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Medium o...' -- The document date (October 16, 2015) is 2409 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Unused Reference: 'RFC5578' is defined on line 2536, but no explicit reference was found in the text == Outdated reference: A later version (-07) exists of draft-ietf-manet-credit-window-00 -- Obsolete informational reference (is this intentional?): RFC 5246 (Obsoleted by RFC 8446) Summary: 1 error (**), 0 flaws (~~), 5 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 Mobile Ad hoc Networks Working Group S. Ratliff 2 Internet-Draft VT iDirect 3 Intended status: Standards Track B. Berry 4 Expires: April 17, 2016 5 S. Jury 6 Cisco Systems 7 D. Satterwhite 8 Broadcom 9 R. Taylor 10 Airbus Defence & Space 11 October 16, 2015 13 Dynamic Link Exchange Protocol (DLEP) 14 draft-ietf-manet-dlep-17 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. A bidirectional, event- 25 driven communication channel between the router and the modem is 26 necessary. 28 Status of This Memo 30 This Internet-Draft is submitted in full conformance with the 31 provisions of BCP 78 and BCP 79. 33 Internet-Drafts are working documents of the Internet Engineering 34 Task Force (IETF). Note that other groups may also distribute 35 working documents as Internet-Drafts. The list of current Internet- 36 Drafts is at http://datatracker.ietf.org/drafts/current/. 38 Internet-Drafts are draft documents valid for a maximum of six months 39 and may be updated, replaced, or obsoleted by other documents at any 40 time. It is inappropriate to use Internet-Drafts as reference 41 material or to cite them other than as "work in progress." 43 This Internet-Draft will expire on April 17, 2016. 45 Copyright Notice 47 Copyright (c) 2015 IETF Trust and the persons identified as the 48 document authors. All rights reserved. 50 This document is subject to BCP 78 and the IETF Trust's Legal 51 Provisions Relating to IETF Documents 52 (http://trustee.ietf.org/license-info) in effect on the date of 53 publication of this document. Please review these documents 54 carefully, as they describe your rights and restrictions with respect 55 to this document. Code Components extracted from this document must 56 include Simplified BSD License text as described in Section 4.e of 57 the Trust Legal Provisions and are provided without warranty as 58 described in the Simplified BSD License. 60 Table of Contents 62 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 63 1.1. Protocol Overview . . . . . . . . . . . . . . . . . . . . 7 64 1.2. Requirements . . . . . . . . . . . . . . . . . . . . . . 8 65 2. Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 8 66 3. Metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 67 3.1. Mandatory Metrics . . . . . . . . . . . . . . . . . . . . 9 68 4. DLEP Signal and Message Processing . . . . . . . . . . . . . 10 69 4.1. Transaction Model . . . . . . . . . . . . . . . . . . . . 11 70 5. DLEP Session Flow . . . . . . . . . . . . . . . . . . . . . . 11 71 5.1. Peer Discovery State . . . . . . . . . . . . . . . . . . 12 72 5.2. Session Initialization State . . . . . . . . . . . . . . 13 73 5.3. In-Session State . . . . . . . . . . . . . . . . . . . . 14 74 5.3.1. Heartbeats . . . . . . . . . . . . . . . . . . . . . 15 75 5.4. Session Termination State . . . . . . . . . . . . . . . . 15 76 6. Extensions . . . . . . . . . . . . . . . . . . . . . . . . . 16 77 6.1. Experiments . . . . . . . . . . . . . . . . . . . . . . . 17 78 7. Scalability . . . . . . . . . . . . . . . . . . . . . . . . . 17 79 8. DLEP Signal and Message Structure . . . . . . . . . . . . . . 17 80 8.1. DLEP Signal Header . . . . . . . . . . . . . . . . . . . 18 81 8.2. DLEP Message Header . . . . . . . . . . . . . . . . . . . 19 82 8.3. DLEP Generic Data Item . . . . . . . . . . . . . . . . . 19 83 9. DLEP Signals and Messages . . . . . . . . . . . . . . . . . . 20 84 9.1. Peer Discovery Signal . . . . . . . . . . . . . . . . . . 21 85 9.2. Peer Offer Signal . . . . . . . . . . . . . . . . . . . . 22 86 9.3. Session Initialization Message . . . . . . . . . . . . . 22 87 9.4. Session Initialization Response Message . . . . . . . . . 23 88 9.5. Session Update Message . . . . . . . . . . . . . . . . . 25 89 9.6. Session Update Response Message . . . . . . . . . . . . . 26 90 9.7. Session Termination Message . . . . . . . . . . . . . . . 26 91 9.8. Session Termination Response Message . . . . . . . . . . 27 92 9.9. Destination Up Message . . . . . . . . . . . . . . . . . 27 93 9.10. Destination Up Response Message . . . . . . . . . . . . . 28 94 9.11. Destination Down Message . . . . . . . . . . . . . . . . 29 95 9.12. Destination Down Response Message . . . . . . . . . . . . 29 96 9.13. Destination Update Message . . . . . . . . . . . . . . . 30 97 9.14. Heartbeat Message . . . . . . . . . . . . . . . . . . . . 31 98 9.15. Link Characteristics Request Message . . . . . . . . . . 31 99 9.16. Link Characteristics Response Message . . . . . . . . . . 32 100 10. DLEP Data Items . . . . . . . . . . . . . . . . . . . . . . . 33 101 10.1. Status . . . . . . . . . . . . . . . . . . . . . . . . . 34 102 10.2. IPv4 Connection Point . . . . . . . . . . . . . . . . . 37 103 10.3. IPv6 Connection Point . . . . . . . . . . . . . . . . . 38 104 10.4. Peer Type . . . . . . . . . . . . . . . . . . . . . . . 39 105 10.5. Heartbeat Interval . . . . . . . . . . . . . . . . . . . 40 106 10.6. Extensions Supported . . . . . . . . . . . . . . . . . . 40 107 10.7. MAC Address . . . . . . . . . . . . . . . . . . . . . . 41 108 10.8. IPv4 Address . . . . . . . . . . . . . . . . . . . . . . 42 109 10.9. IPv6 Address . . . . . . . . . . . . . . . . . . . . . . 43 110 10.10. IPv4 Attached Subnet . . . . . . . . . . . . . . . . . . 44 111 10.11. IPv6 Attached Subnet . . . . . . . . . . . . . . . . . . 45 112 10.12. Maximum Data Rate (Receive) . . . . . . . . . . . . . . 46 113 10.13. Maximum Data Rate (Transmit) . . . . . . . . . . . . . . 46 114 10.14. Current Data Rate (Receive) . . . . . . . . . . . . . . 47 115 10.15. Current Data Rate (Transmit) . . . . . . . . . . . . . . 48 116 10.16. Latency . . . . . . . . . . . . . . . . . . . . . . . . 49 117 10.17. Resources (Receive) . . . . . . . . . . . . . . . . . . 50 118 10.18. Resources (Transmit) . . . . . . . . . . . . . . . . . . 50 119 10.19. Relative Link Quality (Receive) . . . . . . . . . . . . 51 120 10.20. Relative Link Quality (Transmit) . . . . . . . . . . . . 52 121 11. Security Considerations . . . . . . . . . . . . . . . . . . . 52 122 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 53 123 12.1. Registrations . . . . . . . . . . . . . . . . . . . . . 53 124 12.2. Expert Review: Evaluation Guidelines . . . . . . . . . . 54 125 12.3. Signal/Message Type Registration . . . . . . . . . . . . 54 126 12.4. DLEP Data Item Registrations . . . . . . . . . . . . . . 54 127 12.5. DLEP Status Code Registrations . . . . . . . . . . . . . 54 128 12.6. DLEP Extensions Registrations . . . . . . . . . . . . . 54 129 12.7. DLEP Well-known Port . . . . . . . . . . . . . . . . . . 55 130 12.8. DLEP IPv6 Link-local Multicast Address . . . . . . . . . 55 131 13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 55 132 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 55 133 14.1. Normative References . . . . . . . . . . . . . . . . . . 55 134 14.2. Informative References . . . . . . . . . . . . . . . . . 55 135 Appendix A. Discovery Signal Flows . . . . . . . . . . . . . . . 56 136 Appendix B. Peer Level Message Flows . . . . . . . . . . . . . . 56 137 B.1. Session Initialization . . . . . . . . . . . . . . . . . 56 138 B.2. Session Initialization - Refused . . . . . . . . . . . . 57 139 B.3. Router Changes IP Addresses . . . . . . . . . . . . . . . 57 140 B.4. Modem Changes Session-wide Metrics . . . . . . . . . . . 57 141 B.5. Router Terminates Session . . . . . . . . . . . . . . . . 58 142 B.6. Modem Terminates Session . . . . . . . . . . . . . . . . 58 143 B.7. Session Heartbeats . . . . . . . . . . . . . . . . . . . 59 144 B.8. Router Detects a Heartbeat timeout . . . . . . . . . . . 60 145 B.9. Modem Detects a Heartbeat timeout . . . . . . . . . . . . 61 146 Appendix C. Destination Specific Signal Flows . . . . . . . . . 61 147 C.1. Common Destination Signaling . . . . . . . . . . . . . . 61 148 C.2. Multicast Destination Signaling . . . . . . . . . . . . . 62 149 C.3. Link Characteristics Request . . . . . . . . . . . . . . 62 150 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 63 152 1. Introduction 154 There exist today a collection of modem devices that control links of 155 variable datarate and quality. Examples of these types of links 156 include line-of-sight (LOS) terrestrial radios, satellite terminals, 157 and broadband modems. Fluctuations in speed and quality of these 158 links can occur due to configuration, or on a moment-to-moment basis, 159 due to physical phenomena like multipath interference, obstructions, 160 rain fade, etc. It is also quite possible that link quality and 161 datarate vary with respect to individual destinations on a link, and 162 with the type of traffic being sent. As an example, consider the 163 case of an 802.11 access point, serving two associated laptop 164 computers. In this environment, the answer to the question "What is 165 the datarate on the 802.11 link?" is "It depends on which associated 166 laptop we're talking about, and on what kind of traffic is being 167 sent." While the first laptop, being physically close to the access 168 point, may have a datarate of 54Mbps for unicast traffic, the other 169 laptop, being relatively far away, or obstructed by some object, can 170 simultaneously have a datarate of only 32Mbps for unicast. However, 171 for multicast traffic sent from the access point, all traffic is sent 172 at the base transmission rate (which is configurable, but depending 173 on the model of the access point, is usually 24Mbps or less). 175 In addition to utilizing variable datarate links, mobile networks are 176 challenged by the notion that link connectivity will come and go over 177 time, without an effect on a router's interface state (Up or Down). 178 Effectively utilizing a relatively short-lived connection is 179 problematic in IP routed networks, as routing protocols tend to rely 180 on interface state and independent timers at OSI Layer 3 to maintain 181 network convergence (e.g., HELLO messages and/or recognition of DEAD 182 routing adjacencies). These dynamic connections can be better 183 utilized with an event-driven paradigm, where acquisition of a new 184 neighbor (or loss of an existing one) is signaled, as opposed to a 185 paradigm driven by timers and/or interface state. 187 Another complicating factor for mobile networks are the different 188 methods of physically connecting the modem devices to the router. 190 Modems can be deployed as an interface card in a router's chassis, or 191 as a standalone device connected to the router via Ethernet or serial 192 link. In the case of Ethernet attachment, with existing protocols 193 and techniques, routing software cannot be aware of convergence 194 events occurring on the radio link (e.g., acquisition or loss of a 195 potential routing neighbor), nor can the router be aware of the 196 actual capacity of the link. This lack of awareness, along with the 197 variability in datarate, leads to a situation where finding the 198 (current) best route through the network to a given destination is 199 difficult to establish and properly maintain. This is especially 200 true of demand-based access schemes such as Demand Assigned Multiple 201 Access (DAMA) implementations used on some satellite systems. With a 202 DAMA-based system, additional datarate may be available, but will not 203 be used unless the network devices emit traffic at a rate higher than 204 the currently established rate. Increasing the traffic rate does not 205 guarantee additional datarate will be allocated; rather, it may 206 result in data loss and additional retransmissions on the link. 208 Addressing the challenges listed above, the co-authors have developed 209 the Dynamic Link Exchange Protocol, or DLEP. The DLEP protocol runs 210 between a router and its attached modem devices, allowing the modem 211 to communicate link characteristics as they change, and convergence 212 events (acquisition and loss of potential routing destinations). The 213 following diagrams are used to illustrate the scope of DLEP packets. 215 |-------Local Node-------| |-------Remote Node------| 216 | | | | 217 +--------+ +-------+ +-------+ +--------+ 218 | Router |=======| Modem |{~~~~~~~~}| Modem |=======| Router | 219 | | | Device| | Device| | | 220 +--------+ +-------+ +-------+ +--------+ 221 | | | Link | | | 222 |-DLEP--| | Protocol | |-DLEP--| 223 | | | (e.g. | | | 224 | | | 802.11) | | | 226 Figure 1: DLEP Network 228 In Figure 1, when the local modem detects the presence of a remote 229 node, it (the local modem) sends a message to its router via the DLEP 230 protocol. The message consists of an indication of what change has 231 occurred on the link (e.g., presence of a remote node detected), 232 along with a collection of DLEP-defined Data Items that further 233 describe the change. Upon receipt of the message, the local router 234 may take whatever action it deems appropriate, such as initiating 235 discovery protocols, and/or issuing HELLO messages to converge the 236 network. On a continuing, as-needed basis, the modem devices use 237 DLEP to report any characteristics of the link (datarate, latency, 238 etc.) that have changed. DLEP is independent of the link type and 239 topology supported by the modem. Note that the DLEP protocol is 240 specified to run only on the local link between router and modem. 241 Some over the air signaling may be necessary between the local and 242 remote modem in order to provide some parameters in DLEP messages 243 between the local modem and local router, but DLEP does not specify 244 how such over the air signaling is carried out. Over the air 245 signaling is purely a matter for the modem implementer. 247 Figure 2 shows how DLEP can support a configuration where routers are 248 connected with different link types. In this example, Modem A 249 implements a point-to-point link, and Modem B is connected via a 250 shared medium. In both cases, the DLEP protocol is used to report 251 the characteristics of the link (datarate, latency, etc.) to routers. 252 The modem is also able to use the DLEP session to notify the router 253 when the remote node is lost, shortening the time required to re- 254 converge the network. 