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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) -- Obsolete informational reference (is this intentional?): RFC 5246 (Obsoleted by RFC 8446) Summary: 0 errors (**), 0 flaws (~~), 3 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: November 14, 2015 5 S. Jury 6 Cisco Systems 7 D. Satterwhite 8 Broadcom 9 R. Taylor 10 Airbus Defence & Space 11 May 13, 2015 13 Dynamic Link Exchange Protocol (DLEP) 14 draft-ietf-manet-dlep-14 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 November 14, 2015. 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. Core Features and Optional Extensions . . . . . . . . . . . . 10 67 3.1. Negotiation of Optional Extensions . . . . . . . . . . . 10 68 3.2. Protocol Extensions . . . . . . . . . . . . . . . . . . . 11 69 3.3. Experimental Signals and Data Items . . . . . . . . . . . 11 70 4. Metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 71 4.1. Mandatory Metrics . . . . . . . . . . . . . . . . . . . . 12 72 5. DLEP Session Flow . . . . . . . . . . . . . . . . . . . . . . 12 73 5.1. DLEP Router session flow - Discovery case . . . . . . . . 13 74 5.2. DLEP Router session flow - Configured case . . . . . . . 13 75 5.3. DLEP Modem session flow . . . . . . . . . . . . . . . . . 14 76 5.4. Common Session Flow . . . . . . . . . . . . . . . . . . . 15 77 6. DLEP Signal Structure and Processing . . . . . . . . . . . . 16 78 6.1. DLEP Signal Header . . . . . . . . . . . . . . . . . . . 16 79 6.2. DLEP Generic Data Item . . . . . . . . . . . . . . . . . 17 80 7. DLEP Signals . . . . . . . . . . . . . . . . . . . . . . . . 17 81 7.1. Peer Discovery Signal . . . . . . . . . . . . . . . . . . 18 82 7.2. Peer Offer Signal . . . . . . . . . . . . . . . . . . . . 19 83 7.3. Peer Initialization Signal . . . . . . . . . . . . . . . 19 84 7.4. Peer Initialization ACK Signal . . . . . . . . . . . . . 20 85 7.5. Peer Update Signal . . . . . . . . . . . . . . . . . . . 22 86 7.6. Peer Update ACK Signal . . . . . . . . . . . . . . . . . 23 87 7.7. Peer Termination Signal . . . . . . . . . . . . . . . . . 24 88 7.8. Peer Termination ACK Signal . . . . . . . . . . . . . . . 25 89 7.9. Destination Up Signal . . . . . . . . . . . . . . . . . . 25 90 7.10. Destination Up ACK Signal . . . . . . . . . . . . . . . . 26 91 7.11. Destination Down Signal . . . . . . . . . . . . . . . . . 27 92 7.12. Destination Down ACK Signal . . . . . . . . . . . . . . . 27 93 7.13. Destination Update Signal . . . . . . . . . . . . . . . . 28 94 7.14. Heartbeat Signal . . . . . . . . . . . . . . . . . . . . 29 95 7.15. Link Characteristics Request Signal . . . . . . . . . . . 29 96 7.16. Link Characteristics ACK Signal . . . . . . . . . . . . . 30 97 8. DLEP Data Items . . . . . . . . . . . . . . . . . . . . . . . 31 98 8.1. DLEP Version . . . . . . . . . . . . . . . . . . . . . . 32 99 8.2. Status . . . . . . . . . . . . . . . . . . . . . . . . . 33 100 8.3. IPv4 Connection Point . . . . . . . . . . . . . . . . . . 34 101 8.4. IPv6 Connection Point . . . . . . . . . . . . . . . . . . 35 102 8.5. Peer Type . . . . . . . . . . . . . . . . . . . . . . . . 36 103 8.6. Heartbeat Interval . . . . . . . . . . . . . . . . . . . 36 104 8.7. Extensions Supported . . . . . . . . . . . . . . . . . . 37 105 8.8. Experimental Definition . . . . . . . . . . . . . . . . . 38 106 8.9. MAC Address . . . . . . . . . . . . . . . . . . . . . . . 38 107 8.10. IPv4 Address . . . . . . . . . . . . . . . . . . . . . . 39 108 8.11. IPv6 Address . . . . . . . . . . . . . . . . . . . . . . 40 109 8.12. IPv4 Attached Subnet . . . . . . . . . . . . . . . . . . 40 110 8.13. IPv6 Attached Subnet . . . . . . . . . . . . . . . . . . 41 111 8.14. Maximum Data Rate (Receive) . . . . . . . . . . . . . . . 42 112 8.15. Maximum Data Rate (Transmit) . . . . . . . . . . . . . . 43 113 8.16. Current Data Rate (Receive) . . . . . . . . . . . . . . . 43 114 8.17. Current Data Rate (Transmit) . . . . . . . . . . . . . . 44 115 8.18. Latency . . . . . . . . . . . . . . . . . . . . . . . . . 45 116 8.19. Resources (Receive) . . . . . . . . . . . . . . . . . . . 46 117 8.20. Resources (Transmit) . . . . . . . . . . . . . . . . . . 46 118 8.21. Relative Link Quality (Receive) . . . . . . . . . . . . . 47 119 8.22. Relative Link Quality (Transmit) . . . . . . . . . . . . 48 120 8.23. Link Characteristics ACK Timer . . . . . . . . . . . . . 48 121 9. Credit-Windowing . . . . . . . . . . . . . . . . . . . . . . 49 122 9.1. Credit-Windowing Signals . . . . . . . . . . . . . . . . 49 123 9.1.1. Destination Up Signal . . . . . . . . . . . . . . . . 49 124 9.1.2. Destination Up ACK Signal . . . . . . . . . . . . . . 50 125 9.1.3. Destination Update Signal . . . . . . . . . . . . . . 50 126 9.2. Credit-Windowing Data Items . . . . . . . . . . . . . . . 50 127 9.2.1. Credit Grant . . . . . . . . . . . . . . . . . . . . 51 128 9.2.2. Credit Window Status . . . . . . . . . . . . . . . . 52 129 9.2.3. Credit Request . . . . . . . . . . . . . . . . . . . 52 130 10. Security Considerations . . . . . . . . . . . . . . . . . . . 53 131 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 53 132 11.1. Registrations . . . . . . . . . . . . . . . . . . . . . 53 133 11.2. Expert Review: Evaluation Guidelines . . . . . . . . . . 54 134 11.3. Signal Type Registration . . . . . . . . . . . . . . . . 54 135 11.4. DLEP Data Item Registrations . . . . . . . . . . . . . . 55 136 11.5. DLEP Status Code Registrations . . . . . . . . . . . . . 56 137 11.6. DLEP Extensions Registrations . . . . . . . . . . . . . 56 138 11.7. DLEP Well-known Port . . . . . . . . . . . . . . . . . . 57 139 11.8. DLEP Multicast Address . . . . . . . . . . . . . . . . . 57 140 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 57 141 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 57 142 13.1. Normative References . . . . . . . . . . . . . . . . . . 57 143 13.2. Informative References . . . . . . . . . . . . . . . . . 57 144 Appendix A. Peer Level Signal Flows . . . . . . . . . . . . . . 57 145 A.1. Discovery . . . . . . . . . . . . . . . . . . . . . . . . 57 146 A.2. Session Initialization . . . . . . . . . . . . . . . . . 58 147 A.3. Session Initialization - Refused . . . . . . . . . . . . 59 148 A.4. Router Changes IP Addresses . . . . . . . . . . . . . . . 59 149 A.5. Modem Changes Session-wide Metrics . . . . . . . . . . . 59 150 A.6. Router Terminates Session . . . . . . . . . . . . . . . . 60 151 A.7. Modem Terminates Session . . . . . . . . . . . . . . . . 60 152 A.8. Session Heartbeats . . . . . . . . . . . . . . . . . . . 61 153 A.9. Router Detects a Heartbeat timeout . . . . . . . . . . . 62 154 A.10. Modem Detects a Heartbeat timeout . . . . . . . . . . . . 63 155 Appendix B. Destination Specific Signal Flows . . . . . . . . . 