Section 13.17) | 1691 | 18 | Relative Link Quality (Receive) (RLQR) (Section | 1692 | | 13.18) | 1693 | 19 | Relative Link Quality (Transmit) (RLQT) (Section | 1694 | | 13.19) | 1695 | 20 | Maximum Transmission Unit (MTU) (Section 13.20) | 1696 | 21-65407 | Reserved for future extensions | 1697 | 65408-65534 | Private Use. Available for experiments | 1698 | 65535 | Reserved | 1699 +-------------+-----------------------------------------------------+ 1701 Table 1: DLEP Data Item types 1703 13.1. Status 1705 For the Session Termination Message (Section 12.9), the Status Data 1706 Item indicates a reason for the termination. For all response 1707 Messages, the Status Data Item is used to indicate the success or 1708 failure of the previously received Message. 1710 The Status Data Item includes an optional Text field that can be used 1711 to provide a textual description of the status. The use of the Text 1712 field is entirely up to the receiving implementation, e.g., it could 1713 be output to a log file or discarded. If no Text field is supplied 1714 with the Status Data Item, the Length field MUST be set to 1. 1716 The Status Data Item contains the following fields: 1718 0 1 2 3 1719 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 1720 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1721 | Data Item Type | Length | 1722 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1723 | Code | Text... : 1724 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1726 Data Item Type: 1 1728 Length: 1 + Length of text, in octets 1730 Status Code: One of the codes defined in Table 2 below. 1732 Text: UTF-8 encoded string of UNICODE [RFC3629] characters, 1733 describing the cause, used for implementation defined purposes. 1734 Since this field is used for description, implementations SHOULD 1735 limit characters in this field to printable characters. 1737 An implementation MUST NOT assume the Text field is a NUL-terminated 1738 string of printable characters. 1740 +----------+-------------+------------------+-----------------------+ 1741 | Status | Failure | Description | Reason | 1742 | Code | Mode | | | 1743 +----------+-------------+------------------+-----------------------+ 1744 | 0 | Continue | Success | The Message was | 1745 | | | | processed | 1746 | | | | successfully. | 1747 | 1 | Continue | Not Interested | The receiver is not | 1748 | | | | interested in this | 1749 | | | | Message subject, e.g. | 1750 | | | | in a Destination Up | 1751 | | | | Response Message | 1752 | | | | (Section 12.12) to | 1753 | | | | indicate no further | 1754 | | | | Messages about the | 1755 | | | | destination. | 1756 | 2 | Continue | Request Denied | The receiver refuses | 1757 | | | | to complete the | 1758 | | | | request. | 1759 | 3 | Continue | Inconsistent | One or more Data | 1760 | | | Data | Items in the Message | 1761 | | | | describe a logically | 1762 | | | | inconsistent state in | 1763 | | | | the network. For | 1764 | | | | example, in the | 1765 | | | | Destination Up | 1766 | | | | Message (Section | 1767 | | | | 12.11) when an | 1768 | | | | announced subnet | 1769 | | | | clashes with an | 1770 | | | | existing destination | 1771 | | | | subnet. | 1772 | 4-111 | Continue | | Reserved for future | 1773 | | | | extensions. | 1774 | 112-127 | Continue | | Available for | 1775 | | | | experiments. | 1776 | 128 | Terminate | Unknown Message | The Message was not | 1777 | | | | recognized by the | 1778 | | | | implementation. | 1779 | 129 | Terminate | Unexpected | The Message was not | 1780 | | | Message | expected while the | 1781 | | | | device was in the | 1782 | | | | current state, e.g., | 1783 | | | | a Session | 1784 | | | | Initialization | 1785 | | | | Message (Section | 1786 | | | | 12.5) in the In- | 1787 | | | | Session state. | 1788 | 130 | Terminate | Invalid Data | One or more Data | 1789 | | | | Items in the Message | 1790 | | | | are invalid, | 1791 | | | | unexpected or | 1792 | | | | incorrectly | 1793 | | | | duplicated. | 1794 | 131 | Terminate | Invalid | The destination | 1795 | | | Destination | included in the | 1796 | | | | Message does not | 1797 | | | | match a previously | 1798 | | | | announced | 1799 | | | | destination. For | 1800 | | | | example, in the Link | 1801 | | | | Characteristic | 1802 | | | | Response Message | 1803 | | | | (Section 12.19). | 1804 | 132 | Terminate | Timed Out | The session has timed | 1805 | | | | out. | 1806 | 133-239 | Terminate | | Reserved for future | 1807 | | | | extensions. | 1808 | 240-254 | Terminate | | Available for | 1809 | | | | experiments. | 1810 | 255 | Terminate | | Reserved. | 1811 +----------+-------------+------------------+-----------------------+ 1813 Table 2: DLEP Status Codes 1815 13.2. IPv4 Connection Point 1817 The IPv4 Connection Point Data Item indicates the IPv4 address and, 1818 optionally, the TCP port number on the modem available for 1819 connections. If provided, the router MUST use this information to 1820 initiate the TCP connection to the modem. 1822 The IPv4 Connection Point Data Item contains the following fields: 1824 0 1 2 3 1825 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 1826 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1827 | Data Item Type | Length | 1828 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1829 | Flags | IPv4 Address... : 1830 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1831 : ...cont. | TCP Port Number (optional) | 1832 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1834 Data Item Type: 2 1836 Length: 5 (or 7 if TCP Port included) 1838 Flags: Flags field, defined below. 1840 IPv4 Address: The IPv4 address listening on the modem. 1842 TCP Port Number: TCP Port number on the modem. 1844 If the Length field is 7, the port number specified MUST be used to 1845 establish the TCP session. If the TCP Port Number is omitted, i.e. 1847 the Length field is 5, the router MUST use the DLEP well-known port 1848 number (Section 15.14) to establish the TCP connection. 1850 The Flags field is defined as: 1852 0 1 2 3 4 5 6 7 1853 +-+-+-+-+-+-+-+-+ 1854 | Reserved |T| 1855 +-+-+-+-+-+-+-+-+ 1857 T: Use TLS flag, indicating whether the TCP connection to the given 1858 address and port requires the use of TLS [RFC5246] (1), or not 1859 (0). 1861 Reserved: MUST be zero. Left for future assignment. 1863 13.3. IPv6 Connection Point 1865 The IPv6 Connection Point Data Item indicates the IPv6 address and, 1866 optionally, the TCP port number on the modem available for 1867 connections. If provided, the router MUST use this information to 1868 initiate the TCP connection to the modem. 1870 The IPv6 Connection Point Data Item contains the following fields: 1872 0 1 2 3 1873 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 1874 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1875 | Data Item Type | Length | 1876 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1877 | Flags | IPv6 Address : 1878 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1879 : IPv6 Address : 1880 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1881 : IPv6 Address : 1882 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1883 : IPv6 Address : 1884 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1885 : ...cont. | TCP Port Number (optional) | 1886 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1888 Data Item Type: 3 1890 Length: 17 (or 19 if TCP Port included) 1892 Flags: Flags field, defined below. 1894 IPv6 Address: The IPv6 address listening on the modem. 1896 TCP Port Number: TCP Port number on the modem. 1898 If the Length field is 19, the port number specified MUST be used to 1899 establish the TCP session. If the TCP Port Number is omitted, i.e. 1900 the Length field is 17, the router MUST use the DLEP well-known port 1901 number (Section 15.14) to establish the TCP connection. 1903 The Flags field is defined as: 1905 0 1 2 3 4 5 6 7 1906 +-+-+-+-+-+-+-+-+ 1907 | Reserved |T| 1908 +-+-+-+-+-+-+-+-+ 1910 T: Use TLS flag, indicating whether the TCP connection to the given 1911 address and port requires the use of TLS [RFC5246] (1), or not 1912 (0). 