256 +--------+ +--------+ 257 +----+ Modem A| | Modem A+---+ 258 | | Device | <===== // ======> | Device | | 259 | +--------+ P-2-P Link +--------+ | 260 +---+----+ +---+----+ 261 | Router | | Router | 262 | | | | 263 +---+----+ +---+----+ 264 | +--------+ +--------+ | 265 +-----+ Modem B| | Modem B| | 266 | Device | o o o o o o o o | Device +--+ 267 +--------+ o Shared o +--------+ 268 o Medium o 269 o o 270 o o 271 o o 272 o 273 +--------+ 274 | Modem B| 275 | Device | 276 +---+----+ 277 | 278 | 279 +---+----+ 280 | Router | 281 | | 282 +--------+ 284 Figure 2: DLEP Network with Multiple Modem Devices 286 1.1. Protocol Overview 288 As mentioned earlier, DLEP defines a set of messages used by modems 289 and their attached routers. The messages are used to communicate 290 events that occur on the physical link(s) managed by the modem: for 291 example, a remote node entering or leaving the network, or that the 292 link has changed. Associated with these messages are a set of data 293 items - information that describes the remote node (e.g., address 294 information), and/or the characteristics of the link to the remote 295 node. 297 DLEP uses a session-oriented paradigm between the modem device and 298 its associated router. If multiple modem devices are attached to a 299 router (as in Figure 2), or the modem supports multiple connections 300 (via multiple logical or physical interfaces), then separate DLEP 301 sessions exist for each modem or connection. A router and modem form 302 a session by completing the discovery and initialization process. 303 This router-modem session persists unless or until it either (1) 304 times out, based on a heartbeat, or (2) is explicitly torn down by 305 one of the participants. 307 The router/modem session provides a carrier for information exchange 308 concerning 'destinations' that are available via the modem device. 309 Destinations can be identified by either the router or the modem, and 310 represent a specific, addressable location (e.g., an address) that 311 can be reached via the link(s) managed by the modem. A destination 312 can be either physical or logical. 314 The example of a physical destination would be that of a remote, far- 315 end router attached via the variable-quality network. As for a 316 logical destination, the best example is that of Multicast. 318 Multicast traffic destined for the variable-quality network (the 319 network accessed via the DLEP modem) is handled in IP networks by 320 deriving a Layer 2 MAC address based on the Layer 3 address. 321 Leveraging on this scheme, multicast traffic is supported in DLEP 322 simply by treating the derived MAC address as any other destination 323 (albeit a logical one) in the network. To support these logical 324 destinations, one of the DLEP participants (typically, the router) 325 informs the other as to the existence of the logical destination. 326 The modem, once it is aware of the existence of this logical 327 destination, reports link characteristics just as it would for any 328 other destination in the network. The specific algorithms a modem 329 would use to derive metrics on multicast (or logical) destinations 330 are outside the scope of this specification, and is left to specific 331 implementations to decide. 333 The DLEP messages concerning destinations thus become the way for 334 routers and modems to maintain, and notify each other about, an 335 information base representing the physical and logical (e.g., 336 multicast) destinations accessible via the modem device, as well as 337 the link characteristics to those destinations. 339 1.2. Requirements 341 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 342 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 343 "OPTIONAL" in this document are to be interpreted as described in BCP 344 14, RFC 2119 [RFC2119]. 346 2. Assumptions 348 DLEP specifies UDP multicast for single-hop discovery signalling, and 349 TCP for transport of the control messages. Therefore, DLEP assumes 350 that the modem and router have topologically consistent IP addresses 351 assigned. It is RECOMMENDED that DLEP implementations utilize IPv6 352 link-local addresses to reduce the administrative burden of address 353 assignment. Other reliable transports for the protocol are possible, 354 but are outside the scope of this document. 356 DLEP assumes that the MAC address for delivering data traffic is the 357 MAC address used by DLEP to identify the destination. No 358 manipulation or substitution is performed; the MAC address supplied 359 in a Destination Up message (Section 9.9) message is used as the OSI 360 Layer 2 Destination MAC address. DLEP also assumes that MAC 361 addresses are unique within the context of a router-modem session. 363 DLEP assumes that security on the session (e.g., authentication of 364 session partners, encryption of traffic, or both) is dealt with by 365 the underlying transport mechanism (e.g., by using a transport such 366 as TLS [RFC5246]). 368 3. Metrics 370 DLEP includes the ability for the router and modem to communicate 371 metrics that reflect the characteristics (e.g., datarate, latency) of 372 the variable-quality link in use. DLEP does not specify how a given 373 metric value is to be calculated, rather, the protocol assumes that 374 metrics have been calculated with a 'best effort', incorporating all 375 pertinent data that is available to the modem device. 377 DLEP allows for metrics to be sent within two contexts - metrics for 378 a specific destination within the network (e.g., a specific router), 379 and per-session (those that apply to all destinations accessed via 380 the modem). Most metrics can be further subdivided into transmit and 381 receive metrics. In cases where metrics are provided at session 382 level, the receiver MUST propagate the metrics to all entries in its 383 information base for destinations that are accessed via the 384 originator. 386 It is left to implementations to choose sensible default values based 387 on their specific characteristics. Modems having static (non- 388 changing) link metric characteristics MAY report metrics only once 389 for a given destination (or once on a modem-wide basis, if all 390 connections via the modem are of this static nature). 392 DLEP modem implementations MUST announce all metric items that will 393 be reported during the session, and provide default values for those 394 metrics, in the Session Initialization Response message 395 (Section 9.4). In order to use a metric type that was not included 396 in the Session Initialization Response message, modem implementations 397 MUST terminate the session with the router (via the Session Terminate 398 message (Section 9.7)), and establish a new session. 400 A DLEP participant MAY send metrics both in a session context (via 401 the Session Update message) and a specific destination context (via 402 Destination Update) at any time. The most recently received metric 403 value MUST take precedence over any earlier value, regardless of 404 context - that is: 1. If the receiver gets metrics in a specific 405 destination context (via Destination Update), then the specific 406 destination is updated with the new metric. 2. If the receiver gets 407 metrics in a modem-wide context (via Peer Update), then the received 408 metrics for all destinations accessed via the modem MUST be updated 409 to the newly received value. 411 3.1. Mandatory Metrics 413 As mentioned above, DLEP modem implementations MUST announce all 414 supported metric items during the Session Initialization state. 415 However, a modem MUST include the following list of metrics in the 416 Session Initialization Response message (Section 9.4): 418 o Maximum Data Rate (Receive) (Section 10.12) 420 o Maximum Data Rate (Transmit) (Section 10.13) 422 o Current Data Rate (Receive) (Section 10.14) 424 o Current Data Rate (Transmit) (Section 10.15) 426 o Latency (Section 10.16) 428 4. DLEP Signal and Message Processing 430 Most messages in DLEP are members of a request/response pair, e.g. 431 Destination Up message (Section 9.9), and Destination Up Response 432 message (Section 9.10). As mentioned before, session message pairs 433 control the flow of the session through the various states, e.g. an 434 implementation MUST NOT leave the Session Initialization state until 435 a Session Initialization message (Section 9.3) and Session 436 Initialization Response message (Section 9.4) have been exchanged. 438 Destination message pairs describe the arrival and departure of 439 logical destinations, and control the flow of information about the 440 destinations in the several ways. A destination MUST contain a MAC 441 address, it MAY optionally include a Layer 3 address (or addresses). 442 The MAC address MAY reference a logical destination, as in a derived 443 multicast MAC address, as well as a physical device. As destinations 444 are discovered, DLEP routers and modems build an information base of 445 destinations accessible via the modem. 447 DLEP can support MAC addresses in either EUI-48 or EUI-64 format, 448 with the restriction that all MAC addresses for a given DLEP session 449 MUST be in the same format, and MUST be consistent with the MAC 450 address format of the connected modem (e.g., if the modem is 451 connected to the router with an EUI-48 MAC, all destination addresses 452 via that modem MUST be expressed in EUI-48 format). 454 Prior to the exchange of a pair of Destination Up and Destination Up 455 Response messages, no messages concerning the logical destination 456 identified by the MAC Address data item (Section 10.7) may be sent. 457 An implementation receiving a message with such an unannounced 458 destination MUST terminate the session by issuing a Session 459 Termination message (Section 9.7) with a status code of 'Invalid 460 Destination', see Table 3, and transition to the Session Termination 461 state. 463 The receiver of a Destination Up message MAY decline further messages 464 concerning a given destination by sending a Destination Up Response 465 with a status code of 'Not Interested', see Table 3. Receivers of 466 such responses MUST NOT send further messages concerning that 467 destination to the peer. 469 After exchanging a pair of Destination Down (Section 9.11) and 470 Destination Down Response (Section 9.12) messages, no messages 471 concerning the logical destination identified by the MAC Address data 472 item may be a sent without a previously sending a new Destination Up 473 message. An implementation receiving a message about a destination 474 previously announced as 'down' MUST terminate the session by issuing 475 a Session Termination message with a status code of 'Invalid 476 Destination' and transition to the Session Termination state. 478 4.1. Transaction Model 480 DLEP defines a simple message transaction model: Only one (1) request 481 per destination may be in progress at a time. A message transaction 482 is considered complete when a response matching a previously issued 483 request is received. If a peer receives a request for a destination 484 for which there is already an outstanding request, the peer MUST 485 terminate the session by issuing a Session Termination message 486 (Section 9.7) with a status code of 'Unexpected Message', see 487 Table 3, and transition to the Session Termination state. There is 488 no restriction to the total number of message transactions in 489 progress at a time, as long as each transaction refers to a different 490 destination. 492 It should be noted that some requests may take a considerable amount 493 of time for some peers to complete, for example a modem handling a 494 multicast destination up request may have to perform a complex 495 network reconfiguration. A sending implementation MUST be able to 496 handle such long running transactions gracefully. 498 Additionally, only one (1) session request, e.g. a Session 499 Initialization message (Section 9.3) may be in progress at a time. 500 As above, a session transaction is considered complete when a 501 response matching a previously issued request is received. If a peer 502 receives a session request while there is already a session request 503 in progress, the peer MUST terminate the session by issuing a Session 504 Termination message with a status code of 'Unexpected Message', and 505 transition to the Session Termination state. Only the Session 506 Termination message may be issued when a session transaction is in 507 progress. Heartbeat messages (Section 9.14) MUST NOT be considered 508 part of a session transaction. 510 DLEP transactions do not time out and are not cancellable. An 511 implementation can detect if a peer has failed in some way by use of 512 the session heartbeat mechanism during the In-Session state, see 513 Section 5.3. 515 5. DLEP Session Flow 517 All DLEP peers transition through four (4) distinct states during the 518 lifetime of a DLEP session: 520 o Peer Discovery 522 o Session Initialization 523 o In-Session 525 o Session Termination 527 The Peer Discovery state is OPTIONAL to implement for routers. If it 528 is used, this state is the initial state. If it is not used, then 529 one or more preconfigured address/port combinations SHOULD be 530 provided to the router, and the device starts in the Session 531 Initialization state. 533 Modems MUST support the Peer Discovery state. 535 5.1. Peer Discovery State 537 In the Peer Discovery state, routers MUST send UDP packets containing 538 a Peer Discovery signal (Section 9.1) to the DLEP well-known IPv6 539 link-local multicast address (Section 12.8) and port number 540 (Section 12.7), setting the packet source address to a valid local 541 IPv6 address and the source port to an unused port in the range 49152 542 to 65535. If the router implementation supports IPv4, then they MAY 543 also broadcast Peer Discovery signals in UDP packets to the IPv4 544 broadcast address (255.255.255.255), setting the packet source 545 address to a valid local IPv4 address and the source port to an 546 unused port in the range 49152 to 65535. 548 The implementation then waits for a unicast UDP packet containing a 549 Peer Offer signal (Section 9.2) from a potential peer modem. While 550 in the Peer Discovery state, Peer Discovery signals MUST be sent 551 repeatedly by a router, at regular intervals; every three (3) seconds 552 with some jitter is RECOMMENDED. 