63 156 B.1. Common Destination Signaling . . . . . . . . . . . . . . 63 157 B.2. Multicast Destination Signaling . . . . . . . . . . . . . 64 158 B.3. Link Characteristics Request . . . . . . . . . . . . . . 64 159 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 65 161 1. Introduction 163 There exist today a collection of modem devices that control links of 164 variable datarate and quality. Examples of these types of links 165 include line-of-sight (LOS) terrestrial radios, satellite terminals, 166 and cable/DSL modems. Fluctuations in speed and quality of these 167 links can occur due to configuration, or on a moment-to-moment basis, 168 due to physical phenomena like multipath interference, obstructions, 169 rain fade, etc. It is also quite possible that link quality and 170 datarate vary with respect to individual destinations on a link, and 171 with the type of traffic being sent. As an example, consider the 172 case of an 802.11 access point, serving 2 associated laptop 173 computers. In this environment, the answer to the question "What is 174 the datarate on the 802.11 link?" is "It depends on which associated 175 laptop we're talking about, and on what kind of traffic is being 176 sent." While the first laptop, being physically close to the access 177 point, may have a datarate of 54Mbps for unicast traffic, the other 178 laptop, being relatively far away, or obstructed by some object, can 179 simultaneously have a datarate of only 32Mbps for unicast. However, 180 for multicast traffic sent from the access point, all traffic is sent 181 at the base transmission rate (which is configurable, but depending 182 on the model of the access point, is usually 24Mbps or less). 184 In addition to utilizing variable datarate links, mobile networks are 185 challenged by the notion that link connectivity will come and go over 186 time, without an effect on a router's interface state (Up or Down). 187 Effectively utilizing a relatively short-lived connection is 188 problematic in IP routed networks, as routing protocols tend to rely 189 on interface state and independent timers at OSI Layer 3 to maintain 190 network convergence (e.g., HELLO messages and/or recognition of DEAD 191 routing adjacencies). These dynamic connections can be better 192 utilized with an event-driven paradigm, where acquisition of a new 193 neighbor (or loss of an existing one) is signaled, as opposed to a 194 paradigm driven by timers and/or interface state. 196 Another complicating factor for mobile networks are the different 197 methods of physically connecting the modem devices to the router. 198 Modems can be deployed as an interface card in a router's chassis, or 199 as a standalone device connected to the router via Ethernet or serial 200 link. In the case of Ethernet attachment, with existing protocols 201 and techniques, routing software cannot be aware of convergence 202 events occurring on the radio link (e.g., acquisition or loss of a 203 potential routing neighbor), nor can the router be aware of the 204 actual capacity of the link. This lack of awareness, along with the 205 variability in datarate, leads to a situation where finding the 206 (current) best route through the network to a given destination is 207 difficult to establish and properly maintain. This is especially 208 true of demand-based access schemes such as Demand Assigned Multiple 209 Access (DAMA) implementations used on some satellite systems. With a 210 DAMA-based system, additional datarate may be available, but will not 211 be used unless the network devices emit traffic at a rate higher than 212 the currently established rate. Increasing the traffic rate does not 213 guarantee additional datarate will be allocated; rather, it may 214 result in data loss and additional retransmissions on the link. 216 Addressing the challenges listed above, the co-authors have developed 217 the Dynamic Link Exchange Protocol, or DLEP. The DLEP protocol runs 218 between a router and its attached modem devices, allowing the modem 219 to communicate link characteristics as they change, and convergence 220 events (acquisition and loss of potential routing destinations). The 221 following diagrams are used to illustrate the scope of DLEP packets. 223 |-------Local Node-------| |-------Remote Node------| 224 | | | | 225 +--------+ +-------+ +-------+ +--------+ 226 | Router |=======| Modem |{~~~~~~~~}| Modem |=======| Router | 227 | | | Device| | Device| | | 228 +--------+ +-------+ +-------+ +--------+ 229 | | | Link | | | 230 |-DLEP--| | Protocol | |-DLEP--| 231 | | | (e.g. | | | 232 | | | 802.11) | | | 234 Figure 1: DLEP Network 236 In Figure 1, when the local modem detects the presence of a remote 237 node, it (the local modem) sends a signal to its router via the DLEP 238 protocol. The signal consists of an indication of what change has 239 occurred on the link (e.g., presence of a remote node detected), 240 along with a collection of DLEP-defined Data Items that further 241 describe the change. Upon receipt of the signal, the local router 242 may take whatever action it deems appropriate, such as initiating 243 discovery protocols, and/or issuing HELLO messages to converge the 244 network. On a continuing, as-needed basis, the modem devices use 245 DLEP to report any characteristics of the link (datarate, latency, 246 etc.) that have changed. DLEP is independent of the link type and 247 topology supported by the modem. Note that the DLEP protocol is 248 specified to run only on the local link between router and modem. 249 Some over the air signaling may be necessary between the local and 250 remote modem in order to provide some parameters in DLEP signals 251 between the local modem and local router, but DLEP does not specify 252 how such over the air signaling is carried out. Over the air 253 signaling is purely a matter for the modem implementer. 255 Figure 2 shows how DLEP can support a configuration where routers are 256 connected with different link types. In this example, Modem A 257 implements a point-to-point link, and Modem B is connected via a 258 shared medium. In both cases, the DLEP protocol is used to report 259 the characteristics of the link (datarate, latency, etc.) to routers. 260 The modem is also able to use the DLEP session to notify the router 261 when the remote node is lost, shortening the time required to re- 262 converge the network. 