1914 Reserved: MUST be zero. Left for future assignment. 1916 13.4. Peer Type 1918 The Peer Type Data Item is used by the router and modem to give 1919 additional information as to its type and the properties of the over- 1920 the-air control-plane. 1922 With some devices, access to the shared RF medium is strongly 1923 controlled. One example of this would be satellite modems - where 1924 protocols, proprietary in nature, have been developed to insure a 1925 given modem has authorization to connect to the shared medium. 1926 Another example of this class of modems is governmental/military 1927 devices, where elaborate mechanisms have been developed to ensure 1928 that only authorized devices can connect to the shared medium. 1929 Contrasting with the above, there are modems where no such access 1930 control is used. An example of this class of modem would be one that 1931 supports the 802.11 ad-hoc mode of operation. The Secured Medium 1932 flag is used to indicate if access control is in place. 1934 The Peer Type Data Item includes a textual description of the peer 1935 that is envisioned to be used for informational purposes (e.g., as 1936 output in a display command). 1938 The Peer Type Data Item contains the following fields: 1940 0 1 2 3 1941 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 1942 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1943 | Data Item Type | Length | 1944 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1945 | Flags | Description... : 1946 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1948 Data Item Type: 4 1950 Length: 1 + Length of Peer Type string, in octets. 1952 Flags: Flags field, defined below. 1954 Description: UTF-8 encoded string of UNICODE [RFC3629] characters. 1955 For example, a satellite modem might set this variable to 1956 "Satellite terminal". Since this Data Item is intended to provide 1957 additional information for display commands, sending 1958 implementations SHOULD limit the data to printable characters. 1960 An implementation MUST NOT assume the Description field is a NUL- 1961 terminated string of printable characters. 1963 The Flags field is defined as: 1965 0 1 2 3 4 5 6 7 1966 +-+-+-+-+-+-+-+-+ 1967 | Reserved |S| 1968 +-+-+-+-+-+-+-+-+ 1970 S: Secured Medium flag, used by a modem to indicate if the shared RF 1971 medium implements access control (1), or not (0). The Secured 1972 Medium flag only has meaning in Signals and Messages sent by a 1973 modem. 1975 Reserved: MUST be zero. Left for future assignment. 1977 13.5. Heartbeat Interval 1979 The Heartbeat Interval Data Item is used to specify a period in 1980 milliseconds for Heartbeat Messages (Section 12.20). 1982 The Heartbeat Interval Data Item contains the following fields: 1984 0 1 2 3 1985 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 1986 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1987 | Data Item Type | Length | 1988 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1989 | Heartbeat Interval | 1990 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1992 Data Item Type: 5 1994 Length: 4 1996 Heartbeat Interval: The interval in milliseconds, expressed as a 1997 32-bit unsigned integer, for Heartbeat Messages. This value MUST 1998 NOT be 0. 2000 As mentioned before, receipt of any valid DLEP Message MUST reset the 2001 heartbeat interval timer (e.g., valid DLEP Messages take the place 2002 of, and obviate the need for, additional Heartbeat Messages). 2004 13.6. Extensions Supported 2006 The Extensions Supported Data Item is used by the router and modem to 2007 negotiate additional optional functionality they are willing to 2008 support. The Extensions List is a concatenation of the types of each 2009 supported extension, found in the IANA DLEP Extensions repository. 2010 Each Extension Type definition includes which additional Signals and 2011 Data Items are supported. 2013 The Extensions Supported Data Item contains the following fields: 2015 0 1 2 3 2016 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 2017 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2018 | Data Item Type | Length | 2019 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2020 | Extensions List... : 2021 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2023 Data Item Type: 6 2025 Length: Length of the extensions list in octets. This is twice (2x) 2026 the number of extensions. 2028 Extension List: A list of extensions supported, identified by their 2029 2-octet value as listed in the extensions registry. 2031 13.7. MAC Address 2033 The MAC Address Data Item contains the address of the destination on 2034 the remote node. 2036 DLEP can support MAC addresses in either EUI-48 or EUI-64 format, 2037 with the restriction that all MAC addresses for a given DLEP session 2038 MUST be in the same format, and MUST be consistent with the MAC 2039 address format of the connected modem (e.g., if the modem is 2040 connected to the router with an EUI-48 MAC, all destination addresses 2041 via that modem MUST be expressed in EUI-48 format). 2043 Examples of a virtual destination would be a multicast MAC address, 2044 or the broadcast MAC (FF:FF:FF:FF:FF:FF). 2046 0 1 2 3 2047 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 2048 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2049 | Data Item Type | Length | 2050 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2051 | MAC Address : 2052 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2053 : MAC Address : (if EUI-64 used) | 2054 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2056 Data Item Type: 7 2058 Length: 6 for EUI-48 format, or 8 for EUI-64 format 2060 MAC Address: MAC Address of the destination. 2062 13.8. IPv4 Address 2064 When included in the Session Update Message, this Data Item contains 2065 the IPv4 address of the peer. When included in Destination Messages, 2066 this Data Item contains the IPv4 address of the destination. In 2067 either case, the Data Item also contains an indication of whether 2068 this is a new or existing address, or is a deletion of a previously 2069 known address. 2071 The IPv4 Address Data Item contains the following fields: 2073 0 1 2 3 2074 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 2075 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2076 | Data Item Type | Length | 2077 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2078 | Flags | IPv4 Address : 2079 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2080 : ...cont. | 2081 +-+-+-+-+-+-+-+-+ 2083 Data Item Type: 8 2085 Length: 5 2087 Flags: Flags field, defined below. 2089 IPv4 Address: The IPv4 address of the destination or peer. 2091 The Flags field is defined as: 2093 0 1 2 3 4 5 6 7 2094 +-+-+-+-+-+-+-+-+ 2095 | Reserved |A| 2096 +-+-+-+-+-+-+-+-+ 2098 A: Add/Drop flag, indicating whether this is a new or existing 2099 address (1), or a withdrawal of an address (0). 2101 Reserved: MUST be zero. Reserved for future use. 2103 13.8.1. IPv4 Address Processing 2105 Processing of the IPv4 Address Data Item MUST be done within the 2106 context of the DLEP Peer session on which it is presented. 2108 The handling of erroneous or logically inconsistent conditions 2109 depends upon the type of the message that contains the data item: 2111 If the containing message is a Session Message, e.g., Session 2112 Initialization Message (Section 12.5), or Session Update Message 2113 (Section 12.7), the receiver of inconsistent information MUST issue a 2114 Session Termination Message (Section 12.9) containing a Status Data 2115 Item (Section 13.1) with status code set to 130 'Invalid Data', and 2116 transition to the Session Termination state. Examples of such 2117 conditions are: 2119 o An address Drop operation referencing an address that is not 2120 associated with the peer in the current session. 2122 o An address Add operation referencing an address that has already 2123 been added to the peer in the current session. 