554 In the Peer Discovery state, the modem waits for incoming Peer 555 Discovery signals on the DLEP well-known multicast address and port. 556 On receipt of a valid signal, it MUST unicast a Peer Offer signal to 557 the source address and port of the received UDP packet. Peer Offer 558 signals MAY contain the unicast address and port for TCP-based 559 communication with a modem, via the IPv4 Connection Point data item 560 (Section 10.2) or the IPv6 Connection Point data item (Section 10.3), 561 on which it is prepared to accept an incoming TCP connection. If the 562 modem does not include an IPv4 Connection Point data item, nor a IPv6 563 Connection Point data item, then the source address of the packet 564 containing the Peer Offer signal MUST be set to the address on which 565 the modem is willing to accept TCP connections. 567 The modem then begins listening for incoming TCP connections, and, 568 having accepted one, enters the Session Initialization state. 569 Anything other than Peer Discovery signals received on the UDP socket 570 MUST be silently dropped. 572 Modems SHOULD be prepared to accept a TCP connection from a router 573 that is not using the Discovery mechanism, i.e. a connection attempt 574 that occurs without a preceding Peer Discovery signal. The modem 575 MUST accept a TCP connection on only one (1) address/port combination 576 per session. 578 Routers MUST use one or more of the modem address/port combinations 579 from the Peer Offer signal or from a priori configuration to 580 establish a new TCP connection to the modem. If more than one modem 581 address/port combinations is available, router implementations MAY 582 use their own heuristics to determine the order in which they are 583 tried. It is RECOMMENDED that an implementation attempt to connect 584 to any announced IPv6 address/port combinations before attempting to 585 use IPv4 combinations. If a TCP connection cannot be achieved using 586 any of the address/port combinations and the Discovery mechanism is 587 in use, then the router SHOULD resume issuing Peer Discovery signals. 588 If no IPv4 Connection Point data items, nor IPv6 Connection Point 589 data items are included in the Peer Offer signal, the router MUST use 590 the origin address of the UDP packet containing the signal as the IP 591 address, and the DLEP well-known port number. 593 Once a TCP connection has been established with the modem, the router 594 begins a new session and enters the Session Initialization state. It 595 is up to the router implementation if Peer Discovery signals continue 596 to be sent after the device has transitioned to the Session 597 Initialization state. 599 It should be noted that the peer discovery process operates using 600 link-local multicast and is hence inapplicable if the potential peers 601 are separated by more than one hop. 603 5.2. Session Initialization State 605 On entering the Session Initialization state, the router MUST send a 606 Session Initialization message (Section 9.3) to the modem. The 607 router MUST then wait for receipt of a Session Initialization 608 Response message (Section 9.4) from the modem. Receipt of the 609 Session Initialization Response message containing a Status data item 610 (Section 10.1) with value 'Success', see Table 3, indicates that the 611 modem has received and processed the Session Initialization message, 612 and the router MUST transition to the In-Session state. 614 On entering the Session Initialization state, the modem MUST wait for 615 receipt of a Session Initialization message from the router. Upon 616 receipt and successful parsing of a Session Initialization message, 617 the modem MUST send a Session Initialization Response message, and 618 the session MUST transition to the In-Session state. 620 DLEP provides an extension negotiation capability to be used in the 621 Session Initialization state, see Section 6. Extensions supported by 622 an implementation MUST be declared to potential DLEP peers using the 623 Extensions Supported data item (Section 10.6). Once both peers have 624 exchanged initialization messages, an implementation MUST NOT emit 625 any message, signal, data item or status code associated with an 626 extension that was not specified in the received initialization 627 message from its peer. 629 If the router receives any message other than a valid Session 630 Initialization Response, it MUST send a Session Termination message 631 (Section 9.7) with a relevant status code, e.g. 'Unexpected 632 Message', see Table 3, and transition to the Session Termination 633 state. 635 If the modem receives any message other than Session Initialization, 636 or it fails to parse the received message, it MUST NOT send any 637 message, and MUST terminate the TCP connection, then restart at the 638 Peer Discovery state. 640 As mentioned before, the Session Initialization Response message MUST 641 contain metric data items for all metrics that will be used during 642 the session. If an additional metric is to be introduced after the 643 session has started, the session between router and modem MUST be 644 terminated and restarted, and the new metric described in the next 645 Session Initialization Response message. 647 5.3. In-Session State 649 In the In-Session state, messages can flow in both directions between 650 peers, indicating changes to the session state, the arrival or 651 departure of reachable destinations, or changes of the state of the 652 links to the destinations. 654 In addition to the session messages, the participants will transmit 655 messages concerning destinations in the network. These messages 656 trigger creation/maintenance/deletion of destinations in the 657 information base of the recipient. For example, a modem will inform 658 its attached router of the presence of a new destination via the 659 Destination Up message (Section 9.9). Receipt of a Destination Up 660 causes the router to allocate the necessary resources, creating an 661 entry in the information base with the specifics (i.e. MAC Address, 662 Latency, Data Rate, etc.) of the destination. The loss of a 663 destination is communicated via the Destination Down message 664 (Section 9.11), and changes in status to the destination (e.g., 665 varying link quality, or addressing changes) are communicated via the 666 Destination Update message (Section 9.13). The information on a 667 given destination will persist in the router's information base until 668 (1) a Destination Down message is received, indicating that the modem 669 has lost contact with the remote node, or (2) the router/modem 670 transitions to the Session Termination state. 672 As well as receiving metrics about the link, DLEP provides a message 673 allowing a router to request a different datarate or latency from the 674 modem. This message is the Link Characteristics Request message 675 (Section 9.15), and gives the router the ability to deal with 676 requisite increases (or decreases) of allocated datarate/latency in 677 demand-based schemes in a more deterministic manner. 679 The In-Session state is maintained until one of the following 680 conditions occur: 682 o The implementation terminates the session by sending a Session 683 Termination message (Section 9.7)), or 685 o The peer terminates the session, indicated by receiving a Session 686 Termination message. 688 The implementation MUST then transition to the Session Termination 689 state. 691 5.3.1. Heartbeats 693 In order to maintain the In-Session state, periodic Heartbeat 694 messages (Section 9.14) MAY be exchanged between router and modem. 695 These messages are intended to keep the session alive, and to verify 696 bidirectional connectivity between the two participants. Each DLEP 697 peer is responsible for the creation of heartbeat messages. Receipt 698 of any valid DLEP message MUST reset the heartbeat interval timer 699 (i.e., valid DLEP messages take the place of, and obviate the need 700 for, additional Heartbeat messages). 702 Implementations SHOULD allow two (2) heartbeat intervals to expire 703 with no traffic on the router/modem session before terminating the 704 session by issuing a Session Termination message with a status code 705 of 'Timed Out', and then transition to the Session Termination state. 707 5.4. Session Termination State 709 When a DLEP implementation enters the Session Termination state after 710 sending a Session Termination message (Section 9.7) as the result of 711 an invalid message or error, it MUST wait for a Session Termination 712 Response message (Section 9.8) from its peer. If Heartbeat messages 713 (Section 9.14) are in use, senders SHOULD allow four (4) heartbeat 714 intervals to expire before assuming that the peer is unresponsive, 715 and continuing with session termination. If Heartbeat messages are 716 not in use, then if is RECOMMENDED that an interval of eight (8) 717 seconds be used. 719 When an implementation enters the Session Termination state having 720 received a Session Termination message from its peer, it MUST 721 immediately send a Session Termination Response. 723 The sender and receiver of a Session Termination message MUST release 724 all resources allocated for the session, and MUST eliminate all 725 destinations in the information base accessible via the peer 726 represented by the session. Destination Down messages (Section 9.11) 727 MUST NOT be sent. 729 Any messages received after either sending or receiving a Session 730 Termination message MUST be silently ignored. 732 Once Session Termination messages have been exchanged, or timed out, 733 the device MUST terminate the TCP connection to the peer, and return 734 to the relevant initial state. 736 6. Extensions 738 While this document represents the best efforts of the working group 739 to be functionally complete, it is recognized that extensions to DLEP 740 will in all likelihood be necessary as more link types are used. 741 Such extensions are defined as additional rules of behaviour, 742 messages, data items and/or status codes that are not defined in this 743 document. 745 Extensions MUST be negotiated on a per-session basis during session 746 initialization via the Extensions Supported mechanism. 747 Implementations are not required to support any extension in order to 748 be considered DLEP compliant. An extension document, describing the 749 operation of a credit windowing scheme for flow control, is described 750 in [CREDIT]. 752 If interoperable protocol extensions are required, they MUST be 753 standardized either as an update to this document, or as an 754 additional stand-alone specification. The requests for IANA- 755 controlled registries in this document contain sufficient Reserved 756 space for DLEP signals, messages, data items and status codes to 757 accommodate future extensions to the protocol. 759 As multiple protocol extensions MAY be announced during session 760 initialization, authors of protocol extensions MUST consider the 761 interaction of their extension with other published extensions, and 762 specify any incompatibilities. 764 6.1. Experiments 766 This document requests Private Use numbering space in the DLEP 767 signal/message, data item and status code registries for experimental 768 extensions. The intent is to allow for experimentation with new 769 signals, messages, data items, and/or status codes, while still 770 retaining the documented DLEP behavior. 772 Use of the Private Use signals, messages, data items, status codes, 773 or behaviors MUST be announced as DLEP Extensions, during session 774 initialization, using extension identifiers from the Private Use 775 space in the Extensions Supported registry (Table 4), with a value 776 agreed upon (a priori) between the participating peers. DLEP 777 extensions using the Private Use numbering space are commonly 778 referred to as Experiments. 780 Multiple experiments MAY be announced in the Session Initialization 781 messages. However, use of multiple experiments in a single session 782 could lead to interoperability issues or unexpected results (e.g., 783 clashes of experimental signals, messages, data items and/or status 784 code types), and is therefore discouraged. It is left to 785 implementations to determine the correct processing path (e.g., a 786 decision on whether to terminate the session, or to establish a 787 precedence of the conflicting definitions) if such conflicts arise. 789 7. Scalability 791 The protocol is intended to support thousands of destinations on a 792 given modem/router pair. At large scale, implementations SHOULD 793 consider employing techniques to prevent flooding a peer with a large 794 number of messages in a short time. It is recommended that 795 implementations consider a dampening algorithm to prevent a flapping 796 device from generating a large number of Destination Up/Destination 797 Down messages, for example. Implementations SHOULD also consider 798 techniques such as a hysteresis to lessen the impact of rapid, minor 799 fluctuations in link quality. The specific algorithms to be used for 800 handling flapping destinations and minor changes in link quality are 801 outside the scope of this specification. 803 8. DLEP Signal and Message Structure 805 DLEP defines two protocol units used in two different ways: Signals 806 and Messages. Signals are only used in the Discovery mechanism and 807 are carried in UDP datagrams. Messages are used bi-directionally 808 over a TCP connection between two peers, in the Session 809 Initialization, In-Session and Session Termination states. 811 Both signals and messages consist of a header followed by an 812 unordered list of data items. Headers consist of Type and Length 813 information, while data items are encoded as TLV (Type-Length-Value) 814 structures. In this document, the data items following a signal or 815 message header are described as being 'contained in' the signal or 816 message. 818 There is no restriction on the order of data items following a 819 header, and the multiplicity of duplicate data items is defined by 820 the definition of the signal or message declared by the type in the 821 header. 823 All integers in header fields and values MUST be in network byte- 824 order. 826 8.1. DLEP Signal Header 828 The DLEP signal header contains the following fields: 830 0 1 2 3 831 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 1 832 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 833 | 'D' | 'L' | 'E' | 'P' | 834 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 835 | Signal Type | Length | 836 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 838 Figure 3: DLEP Signal Header 840 "DLEP": Every signal MUST start with the characters: U+44, U+4C, 841 U+45, U+50. 843 Signal Type: An 16-bit unsigned integer containing one of the DLEP 844 Signal/Message Type values defined in this document. 