264 +--------+ +--------+ 265 +----+ Modem A| | Modem A+---+ 266 | | Device | <===== // ======> | Device | | 267 | +--------+ P-2-P Link +--------+ | 268 +---+----+ +---+----+ 269 | Router | | Router | 270 | | | | 271 +---+----+ +---+----+ 272 | +--------+ +--------+ | 273 +-----+ Modem B| | Modem B| | 274 | Device | o o o o o o o o | Device +--+ 275 +--------+ o Shared o +--------+ 276 o Medium o 277 o o 278 o o 279 o o 280 o 281 +--------+ 282 | Modem B| 283 | Device | 284 +---+----+ 285 | 286 | 287 +---+----+ 288 | Router | 289 | | 290 +--------+ 292 Figure 2: DLEP Network with Multiple Modem Devices 294 1.1. Protocol Overview 296 As mentioned earlier, DLEP defines a set of signals used by modems 297 and their attached routers. The signals are used to communicate 298 events that occur on the physical link(s) managed by the modem: for 299 example, a remote node entering or leaving the network, or that the 300 link has changed. Associated with these signals are a set of data 301 items - information that describes the remote node (e.g., address 302 information), and/or the characteristics of the link to the remote 303 node. 305 The protocol is defined as a collection of type-length-value (TLV) 306 based formats, specifying the signals that are exchanged between a 307 router and a modem, and the data items associated with the signal. 308 This document specifies transport of DLEP signals and data items via 309 the TCP transport, with a UDP-based discovery mechanism. Other 310 transports for the protocol are possible, but are outside the scope 311 of this document. 313 DLEP uses a session-oriented paradigm between the modem device and 314 its associated router. If multiple modem devices are attached to a 315 router (as in Figure 2), or the modem supports multiple connections 316 (via multiple logical or physical interfaces), then separate DLEP 317 sessions exist for each modem or connection. This router/modem 318 session provides a carrier for information exchange concerning 319 'destinations' that are available via the modem device. A 320 'destination' can be either physical (as in the case of a specific 321 far-end router), or a logical destination (as in a Multicast group). 322 As such, all of the destination-level exchanges in DLEP can be 323 envisioned as building an information base concerning the remote 324 nodes, and the link characteristics to those nodes. 326 Multicast traffic destined for the variable-quality network (the 327 network accessed via the DLEP modem) is handled in IP networks by 328 deriving a Layer 2 MAC address based on the Layer 3 address. 329 Leveraging on this scheme, multicast traffic is supported in DLEP 330 simply by treating the derived MAC address as any other 'destination' 331 (albeit a logical one) in the network. To support these logical 332 destinations, one of the DLEP participants (typically, the router) 333 informs the other as to the existence of the logical destination. 334 The modem, once it is aware of the existence of this logical 335 destination, reports link characteristics just as it would for any 336 other destination in the network. The specific algorithms a modem 337 would use to derive metrics on multicast (or logical) destinations 338 are outside the scope of this specification, and is left to specific 339 implementations to decide. 341 1.2. Requirements 343 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 344 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 345 "OPTIONAL" in this document are to be interpreted as described in BCP 346 14, RFC 2119 [RFC2119]. 348 2. Assumptions 350 Routers and modems that exist as part of the same node (e.g., that 351 are locally connected) can use a discovery technique to locate each 352 other, thus avoiding a priori configuration. The router is 353 responsible for initializing the discovery process, using the Peer 354 Discovery signal (Section 7.1). 356 DLEP uses a session-oriented paradigm. A router and modem form a 357 session by completing the discovery and initialization process. This 358 router-modem session persists unless or until it either (1) times 359 out, based on the timeout values supplied, or (2) is explicitly torn 360 down by one of the participants. Note that while use of timers in 361 DLEP is optional, it is strongly RECOMMENDED that implementations 362 choose to run with timers enabled. 364 DLEP assumes that the MAC address for delivering data traffic is the 365 MAC specified in the Destination Up signal (Section 7.9). No 366 manipulation or substitution is performed; the MAC address supplied 367 in Destination Up is used as the OSI Layer 2 Destination MAC address. 368 DLEP also assumes that MAC addresses MUST be unique within the 369 context of a router-modem session. Additionally, DLEP can support 370 MAC addresses in either EUI-48 or EUI-64 format, with the restriction 371 that ALL MAC addresses for a given DLEP session MUST be in the same 372 format, and MUST be consistent with the MAC address format of the 373 connected modem (e.g., if the modem is connected to the router with 374 an EUI-48 MAC, all destination addresses via that modem MUST be 375 expressed in EUI-48 format). 377 DLEP uses UDP multicast for single-hop discovery, and TCP for 378 transport of the control signals. Therefore, DLEP assumes that the 379 modem and router have topologically consistent IP addresses assigned. 380 It is RECOMMENDED that DLEP implementations utilize IPv6 link-local 381 addresses to reduce the administrative burden of address assignment. 383 Destinations can be identified by either the router or the modem, and 384 represent a specific destination (e.g., an address) that exists on 385 the link(s) managed by the modem. A destination MUST contain a MAC 386 address, it MAY optionally include a Layer 3 address (or addresses). 387 Note that since a destination is a MAC address, the MAC could 388 reference a logical destination, as in a derived multicast MAC 389 address, as well as a physical device. As destinations are 390 discovered, DLEP routers and modems build an information base on 391 destinations accessible via the modem. 393 The DLEP signals concerning destinations thus become the way for 394 routers and modems to maintain, and notify each other about, an 395 information base representing the physical and logical (e.g., 396 multicast) destinations accessible via the modem device. The 397 information base would contain addressing information (i.e. MAC 398 address, and OPTIONALLY, Layer 3 addresses), link characteristics 399 (metrics), and OPTIONALLY, flow control information (credits). 401 DLEP assumes that any signal not understood by a receiver MUST result 402 in an error indication being sent to the originator, and also MUST 403 result in termination of the session between the DLEP peers. Any 404 DLEP data item not understood by a receiver MUST also result in 405 termination of the session. 407 DLEP assumes that security on the session (e.g., authentication of 408 session partners, encryption of traffic, or both) is dealt with by 409 the underlying transport mechanism (e.g., by using a transport such 410 as TLS [RFC5246]). 412 This document specifies an implementation of the DLEP signals and 413 data items running over the TCP transport. It is assumed that DLEP 414 running over other transport mechanisms would be documented 415 separately. 