2125 If the containing message is a Destination Message, e.g., Destination 2126 Up Message (Section 12.11), or Destination Update Message 2127 (Section 12.17), the receiver of inconsistent information MAY issue 2128 the appropriate response message containing a Status Data Item, with 2129 status code set to 3 'Inconsistent Data', but MUST continue with 2130 session processing. Examples of such conditions are: 2132 o An address Add operation referencing an address that has already 2133 been added to the destination in the current session. 2135 o An address Add operation referencing an address that is associated 2136 with a different destination or the peer in the current session. 2138 o An address Add operation referencing an address that makes no 2139 sense, for example defined as not forwardable in [RFC6890]. 2141 o An address Drop operation referencing an address that is not 2142 associated with the destination in the current session. 2144 If no response message is appropriate, for example, the Destination 2145 Update Message, then the implementation MUST continue with session 2146 processing. 2148 Modems that do not track IPv4 addresses MUST silently ignore IPv4 2149 Address Data Items. 2151 13.9. IPv6 Address 2153 When included in the Session Update Message, this Data Item contains 2154 the IPv6 address of the peer. When included in Destination Messages, 2155 this Data Item contains the IPv6 address of the destination. In 2156 either case, the Data Item also contains an indication of whether 2157 this is a new or existing address, or is a deletion of a previously 2158 known address. 2160 The IPv6 Address Data Item contains the following fields: 2162 0 1 2 3 2163 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 2164 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2165 | Data Item Type | Length | 2166 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2167 | Flags | IPv6 Address : 2168 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2169 : IPv6 Address : 2170 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2171 : IPv6 Address : 2172 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2173 : IPv6 Address : 2174 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2175 : IPv6 Address | 2176 +-+-+-+-+-+-+-+-+ 2178 Data Item Type: 9 2180 Length: 17 2182 Flags: Flags field, defined below. 2184 IPv6 Address: IPv6 Address of the destination or peer. 2186 The Flags field is defined as: 2188 0 1 2 3 4 5 6 7 2189 +-+-+-+-+-+-+-+-+ 2190 | Reserved |A| 2191 +-+-+-+-+-+-+-+-+ 2193 A: Add/Drop flag, indicating whether this is a new or existing 2194 address (1), or a withdrawal of an address (0). 2196 Reserved: MUST be zero. Reserved for future use. 2198 13.9.1. IPv6 Address Processing 2200 Processing of the IPv6 Address Data Item MUST be done within the 2201 context of the DLEP Peer session on which it is presented. 2203 The handling of erroneous or logically inconsistent conditions 2204 depends upon the type of the message that contains the data item: 2206 If the containing message is a Session Message, e.g., Session 2207 Initialization Message (Section 12.5), or Session Update Message 2208 (Section 12.7), the receiver of inconsistent information MUST issue a 2209 Session Termination Message (Section 12.9) containing a Status Data 2210 Item (Section 13.1) with status code set to 130 'Invalid Data', and 2211 transition to the Session Termination state. Examples of such 2212 conditions are: 2214 o An address Drop operation referencing an address that is not 2215 associated with the peer in the current session. 2217 o An address Add operation referencing an address that has already 2218 been added to the peer in the current session. 2220 If the containing message is a Destination Message, e.g., Destination 2221 Up Message (Section 12.11), or Destination Update Message 2222 (Section 12.17), the receiver of inconsistent information MAY issue 2223 the appropriate response message containing a Status Data Item, with 2224 status code set to 3 'Inconsistent Data', but MUST continue with 2225 session processing. Examples of such conditions are: 2227 o An address Add operation referencing an address that has already 2228 been added to the destination in the current session. 2230 o An address Add operation referencing an address that is associated 2231 with a different destination or the peer in the current session. 2233 o An address Add operation referencing an address that makes no 2234 sense, for example defined as not forwardable in [RFC6890]. 2236 o An address Drop operation referencing an address that is not 2237 associated with the destination in the current session. 2239 If no response message is appropriate, for example, the Destination 2240 Update Message, then the implementation MUST continue with session 2241 processing. 2243 Modems that do not track IPv6 addresses MUST silently ignore IPv6 2244 Address Data Items. 2246 13.10. IPv4 Attached Subnet 2248 The DLEP IPv4 Attached Subnet allows a device to declare that it has 2249 an IPv4 subnet (e.g., a stub network) attached, that it has become 2250 aware of an IPv4 subnet being present at a remote destination, or 2251 that it has become aware of the loss of a subnet at the remote 2252 destination. 2254 The DLEP IPv4 Attached Subnet Data Item contains the following 2255 fields: 2257 0 1 2 3 2258 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 2259 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2260 | Data Item Type | Length | 2261 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2262 | Flags | IPv4 Attached Subnet : 2263 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2264 : ...cont. |Prefix Length | 2265 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2267 Data Item Type: 10 2269 Length: 6 2271 Flags: Flags field, defined below. 2273 IPv4 Subnet: The IPv4 subnet reachable at the destination. 2275 Prefix Length: Length of the prefix (0-32) for the IPv4 subnet. A 2276 prefix length outside the specified range MUST be considered as 2277 invalid. 2279 The Flags field is defined as: 2281 0 1 2 3 4 5 6 7 2282 +-+-+-+-+-+-+-+-+ 2283 | Reserved |A| 2284 +-+-+-+-+-+-+-+-+ 2286 A: Add/Drop flag, indicating whether this is a new or existing subnet 2287 address (1), or a withdrawal of a subnet address (0). 2289 Reserved: MUST be zero. Reserved for future use. 2291 13.10.1. IPv4 Attached Subnet Processing 2293 Processing of the IPv4 Attached Subnet Data Item MUST be done within 2294 the context of the DLEP Peer session on which it is presented. 2296 If the containing message is a Session Message, e.g., Session 2297 Initialization Message (Section 12.5), or Session Update Message 2298 (Section 12.7), the receiver of inconsistent information MUST issue a 2299 Session Termination Message (Section 12.9) containing a Status Data 2300 Item (Section 13.1) with status code set to 130 'Invalid Data', and 2301 transition to the Session Termination state. Examples of such 2302 conditions are: 2304 o A subnet Drop operation referencing a subnet that is not 2305 associated with the peer in the current session. 2307 o A subnet Add operation referencing a subnet that has already been 2308 added to the peer in the current session. 2310 If the containing message is a Destination Message, e.g., Destination 2311 Up Message (Section 12.11), or Destination Update Message 2312 (Section 12.17), the receiver of inconsistent information MAY issue 2313 the appropriate response message containing a Status Data Item, with 2314 status code set to 3 'Inconsistent Data', but MUST continue with 2315 session processing. Examples of such conditions are: 2317 o A subnet Add operation referencing a subnet that has already been 2318 added to the destination in the current session. 2320 o A subnet Add operation referencing a subnet that is associated 2321 with a different destination in the current session. 2323 o An subnet Add operation referencing an subnet that makes no sense, 2324 for example defined as not forwardable in [RFC6890]. 2326 o A subnet Drop operation referencing a subnet that is not 2327 associated with the destination in the current session. 2329 If no response message is appropriate, for example, the Destination 2330 Update Message, then the implementation MUST continue with session 2331 processing. 