846 Length: The length in octets, expressed as a 16-bit unsigned 847 integer, of all of the DLEP data items associated with this 848 signal. This length SHALL NOT include the length of the header 849 itself. 851 The DLEP signal header is immediately followed by one or more DLEP 852 data items, encoded in TLVs, as defined in this document. 854 If an unrecognized, or unexpected signal is received, or a received 855 signal contains unrecognized, invalid, or disallowed duplicate data 856 items, the receiving peer MUST ignore the signal. 858 8.2. DLEP Message Header 860 The DLEP message header contains the following fields: 862 0 1 2 3 863 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 1 864 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 865 | Message Type | Length | 866 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 868 Figure 4: DLEP Message Header 870 Message Type: An 16-bit unsigned integer containing one of the DLEP 871 Signal/Message Type values defined in this document. 873 Length: The length in octets, expressed as a 16-bit unsigned 874 integer, of all of the DLEP data items associated with this 875 message. This length SHALL NOT include the length of the header 876 itself. 878 The DLEP message header is immediately followed by one or more DLEP 879 data items, encoded in TLVs, as defined in this document. 881 If an unrecognized, or unexpected message is received, or a received 882 message contains unrecognized, invalid, or disallowed duplicate data 883 items, the receiving peer MUST issue a Session Termination message 884 (Section 9.7) with a Status data item (Section 10.1) containing the 885 most relevant status code, and transition to the Session Termination 886 state. 888 8.3. DLEP Generic Data Item 890 All DLEP data items contain the following fields: 892 0 1 2 3 893 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 1 894 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 895 | Data Item Type | Length | 896 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 897 | Value... : 898 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 900 Figure 5: DLEP Generic Data Item 902 Data Item Type: An 16-bit unsigned integer field specifying the type 903 of data item being sent. 905 Length: The length in octets, expressed as an 16-bit unsigned 906 integer, of the value field of the data item. This length SHALL 907 NOT include the length of the header itself. 909 Value: A field of octets, which contains data specific to a 910 particular data item. 912 9. DLEP Signals and Messages 914 As mentioned above, all DLEP signals begin with the DLEP signal 915 header, and all DLEP messages begin with the DLEP message header. 916 Therefore, in the following descriptions of specific signals and 917 messages, this header is assumed, and will not be replicated. 919 Following is the set of core signals and messages that MUST be 920 recognized by a DLEP compliant implementation. As mentioned before, 921 not all messages may be used during a session, but an implementation 922 MUST correctly process these messages when received. 924 The core DLEP signals and messages are: 926 +-------------+-----------------------------------------------------+ 927 | Type Code | Description | 928 +-------------+-----------------------------------------------------+ 929 | 0 | Reserved | 930 | 1 | Peer Discovery signal (Section 9.1) | 931 | 2 | Peer Offer signal (Section 9.2) | 932 | 3 | Session Initialization message (Section 9.3) | 933 | 4 | Session Initialization Response message (Section | 934 | | 9.4) | 935 | 5 | Session Update message (Section 9.5) | 936 | 6 | Session Update Response message (Section 9.6) | 937 | 7 | Session Termination message (Section 9.7) | 938 | 8 | Session Termination Response message (Section 9.8) | 939 | 9 | Destination Up message (Section 9.9) | 940 | 10 | Destination Up Response message (Section 9.10) | 941 | 11 | Destination Down message (Section 9.11) | 942 | 12 | Destination Down Response message (Section 9.12) | 943 | 13 | Destination Update message (Section 9.13) | 944 | 14 | Heartbeat message (Section 9.14) | 945 | 15 | Link Characteristics Request message (Section 9.15) | 946 | 16 | Link Characteristics Response message (Section | 947 | | 9.16) | 948 | 17-65519 | Reserved for future extensions | 949 | 65520-65534 | Private Use. Available for experiments | 950 | 65535 | Reserved | 951 +-------------+-----------------------------------------------------+ 953 Table 1: DLEP Signal/Message types 955 9.1. Peer Discovery Signal 957 A Peer Discovery signal SHOULD be sent by a router to discover DLEP 958 modems in the network. The Peer Offer signal (Section 9.2) is 959 required to complete the discovery process. Implementations MAY 960 implement their own retransmit heuristics in cases where it is 961 determined the Peer Discovery signal has timed out. 963 To construct a Peer Discovery signal, the Signal Type value in the 964 signal header is set to 1, from Table 1. 966 The Peer Discovery signal MAY contain the following data item: 968 o Peer Type (Section 10.4) 970 9.2. Peer Offer Signal 972 A Peer Offer signal MUST be sent by a DLEP modem in response to a 973 valid Peer Discovery signal (Section 9.1). 975 The Peer Offer signal MUST be sent to the unicast address of the 976 originator of the Peer Discovery signal. 978 To construct a Peer Offer signal, the Signal Type value in the signal 979 header is set to 2, from Table 1. 981 The Peer Offer signal MAY contain the following data item: 983 o Peer Type (Section 10.4) 985 The Peer Offer signal MAY contain one or more of any of the following 986 data items, with different values: 988 o IPv4 Connection Point (Section 10.2) 990 o IPv6 Connection Point (Section 10.3) 992 The IP Connection Point data items indicate the unicast address the 993 receiver of Peer Offer MUST use when connecting the DLEP TCP session. 994 If multiple IP Connection Point data items are present in the Peer 995 Offer signal, implementations MAY use their own heuristics to select 996 the address to connect to. If no IP Connection Point data items are 997 included in the Peer Offer signal, the receiver MUST use the origin 998 address of the signal as the IP address, and the DLEP well-known port 999 number (Section 12.7) to establish the TCP connection. 1001 9.3. Session Initialization Message 1003 A Session Initialization message MUST be sent by a router as the 1004 first message of the DLEP TCP session. It is sent by the router 1005 after a TCP connect to an address/port combination that was obtained 1006 either via receipt of a Peer Offer, or from a priori configuration. 1008 If any optional extensions are supported by the implementation, they 1009 MUST be enumerated in the Extensions Supported data item. If an 1010 Extensions Supported data item does not exist in a Session 1011 Initialization message, the receiver of the message MUST conclude 1012 that there is no support for extensions in the sender. 1014 Implementations supporting the Heartbeat Interval (Section 10.5) 1015 should understand that heartbeats are not fully established until 1016 receipt of Session Initialization Response message (Section 9.4), and 1017 should therefore implement their own timeout and retry heuristics for 1018 this message. 1020 To construct a Session Initialization message, the Message Type value 1021 in the message header is set to 3, from Table 1. 1023 The Session Initialization message MUST contain one of each of the 1024 following data items: 1026 o Heartbeat Interval (Section 10.5) 1028 The Session Initialization message MAY contain one of each of the 1029 following data items: 1031 o Peer Type (Section 10.4) 1033 o Extensions Supported (Section 10.6) 1035 A Session Initialization message MUST be acknowledged by the receiver 1036 issuing a Session Initialization Response message (Section 9.4). 1038 As an exception to the general rule that an implementation receiving 1039 an unrecognized data item in a message terminating the session with 1040 an error, see Section 8.2, if a Session Initialization message 1041 contains one or more Extension Supported data items announcing 1042 support for extensions that the implementation does not recognize, 1043 then the implementation MAY ignore data items it does not recognize. 1045 9.4. Session Initialization Response Message 1047 A Session Initialization Response message MUST be sent in response to 1048 a received Session Initialization message (Section 9.3). The Session 1049 Initialization Response message completes the DLEP session 1050 establishment; the sender of the message should transition to the In- 1051 Session state when the message is sent, and the receiver should 1052 transition to the In-Session state upon receipt (and successful 1053 parsing) of an acceptable Session Initialization Response message. 1055 All supported metric data items MUST be included in the Session 1056 Initialization Response message, with default values to be used on a 1057 'modem-wide' basis. This can be viewed as the modem 'declaring' all 1058 supported metrics at DLEP session initialization. Receipt of any 1059 DLEP message containing a metric data item not included in the 1060 Session Initialization Response message MUST be treated as an error, 1061 resulting in the termination of the DLEP session between router and 1062 modem. 1064 If any optional extensions are supported by the modem, they MUST be 1065 enumerated in the Extensions Supported data item. If an Extensions 1066 Supported data item does not exist in a Session Initialization 1067 Response message, the receiver of the message MUST conclude that 1068 there is no support for extensions in the sender. 1070 After the Session Initialization/Session Initialization Response 1071 messages have been successfully exchanged, implementations MUST only 1072 use extensions that are supported by BOTH peers. 1074 To construct a Session Initialization Response message, the Message 1075 Type value in the message header is set to 4, from Table 1. 1077 The Session Initialization Response message MUST contain one of each 1078 of the following data items: 1080 o Heartbeat Interval (Section 10.5) 1082 o Maximum Data Rate (Receive) (Section 10.12) 1084 o Maximum Data Rate (Transmit) (Section 10.13) 1086 o Current Data Rate (Receive) (Section 10.14) 1088 o Current Data Rate (Transmit) (Section 10.15) 1090 o Latency (Section 10.16) 1092 The Session Initialization Response message MUST contain one of each 1093 of the following data items, if the data item will be used during the 1094 lifetime of the session: 1096 o Resources (Receive) (Section 10.17) 1098 o Resources (Transmit) (Section 10.18) 1100 o Relative Link Quality (Receive) (Section 10.19) 1102 o Relative Link Quality (Transmit) (Section 10.20) 1104 The Session Initialization Response message MAY contain one of each 1105 of the following data items: 1107 o Status (Section 10.1) 1109 o Peer Type (Section 10.4) 1111 o Extensions Supported (Section 10.6) 1112 A receiver of a Session Initialization Response message without a 1113 Status data item MUST behave as if a Status data item with code 1114 'Success' had been received. 1116 9.5. Session Update Message 1118 A Session Update message MAY be sent by a DLEP peer to indicate local 1119 Layer 3 address changes, or metric changes on a modem-wide basis. 1120 For example, addition of an IPv4 address to the router MAY prompt a 1121 Session Update message to its attached DLEP modems. Also, for 1122 example, a modem that changes its Maximum Data Rate (Receive) for all 1123 destinations MAY reflect that change via a Session Update message to 1124 its attached router(s). 1126 Concerning Layer 3 addresses: If the modem is capable of 1127 understanding and forwarding this information (via proprietary 1128 mechanisms), the address update would prompt any remote DLEP modems 1129 (DLEP-enabled modems in a remote node) to issue a Destination Update 1130 message (Section 9.13) to their local routers with the new (or 1131 deleted) addresses. Modems that do not track Layer 3 addresses 1132 SHOULD silently parse and ignore Layer 3 data items. The Session 1133 Update message MUST be acknowledged with a Session Update Response 1134 message (Section 9.6). 1136 If metrics are supplied with the Session Update message (e.g., 1137 Maximum Data Rate), these metrics are considered to be modem-wide, 1138 and therefore MUST be applied to all destinations in the information 1139 base associated with the router/modem session. 1141 To construct a Session Update message, the Message Type value in the 1142 message header is set to 5, from Table 1. 1144 The Session Update message MAY contain one of each of the following 1145 data items: 1147 o Maximum Data Rate (Receive) (Section 10.12) 1149 o Maximum Data Rate (Transmit) (Section 10.13) 1151 o Current Data Rate (Receive) (Section 10.14) 1153 o Current Data Rate (Transmit) (Section 10.15) 1155 o Latency (Section 10.16) 1157 o Resources (Receive) (Section 10.17) 1159 o Resources (Transmit) (Section 10.18) 1160 o Relative Link Quality (Receive) (Section 10.19) 1162 o Relative Link Quality (Transmit) (Section 10.20) 1164 The Session Update message MAY contain one or more of the following 1165 data items, with different values: 1167 o IPv4 Address (Section 10.8) 1169 o IPv6 Address (Section 10.9) 1171 A Session Update message MUST be acknowledged by the receiver issuing 1172 a Session Update Response message (Section 9.6). 1174 9.6. Session Update Response Message 1176 A Session Update Response message MUST be sent by implementations to 1177 indicate whether a Session Update message (Section 9.5) was 1178 successfully received. 1180 To construct a Session Update Response message, the Message Type 1181 value in the message header is set to 6, from Table 1. 1183 The Session Update Response message MAY contain one of each of the 1184 following data items: 1186 o Status (Section 10.1) 1188 A receiver of a Session Update Response message without a Status data 1189 item MUST behave as if a Status data item with code 'Success' had 1190 been received. 1192 9.7. Session Termination Message 1194 A Session Termination message MUST be sent by a DLEP participant when 1195 the router/modem session needs to be terminated. 1197 To construct a Session Termination message, the Message Type value in 1198 the message header is set to 7, from Table 1. 1200 The Session Termination message MAY contain one of each of the 1201 following data items: 1203 o Status (Section 10.1) 1205 A receiver of a Session Termination message without a Status data 1206 item MUST behave as if a Status of 'Unknown reason for Session 1207 Termination' has been received. 