417 3. Core Features and Optional Extensions 419 DLEP has a core set of signals and data items that MUST be processed 420 without error by an implementation in order to guarantee 421 interoperability and therefore make the implementation DLEP 422 compliant. This document defines the core set of signals and data 423 items, listing them as 'mandatory'. It should be noted that some 424 core signals and data items might not be used during the lifetime of 425 a single DLEP session, but a compliant implementation MUST support 426 them. 428 While this document represents the best efforts of the working group 429 to be functionally complete, it is recognized that extensions to DLEP 430 will in all likelihood be necessary as more link types are used. To 431 support future extension of DLEP, this document describes an 432 extension negotiation capability to be used during session 433 initialization via the Extensions Supported data item, documented in 434 Section 8.7 of this document. 436 All extensions are considered OPTIONAL. Only the DLEP functionality 437 listed as 'mandatory' is required by implementation in order to be 438 DLEP compliant. 440 This specification defines one extension, Credit windowing, exposed 441 via the Extensions Supported mechanism that implementations MAY 442 choose to implement, or to omit. 444 3.1. Negotiation of Optional Extensions 446 Optional extensions supported by an implementation MUST be declared 447 to potential DLEP peers using the Extensions Supported data item 448 (Section 8.7) during the session initialization sequence. Once both 449 peers have exchanged initialization signals, an implementation MUST 450 NOT emit any signal or data item associated with an optional 451 extension that was not specified in the received initialization 452 signal from its peer. 454 3.2. Protocol Extensions 456 If/when protocol extensions are required, they should be standardized 457 either as an update to this document, or as an additional stand-alone 458 specification. The requests for IANA-controlled registries in this 459 document contain sufficient reserved space, both in terms of DLEP 460 signals and DLEP data items, to accommodate future extensions to the 461 protocol and the data transferred. 463 3.3. Experimental Signals and Data Items 465 This document requests numbering space in both the DLEP signal and 466 data item registries for experimental items. The intent is to allow 467 for experimentation with either (1) new signals, (2) new data items, 468 or (3) both new signals and new data items, while still retaining the 469 documented DLEP behavior. If a given experiment proves successful, 470 it SHOULD be documented as an update to this document, or as a stand- 471 alone specification. 473 Use of the experimental signals, data items, or behaviors MUST be 474 announced by inclusion of an Experimental Definition data item 475 (Section 8.8) with a value agreed upon (a priori) between the 476 participating peers. The exact mechanism for a priori communication 477 of the experimental definition formats is beyond the scope of this 478 document. 480 Multiple Experimental Definition data items MAY appear in the Peer 481 Initialization/Peer Initialization ACK sequence. However, use of 482 multiple experiments in a single peer session could lead to 483 interoperability issues or unexpected results (e.g., redefinition of 484 experimental signals and/or data items), and is therefore 485 discouraged. It is left to implementations to determine the correct 486 processing path (e.g., a decision on whether to terminate the peer 487 session, or to establish a precedence of the conflicting definitions) 488 if such conflicts arise. 490 4. Metrics 492 DLEP includes the ability for the router and modem to communicate 493 metrics that reflect the characteristics (e.g., datarate, latency) of 494 the variable-quality link in use. DLEP does NOT specify how a given 495 metric value is to be calculated, rather, the protocol assumes that 496 metrics have been calculated with a 'best effort', incorporating all 497 pertinent data that is available to the modem device. 499 DLEP allows for metrics to be sent within two contexts - metrics for 500 a specific destination within the network (e.g., a specific router), 501 and 'modem-wide' (those that apply to all destinations accessed via 502 the modem). Most metrics can be further subdivided into transmit and 503 receive metrics. Metrics supplied on DLEP Peer signals are, by 504 definition, modem-wide; metrics supplied on Destination signals are, 505 by definition, used for the specific logical destination only. 507 DLEP modem implementations MUST announce all supported metric items, 508 and provide default values for those metrics, in the Peer 509 Initialization ACK signal (Section 7.4). In order to introduce a new 510 metric type, DLEP modem implementations MUST terminate the session 511 with the router (via the Peer Terminate signal (Section 7.7)), and 512 allow for session re-establishment. 514 It is left to implementations to choose sensible default values based 515 on their specific characteristics. Modems having static (non- 516 changing) link metric characteristics MAY report metrics only once 517 for a given destination (or once on a modem-wide basis, if all 518 connections via the modem are of this static nature). 520 The approach of allowing for different contexts for metric data 521 increases both the flexibility and the complexity of using metric 522 data. This document details the mechanism whereby the data is 523 transmitted, however, the specific algorithms (precedence, etc.) for 524 utilizing the dual-context metrics are out of scope and not addressed 525 by this document. 527 4.1. Mandatory Metrics 529 As mentioned above, DLEP modem implementations MUST announce all 530 supported metric items during session initialization. However, an 531 implementation MUST include the following list of metrics: 533 o Maximum Data Rate (Receive) (Section 8.14) 535 o Maximum Data Rate (Transmit) (Section 8.15) 537 o Current Data Rate (Receive) (Section 8.16) 539 o Current Data Rate (Transmit) (Section 8.17) 541 o Latency (Section 8.18) 543 5. DLEP Session Flow 545 For routers supporting DLEP, support of Discovery is optional. 546 Discovery is initiated in the DLEP modem by sending the Peer 547 Discovery Signal (Section 7.1) to a well-known multicast address. 548 However, support for receipt and processing of the signal is optional 549 in the router (see Appendix A for flow diagrams of the discovery 550 signal). Due to the optional (on the router) support for discovery, 551 normal session flow is described for both the 'Discovery case', and 552 the 'Configured case'. Again, for modem implementations of DLEP, 553 support of Discovery is mandatory; therefore, that is the only case 554 to be described. 