2333 Modems that do not track IPv4 subnets MUST silently ignore IPv4 2334 Attached Subnet Data Items. 2336 13.11. IPv6 Attached Subnet 2338 The DLEP IPv6 Attached Subnet allows a device to declare that it has 2339 an IPv6 subnet (e.g., a stub network) attached, that it has become 2340 aware of an IPv6 subnet being present at a remote destination, or 2341 that it has become aware of the loss of a subnet at the remote 2342 destination. 2344 The DLEP IPv6 Attached Subnet Data Item contains the following 2345 fields: 2347 0 1 2 3 2348 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 2349 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2350 | Data Item Type | Length | 2351 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2352 | Flags | IPv6 Attached Subnet : 2353 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2354 : IPv6 Attached Subnet : 2355 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2356 : IPv6 Attached Subnet : 2357 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2358 : IPv6 Attached Subnet : 2359 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2360 : ...cont. | Prefix Len. | 2361 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2363 Data Item Type: 11 2365 Length: 18 2367 Flags: Flags field, defined below. 2369 IPv6 Attached Subnet: The IPv6 subnet reachable at the destination. 2371 Prefix Length: Length of the prefix (0-128) for the IPv6 subnet. A 2372 prefix length outside the specified range MUST be considered as 2373 invalid. 2375 The Flags field is defined as: 2377 0 1 2 3 4 5 6 7 2378 +-+-+-+-+-+-+-+-+ 2379 | Reserved |A| 2380 +-+-+-+-+-+-+-+-+ 2382 A: Add/Drop flag, indicating whether this is a new or existing subnet 2383 address (1), or a withdrawal of a subnet address (0). 2385 Reserved: MUST be zero. Reserved for future use. 2387 13.11.1. IPv6 Attached Subnet Processing 2389 Processing of the IPv6 Attached Subnet Data Item MUST be done within 2390 the context of the DLEP Peer session on which it is presented. 2392 If the containing message is a Session Message, e.g., Session 2393 Initialization Message (Section 12.5), or Session Update Message 2394 (Section 12.7), the receiver of inconsistent information MUST issue a 2395 Session Termination Message (Section 12.9) containing a Status Data 2396 Item (Section 13.1) with status code set to 130 'Invalid Data', and 2397 transition to the Session Termination state. Examples of such 2398 conditions are: 2400 o A subnet Drop operation referencing a subnet that is not 2401 associated with the peer in the current session. 2403 o A subnet Add operation referencing a subnet that has already been 2404 added to the peer in the current session. 2406 If the containing message is a Destination Message, e.g., Destination 2407 Up Message (Section 12.11), or Destination Update Message 2408 (Section 12.17), the receiver of inconsistent information MAY issue 2409 the appropriate response message containing a Status Data Item, with 2410 status code set to 3 'Inconsistent Data', but MUST continue with 2411 session processing. Examples of such conditions are: 2413 o A subnet Add operation referencing a subnet that has already been 2414 added to the destination in the current session. 2416 o A subnet Add operation referencing a subnet that is associated 2417 with a different destination in the current session. 2419 o An subnet Add operation referencing an subnet that makes no sense, 2420 for example defined as not forwardable in [RFC6890]. 2422 o A subnet Drop operation referencing a subnet that is not 2423 associated with the destination in the current session. 2425 If no response message is appropriate, for example, the Destination 2426 Update Message, then the implementation MUST continue with session 2427 processing. 2429 Modems that do not track IPv6 subnets MUST silently ignore IPv6 2430 Attached Subnet Data Items. 2432 13.12. Maximum Data Rate (Receive) 2434 The Maximum Data Rate (Receive) (MDRR) Data Item is used to indicate 2435 the maximum theoretical data rate, in bits per second, that can be 2436 achieved while receiving data on the link. 2438 The Maximum Data Rate (Receive) Data Item contains the following 2439 fields: 2441 0 1 2 3 2442 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 2443 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2444 | Data Item Type | Length | 2445 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2446 | MDRR (bps) : 2447 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2448 : MDRR (bps) | 2449 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2451 Data Item Type: 12 2453 Length: 8 2455 Maximum Data Rate (Receive): A 64-bit unsigned integer, representing 2456 the maximum theoretical data rate, in bits per second (bps), that 2457 can be achieved while receiving on the link. 2459 13.13. Maximum Data Rate (Transmit) 2461 The Maximum Data Rate (Transmit) (MDRT) Data Item is used to indicate 2462 the maximum theoretical data rate, in bits per second, that can be 2463 achieved while transmitting data on the link. 2465 The Maximum Data Rate (Transmit) Data Item contains the following 2466 fields: 2468 0 1 2 3 2469 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 2470 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2471 | Data Item Type | Length | 2472 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2473 | MDRT (bps) : 2474 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2475 : MDRT (bps) | 2476 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2478 Data Item Type: 13 2480 Length: 8 2482 Maximum Data Rate (Transmit): A 64-bit unsigned integer, 2483 representing the maximum theoretical data rate, in bits per second 2484 (bps), that can be achieved while transmitting on the link. 2486 13.14. Current Data Rate (Receive) 2488 The Current Data Rate (Receive) (CDRR) Data Item is used to indicate 2489 the rate at which the link is currently operating for receiving 2490 traffic. 2492 When used in the Link Characteristics Request Message 2493 (Section 12.18), Current Data Rate (Receive) represents the desired 2494 receive rate, in bits per second, on the link. 2496 The Current Data Rate (Receive) Data Item contains the following 2497 fields: 2499 0 1 2 3 2500 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 2501 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2502 | Data Item Type | Length | 2503 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2504 | CDRR (bps) : 2505 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2506 : CDRR (bps) | 2507 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2509 Data Item Type: 14 2511 Length: 8 2513 Current Data Rate (Receive): A 64-bit unsigned integer, representing 2514 the current data rate, in bits per second, that can currently be 2515 achieved while receiving traffic on the link. 2517 If there is no distinction between Current Data Rate (Receive) and 2518 Maximum Data Rate (Receive) (Section 13.12), Current Data Rate 2519 (Receive) MUST be set equal to the Maximum Data Rate (Receive). The 2520 Current Data Rate (Receive) MUST NOT exceed the Maximum Data Rate 2521 (Receive). 2523 13.15. Current Data Rate (Transmit) 2525 The Current Data Rate (Transmit) (CDRT) Data Item is used to indicate 2526 the rate at which the link is currently operating for transmitting 2527 traffic. 2529 When used in the Link Characteristics Request Message 2530 (Section 12.18), Current Data Rate (Transmit) represents the desired 2531 transmit rate, in bits per second, on the link. 2533 The Current Data Rate (Transmit) Data Item contains the following 2534 fields: 2536 0 1 2 3 2537 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 2538 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2539 | Data Item Type | Length | 2540 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2541 | CDRT (bps) : 2542 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2543 : CDRT (bps) | 2544 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2546 Data Item Type: 15 2548 Length: 8 2550 Current Data Rate (Transmit): A 64-bit unsigned integer, 2551 representing the current data rate, in bits per second, that can 2552 currently be achieved while transmitting traffic on the link. 2554 If there is no distinction between Current Data Rate (Transmit) and 2555 Maximum Data Rate (Transmit) (Section 13.13), Current Data Rate 2556 (Transmit) MUST be set equal to the Maximum Data Rate (Transmit). 