1209 A Session Termination message MUST be acknowledged by the receiver 1210 issuing a Session Termination Response message (Section 9.8). 1212 9.8. Session Termination Response Message 1214 A Session Termination Response message MUST be sent by a DLEP peer in 1215 response to a received Session Termination message (Section 9.7). 1217 Receipt of a Session Termination Response message completes the 1218 teardown of the router/modem session. 1220 To construct a Session Termination Response message, the Message Type 1221 value in the message header is set to 8, from Table 1. 1223 The Session Termination Response message MAY contain one of each of 1224 the following data items: 1226 o Status (Section 10.1) 1228 A receiver of a Session Termination Response message without a Status 1229 data item MUST behave as if a Status data item with status code 1230 'Success', implying graceful termination, had been received. 1232 9.9. Destination Up Message 1234 A Destination Up message can be sent either by the modem, to indicate 1235 that a new remote node has been detected, or by the router, to 1236 indicate the presence of a new logical destination (e.g., a Multicast 1237 group) in the network. 1239 A Destination Up message MUST be acknowledged by the receiver issuing 1240 a Destination Up Response message (Section 9.10). When a Destination 1241 Up message is received and successfully processed, the receiver 1242 should add knowledge of the new destination to its information base, 1243 indicating that the destination is accessible via the modem/router 1244 pair. 1246 To construct a Destination Up message, the Message Type value in the 1247 message header is set to 9, from Table 1. 1249 The Destination Up message MUST contain one of each of the following 1250 data items: 1252 o MAC Address (Section 10.7) 1254 The Destination Up message MAY contain one of each of the following 1255 data items: 1257 o Maximum Data Rate (Receive) (Section 10.12) 1259 o Maximum Data Rate (Transmit) (Section 10.13) 1261 o Current Data Rate (Receive) (Section 10.14) 1263 o Current Data Rate (Transmit) (Section 10.15) 1265 o Latency (Section 10.16) 1267 o Resources (Receive) (Section 10.17) 1269 o Resources (Transmit) (Section 10.18) 1271 o Relative Link Quality (Receive) (Section 10.19) 1273 o Relative Link Quality (Transmit) (Section 10.20) 1275 The Destination Up message MAY contain one or more of the following 1276 data items, with different values: 1278 o IPv4 Address (Section 10.8) 1280 o IPv6 Address (Section 10.9) 1282 o IPv4 Attached Subnet (Section 10.10) 1284 o IPv6 Attached Subnet (Section 10.11) 1286 If the sender has IPv4 and/or IPv6 address information for a 1287 destination it SHOULD include the relevant data items in the 1288 Destination Up message, reducing the need for the receiver to probe 1289 for any address. 1291 9.10. Destination Up Response Message 1293 A DLEP participant MUST send a Destination Up Response message to 1294 indicate whether a Destination Up message (Section 9.9) was 1295 successfully processed. 1297 To construct a Destination Up Response message, the Message Type 1298 value in the message header is set to 10, from Table 1. 1300 The Destination Up Response message MUST contain one of each of the 1301 following data items: 1303 o MAC Address (Section 10.7) 1304 The Destination Up Response message MAY contain one of each of the 1305 following data items: 1307 o Status (Section 10.1) 1309 A receiver of a Destination Up Response message without a Status data 1310 item MUST behave as if a Status data item with status code 'Success' 1311 had been received. 1313 9.11. Destination Down Message 1315 A DLEP peer MUST send a Destination Down message to report when a 1316 destination (a remote node or a multicast group) is no longer 1317 reachable. A Destination Down Response message (Section 9.12) MUST 1318 be sent by the recipient of a Destination Down message to confirm 1319 that the relevant data has been removed from the information base. 1321 To construct a Destination Down message, the Message Type value in 1322 the message header is set to 11, from Table 1. 1324 The Destination Down message MUST contain one of each of the 1325 following data items: 1327 o MAC Address (Section 10.7) 1329 9.12. Destination Down Response Message 1331 A DLEP participant MUST send a Destination Down Response message to 1332 indicate whether a received Destination Down message (Section 9.11) 1333 was successfully processed. If successfully processed, the sender of 1334 the Response MUST have removed all entries in the information base 1335 that pertain to the referenced destination. 1337 To construct a Destination Down Response message, the Message Type 1338 value in the message header is set to 12, from Table 1. 1340 The Destination Down Response message MUST contain one of each of the 1341 following data items: 1343 o MAC Address (Section 10.7) 1345 The Destination Down Response message MAY contain one of each of the 1346 following data items: 1348 o Status (Section 10.1) 1349 A receiver of a Destination Down Response message without a Status 1350 data item MUST behave as if a Status data item with status code 1351 'Success' had been received. 1353 9.13. Destination Update Message 1355 A DLEP participant SHOULD send the Destination Update message when it 1356 detects some change in the information base for a given destination 1357 (remote node or multicast group). Some examples of changes that 1358 would prompt a Destination Update message are: 1360 o Change in link metrics (e.g., Data Rates) 1362 o Layer 3 addressing change 1364 To construct a Destination Update message, the Message Type value in 1365 the message header is set to 13, from Table 1. 1367 The Destination Update message MUST contain one of each of the 1368 following data items: 1370 o MAC Address (Section 10.7) 1372 The Destination Update message MAY contain one of each of the 1373 following data items: 1375 o Maximum Data Rate (Receive) (Section 10.12) 1377 o Maximum Data Rate (Transmit) (Section 10.13) 1379 o Current Data Rate (Receive) (Section 10.14) 1381 o Current Data Rate (Transmit) (Section 10.15) 1383 o Latency (Section 10.16) 1385 o Resources (Receive) (Section 10.17) 1387 o Resources (Transmit) (Section 10.18) 1389 o Relative Link Quality (Receive) (Section 10.19) 1391 o Relative Link Quality (Transmit) (Section 10.20) 1393 The Destination Update message MAY contain one or more of the 1394 following data items, with different values: 1396 o IPv4 Address (Section 10.8) 1397 o IPv6 Address (Section 10.9) 1399 9.14. Heartbeat Message 1401 While Heartbeat messages are not required by DLEP implementations, it 1402 is strongly RECOMMENDED that Heartbeat messages be used. 1404 A Heartbeat message SHOULD be sent by a DLEP participant every N 1405 seconds, where N is defined in the Heartbeat Interval data item of 1406 the Session Initialization message (Section 9.3) or Session 1407 Initialization Response message (Section 9.4). 1409 Note that implementations setting the Heartbeat Interval to 0 1410 effectively sets the interval to an infinite value, turning off 1411 Heartbeat messages. Great care MUST be taken when exercising this 1412 option. 1414 The message is used by participants to detect when a DLEP session 1415 partner (either the modem or the router) is no longer communicating. 1416 Participants SHOULD allow two (2) heartbeat intervals to expire with 1417 no traffic on the router/modem session before initiating DLEP session 1418 termination procedures. 1420 To construct a Heartbeat message, the Message Type value in the 1421 message header is set to 14, from Table 1. 1423 There are no valid data items for the Heartbeat message. 1425 9.15. Link Characteristics Request Message 1427 The Link Characteristics Request message MAY be sent by the router to 1428 request that the modem initiate changes for specific characteristics 1429 of the link. The request can reference either a real destination 1430 (e.g., a remote node), or a logical destination (e.g., a multicast 1431 group) within the network. 1433 The Link Characteristics Request message MAY contain either a Current 1434 Data Rate (CDRR or CDRT) data item to request a different datarate 1435 than what is currently allocated, a Latency data item to request that 1436 traffic delay on the link not exceed the specified value, or both. A 1437 Link Characteristics Response message (Section 9.16) is required to 1438 complete the request. Issuing a Link Characteristics Request with 1439 ONLY the MAC Address data item is a mechanism a peer MAY use to 1440 request metrics (via the Link Characteristics Response) from its 1441 partner. 1443 The sender of a Link Characteristics Request message should be aware 1444 that a request may take an extended period of time to complete. 1446 To construct a Link Characteristics Request message, the Message Type 1447 value in the message header is set to 15, from Table 1. 1449 The Link Characteristics Request message MUST contain one of each of 1450 the following data items: 1452 o MAC Address (Section 10.7) 1454 The Link Characteristics Request message MAY contain one of each of 1455 the following data items: 1457 o Current Data Rate (Receive) (Section 10.14) 1459 o Current Data Rate (Transmit) (Section 10.15) 1461 o Latency (Section 10.16) 1463 9.16. Link Characteristics Response Message 1465 A DLEP participant MUST send a Link Characteristics Response message 1466 to indicate whether a received Link Characteristics Request message 1467 (Section 9.15) was successfully processed. The Link Characteristics 1468 Response message SHOULD contain a complete set of metric data items, 1469 and MUST contain a full set (i.e. those declared in the Session 1470 Initialization Response message (Section 9.4)), if metrics were 1471 requested by only including a MAC address data item. It MUST contain 1472 the same metric types as the request. The values in the metric data 1473 items in the Link Characteristics Response message MUST reflect the 1474 link characteristics after the request has been processed. 1476 If an implementation is not able to alter the characteristics of the 1477 link in the manner requested, then a Status data item with status 1478 code 'Request Denied', see Table 3, MUST be added to the message. 1480 To construct a Link Characteristics Response message, the Message 1481 Type value in the message header is set to 16, from Table 1. 1483 The Link Characteristics Response message MUST contain one of each of 1484 the following data items: 1486 o MAC Address (Section 10.7) 1488 The Link Characteristics Response message SHOULD contain one of each 1489 of the following data items: 1491 o Maximum Data Rate (Receive) (Section 10.12) 1493 o Maximum Data Rate (Transmit) (Section 10.13) 1494 o Current Data Rate (Receive) (Section 10.14) 1496 o Current Data Rate (Transmit) (Section 10.15) 1498 o Latency (Section 10.16) 1500 The Link Characteristics Response message MAY contain one of each of 1501 the following data items: 1503 o Resources (Receive) (Section 10.17) 1505 o Resources (Transmit) (Section 10.18) 1507 o Relative Link Quality (Receive) (Section 10.19) 1509 o Relative Link Quality (Transmit) (Section 10.20) 1511 o Status (Section 10.1) 1513 A receiver of a Link Characteristics Response message without a 1514 Status data item MUST behave as if a Status data item with status 1515 code 'Success' had been received. 1517 10. DLEP Data Items 1519 Following is the list of core data items that MUST be recognized by a 1520 DLEP compliant implementation. As mentioned before, not all data 1521 items need be used during a session, but an implementation MUST 1522 correctly process these data items when correctly associated with a 1523 signal or message. 1525 The core DLEP data items are: 1527 +-------------+-----------------------------------------------------+ 1528 | Type Code | Description | 1529 +-------------+-----------------------------------------------------+ 1530 | 0 | Reserved | 1531 | 1 | Status (Section 10.1) | 1532 | 2 | IPv4 Connection Point (Section 10.2) | 1533 | 3 | IPv6 Connection Point (Section 10.3) | 1534 | 4 | Peer Type (Section 10.4) | 1535 | 5 | Heartbeat Interval (Section 10.5) | 1536 | 6 | Extensions Supported (Section 10.6) | 1537 | 7 | MAC Address (Section 10.7) | 1538 | 8 | IPv4 Address (Section 10.8) | 1539 | 9 | IPv6 Address (Section 10.9) | 1540 | 10 | IPv4 Attached Subnet (Section 10.10) | 1541 | 11 | IPv6 Attached Subnet (Section 10.11) | 1542 | 12 | Maximum Data Rate (Receive) MDRR) (Section 10.12) | 1543 | 13 | Maximum Data Rate (Transmit) (MDRT) (Section 10.13) | 1544 | 14 | Current Data Rate (Receive) (CDRR) (Section 10.14) | 1545 | 15 | Current Data Rate (Transmit) (CDRT) (Section 10.15) | 1546 | 16 | Latency (Section 10.16) | 1547 | 17 | Resources (Receive) (RESR) (Section 10.17) | 1548 | 18 | Resources (Transmit) (REST) (Section 10.18) | 1549 | 19 | Relative Link Quality (Receive) (RLQR) (Section | 1550 | | 10.19) | 1551 | 20 | Relative Link Quality (Transmit) (RLQT) (Section | 1552 | | 10.20) | 1553 | 21-65407 | Reserved for future extensions | 1554 | 65408-65534 | Private Use. Available for experiments | 1555 | 65535 | Reserved | 1556 +-------------+-----------------------------------------------------+ 1558 Table 2: DLEP Data Item types 1560 10.1. Status 1562 The Status data item MAY appear in the Session Initialization 1563 Response (Section 9.4), Session Termination (Section 9.7), Session 1564 Termination Response (Section 9.8), Session Update Response 1565 (Section 9.6), Destination Up Response (Section 9.10), Destination 1566 Down Response (Section 9.12) and Link Characteristics Response 1567 (Section 9.16) messages. 1569 For the Session Termination message (Section 9.7), the Status data 1570 item indicates a reason for the termination. For all acknowledgement 1571 messages, the Status data item is used to indicate the success or 1572 failure of the previously received message. 1574 The status data item includes an optional Text field that can be used 1575 to provide a textual description of the status. The use of the Text 1576 field is entirely up to the receiving implementation, i.e., it could 1577 be output to a log file or discarded. If no Text field is supplied 1578 with the Status data item, the Length field MUST be set to 1. 