556 5.1. DLEP Router session flow - Discovery case 558 If the DLEP router implementation is utilizing the optional discovery 559 mechanism, then the implementation will initialize a UDP socket, 560 binding it to an arbitrary port. This UDP socket is used to send the 561 Peer Discovery signal (Section 7.1) to the DLEP link-local multicast 562 address and port (TBD). The implementation then waits on receipt of 563 a Peer Offer signal (Section 7.2), which MAY contain the unicast 564 address and port for TCP-based communication with a DLEP modem, via 565 the IPv4 Connection Point data item (Section 8.3) or the IPv6 566 Connection Point data item (Section 8.4). The Peer Offer signal MAY 567 contain multiple IP Connection Point data items. If more than one IP 568 Connection Point data items is in the Peer Offer, router 569 implementations MAY use their own heuristics to determine the best 570 address/port combination. If no IP Connection Point data items are 571 included in the Peer Offer signal, the receiver MUST use the origin 572 address of the signal as the IP address, and the DLEP well-known port 573 number (Section 11.7) to establish the TCP connection. At this 574 point, the router implementation MAY either destroy the UDP socket, 575 or continue to issue Peer Discovery signals to the link-local 576 address/port combination. In either case, the TCP session 577 initialization occurs as in the configured case. 579 5.2. DLEP Router session flow - Configured case 581 When a DLEP router implementation has the address and port 582 information for a TCP connection to a modem (obtained either via 583 configuration or via the discovery process described above), the 584 router will initialize and bind a TCP socket. This socket is used to 585 connect to the DLEP modem software. After a successful TCP connect, 586 the router implementation MUST issue a Peer Initialization signal 587 (Section 7.3) to the DLEP modem. After sending the Peer 588 Initialization, the router implementation MUST wait for receipt of a 589 Peer Initialization ACK signal (Section 7.4) from the modem. Receipt 590 of the Peer Initialization ACK signal containing a Status data item 591 (Section 8.2) with value 'Success', indicates that the modem has 592 received and processed the Peer Initialization, and the session MUST 593 transition to the 'in session' state. At this point, signals 594 regarding destinations in the network, and/or Peer Update signals 595 (Section 7.5), can flow on the DLEP session between modem and router, 596 and Heartbeat signals can begin to flow, if Heartbeats are used. The 597 'in session' state is maintained until one of the following 598 conditions occur: 600 o The session is explicitly terminated (using Peer Termination), or 602 o The session times out, based on supplied timeout values. 604 5.3. DLEP Modem session flow 606 DLEP modem implementations MUST support the discovery mechanism. 607 Therefore, the normal flow is as follows: 609 The implementation will initialize a UDP socket, binding that socket 610 to the DLEP link-local multicast address (TBD) and the DLEP well- 611 known port number (also TBD). The implementation will then 612 initialize a TCP socket, on a unicast address and port. This socket 613 is used to listen for incoming TCP connection requests. 615 When the modem implementation receives a Peer Discovery signal 616 (Section 7.1) on the UDP socket, it responds by issuing a Peer Offer 617 signal (Section 7.2) to the sender of the Peer Discovery signal. The 618 Peer Offer signal MAY contain the unicast address and port of the 619 listening TCP socket, as described above. A DLEP modem 620 implementation MAY respond with ALL address/port combinations that 621 have an active TCP listen posted. Anything other than Peer Discovery 622 signals received on the UDP socket MUST be silently dropped. 624 When the DLEP modem implementation accepts a connection via TCP, it 625 MUST wait for receipt of a Peer Initialization signal (Section 7.3), 626 sent by the router. Upon receipt and successful parsing of a Peer 627 Initialization signal, the modem MUST respond with a Peer 628 Initialization ACK signal (Section 7.4). The Peer Initialization ACK 629 signal MUST contain metric data items for ALL supported metrics. If 630 an additional metric is to be introduced, the DLEP session between 631 router and modem MUST be terminated and restarted, and the new metric 632 described in a Peer Initialization ACK signal. Once the Peer 633 Initialization signal (Section 7.3) and Peer Initialization ACK 634 signal (Section 7.4) have been exchanged, the session is transitioned 635 to the 'in session' state. As in the router case, when the 'in 636 session' state is reached, signals regarding destinations in the 637 network, and/or Peer Update signals (Section 7.5), can flow on the 638 DLEP session between modem and router, and Heartbeat signals can 639 begin to flow, if Heartbeats are used. The 'in session' state 640 persists until the session is explicitly terminated (using Peer 641 Termination), or it times out (based on timeout values). 643 5.4. Common Session Flow 645 In order to maintain the session between router and modem, periodic 646 Heartbeat signals (Section 7.14) MAY be exchanged. These signals are 647 intended to keep the session alive, and to verify bidirectional 648 connectivity between the two participants. If heartbeat signals are 649 exchanged, they do not begin until the DLEP peer session has entered 650 the 'in session' state. Each DLEP peer is responsible for the 651 creation of heartbeat signals. Receipt of any DLEP signal SHOULD 652 reset the heartbeat interval timer (i.e., valid DLEP signals take the 653 place of, and obviate the need for, Heartbeat signals). 655 DLEP also provides a Peer Update signal (Section 7.5), intended to 656 communicate some change in status (e.g., a change of layer 3 address 657 parameters, or a modem-wide link change). 659 In addition to the local (Peer level) signals above, the participants 660 will transmit DLEP signals concerning destinations in the network. 661 These signals trigger creation/maintenance/deletion of destinations 662 in the information base of the recipient. For example, a modem will 663 inform its attached router of the presence of a new destination via 664 the Destination Up signal (Section 7.9). Receipt of a Destination Up 665 causes the router to allocate the necessary resources, creating an 666 entry in the information base with the specifics (i.e. MAC Address, 667 Latency, Data Rate, etc.) of the destination. The loss of a 668 destination is communicated via the Destination Down signal 669 (Section 7.11), and changes in status to the destination (e.g., 670 varying link quality, or addressing changes) are communicated via the 671 Destination Update signal (Section 7.13). The information on a given 672 destination will persist in the router's information base until (1) a 673 Destination Down signal is received, indicating that the modem has 674 lost contact with the remote node, or (2) the router/modem session 675 terminates, indicating that the router has lost contact with its own 676 local modem. 