2557 The Current Data Rate (Transmit) MUST NOT exceed the Maximum Data 2558 Rate (Transmit). 2560 13.16. Latency 2562 The Latency Data Item is used to indicate the amount of latency, in 2563 microseconds, on the link. 2565 The Latency value is reported as transmission delay. The calculation 2566 of latency is implementation dependent. For example, the latency may 2567 be a running average calculated from the internal queuing. 2569 The Latency Data Item contains the following fields: 2571 0 1 2 3 2572 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 2573 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2574 | Data Item Type | Length | 2575 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2576 | Latency : 2577 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2578 : Latency | 2579 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2580 Data Item Type: 16 2582 Length: 8 2584 Latency: A 64-bit unsigned integer, representing the transmission 2585 delay, in microseconds, that a packet encounters as it is 2586 transmitted over the link. 2588 13.17. Resources 2590 The Resources (RES) Data Item is used to indicate the amount of 2591 finite resources available for data transmission and reception at the 2592 destination as a percentage, with 0 meaning 'no resources remaining', 2593 and 100 meaning 'a full supply', assuming that when Resources reaches 2594 0 data transmission and/or reception will cease. 2596 An example of such resources might be battery life, but could equally 2597 be magic beans. The list of resources that might be considered is 2598 beyond the scope of this document, and is left to implementations to 2599 decide. 2601 This Data Item is designed to be used as an indication of some 2602 capability of the modem and/or router at the destination. 2604 The Resources Data Item contains the following fields: 2606 0 1 2 3 2607 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 2608 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2609 | Data Item Type | Length | 2610 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2611 | RES | 2612 +-+-+-+-+-+-+-+-+ 2614 Data Item Type: 17 2616 Length: 1 2618 Resources: An 8-bit unsigned integer percentage, 0-100, representing 2619 the amount of resources available. Any value greater than 100 2620 MUST be considered as invalid. 2622 If a device cannot calculate Resources, this Data Item MUST NOT be 2623 issued. 2625 13.18. Relative Link Quality (Receive) 2627 The Relative Link Quality (Receive) (RLQR) Data Item is used to 2628 indicate the quality of the link to a destination for receiving 2629 traffic, with 0 meaning 'worst quality', and 100 meaning 'best 2630 quality'. 2632 Quality in this context is defined as an indication of the stability 2633 of a link for reception; a destination with high Relative Link 2634 Quality (Receive) is expected to have generally stable DLEP metrics, 2635 and the metrics of a destination with low Relative Link Quality 2636 (Receive) can be expected to rapidly fluctuate over a wide range. 2638 The Relative Link Quality (Receive) Data Item contains the following 2639 fields: 2641 0 1 2 3 2642 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 2643 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2644 | Data Item Type | Length | 2645 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2646 | RLQR | 2647 +-+-+-+-+-+-+-+-+ 2649 Data Item Type: 18 2651 Length: 1 2653 Relative Link Quality (Receive): A non-dimensional unsigned 8-bit 2654 integer, 0-100, representing relative quality of the link for 2655 receiving traffic. Any value greater than 100 MUST be considered 2656 as invalid. 2658 If a device cannot calculate the Relative Link Quality (Receive), 2659 this Data Item MUST NOT be issued. 2661 13.19. Relative Link Quality (Transmit) 2663 The Relative Link Quality (Transmit) (RLQT) Data Item is used to 2664 indicate the quality of the link to a destination for transmitting 2665 traffic, with 0 meaning 'worst quality', and 100 meaning 'best 2666 quality'. 2668 Quality in this context is defined as an indication of the stability 2669 of a link for transmission; a destination with high Relative Link 2670 Quality (Transmit) is expected to have generally stable DLEP metrics, 2671 and the metrics of a destination with low Relative Link Quality 2672 (Transmit) can be expected to rapidly fluctuate over a wide range. 2674 The Relative Link Quality (Transmit) Data Item contains the following 2675 fields: 2677 0 1 2 3 2678 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 2679 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2680 | Data Item Type | Length | 2681 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2682 | RLQT | 2683 +-+-+-+-+-+-+-+-+ 2685 Data Item Type: 19 2687 Length: 1 2689 Relative Link Quality (Transmit): A non-dimensional unsigned 8-bit 2690 integer, 0-100, representing relative quality of the link for 2691 transmitting traffic. Any value greater than 100 MUST be 2692 considered as invalid. 2694 If a device cannot calculate the Relative Link Quality (Transmit), 2695 this Data Item MUST NOT be issued. 2697 13.20. Maximum Transmission Unit (MTU) 2699 The Maximum Transmission Unit (MTU) Data Item is used to indicate the 2700 maximum size, in octets, of an IP packet that can be transmitted 2701 without fragmentation, including headers, but excluding any lower 2702 layer headers. 2704 The Maximum Transmission Unit Data Item contains the following 2705 fields: 2707 0 1 2 3 2708 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 2709 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2710 | Data Item Type | Length | 2711 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2712 | MTU | 2713 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2715 Data Item Type: 20 2717 Length: 2 2719 Maximum Transmission Unit: The maximum size, in octets, of an IP 2720 packet that can be transmitted without fragmentation, including 2721 headers, but excluding any lower layer headers. 2723 If a device cannot calculate the Maximum Transmission Unit, this Data 2724 Item MUST NOT be issued. 2726 14. Security Considerations 2728 The potential security concerns when using DLEP are: 2730 1. An attacker might pretend to be a DLEP participant, either at 2731 DLEP session initialization, or by injection of DLEP Messages 2732 once a session has been established. 2734 2. DLEP Data Items could be altered by an attacker, causing the 2735 receiving implementation to inappropriately alter its information 2736 base concerning network status. 2738 3. An attacker could join an unsecured radio network and inject 2739 over-the-air signals that maliciously influence the information 2740 reported by a DLEP modem, causing a router to forward traffic to 2741 an inappropriate destination. 2743 The implications of attacks on DLEP peers are directly proportional 2744 to the extent to which DLEP data is used within the control plane. 2745 While the use of DLEP data in other control plane components is out 2746 of scope for this document, as an example, if DLEP statistics are 2747 incorporated into route cost calculations, adversaries masquerading 2748 as a DLEP peer, and injecting malicious data via DLEP, could cause 2749 suboptimal route selection, adversely impacting network performance. 2750 Similar issues can arise if DLEP data is used as an input to policing 2751 algorithms - injection of malicious data via DLEP can cause those 2752 policing algorithms to make incorrect decisions, degrading network 2753 throughput. 2755 For these reasons, security of the DLEP transport must be considered 2756 at both the transport layer, and at Layer 2. 