1580 The Status data item contains the following fields: 1582 0 1 2 3 1583 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 1584 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1585 | Data Item Type | Length | 1586 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1587 | Code | Text... : 1588 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1590 Data Item Type: 1 1592 Length: 1 + Length of text, in octets 1594 Status Code: One of the codes defined in Table 3 below. 1596 Text: UTF-8 encoded string, describing the cause, used for 1597 implementation defined purposes. Since this field is used for 1598 description, implementations SHOULD limit characters in this field 1599 to printable characters. Implementations receiving this data item 1600 SHOULD check for printable characters in the field. 1602 An implementation MUST NOT assume the Text field is NUL-terminated. 1604 +-------------+---------+-----------+-------------------------------+ 1605 | Status Code | Value | Failure | Reason | 1606 | | | Mode | | 1607 +-------------+---------+-----------+-------------------------------+ 1608 | Success | 0 | Success | The message was processed | 1609 | | | | successfully. | 1610 | Unknown | 1 | Terminate | The message was not | 1611 | Message | | | recognized by the | 1612 | | | | implementation. | 1613 | Unexpected | 2 | Terminate | The message was not expected | 1614 | Message | | | while the device was in the | 1615 | | | | current state, e.g., a | 1616 | | | | Session Initialization | 1617 | | | | message (Section 9.3) in the | 1618 | | | | In-Session state. | 1619 | Invalid | 3 | Terminate | One or more data items in the | 1620 | Data | | | message are invalid, | 1621 | | | | unexpected or incorrectly | 1622 | | | | duplicated. | 1623 | Invalid | 4 | Terminate | The destination provided in | 1624 | Destination | | | the message does not match a | 1625 | | | | previously announced | 1626 | | | | destination. For example, in | 1627 | | | | the Link Characteristic | 1628 | | | | Response message (Section | 1629 | | | | 9.16). | 1630 | Timed Out | 5 | Terminate | The session has timed out. | 1631 | | 6-90 | Terminate | Reserved for future | 1632 | | | | extensions. | 1633 | | | | | 1635 | Not | 100 | Continue | The receiver is not | 1636 | Interested | | | interested in this message | 1637 | | | | subject, e.g. a Destination | 1638 | | | | Up Response message (Section | 1639 | | | | 9.10) to indicate no further | 1640 | | | | messages about the | 1641 | | | | destination. | 1642 | Request | 101 | Continue | The receiver refuses to | 1643 | Denied | | | complete the request. | 1644 | | 102-243 | Continue | Reserved for future | 1645 | | | | extensions. | 1646 | | | | | 1648 | | 255 | Terminate | Reserved. | 1649 +-------------+---------+-----------+-------------------------------+ 1651 Table 3: DLEP Status Codes 1653 A failure mode of 'Terminate' indicates that the session MUST be 1654 terminated after sending a response containing the status code. A 1655 failure mode of 'Continue' indicates that the session SHOULD continue 1656 as normal. 1658 10.2. IPv4 Connection Point 1660 The IPv4 Connection Point data item MAY appear in the Peer Offer 1661 signal (Section 9.2). 1663 The IPv4 Connection Point data item indicates the IPv4 address and, 1664 optionally, the TCP port number on the DLEP modem available for 1665 connections. If provided, the receiver MUST use this information to 1666 perform the TCP connect to the DLEP server. 1668 The IPv4 Connection Point data item contains the following fields: 1670 0 1 2 3 1671 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 1672 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1673 | Data Item Type | Length | 1674 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1675 | Flags | IPv4 Address... : 1676 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1677 : ...cont. | TCP Port Number (optional) | 1678 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1680 Data Item Type: 2 1682 Length: 5 (or 7 if TCP Port included) 1684 Flags: Flags field, defined below. 1686 IPv4 Address: The IPv4 address listening on the DLEP modem. 1688 TCP Port Number: TCP Port number on the DLEP modem. 1690 If the Length field is 7, the port number specified MUST be used to 1691 establish the TCP session. If the TCP Port Number is omitted, i.e. 1692 the Length field is 5, the receiver MUST use the DLEP well-known port 1693 number (Section 12.7) to establish the TCP connection. 1695 The Flags field is defined as: 1697 0 1 2 3 4 5 6 7 1698 +-+-+-+-+-+-+-+-+ 1699 | MBZ |T| 1700 +-+-+-+-+-+-+-+-+ 1701 T: Use TLS flag, indicating whether the TCP connection requires the 1702 use of TLS (1), or not (0). 1704 MBZ: MUST be zero. Reserved for future use. 1706 10.3. IPv6 Connection Point 1708 The IPv6 Connection Point data item MAY appear in the Peer Offer 1709 signal (Section 9.2). 1711 The IPv6 Connection Point data item indicates the IPv6 address and, 1712 optionally, the TCP port number on the DLEP modem available for 1713 connections. If provided, the receiver MUST use this information to 1714 perform the TCP connect to the DLEP server. 1716 The IPv6 Connection Point 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 | Flags | IPv6 Address : 1724 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1725 : IPv6 Address : 1726 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1727 : IPv6 Address : 1728 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1729 : IPv6 Address : 1730 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1731 : ...cont. | TCP Port Number (optional) | 1732 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1734 Data Item Type: 3 1736 Length: 17 (or 19 if TCP Port included) 1738 Flags: Flags field, defined below. 1740 IPv6 Address: The IPv6 address listening on the DLEP modem. 1742 TCP Port Number: TCP Port number on the DLEP modem. 1744 If the Length field is 19, the port number specified MUST be used to 1745 establish the TCP session. If the TCP Port Number is omitted, i.e. 1746 the Length field is 17, the receiver MUST use the DLEP well-known 1747 port number (Section 12.7) to establish the TCP connection. 1749 The Flags field is defined as: 1751 0 1 2 3 4 5 6 7 1752 +-+-+-+-+-+-+-+-+ 1753 | MBZ |T| 1754 +-+-+-+-+-+-+-+-+ 1756 T: Use TLS flag, indicating whether the TCP connection requires the 1757 use of TLS (1), or not (0). 1759 MBZ: MUST be zero. Reserved for future use. 1761 10.4. Peer Type 1763 The Peer Type data item MAY appear in the Peer Discovery 1764 (Section 9.1) and Peer Offer (Section 9.2) signals, and the Session 1765 Initialization (Section 9.3) and Session Initialization Response 1766 (Section 9.4) messages. 1768 The Peer Type data item is used by the router and modem to give 1769 additional information as to its type. The peer type is a string and 1770 is envisioned to be used for informational purposes (e.g., as output 1771 in a display command). 1773 The Peer Type data item contains the following fields: 1775 0 1 2 3 1776 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 1777 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1778 | Data Item Type | Length | 1779 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1780 | Peer Type... : 1781 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1783 Data Item Type: 4 1785 Length: Length of peer type string, in octets. 1787 Peer Type: UTF-8 encoded string. For example, a satellite modem 1788 might set this variable to "Satellite terminal". Since this data 1789 item is intended to provide additional information for display 1790 commands, sending implementations SHOULD limit the data to 1791 printable characters, and receiving implementations SHOULD check 1792 the data for printable characters. 1794 An implementation MUST NOT assume the Peer Type field is NUL- 1795 terminated. 1797 10.5. Heartbeat Interval 1799 The Heartbeat Interval data item MUST appear in both the Session 1800 Initialization (Section 9.3) and Session Initialization Response 1801 (Section 9.4) messages to indicate the Heartbeat timeout window to be 1802 used by the sender. 1804 The Interval is used to specify a period (in seconds) for Heartbeat 1805 messages (Section 9.14). By specifying an Interval value of 0, 1806 implementations MAY indicate the desire to disable Heartbeat messages 1807 entirely (i.e., the Interval is set to an infinite value). However, 1808 it is RECOMMENDED that implementations use non-0 timer values. 1810 The Heartbeat Interval data item contains the following fields: 1812 0 1 2 3 1813 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 1814 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1815 | Data Item Type | Length | 1816 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1817 | Interval | 1818 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1820 Data Item Type: 5 1822 Length: 2 1824 Interval: 0 = Do not use heartbeats on this DLEP session. Non-zero 1825 = Interval, in seconds, for heartbeat messages. 1827 10.6. Extensions Supported 1829 The Extensions Supported data item MAY be used in both the Session 1830 Initialization (Section 9.3) and Session Initialization Response 1831 (Section 9.4) messages. 1833 The Extensions Supported data item is used by the router and modem to 1834 negotiate additional optional functionality they are willing to 1835 support. The Extensions List is a concatenation of the types of each 1836 supported extension, found in the IANA DLEP Extensions repository. 1837 Each Extension Type definition includes which additional signals and 1838 data-items are supported. 1840 The Extensions Supported data item contains the following fields: 1842 0 1 2 3 1843 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 1844 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1845 | Data Item Type | Length | 1846 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1847 | Extensions List... 1848 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1850 Data Item Type: 6 1852 Length: Length of the extensions list in octets. This is twice (2x) 1853 the number of extensions. 1855 Extension List: A list of extensions supported, identified by their 1856 2-octet value as listed in the extensions registry. 1858 10.7. MAC Address 1860 The MAC address data item MUST appear in all destination-oriented 1861 messages (i.e., Destination Up (Section 9.9), Destination Up Response 1862 (Section 9.10), Destination Down (Section 9.11), Destination Down 1863 Response (Section 9.12), Destination Update (Section 9.13), Link 1864 Characteristics Request (Section 9.15), and Link Characteristics 1865 Response (Section 9.16)). 1867 The MAC Address data item contains the address of the destination on 1868 the remote node. The MAC address MAY be either a physical or a 1869 virtual destination, and MAY be expressed in EUI-48 or EUI-64 format. 1870 Examples of a virtual destination would be a multicast MAC address, 1871 or the broadcast MAC (FF:FF:FF:FF:FF:FF). 1873 0 1 2 3 1874 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 1875 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1876 | Data Item Type | Length | 1877 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1878 | MAC Address : 1879 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1880 : MAC Address : 1881 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1882 : MAC Address : (if EUI-64 used) | 1883 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1885 Data Item Type: 7 1887 Length: 6 for EUI-48 format, or 8 for EUI-64 format 1889 MAC Address: MAC Address of the destination. 1891 10.8. IPv4 Address 1893 The IPv4 Address data item MAY appear in the Session Update 1894 (Section 9.5), Destination Up (Section 9.9) and Destination Update 1895 (Section 9.13) messages. 1897 When included in Destination messages, this data item contains the 1898 IPv4 address of the destination. When included in the Session Update 1899 message, this data item contains the IPv4 address of the peer. In 1900 either case, the data item also contains an indication of whether 1901 this is a new or existing address, or is a deletion of a previously 1902 known address. 1904 The IPv4 Address data item contains the following fields: 1906 0 1 2 3 1907 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 1908 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1909 | Data Item Type | Length | 1910 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1911 | Flags | IPv4 Address : 1912 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1913 : ...cont. | 1914 +-+-+-+-+-+-+-+-+ 1916 Data Item Type: 8 1918 Length: 5 1920 Flags: Flags field, defined below. 1922 IPv4 Address: The IPv4 address of the destination or peer. 1924 The Flags field is defined as: 1926 0 1 2 3 4 5 6 7 1927 +-+-+-+-+-+-+-+-+ 1928 | MBZ |A| 1929 +-+-+-+-+-+-+-+-+ 1931 A: Add/Drop flag, indicating whether this is a new or existing 1932 address (1), or a withdrawal of an address (0). 1934 MBZ: MUST be zero. Reserved for future use. 1936 10.9. IPv6 Address 1938 The IPv6 Address data item MAY appear in the Session Update 1939 (Section 9.5), Destination Up (Section 9.9) and Destination Update 1940 (Section 9.13) messages. When included in Destination messages, this 1941 data item contains the IPv6 address of the destination. When 1942 included in the Session Update message, this data item contains the 1943 IPv6 address of the peer. In either case, the data item also 1944 contains an indication of whether this is a new or existing address, 1945 or is a deletion of a previously known address. 1947 The IPv6 Address data item contains the following fields: 1949 0 1 2 3 1950 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 1951 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1952 | Data Item Type | Length | 1953 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1954 | Flags | IPv6 Address : 1955 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1956 : IPv6 Address : 1957 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1958 : IPv6 Address : 1959 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1960 : IPv6 Address : 1961 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1962 : IPv6 Address | 1963 +-+-+-+-+-+-+-+-+ 1965 Data Item Type: 9 1967 Length: 17 1969 Flags: Flags field, defined below. 1971 IPv6 Address: IPv6 Address of the destination or peer. 1973 The Flags field is defined as: 1975 0 1 2 3 4 5 6 7 1976 +-+-+-+-+-+-+-+-+ 1977 | MBZ |A| 1978 +-+-+-+-+-+-+-+-+ 1980 A: Add/Drop flag, indicating whether this is a new or existing 1981 address (1), or a withdrawal of an address (0). 1983 MBZ: MUST be zero. Reserved for future use. 1985 10.10. IPv4 Attached Subnet 1987 The DLEP IPv4 Attached Subnet allows a device to declare that it has 1988 an IPv4 subnet (e.g., a stub network) attached, that it has become 1989 aware of an IPv4 subnet being present at a remote destination, or 1990 that it has become aware of the loss of a subnet at the remote 1991 destination. The IPv4 Attached Subnet data item MAY appear in the 1992 Destination Up (Section 9.9) message. 