678 Metrics can be expressed within the context of a specific destination 679 via the Destination Update signal, or on a modem-wide basis via the 680 Peer Update signal. In cases where metrics are provided at peer 681 level, the receiver MUST propagate the metrics to all entries in its 682 information base for destinations that are accessed via the 683 originator. A DLEP participant MAY send metrics both in a router/ 684 modem session context (via the Peer Update signal) and a specific 685 destination context (via Destination Update) at any time. The 686 heuristics for applying received metrics is left to implementations. 688 In addition to receiving metrics about the link, DLEP provides a 689 signal allowing a router to request a different datarate, or latency, 690 from the modem. This signal is referred to as the Link 691 Characteristics Request signal (Section 7.15), and gives the router 692 the ability to deal with requisite increases (or decreases) of 693 allocated datarate/latency in demand-based schemes in a more 694 deterministic manner. 696 6. DLEP Signal Structure and Processing 698 Communication between DLEP peers consists of a bidirectional stream 699 of signals (messages), each signal consisting of a signal header and 700 an unordered list of data items. Signal headers consist of Type and 701 Length information, while data items are encoded as TLV (Type-Length- 702 Value) structures. In this document, the data items following the 703 signal header are described as being 'contained in' the signal. 705 All integer values structures MUST be in network byte-order. 707 There is no restriction on the order of data items following a 708 signal, and the multiplicity of duplicate data items is defined by 709 the definition of the signal declared by the type in the signal 710 header. 712 If an unrecognized, or unexpected signal is received, or a received 713 signal contains unrecognized, invalid, or disallowed duplicate data 714 items, the receiving peer MUST terminate the session by issuing a 715 Peer Termination signal (Section 7.7) with a Status data item 716 (Section 8.2) containing the most relevant status code, and then 717 close the TCP connection. 719 6.1. DLEP Signal Header 721 The DLEP signal header contains the following fields: 723 0 1 2 724 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 725 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 726 | Signal Type | Length | 727 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 729 Figure 3: DLEP Signal Header 731 Signal Type: An 8-bit unsigned integer containing one of the DLEP 732 Signal Type values defined in this document. 734 Length: The length, expressed as a 16-bit unsigned integer, of all 735 of the DLEP data items associated with this signal. This length 736 does not include the length of the header itself 738 The DLEP Signal Header is immediately followed by one or more DLEP 739 data items, encoded in TLVs, as defined in this document. 741 6.2. DLEP Generic Data Item 743 All DLEP data items contain the following fields: 745 0 1 2 3 746 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 1 747 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 748 | Data Item Type| Length | Value... | 749 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 751 Figure 4: DLEP Generic Data Item 753 Data Item Type: An 8-bit unsigned integer field specifying the data 754 item being sent. 756 Length: The length, expressed as an 8-bit unsigned integer, of the 757 value field of the data item. 759 Value: A field of length which contains data specific to a 760 particular data item. 762 7. DLEP Signals 764 As mentioned above, all DLEP signals begin with the DLEP signal 765 header structure. Therefore, in the following descriptions of 766 specific signals, this header structure is assumed, and will not be 767 replicated. 769 Following is the set of MANDATORY signals that must be recognized by 770 a DLEP compliant implementation. As mentioned before, not all 771 signals may be used during a session, but an implementation MUST 772 correctly process these signals when received. 774 The mandatory DLEP signals are: 776 +--------+--------------------+----------------------+--------------+ 777 | Signal | Description | Mnemonic | Section | 778 +--------+--------------------+----------------------+--------------+ 779 | TBD | Peer Discovery | DLEP_PEER_DISCOVERY | Section 7.1 | 780 | TBD | Peer Offer | DLEP_PEER_OFFER | Section 7.2 | 781 | TBD | Peer | DLEP_PEER_INIT | Section 7.3 | 782 | | Initialization | | | 783 | TBD | Peer | DLEP_PEER_INIT_ACK | Section 7.4 | 784 | | Initialization ACK | | | 785 | TBD | Peer Update | DLEP_PEER_UPDATE | Section 7.5 | 786 | TBD | Peer Update ACK | DLEP_PEER_UPDATE_ACK | Section 7.6 | 787 | TBD | Peer Termination | DLEP_PEER_TERM | Section 7.7 | 788 | TBD | Peer Termination | DLEP_PEER_TERM_ACK | Section 7.8 | 789 | | ACK | | | 790 | TBD | Destination Up | DLEP_DEST_UP | Section 7.9 | 791 | TBD | Destination Up ACK | DLEP_DEST_UP_ACK | Section 7.10 | 792 | TBD | Destination Down | DLEP_DEST_DOWN | Section 7.11 | 793 | TBD | Destination Down | DLEP_DEST_DOWN_ACK | Section 7.12 | 794 | | ACK | | | 795 | TBD | Destination Update | DLEP_DEST_UPDATE | Section 7.13 | 796 | TBD | Heartbeat | DLEP_PEER_HEARTBEAT | Section 7.14 | 797 | TBD | Link | DLEP_LINK_CHAR_REQ | Section 7.15 | 798 | | Characteristics | | | 799 | | Request | | | 800 | TBD | Link | DLEP_LINK_CHAR_ACK | Section 7.16 | 801 | | Characteristics | | | 802 | | ACK | | | 803 +--------+--------------------+----------------------+--------------+ 805 Table 1: DLEP Signal Values 807 7.1. Peer Discovery Signal 809 A Peer Discovery signal SHOULD be sent by a router to discover DLEP 810 modems in the network. The Peer Offer signal (Section 7.2) is 811 required to complete the discovery process. Implementations MAY 812 implement their own retry heuristics in cases where it is determined 813 the Peer Discovery signal has timed out. 815 To construct a Peer Discovery signal, the Signal Type value in the 816 signal header is set to DLEP_PEER_DISCOVERY in Table 1. 818 The Peer Discovery signal MUST contain the following data item: 820 o DLEP Version (Section 8.1) 822 The Peer Discovery signal MAY contain the following data item: 824 o Peer Type (Section 8.5) 826 7.2. Peer Offer Signal 828 A Peer Offer signal MUST be sent by a DLEP modem in response to a 829 valid Peer Discovery signal (Section 7.1). 