2758 At the transport layer, when TLS is in use, each peer SHOULD check 2759 the validity of credentials presented by the other peer during TLS 2760 session establishment. Implementations following the "dedicated 2761 deployments" model attempting to use TLS MAY need to consider use of 2762 pre-shared keys for credentials, and provide specialized techniques 2763 for peer identity validation, and MAY refer to [RFC5487] for 2764 additional details. Implementations following the "networked 2765 deployment" model described in Implementation Scenarios SHOULD refer 2766 to [RFC7525] for additional details. 2768 At layer 2 - since DLEP is restricted to operation over a single 2769 (possibly logical) hop, implementations SHOULD also secure the Layer 2770 2 link. Examples of technologies that can be deployed to secure the 2771 Layer 2 link include [IEEE-802.1AE] and [IEEE-802.1X]. 2773 By examining the Secured Medium flag in the Peer Type Data Item 2774 (Section 13.4), a router can decide if it is able to trust the 2775 information supplied via a DLEP modem. If this is not the case, then 2776 the router SHOULD consider restricting the size of attached subnets, 2777 announced in IPv4 Attached Subnet Data Items (Section 13.10) and/or 2778 IPv6 Attached Subnet Data Items (Section 13.11), that are considered 2779 for route selection. 2781 To avoid potential denial of service attack, it is RECOMMENDED that 2782 implementations using the Peer Discovery mechanism maintain an 2783 information base of hosts that persistently fail Session 2784 Initialization having provided an acceptable Peer Discovery Signal, 2785 and ignore subsequent Peer Discovery Signals from such hosts. 2787 This specification does not address security of the data plane, as it 2788 (the data plane) is not affected, and standard security procedures 2789 can be employed. 2791 15. IANA Considerations 2793 15.1. Registrations 2795 Upon approval of this document, IANA is requested to create a new 2796 protocol registry for Dynamic Link Exchange Protocol (DLEP). The 2797 remainder of this section requests the creation of new DLEP specific 2798 registries. 2800 15.2. Signal Type Registration 2802 Upon approval of this document, IANA is requested to create a new 2803 DLEP registry, named "Signal Type Values". 2805 The following table provides initial registry values and the 2806 [RFC5226] defined policies that should apply to the registry: 2808 +--------------+-------------------------+ 2809 | Type Code | Description/Policy | 2810 +--------------+-------------------------+ 2811 | 0 | Reserved | 2812 | 1 | Peer Discovery Signal | 2813 | 2 | Peer Offer Signal | 2814 | 3-65519 | Specification Required | 2815 | 65520-65534 | Private Use | 2816 | 65535 | Reserved | 2817 +--------------+-------------------------+ 2819 15.3. Message Type Registration 2821 Upon approval of this document, IANA is requested to create a new 2822 DLEP registry, named "Message Type Values". 2824 The following table provides initial registry values and the 2825 [RFC5226] defined policies that should apply to the registry: 2827 +--------------+------------------------------------------+ 2828 | Type Code | Description/Policy | 2829 +--------------+------------------------------------------+ 2830 | 0 | Reserved | 2831 | 1 | Session Initialization Message | 2832 | 2 | Session Initialization Response Message | 2833 | 3 | Session Update Message | 2834 | 4 | Session Update Response Message | 2835 | 5 | Session Termination Message | 2836 | 6 | Session Termination Response Message | 2837 | 7 | Destination Up Message | 2838 | 8 | Destination Up Response Message | 2839 | 9 | Destination Announce Message | 2840 | 10 | Destination Announce Response Message | 2841 | 11 | Destination Down Message | 2842 | 12 | Destination Down Response Message | 2843 | 13 | Destination Update Message | 2844 | 14 | Link Characteristics Request Message | 2845 | 15 | Link Characteristics Response Message | 2846 | 16 | Heartbeat Message | 2847 | 17-65519 | Specification Required | 2848 | 65520-65534 | Private Use | 2849 | 65535 | Reserved | 2850 +--------------+------------------------------------------+ 2852 15.4. DLEP Data Item Registrations 2854 Upon approval of this document, IANA is requested to create a new 2855 DLEP registry, named "Data Item Type Values". 2857 The following table provides initial registry values and the 2858 [RFC5226] defined policies that should apply to the registry: 2860 +-------------------+------------------------------------------+ 2861 | Type Code | Description/Policy | 2862 +-------------------+------------------------------------------+ 2863 | 0 | Reserved | 2864 | 1 | Status | 2865 | 2 | IPv4 Connection Point | 2866 | 3 | IPv6 Connection Point | 2867 | 4 | Peer Type | 2868 | 5 | Heartbeat Interval | 2869 | 6 | Extensions Supported | 2870 | 7 | MAC Address | 2871 | 8 | IPv4 Address | 2872 | 9 | IPv6 Address | 2873 | 10 | IPv4 Attached Subnet | 2874 | 11 | IPv6 Attached Subnet | 2875 | 12 | Maximum Data Rate (Receive) (MDRR) | 2876 | 13 | Maximum Data Rate (Transmit) (MDRT) | 2877 | 14 | Current Data Rate (Receive) (CDRR) | 2878 | 15 | Current Data Rate (Transmit) (CDRT) | 2879 | 16 | Latency | 2880 | 17 | Resources (RES) | 2881 | 18 | Relative Link Quality (Receive) (RLQR) | 2882 | 19 | Relative Link Quality (Transmit) (RLQT) | 2883 | 20 | Maximum Transmission Unit (MTU) | 2884 | 21-65407 | Specification Required | 2885 | 65408-65534 | Private Use | 2886 | 65535 | Reserved | 2887 +-------------------+------------------------------------------+ 2889 15.5. DLEP Status Code Registrations 2891 Upon approval of this document, IANA is requested to create a new 2892 DLEP registry, named "Status Code Values". 2894 The following table provides initial registry values and the 2895 [RFC5226] defined policies that should apply to the registry: 2897 +--------------+---------------+-------------------------+ 2898 | Status Code | Failure Mode | Description/Policy | 2899 +--------------+---------------+-------------------------+ 2900 | 0 | Continue | Success | 2901 | 1 | Continue | Not Interested | 2902 | 2 | Continue | Request Denied | 2903 | 3 | Continue | Inconsistent Data | 2904 | 4-111 | Continue | Specification Required | 2905 | 112-127 | Continue | Private Use | 2906 | 128 | Terminate | Unknown Message | 2907 | 129 | Terminate | Unexpected Message | 2908 | 130 | Terminate | Invalid Data | 2909 | 131 | Terminate | Invalid Destination | 2910 | 132 | Terminate | Timed Out | 2911 | 133-239 | Terminate | Specification Required | 2912 | 240-254 | Terminate | Private Use | 2913 | 255 | Terminate | Reserved | 2914 +--------------+---------------+-------------------------+ 2916 15.6. DLEP Extensions Registrations 2918 Upon approval of this document, IANA is requested to create a new 2919 DLEP registry, named "Extension Type Values". 2921 The following table provides initial registry values and the 2922 [RFC5226] defined policies that should apply to the registry: 2924 +--------------+---------------------------+ 2925 | Code | Description/Policy | 2926 +--------------+---------------------------+ 2927 | 0 | Reserved | 2928 | 1-65519 | Specification Required | 2929 | 65520-65534 | Private Use | 2930 | 65535 | Reserved | 2931 +--------------+---------------------------+ 2933 Table 3: DLEP Extension types 2935 15.7. DLEP IPv4 Connection Point Flags 2937 Upon approval of this document, IANA is requested to create a new 2938 DLEP registry, named "IPv4 Connection Point Flags". 2940 The following table provides initial registry values and the 2941 [RFC5226] defined policies that should apply to the registry: 2943 +------------+------------------------------------+ 2944 | Bit | Description/Policy | 2945 +------------+------------------------------------+ 2946 | 0-6 | Unassigned/Specification Required | 2947 | 7 | Use TLS [RFC5246] indicator | 2948 +------------+------------------------------------+ 2950 15.8. DLEP IPv6 Connection Point Flags 2952 Upon approval of this document, IANA is requested to create a new 2953 DLEP registry, named "IPv6 Connection Point Flags". 