1994 The DLEP IPv4 Attached Subnet data item contains the following 1995 fields: 1997 0 1 2 3 1998 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 1999 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2000 | Data Item Type | Length | 2001 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2002 | Flags | IPv4 Attached Subnet : 2003 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2004 : ...cont. |Prefix Length | 2005 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2007 Data Item Type: 10 2009 Length: 6 2011 Flags: Flags field, defined below. 2013 IPv4 Subnet: The IPv4 subnet reachable at the destination. 2015 Prefix Length: Length of the prefix (1-32) for the IPv4 subnet. A 2016 prefix length outside the specified range MUST be considered as 2017 invalid. 2019 The Flags field is defined as: 2021 0 1 2 3 4 5 6 7 2022 +-+-+-+-+-+-+-+-+ 2023 | MBZ |A| 2024 +-+-+-+-+-+-+-+-+ 2026 A: Add/Drop flag, indicating whether this is a new or existing subnet 2027 address (1), or a withdrawal of a subnet address (0). 2029 MBZ: MUST be zero. Reserved for future use. 2031 10.11. IPv6 Attached Subnet 2033 The DLEP IPv6 Attached Subnet allows a device to declare that it has 2034 an IPv6 subnet (e.g., a stub network) attached, or that it has become 2035 aware of an IPv6 subnet being present at a remote destination. The 2036 IPv6 Attached Subnet data item MAY appear in the Destination Up 2037 (Section 9.9) message. As in the case of the IPv4 attached Subnet 2038 data item above, once an IPv6 attached subnet has been declared, it 2039 SHALL NOT be withdrawn without withdrawing the destination (via the 2040 Destination Down message (Section 9.11)) and re-issuing the 2041 Destination Up message. 2043 The DLEP IPv6 Attached Subnet data item contains the following 2044 fields: 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 | Flags | IPv6 Attached Subnet : 2052 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2053 : IPv6 Attached Subnet : 2054 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2055 : IPv6 Attached Subnet : 2056 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2057 : IPv6 Attached Subnet : 2058 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2059 : ...cont. | Prefix Len. | 2060 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2062 Data Item Type: 11 2064 Length: 18 2066 Flags: Flags field, defined below. 2068 IPv6 Attached Subnet: The IPv6 subnet reachable at the destination. 2070 Prefix Length: Length of the prefix (1-128) for the IPv6 subnet. A 2071 prefix length outside the specified range MUST be considered as 2072 invalid. 2074 The Flags field is defined as: 2076 0 1 2 3 4 5 6 7 2077 +-+-+-+-+-+-+-+-+ 2078 | MBZ |A| 2079 +-+-+-+-+-+-+-+-+ 2081 A: Add/Drop flag, indicating whether this is a new or existing subnet 2082 address (1), or a withdrawal of a subnet address (0). 2084 MBZ: MUST be zero. Reserved for future use. 2086 10.12. Maximum Data Rate (Receive) 2088 The Maximum Data Rate (Receive) (MDRR) data item MUST appear in the 2089 Session Initialization Response message (Section 9.4), and MAY appear 2090 in the Session Update (Section 9.5), Destination Up (Section 9.9), 2091 Destination Update (Section 9.13) and Link Characteristics Response 2092 (Section 9.16) messages to indicate the maximum theoretical data 2093 rate, in bits per second, that can be achieved while receiving data 2094 on the link. 2096 The Maximum Data Rate (Receive) data item contains the following 2097 fields: 2099 0 1 2 3 2100 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 2101 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2102 | Data Item Type | Length | 2103 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2104 | MDRR (bps) : 2105 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2106 : MDRR (bps) | 2107 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2109 Data Item Type: 12 2111 Length: 8 2113 Maximum Data Rate (Receive): A 64-bit unsigned integer, representing 2114 the maximum theoretical data rate, in bits per second (bps), that 2115 can be achieved while receiving on the link. 2117 10.13. Maximum Data Rate (Transmit) 2119 The Maximum Data Rate (Transmit) (MDRT) data item MUST appear in the 2120 Session Initialization Response message (Section 9.4), and MAY appear 2121 in the Session Update (Section 9.5), Destination Up (Section 9.9), 2122 Destination Update (Section 9.13) and Link Characteristics Response 2123 (Section 9.16) messages to indicate the maximum theoretical data 2124 rate, in bits per second, that can be achieved while transmitting 2125 data on the link. 2127 The Maximum Data Rate (Transmit) data item contains the following 2128 fields: 2130 0 1 2 3 2131 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 2132 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2133 | Data Item Type | Length | 2134 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2135 | MDRT (bps) : 2136 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2137 : MDRT (bps) | 2138 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2140 Data Item Type: 13 2142 Length: 8 2144 Maximum Data Rate (Transmit): A 64-bit unsigned integer, 2145 representing the maximum theoretical data rate, in bits per second 2146 (bps), that can be achieved while transmitting on the link. 2148 10.14. Current Data Rate (Receive) 2150 The Current Data Rate (Receive) (CDRR) data item MUST appear in the 2151 Session Initialization Response message (Section 9.4), and MAY appear 2152 in the Session Update (Section 9.5), Destination Up (Section 9.9), 2153 Destination Update (Section 9.13) and Link Characteristics Response 2154 (Section 9.16) messages to indicate the rate at which the link is 2155 currently operating for receiving traffic. 2157 When used in the Link Characteristics Request message (Section 9.15), 2158 CDRR represents the desired receive rate, in bits per second, on the 2159 link. 2161 The Current Data Rate (Receive) data item contains the following 2162 fields: 2164 0 1 2 3 2165 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 2166 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2167 | Data Item Type | Length | 2168 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2169 | CDRR (bps) : 2170 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2171 : CDRR (bps) | 2172 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2174 Data Item Type: 14 2176 Length: 8 2178 Current Data Rate (Receive): A 64-bit unsigned integer, representing 2179 the current data rate, in bits per second, that can currently be 2180 achieved while receiving traffic on the link. 2182 If there is no distinction between current and maximum receive data 2183 rates, current data rate receive MUST be set equal to the maximum 2184 data rate receive. 2186 10.15. Current Data Rate (Transmit) 2188 The Current Data Rate Transmit (CDRT) data item MUST appear in the 2189 Session Initialization Response message (Section 9.4), and MAY appear 2190 in the Session Update (Section 9.5), Destination Up (Section 9.9), 2191 Destination Update (Section 9.13), and Link Characteristics Response 2192 (Section 9.16) messages to indicate the rate at which the link is 2193 currently operating for transmitting traffic. 2195 When used in the Link Characteristics Request message (Section 9.15), 2196 CDRT represents the desired transmit rate, in bits per second, on the 2197 link. 2199 The Current Data Rate (Transmit) data item contains the following 2200 fields: 2202 0 1 2 3 2203 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 2204 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2205 | Data Item Type | Length | 2206 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2207 | CDRT (bps) : 2208 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2209 : CDRT (bps) | 2210 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2211 Data Item Type: 15 2213 Length: 8 2215 Current Data Rate (Transmit): A 64-bit unsigned integer, 2216 representing the current data rate, in bits per second, that can 2217 currently be achieved while transmitting traffic on the link. 2219 If there is no distinction between current and maximum transmit data 2220 rates, current data rate transmit MUST be set equal to the maximum 2221 data rate transmit. 2223 10.16. Latency 2225 The Latency data item MUST appear in the Session Initialization 2226 Response message (Section 9.4), and MAY appear in the Session Update 2227 (Section 9.5), Destination Up (Section 9.9), Destination Update 2228 (Section 9.13), and Link Characteristics Response (Section 9.16) 2229 messages to indicate the amount of latency, in microseconds, on the 2230 link. 2232 When used in the Link Characteristics Request message (Section 9.15), 2233 Latency represents the maximum latency desired on the link. 2235 The Latency value is reported as delay. The calculation of latency 2236 is implementation dependent. For example, the latency may be a 2237 running average calculated from the internal queuing. 2239 0 1 2 3 2240 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 2241 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2242 | Data Item Type | Length | 2243 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2244 | Latency : 2245 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2246 : Latency | 2247 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2249 Data Item Type: 16 2251 Length: 8 2253 Latency: A 64-bit unsigned integer, representing the transmission 2254 delay, in microseconds, that a packet encounters as it is 2255 transmitted over the link. 2257 10.17. Resources (Receive) 2259 The Resources (Receive) (RESR) data item MAY appear in the Session 2260 Initialization Response message (Section 9.4), Session Update 2261 (Section 9.5), Destination Up (Section 9.9), Destination Update 2262 (Section 9.13) and Link Characteristics Response (Section 9.16) 2263 messages to indicate the amount of resources for reception (with 0 2264 meaning 'no resources available', and 100 meaning 'all resources 2265 available') at the destination. The list of resources that might be 2266 considered is beyond the scope of this document, and is left to 2267 implementations to decide. 2269 The Resources (Receive) data item contains the following fields: 2271 0 1 2 3 2272 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 2273 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2274 | Data Item Type | Length | 2275 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2276 | RESR | 2277 +-+-+-+-+-+-+-+-+ 2279 Data Item Type: 17 2281 Length: 1 2283 Resources (Receive): An 8-bit integer percentage, 0-100, 2284 representing the amount of resources allocated to receiving data. 2285 Any value greater than 100 MUST be considered as invalid. 2287 If a device cannot calculate RESR, this data item SHOULD NOT be 2288 issued. 2290 10.18. Resources (Transmit) 2292 The Resources (Transmit) (REST) data item MAY appear in the Session 2293 Initialization Response message (Section 9.4), Session Update 2294 (Section 9.5), Destination Up (Section 9.9), Destination Update 2295 (Section 9.13) and Link Characteristics Response (Section 9.16) 2296 messages to indicate the amount of resources for transmission (with 0 2297 meaning 'no resources available', and 100 meaning 'all resources 2298 available') at the destination. The list of resources that might be 2299 considered is beyond the scope of this document, and is left to 2300 implementations to decide. 2302 The Resources (Transmit) data item contains the following fields: 2304 0 1 2 3 2305 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 2306 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2307 | Data Item Type | Length | 2308 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2309 | REST | 2310 +-+-+-+-+-+-+-+-+ 2312 Data Item Type: 18 2314 Length: 1 2316 Resources (Transmit): An 8-bit integer percentage, 0-100, 2317 representing the amount of resources allocated to transmitting 2318 data. Any value greater than 100 MUST be considered as invalid. 2320 If a device cannot calculate REST, this data item SHOULD NOT be 2321 issued. 2323 10.19. Relative Link Quality (Receive) 2325 The Relative Link Quality (Receive) (RLQR) data item MAY appear in 2326 the Session Initialization Response message (Section 9.4), Session 2327 Update (Section 9.5), Destination Up (Section 9.9), Destination 2328 Update (Section 9.13) and Link Characteristics Response 2329 (Section 9.16) messages to indicate the quality of the link for 2330 receiving data. 2332 The Relative Link Quality (Receive) data item contains the following 2333 fields: 2335 0 1 2 3 2336 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 2337 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2338 | Data Item Type | Length | 2339 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2340 | RLQR | 2341 +-+-+-+-+-+-+-+-+ 2343 Data Item Type: 19 2345 Length: 1 2347 Relative Link Quality (Receive): A non-dimensional 8-bit integer, 2348 0-100, representing relative link quality. A value of 100 2349 represents a link of the highest quality. Any value greater than 2350 100 MUST be considered as invalid. 2352 If a device cannot calculate the RLQR, this data item SHOULD NOT be 2353 issued. 2355 10.20. Relative Link Quality (Transmit) 2357 The Relative Link Quality (Transmit) (RLQT) data item MAY appear in 2358 the Session Initialization Response message (Section 9.4), Session 2359 Update (Section 9.5), Destination Up (Section 9.9), Destination 2360 Update (Section 9.13) and Link Characteristics Response 2361 (Section 9.16) messages to indicate the quality of the link for 2362 transmitting data. 2364 The Relative Link Quality (Transmit) data item contains the following 2365 fields: 2367 0 1 2 3 2368 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 2369 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2370 | Data Item Type | Length | 2371 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2372 | RLQT | 2373 +-+-+-+-+-+-+-+-+ 2375 Data Item Type: 20 2377 Length: 1 2379 Relative Link Quality (Transmit): A non-dimensional 8-bit integer, 2380 0-100, representing relative link quality. A value of 100 2381 represents a link of the highest quality. Any value greater than 2382 100 MUST be considered as invalid. 2384 If a device cannot calculate the RLQT, this data item SHOULD NOT be 2385 issued. 