831 The Peer Offer signal MUST be sent to the unicast address of the 832 originator of the Peer Discovery signal. 834 To construct a Peer Offer signal, the Signal Type value in the signal 835 header is set to DLEP_PEER_OFFER in Table 1. 837 The Peer Offer signal MUST contain the following data item: 839 o DLEP Version (Section 8.1) 841 The Peer Offer signal MAY contain the following data item: 843 o Peer Type (Section 8.5) 845 The Peer Offer signal MAY contain one or more of any of the following 846 data items, with different values: 848 o IPv4 Connection Point (Section 8.3) 850 o IPv6 Connection Point (Section 8.4) 852 The IP Connection Point data items indicate the unicast address the 853 receiver of Peer Offer MUST use when connecting the DLEP TCP session. 854 If multiple IP Connection Point data items are present in the Peer 855 Offer signal, implementations MAY use their own heuristics to select 856 the address to connect to. If no IP Connection Point data items are 857 included in the Peer Offer signal, the receiver MUST use the origin 858 address of the signal as the IP address, and the DLEP well-known port 859 number (Section 11.7) to establish the TCP connection. 861 7.3. Peer Initialization Signal 863 A Peer Initialization signal MUST be sent by a router as the first 864 signal of the DLEP TCP session. It is sent by the router after a TCP 865 connect to an address/port combination that was obtained either via 866 receipt of a Peer Offer, or from a priori configuration. 868 If any optional extensions are supported by the implementation, they 869 MUST be enumerated in the Extensions Supported data item. If an 870 Extensions Supported data item does not exist in a Peer 871 Initialization signal, the receiver of the signal MUST conclude that 872 there is NO support for extensions in the sender. 874 If any experimental signals or data items are used by the 875 implementation, they MUST be enumerated in one or more Experimental 876 Definition data items. If there are no Experimental Definition data 877 items in a Peer Initialization signal, the receiver of the signal 878 MUST conclude that no experimental definitions are in use by the 879 sender. 881 Implementations supporting the Heartbeat Interval (Section 8.6) 882 should understand that heartbeats are not fully established until 883 receipt of Peer Initialization ACK Signal (Section 7.4), and should 884 therefore implement their own timeout and retry heuristics for this 885 signal. 887 To construct a Peer Initialization signal, the Signal Type value in 888 the signal header is set to DLEP_PEER_INIT in Table 1. 890 The Peer Initialization signal MUST contain one of each of the 891 following data items: 893 o DLEP Version (Section 8.1) 895 o Heartbeat Interval (Section 8.6) 897 The Peer Initialization signal MAY contain one of each of the 898 following data items: 900 o Peer Type (Section 8.5) 902 o Extensions Supported (Section 8.7) 904 The Peer Initialization signal MAY contain one or more of any of the 905 following data items, with different values: 907 o Experimental Definition (Section 8.8) 909 A Peer Initialization signal MUST be acknowledged by the receiver 910 issuing a Peer Initialization ACK signal (Section 7.4). 912 7.4. Peer Initialization ACK Signal 914 A Peer Initialization ACK signal MUST be sent in response to a 915 received Peer Initialization signal (Section 7.3). The Peer 916 Initialization ACK signal completes the DLEP session establishment; 917 the sender of the signal should transition to an 'in-session' state 918 when the signal is sent, and the receiver should transition to the 919 'in-session' state upon receipt (and successful parsing) of an 920 acceptable Peer Initialization ACK signal. 922 All supported metric data items MUST be included in the Peer 923 Initialization ACK signal, with default values to be used on a 924 'modem-wide' basis. This can be viewed as the modem 'declaring' all 925 supported metrics at DLEP session initialization. Receipt of any 926 DLEP signal containing a metric data item NOT included in the Peer 927 Initialization ACK signal MUST be treated as an error, resulting in 928 the termination of the DLEP session between router and modem. 930 If any optional extensions are supported by the modem, they MUST be 931 enumerated in the Extensions Supported data item. If an Extensions 932 Supported data item does NOT exist in a Peer Initialization ACK 933 signal, the receiver of the signal MUST conclude that there is NO 934 support for extensions in the sender. 936 If any experimental signals or data items are used by the 937 implementation, they MUST be enumerated in one or more Experimental 938 Definition data items. If there are no Experimental Definition data 939 items in a Peer Initialization ACK signal, the receiver of the signal 940 MUST conclude that NO experimental definitions are in use by the 941 sender. 943 After the Peer Initialization/Peer Initialization ACK signals have 944 been successfully exchanged, implementations MUST only use extensions 945 and experimental definitions that are supported by BOTH peers. 947 To construct a Peer Initialization ACK signal, the Signal Type value 948 in the signal header is set to DLEP_PEER_INIT_ACK in Table 1. 950 The Peer Initialization ACK signal MUST contain one of each of the 951 following data items: 953 o DLEP Version (Section 8.1) 955 o Heartbeat Interval (Section 8.6) 957 o Maximum Data Rate (Receive) (Section 8.14) 959 o Maximum Data Rate (Transmit) (Section 8.15) 961 o Current Data Rate (Receive) (Section 8.16) 963 o Current Data Rate (Transmit) (Section 8.17) 965 o Latency (Section 8.18) 966 The Peer Initialization ACK signal MUST contain one of each of the 967 following data items, if the data item will be used during the 968 lifetime of the session: 970 o Resources (Receive) (Section 8.19) 972 o Resources (Transmit) (Section 8.20) 974 o Relative Link Quality (Receive) (Section 8.21) 976 o Relative Link Quality (Transmit) (Section 8.22) 978 The Peer Initialization ACK signal MAY contain one of each of the 979 following data items: 981 o Status (Section 8.2) 983 o Peer Type (Section 8.5) 985 o Extensions Supported (Section 8.7) 987 The Peer Initialization ACK signal MAY contain one or more of any of 988 the following data items, with different values: 990 o Experimental Definition (Section 8.8) 992 7.5. Peer Update Signal 994 A Peer Update signal MAY be sent by a DLEP peer to indicate local 995 Layer 3 address changes, or metric changes on a modem-wide basis. 996 For example, addition of an IPv4 address to the router MAY prompt a 997 Peer Update signal to its attached DLEP modems. Also, for example, a 998 modem that changes its Maximum Data Rate (Receive) for all 999 destinations MAY reflect that change via a Peer Update signal to its 1000 attached router(s). 