2955 The following table provides initial registry values and the 2956 [RFC5226] defined policies that should apply to the registry: 2958 +------------+------------------------------------+ 2959 | Bit | Description/Policy | 2960 +------------+------------------------------------+ 2961 | 0-6 | Unassigned/Specification Required | 2962 | 7 | Use TLS [RFC5246] indicator | 2963 +------------+------------------------------------+ 2965 15.9. DLEP Peer Type Flag 2967 Upon approval of this document, IANA is requested to create a new 2968 DLEP registry, named "Peer Type Flags". 2970 The following table provides initial registry values and the 2971 [RFC5226] defined policies that should apply to the registry: 2973 +------------+------------------------------------+ 2974 | Bit | Description/Policy | 2975 +------------+------------------------------------+ 2976 | 0-6 | Unassigned/Specification Required | 2977 | 7 | Secured Medium indicator | 2978 +------------+------------------------------------+ 2980 15.10. DLEP IPv4 Address Flag 2982 Upon approval of this document, IANA is requested to create a new 2983 DLEP registry, named "IPv4 Address Flags". 2985 The following table provides initial registry values and the 2986 [RFC5226] defined policies that should apply to the registry: 2988 +------------+------------------------------------+ 2989 | Bit | Description/Policy | 2990 +------------+------------------------------------+ 2991 | 0-6 | Unassigned/Specification Required | 2992 | 7 | Add/Drop indicator | 2993 +------------+------------------------------------+ 2995 15.11. DLEP IPv6 Address Flag 2997 Upon approval of this document, IANA is requested to create a new 2998 DLEP registry, named "IPv6 Address Flags". 3000 The following table provides initial registry values and the 3001 [RFC5226] defined policies that should apply to the registry: 3003 +------------+------------------------------------+ 3004 | Bit | Description/Policy | 3005 +------------+------------------------------------+ 3006 | 0-6 | Unassigned/Specification Required | 3007 | 7 | Add/Drop indicator | 3008 +------------+------------------------------------+ 3010 15.12. DLEP IPv4 Attached Subnet Flag 3012 Upon approval of this document, IANA is requested to create a new 3013 DLEP registry, named "IPv4 Attached Subnet Flags". 3015 The following table provides initial registry values and the 3016 [RFC5226] defined policies that should apply to the registry: 3018 +------------+------------------------------------+ 3019 | Bit | Description/Policy | 3020 +------------+------------------------------------+ 3021 | 0-6 | Unassigned/Specification Required | 3022 | 7 | Add/Drop indicator | 3023 +------------+------------------------------------+ 3025 15.13. DLEP IPv6 Attached Subnet Flag 3027 Upon approval of this document, IANA is requested to create a new 3028 DLEP registry, named "IPv6 Attached Subnet Flags". 3030 The following table provides initial registry values and the 3031 [RFC5226] defined policies that should apply to the registry: 3033 +------------+------------------------------------+ 3034 | Bit | Description/Policy | 3035 +------------+------------------------------------+ 3036 | 0-6 | Unassigned/Specification Required | 3037 | 7 | Add/Drop indicator | 3038 +------------+------------------------------------+ 3040 15.14. DLEP Well-known Port 3042 Upon approval of this document, IANA is requested to assign a single 3043 value in the "Service Name and Transport Protocol Port Number 3044 Registry" found at https://www.iana.org/assignments/service-names- 3045 port-numbers/service-names-port-numbers.xhtml for use by "DLEP", as 3046 defined in this document. This assignment should be valid for TCP 3047 and UDP. 3049 15.15. DLEP IPv4 Link-local Multicast Address 3051 Upon approval of this document, IANA is requested to assign an IPv4 3052 multicast address registry found at http://www.iana.org/assignments/ 3053 multicast-addresses for use as the "IPv4 DLEP Discovery Address". 3055 15.16. DLEP IPv6 Link-local Multicast Address 3057 Upon approval of this document, IANA is requested to assign an IPv6 3058 multicast address registry found at http://www.iana.org/assignments/ 3059 multicast-addresses for use as the "IPv6 DLEP Discovery Address". 3061 16. Acknowledgments 3063 We would like to acknowledge and thank the members of the DLEP design 3064 team, who have provided invaluable insight. The members of the 3065 design team are: Teco Boot, Bow-Nan Cheng, John Dowdell, and Henning 3066 Rogge. 3068 We would also like to acknowledge the influence and contributions of 3069 Greg Harrison, Chris Olsen, Martin Duke, Subir Das, Jaewon Kang, 3070 Vikram Kaul, Nelson Powell, Lou Berger, and Victoria Pritchard. 3072 17. References 3074 17.1. Normative References 3076 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 3077 Requirement Levels", BCP 14, RFC 2119, 3078 DOI 10.17487/RFC2119, March 1997, 3079 . 3081 [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO 3082 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November 3083 2003, . 3085 [RFC5082] Gill, V., Heasley, J., Meyer, D., Savola, P., Ed., and C. 3086 Pignataro, "The Generalized TTL Security Mechanism 3087 (GTSM)", RFC 5082, DOI 10.17487/RFC5082, October 2007, 3088 . 3090 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 3091 (TLS) Protocol Version 1.2", RFC 5246, 3092 DOI 10.17487/RFC5246, August 2008, 3093 . 3095 17.2. Informative References 3097 [IEEE-802.1AE] 3098 "IEEE Standards for Local and Metropolitan Area Networks: 3099 Media Access Control (MAC) Security", 3100 DOI 10.1109/IEEESTD.2006.245590, August 2006. 3102 [IEEE-802.1X] 3103 "IEEE Standards for Local and Metropolitan Area Networks: 3104 Port based Network Access Control", 3105 DOI 10.1109/IEEESTD.2010.5409813, February 2010. 3107 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 3108 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 3109 DOI 10.17487/RFC5226, May 2008, 3110 . 3112 [RFC5487] Badra, M., "Pre-Shared Key Cipher Suites for TLS with SHA- 3113 256/384 and AES Galois Counter Mode", RFC 5487, 3114 DOI 10.17487/RFC5487, March 2009, 3115 . 3117 [RFC5578] Berry, B., Ed., Ratliff, S., Paradise, E., Kaiser, T., and 3118 M. Adams, "PPP over Ethernet (PPPoE) Extensions for Credit 3119 Flow and Link Metrics", RFC 5578, DOI 10.17487/RFC5578, 3120 February 2010, . 3122 [RFC6890] Cotton, M., Vegoda, L., Bonica, R., Ed., and B. Haberman, 3123 "Special-Purpose IP Address Registries", BCP 153, 3124 RFC 6890, DOI 10.17487/RFC6890, April 2013, 3125 . 3127 [RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre, 3128 "Recommendations for Secure Use of Transport Layer 3129 Security (TLS) and Datagram Transport Layer Security 3130 (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May 3131 2015, . 3133 Appendix A. Discovery Signal Flows 3135 Router Modem Signal Description 3136 ======================================================================== 3138 | Router initiates discovery, starts 3139 | a timer, send Peer Discovery 3140 |-------Peer Discovery---->X Signal. 3142 ~ ~ ~ ~ ~ ~ ~ Router discovery timer expires 3143 without receiving Peer Offer. 3145 | Router sends another Peer 3146 |-------Peer Discovery---------->| Discovery Signal. 3147 | 3148 | Modem receives Peer Discovery 3149 | Signal. 3150 | 3151 | Modem sends Peer Offer with 3152 |<--------Peer Offer-------------| Connection Point information. 3153 : 3154 : Router MAY cancel discovery timer 3155 : and stop sending Peer Discovery 3156 : Signals. 3158 Appendix B. Peer Level Message Flows 3160 B.1. Session Initialization 3161 Router Modem Message Description 3162 ======================================================================== 3164 | Router connects to discovered or 3165 | pre-configured Modem Connection 3166 |--TCP connection established---> Point. 3167 | 3168 | Router sends Session 3169 |----Session Initialization----->| Initialization Message. 3170 | 3171 | Modem receives Session 3172 | Initialization Message. 3173 | 3174 | Modem sends Session Initialization 3175 |<--Session Initialization Resp.-| Response, with Success Status Data 3176 | | Item. 3177 | | 3178 |<<============================>>| Session established. Heartbeats 3179 : : begin. 