2387 11. Security Considerations 2389 The potential security concerns when using DLEP are: 2391 1. DLEP peers may be 'spoofed' by an attacker, either at DLEP 2392 session initialization, or by injection of messages once a 2393 session has been established, and/or 2395 2. DLEP data items could be altered by an attacker, causing the 2396 receiving peer to inappropriately alter its information base 2397 concerning network status. 2399 If the modem and router are separated by more than a single hop, 2400 session messages could be altered in order to subvert the behaviour 2401 of either or both DLEP participants. Under these circumstances, DLEP 2402 participants MUST implement TLS [RFC5246]. 2404 To avoid potential denial of service attack, it is RECOMMENDED that 2405 implementations using the Peer Discovery mechanism maintain an 2406 information base of peers that persistently fail Session 2407 Initialization having provided an acceptable Discovery signal, and 2408 ignore Peer Discovery signals from such peers. 2410 This specification does not address security of the data plane, as it 2411 (the data plane) is not affected, and standard security procedures 2412 can be employed. 2414 12. IANA Considerations 2416 This section specifies requests to IANA. 2418 12.1. Registrations 2420 This specification defines: 2422 o A new repository for DLEP signals and messages, with sixteen (16) 2423 values currently assigned. 2425 o Reservation of a Private Use numbering space for experimental DLEP 2426 signals and messages. 2428 o A new repository for DLEP data items, with twenty-four (24) values 2429 currently assigned. 2431 o Reservation of a Private Use numbering space in the data items 2432 repository for experimental data items. 2434 o A new repository for DLEP status codes, with eight (8) currently 2435 assigned. 2437 o Reservation of a Private Use numbering space in the status codes 2438 repository for experimental status codes. 2440 o A new repository for DLEP extensions, with one (1) value currently 2441 assigned. 2443 o Reservation of a Private Use numbering space in the extension 2444 repository for experimental extensions. 2446 o A request for allocation of a well-known port for DLEP TCP and UDP 2447 communication. 2449 o A request for allocation of a multicast IP address for DLEP 2450 discovery. 2452 12.2. Expert Review: Evaluation Guidelines 2454 No additional guidelines for expert review are anticipated. 2456 12.3. Signal/Message Type Registration 2458 A new repository must be created with the values of the DLEP signals 2459 and messages. 2461 All signal and message values are in the range [0..65535], defined in 2462 Table 1. 2464 12.4. DLEP Data Item Registrations 2466 A new repository for DLEP data items must be created. 2468 All data item values are in the range [0..65535], defined in Table 2. 2470 12.5. DLEP Status Code Registrations 2472 A new repository for DLEP status codes must be created. 2474 All status codes are in the range [0..255], defined in Table 3. 2476 12.6. DLEP Extensions Registrations 2478 A new repository for DLEP extensions must be created. 2480 All extension values are in the range [0..65535]. Current 2481 allocations are: 2483 +-------------+-----------------------------------------------------+ 2484 | Code | Description | 2485 +-------------+-----------------------------------------------------+ 2486 | 0 | Reserved | 2487 | 1 | Credit Windowing | 2488 | 2-65519 | Reserved for future extensions | 2489 | 65520-65534 | Private Use. Available for experiments | 2490 | 65535 | Reserved | 2491 +-------------+-----------------------------------------------------+ 2493 Table 4: DLEP Extension types 2495 12.7. DLEP Well-known Port 2497 It is requested that IANA allocate a single well-known port number 2498 for both TCP and UDP, for DLEP communication. SCTP port allocation 2499 is not required. 2501 12.8. DLEP IPv6 Link-local Multicast Address 2503 It is requested that IANA allocate an IPv6 link-local multicast 2504 address for DLEP discovery signals. 2506 13. Acknowledgements 2508 We would like to acknowledge and thank the members of the DLEP design 2509 team, who have provided invaluable insight. The members of the 2510 design team are: Teco Boot, Bow-Nan Cheng, John Dowdell, and Henning 2511 Rogge. 2513 We would also like to acknowledge the influence and contributions of 2514 Greg Harrison, Chris Olsen, Martin Duke, Subir Das, Jaewon Kang, 2515 Vikram Kaul, Nelson Powell and Victoria Mercieca. 2517 14. References 2519 14.1. Normative References 2521 [CREDIT] Ratliff, S., "Credit Windowing extension for DLEP", draft- 2522 ietf-manet-credit-window-00 IETF draft, October 2015. 2524 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 2525 Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/ 2526 RFC2119, March 1997, 2527 . 2529 14.2. Informative References 2531 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 2532 (TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/ 2533 RFC5246, August 2008, 2534 . 2536 [RFC5578] Berry, B., Ed., Ratliff, S., Paradise, E., Kaiser, T., and 2537 M. Adams, "PPP over Ethernet (PPPoE) Extensions for Credit 2538 Flow and Link Metrics", RFC 5578, DOI 10.17487/RFC5578, 2539 February 2010, . 2541 Appendix A. Discovery Signal Flows 2543 Router Modem Signal Description 2544 ======================================================================== 2546 | Router initiates discovery, starts 2547 | a timer, send Peer Discovery 2548 |-------Peer Discovery---->|| signal. 2550 ~ ~ ~ ~ ~ ~ ~ Router discovery timer expires 2551 without receiving Peer Offer. 2553 | Router sends another Peer 2554 |-------Peer Discovery---------->| Discovery signal. 2555 | 2556 | Modem receives Peer Discovery 2557 | signal. 2558 | 2559 | Modem sends Peer Offer with 2560 |<--------Peer Offer-------------| Connection Point information. 2561 : 2562 : Router MAY cancel discovery timer 2563 : and stop sending Peer Discovery 2564 : signals. 2566 Appendix B. Peer Level Message Flows 2568 B.1. Session Initialization 2570 Router Modem Signal Description 2571 ======================================================================== 2573 | Router connects to discovered or 2574 | pre-configured Modem Connection 2575 |---------TCP connect----------> Point. 2576 | 2577 | Router sends Session Initialization 2578 |----Session Initialization----->| message. 2579 | 2580 | Modem receives Session Initialization 2581 | message. 2582 | 2583 | Modem sends Session Initialization 2584 |<--Session Initialization Resp.-| Response, with Success status data item. 2585 | | 2586 |<<============================>>| Session established. Heartbeats 2587 : : begin. 2589 B.2. Session Initialization - Refused 2591 Router Modem Signal Description 2592 ======================================================================== 2594 | Router connects to discovered or 2595 | pre-configured Modem Connection 2596 |---------TCP connect----------> Point. 2597 | 2598 | Router sends Session Initialization 2599 |-----Session Initialization---->| message. 2600 | 2601 | Modem receives Session Initialization 2602 | message, and will not support the 2603 | advertised extensions. 2604 | 2605 | Modem sends Session Initialization 2606 | Response, with 'Request Denied' status 2607 |<-Session Initialization Resp.--| data item. 2608 | 2609 | 2610 | Router receives negative Session 2611 | Initialization Response, closes 2612 ||---------TCP close------------|| TCP connection. 2614 B.3. Router Changes IP Addresses 2616 Router Modem Signal Description 2617 ======================================================================== 2619 | Router sends Session Update message to 2620 |-------Session Update---------->| announce change of IP address 2621 | 2622 | Modem receives Session Update message 2623 | and updates internal state. 2624 | 2625 |<----Session Update Response----| Modem sends Session Update Response. 2627 B.4. Modem Changes Session-wide Metrics 2628 Router Modem Signal Description 2629 ======================================================================== 2631 | Modem sends Session Update message to 2632 | announce change of modem-wide 2633 |<--------Session Update---------| metrics 2634 | 2635 | Router receives Session Update message 2636 | and updates internal state. 2637 | 2638 |----Session Update Response---->| Router sends Session Update Response. 2640 B.5. Router Terminates Session 2642 Router Modem Signal Description 2643 ======================================================================== 2645 | Router sends Session Termination 2646 |------Session Termination------>| message with Status data item. 2647 | | 2648 |-------TCP shutdown (send)---> | Router stops sending messages. 2649 | 2650 | Modem receives Session Termination, 2651 | stops counting received heartbeats 2652 | and stops sending heartbeats. 2653 | 2654 | Modem sends Session Termination Response 2655 |<---Session Termination Resp.---| with Status 'Success'. 2656 | 2657 | Modem stops sending messages. 2658 | 2659 ||---------TCP close------------|| Session terminated. 2661 B.6. Modem Terminates Session 2662 Router Modem Signal Description 2663 ======================================================================== 2665 | Modem sends Session Termination 2666 |<----Session Termination--------| message with Status data item. 2667 | 2668 | Modem stops sending messages. 2669 | 2670 | Router receives Session Termination, 2671 | stops counting received heartbeats 2672 | and stops sending heartbeats. 2673 | 2674 | Router sends Session Termination Response 2675 |---Session Termination Resp.--->| with Status 'Success'. 2676 | 2677 | Router stops sending messages. 2678 | 2679 ||---------TCP close------------|| Session terminated. 2681 B.7. Session Heartbeats 2682 Router Modem Signal Description 2683 ======================================================================== 2685 |----------Heartbeat------------>| Router sends heartbeat message 2686 | 2687 | Modem resets heartbeats missed 2688 | counter. 2690 ~ ~ ~ ~ ~ ~ ~ 2692 |---------[Any message]--------->| When the Modem receives any message 2693 | from the Router. 2694 | 2695 | Modem resets heartbeats missed 2696 | counter. 2698 ~ ~ ~ ~ ~ ~ ~ 2700 |<---------Heartbeat-------------| Modem sends heartbeat message 2701 | 2702 | Router resets heartbeats missed 2703 | counter. 2705 ~ ~ ~ ~ ~ ~ ~ 2707 |<--------[Any message]----------| When the Router receives any 2708 | message from the Modem. 2709 | 2710 | Modem resets heartbeats missed 2711 | counter. 2713 B.8. Router Detects a Heartbeat timeout 2715 Router Modem Signal Description 2716 ======================================================================== 2718 ||<----------------------| Router misses a heartbeat 2720 | ||<----------------------| Router misses too many heartbeats 2721 | 2722 | 2723 |------Session Termination------>| Router sends Session Termination 2724 | message with 'Timeout' Status 2725 | data item. 2726 : 2727 : Termination proceeds as above. 2729 B.9. Modem Detects a Heartbeat timeout 2731 Router Modem Signal Description 2732 ======================================================================== 2734 |---------------------->|| Modem misses a heartbeat 2736 |---------------------->|| | Modem misses too many heartbeats 2737 | 2738 | 2739 |<-----Session Termination-------| Modem sends Session Termination 2740 | message with 'Timeout' Status 2741 | data item. 2742 : 2743 : Termination proceeds as above. 2745 Appendix C. Destination Specific Signal Flows 2747 C.1. Common Destination Signaling 2749 Router Modem Signal Description 2750 ======================================================================== 2752 | Modem detects a new logical 2753 | destination is reachable, and 2754 |<-------Destination Up----------| sends Destination Up message. 2755 | 2756 |------Destination Up Resp.----->| Router sends Destination Up Response. 2758 ~ ~ ~ ~ ~ ~ ~ 2759 | Modem detects change in logical 2760 | destination metrics, and sends 2761 |<-------Destination Update------| Destination Update message. 2763 ~ ~ ~ ~ ~ ~ ~ 2764 | Modem detects change in logical 2765 | destination metrics, and sends 2766 |<-------Destination Update------| Destination Update message. 2768 ~ ~ ~ ~ ~ ~ ~ 2769 | Modem detects logical destination 2770 | is no longer reachable, and sends 2771 |<-------Destination Down--------| Destination Down message. 2772 | 2773 | Router receives Destination Down, 2774 | updates internal state, and sends 2775 |------Destination Down Resp.--->| Destination Down Response message. 2777 C.2. Multicast Destination Signaling 2779 Router Modem Signal Description 2780 ======================================================================== 2782 | Router detects a new multicast 2783 | destination is in use, and sends 2784 |--------Destination Up--------->| Destination Up message. 2785 | 2786 | Modem updates internal state to 2787 | monitor multicast destination, and 2788 |<-----Destination Up Resp.------| sends Destination Up Response. 2790 ~ ~ ~ ~ ~ ~ ~ 2791 | Modem detects change in multicast 2792 | destination metrics, and sends 2793 |<-------Destination Update------| Destination Update message. 2795 ~ ~ ~ ~ ~ ~ ~ 2796 | Modem detects change in multicast 2797 | destination metrics, and sends 2798 |<-------Destination Update------| Destination Update message. 2800 ~ ~ ~ ~ ~ ~ ~ 2801 | Router detects multicast 2802 | destination is no longer in use, 2803 |--------Destination Down------->| and sends Destination Down message. 2804 | 2805 | Modem receives Destination Down, 2806 | updates internal state, and sends 2807 |<-----Destination Down Resp.----| Destination Down Response message. 2809 C.3. Link Characteristics Request 2810 Router Modem Signal Description 2811 ======================================================================== 2813 Destination has already been 2814 ~ ~ ~ ~ ~ ~ ~ announced by either peer. 2816 | Router requires different 2817 | Characteristics for the 2818 | destination, and sends Link 2819 |--Link Characteristics Request->| Characteristics Request message. 2820 | 2821 | Modem attempts to adjust link 2822 | status to meet the received 2823 | request, and sends a Link 2824 | Characteristics Response 2825 |<---Link Characteristics Resp.--| message with the new values. 2827 Authors' Addresses 2829 Stan Ratliff 2830 VT iDirect 2831 13861 Sunrise Valley Drive, Suite 300 2832 Herndon, VA 20171 2833 USA 2835 Email: sratliff@idirect.net 2837 Bo Berry 2839 Shawn Jury 2840 Cisco Systems 2841 170 West Tasman Drive 2842 San Jose, CA 95134 2843 USA 2845 Email: sjury@cisco.com 2847 Darryl Satterwhite 2848 Broadcom 2850 Email: dsatterw@broadcom.com 2851 Rick Taylor 2852 Airbus Defence & Space 2853 Quadrant House 2854 Celtic Springs 2855 Coedkernew 2856 Newport NP10 8FZ 2857 UK 2859 Email: rick.taylor@airbus.com