3181 B.2. Session Initialization - Refused 3183 Router Modem Message Description 3184 ======================================================================== 3186 | Router connects to discovered or 3187 | pre-configured Modem Connection 3188 |--TCP connection established---> Point. 3189 | 3190 | Router sends Session 3191 |-----Session Initialization---->| Initialization Message. 3192 | 3193 | Modem receives Session 3194 | Initialization Message, and will 3195 | not support the advertised 3196 | extensions. 3197 | 3198 | Modem sends Session Initialization 3199 | Response, with 'Request Denied' 3200 |<-Session Initialization Resp.--| Status Data Item. 3201 | 3202 | 3203 | Router receives negative Session 3204 | Initialization Response, closes 3205 ||---------TCP close------------|| TCP connection. 3207 B.3. Router Changes IP Addresses 3209 Router Modem Message Description 3210 ======================================================================== 3212 | Router sends Session Update 3213 |-------Session Update---------->| Message to announce change of IP 3214 | address 3215 | 3216 | Modem receives Session Update 3217 | Message and updates internal 3218 | state. 3219 | 3220 |<----Session Update Response----| Modem sends Session Update 3221 | Response. 3223 B.4. Modem Changes Session-wide Metrics 3225 Router Modem Message Description 3226 ======================================================================== 3228 | Modem sends Session Update Message 3229 | to announce change of modem-wide 3230 |<--------Session Update---------| metrics 3231 | 3232 | Router receives Session Update 3233 | Message and updates internal 3234 | state. 3235 | 3236 |----Session Update Response---->| Router sends Session Update 3237 | Response. 3239 B.5. Router Terminates Session 3240 Router Modem Message Description 3241 ======================================================================== 3243 | Router sends Session Termination 3244 |------Session Termination------>| Message with Status Data Item. 3245 | | 3246 |-------TCP shutdown (send)---> | Router stops sending Messages. 3247 | 3248 | Modem receives Session 3249 | Termination, stops counting 3250 | received heartbeats and stops 3251 | sending heartbeats. 3252 | 3253 | Modem sends Session Termination 3254 |<---Session Termination Resp.---| Response with Status 'Success'. 3255 | 3256 | Modem stops sending Messages. 3257 | 3258 ||---------TCP close------------|| Session terminated. 3260 B.6. Modem Terminates Session 3262 Router Modem Message Description 3263 ======================================================================== 3265 | Modem sends Session Termination 3266 |<----Session Termination--------| Message with Status Data Item. 3267 | 3268 | Modem stops sending Messages. 3269 | 3270 | Router receives Session 3271 | Termination, stops counting 3272 | received heartbeats and stops 3273 | sending heartbeats. 3274 | 3275 | Router sends Session Termination 3276 |---Session Termination Resp.--->| Response with Status 'Success'. 3277 | 3278 | Router stops sending Messages. 3279 | 3280 ||---------TCP close------------|| Session terminated. 3282 B.7. Session Heartbeats 3283 Router Modem Message Description 3284 ======================================================================== 3286 |----------Heartbeat------------>| Router sends heartbeat Message 3287 | 3288 | Modem resets heartbeats missed 3289 | counter. 3291 ~ ~ ~ ~ ~ ~ ~ 3293 |---------[Any Message]--------->| When the Modem receives any 3294 | Message from the Router. 3295 | 3296 | Modem resets heartbeats missed 3297 | counter. 3299 ~ ~ ~ ~ ~ ~ ~ 3301 |<---------Heartbeat-------------| Modem sends heartbeat Message 3302 | 3303 | Router resets heartbeats missed 3304 | counter. 3306 ~ ~ ~ ~ ~ ~ ~ 3308 |<--------[Any Message]----------| When the Router receives any 3309 | Message from the Modem. 3310 | 3311 | Modem resets heartbeats missed 3312 | counter. 3314 B.8. Router Detects a Heartbeat timeout 3316 Router Modem Message Description 3317 ======================================================================== 3319 X<----------------------| Router misses a heartbeat 3321 | X<----------------------| Router misses too many heartbeats 3322 | 3323 | 3324 |------Session Termination------>| Router sends Session Termination 3325 | Message with 'Timeout' Status 3326 | Data Item. 3327 : 3328 : Termination proceeds... 3330 B.9. Modem Detects a Heartbeat timeout 3332 Router Modem Message Description 3333 ======================================================================== 3335 |---------------------->X Modem misses a heartbeat 3337 |---------------------->X | Modem misses too many heartbeats 3338 | 3339 | 3340 |<-----Session Termination-------| Modem sends Session Termination 3341 | Message with 'Timeout' Status 3342 | Data Item. 3343 : 3344 : Termination proceeds... 3346 Appendix C. Destination Specific Message Flows 3348 C.1. Common Destination Notification 3349 Router Modem Message Description 3350 ======================================================================== 3352 | Modem detects a new logical 3353 | destination is reachable, and 3354 |<-------Destination Up----------| sends Destination Up Message. 3355 | 3356 |------Destination Up Resp.----->| Router sends Destination Up 3357 | Response. 3359 ~ ~ ~ ~ ~ ~ ~ 3360 | Modem detects change in logical 3361 | destination metrics, and sends 3362 |<-------Destination Update------| Destination Update Message. 3364 ~ ~ ~ ~ ~ ~ ~ 3365 | Modem detects change in logical 3366 | destination metrics, and sends 3367 |<-------Destination Update------| Destination Update Message. 3369 ~ ~ ~ ~ ~ ~ ~ 3370 | Modem detects logical destination 3371 | is no longer reachable, and sends 3372 |<-------Destination Down--------| Destination Down Message. 3373 | 3374 | Router receives Destination Down, 3375 | updates internal state, and sends 3376 |------Destination Down Resp.--->| Destination Down Response Message. 3378 C.2. Multicast Destination Notification 3379 Router Modem Message Description 3380 ======================================================================== 3382 | Router detects a new multicast 3383 | destination is in use, and sends 3384 |-----Destination Announce------>| Destination Announce Message. 3385 | 3386 | Modem updates internal state to 3387 | monitor multicast destination, and 3388 |<-----Dest. Announce Resp.------| sends Destination Announce 3389 Response. 3391 ~ ~ ~ ~ ~ ~ ~ 3392 | Modem detects change in multicast 3393 | destination metrics, and sends 3394 |<-------Destination Update------| Destination Update Message. 3396 ~ ~ ~ ~ ~ ~ ~ 3397 | Modem detects change in multicast 3398 | destination metrics, and sends 3399 |<-------Destination Update------| Destination Update Message. 3401 ~ ~ ~ ~ ~ ~ ~ 3402 | Router detects multicast 3403 | destination is no longer in use, 3404 |--------Destination Down------->| and sends Destination Down 3405 | Message. 3406 | 3407 | Modem receives Destination Down, 3408 | updates internal state, and sends 3409 |<-----Destination Down Resp.----| Destination Down Response Message. 3411 C.3. Link Characteristics Request 3412 Router Modem Message Description 3413 ======================================================================== 3415 Destination has already been 3416 ~ ~ ~ ~ ~ ~ ~ announced by either peer. 3418 | Router requires different 3419 | Characteristics for the 3420 | destination, and sends Link 3421 |--Link Characteristics Request->| Characteristics Request Message. 3422 | 3423 | Modem attempts to adjust link 3424 | properties to meet the received 3425 | request, and sends a Link 3426 | Characteristics Response 3427 |<---Link Characteristics Resp.--| Message with the new values. 3429 Authors' Addresses 3431 Stan Ratliff 3432 VT iDirect 3433 13861 Sunrise Valley Drive, Suite 300 3434 Herndon, VA 20171 3435 USA 3437 Email: sratliff@idirect.net 3439 Shawn Jury 3440 Cisco Systems 3441 170 West Tasman Drive 3442 San Jose, CA 95134 3443 USA 3445 Email: sjury@cisco.com 3447 Darryl Satterwhite 3448 Broadcom 3450 Email: dsatterw@broadcom.com 3451 Rick Taylor 3452 Airbus Defence & Space 3453 Quadrant House 3454 Celtic Springs 3455 Coedkernew 3456 Newport NP10 8FZ 3457 UK 3459 Email: rick.taylor@airbus.com 3461 Bo Berry