1002 Concerning Layer 3 addresses, if the modem is capable of 1003 understanding and forwarding this information (via proprietary 1004 mechanisms), the address update would prompt any remote DLEP modems 1005 (DLEP-enabled modems in a remote node) to issue a Destination Update 1006 signal (Section 7.13) to their local routers with the new (or 1007 deleted) addresses. Modems that do not track Layer 3 addresses 1008 SHOULD silently parse and ignore Layer 3 data items. The Peer Update 1009 Signal MUST be acknowledged with a Peer Update ACK signal 1010 (Section 7.6). 1012 If metrics are supplied with the Peer Update signal (e.g., Maximum 1013 Data Rate), these metrics are considered to be modem-wide, and 1014 therefore MUST be applied to all destinations in the information base 1015 associated with the router/modem session. 1017 Supporting implementations are free to employ heuristics to 1018 retransmit Peer Update signals. The sending of Peer Update signals 1019 for Layer 3 address changes SHOULD cease when either participant 1020 (router or modem) determines that the other implementation does NOT 1021 support Layer 3 address tracking. 1023 To construct a Peer Update signal, the Signal Type value in the 1024 signal header is set to DLEP_PEER_UPDATE in Table 1. 1026 The Peer Update signal MAY contain one of each of the following data 1027 items: 1029 o Maximum Data Rate (Receive) (Section 8.14) 1031 o Maximum Data Rate (Transmit) (Section 8.15) 1033 o Current Data Rate (Receive) (Section 8.16) 1035 o Current Data Rate (Transmit) (Section 8.17) 1037 o Latency (Section 8.18) 1039 o Resources (Receive) (Section 8.19) 1041 o Resources (Transmit) (Section 8.20) 1043 o Relative Link Quality (Receive) (Section 8.21) 1045 o Relative Link Quality (Transmit) (Section 8.22) 1047 The Peer Update signal MAY contain one or more of the following data 1048 items, with different values: 1050 o IPv4 Address (Section 8.10) 1052 o IPv6 Address (Section 8.11) 1054 A Peer Update signal MUST be acknowledged by the receiver issuing a 1055 Peer Update ACK signal (Section 7.6). 1057 7.6. Peer Update ACK Signal 1059 A Peer Update ACK signal MUST be sent by implementations to indicate 1060 whether a Peer Update signal (Section 7.5) was successfully received. 1062 To construct a Peer Update ACK signal, the Signal Type value in the 1063 signal header is set to DLEP_PEER_UPDATE_ACK in Table 1. 1065 The Peer Update ACK signal MAY contain one of each of the following 1066 data items: 1068 o Status (Section 8.2) 1070 A receiver of a Peer Update ACK signal without a Status data item 1071 MUST behave as if a Status data item with code 'Success' had been 1072 received. 1074 7.7. Peer Termination Signal 1076 A Peer Termination signal MUST be sent by a DLEP participant when the 1077 router/modem session needs to be terminated. Implementations 1078 receiving a Peer Termination signal MUST send a Peer Termination ACK 1079 signal (Section 7.8) to confirm the termination process. 1081 The receiver of a Peer Termination signal MUST release all resources 1082 allocated for the router/modem session, and MUST eliminate all 1083 destinations in the information base accessible via the router/modem 1084 pair represented by the session. Router and modem state machines are 1085 returned to the 'discovery' state. No Destination Down signals 1086 (Section 7.11) are sent. 1088 The sender of a Peer Termination signal is free to define its 1089 heuristics in event of a timeout. It may resend the Peer Termination 1090 or free resources and return to the 'discovery' state. 1092 To construct a Peer Termination signal, the Signal Type value in the 1093 signal header is set to DLEP_PEER_TERM in Table 1. 1095 The Peer Termination signal MAY contain one of each of the following 1096 data items: 1098 o Status (Section 8.2) 1100 A receiver of a Peer Termination signal without a Status data item 1101 MUST behave as if a Status of 'Unknown reason for Peer Termination' 1102 has been received. 1104 A Peer Termination signal MUST be acknowledged by the receiver 1105 issuing a Peer Termination ACK signal (Section 7.8). 1107 7.8. Peer Termination ACK Signal 1109 A Peer Termination ACK signal MUST be sent by a DLEP peer in response 1110 to a received Peer Termination signal (Section 7.7). Receipt of a 1111 Peer Termination ACK signal completes the teardown of the router/ 1112 modem session. 1114 To construct a Peer Termination ACK signal, the Signal Type value in 1115 the signal header is set to DLEP_PEER_TERM_ACK in Table 1. 1117 The Peer Termination ACK signal MAY contain one of each of the 1118 following data items: 1120 o Status (Section 8.2) 1122 A receiver of a Peer Termination ACK signal without a Status data 1123 item MUST behave as if a Status data item with status code 'Success', 1124 implying graceful termination, had been received. 1126 7.9. Destination Up Signal 1128 A Destination Up signal can be sent either by the modem, to indicate 1129 that a new remote node has been detected, or by the router, to 1130 indicate the presence of a new logical destination (e.g., a Multicast 1131 group) in the network. 1133 A Destination Up signal MUST be acknowledged by the receiver issuing 1134 a Destination Up ACK signal (Section 7.10). The sender of the 1135 Destination Up signal is free to define its retry heuristics in event 1136 of a timeout. When a Destination Up signal is received and 1137 successfully processed, the receiver should add knowledge of the new 1138 destination to its information base, indicating that the destination 1139 is accessible via the modem/router pair. 1141 To construct a Destination Up signal, the Signal Type value in the 1142 signal header is set to DLEP_DEST_UP in Table 1. 1144 The Destination Up signal MUST contain one of each of the following 1145 data items: 1147 o MAC Address (Section 8.9) 1149 The Destination Up signal MAY contain one of each of the following 1150 data items: 1152 o Maximum Data Rate (Receive) (Section 8.14) 1154 o Maximum Data Rate (Transmit) (Section 8.15) 1155 o Current Data Rate (Receive) (Section 8.16) 1157 o Current Data Rate (Transmit) (Section 8.17) 1159 o Latency (Section 8.18) 1161 o Resources (Receive) (Section 8.19) 1163 o Resources (Transmit) (Section 8.20) 1165 o Relative Link Quality (Receive) (Section 8.21) 1167 o Relative Link Quality (Transmit) (Section 8.22) 1169 The Destination Up signal MAY contain one or more of the following 1170 data items, with different values: 1172 o IPv4 Address (Section 8.10) 1174 o IPv6 Address (Section 8.11) 1176 o IPv4 Attached Subnet (Section 8.12) 1178 o IPv6 Attached Subnet (Section 8.13) 1180 If the sender has IPv4 and/or IPv6 address information for a 1181 destination it SHOULD include the relevant data items in the 1182 Destination Up signal, reducing the need for the receiver to probe 1183 for any address. 1185 7.10. Destination Up ACK Signal 1187 A DLEP participant MUST send a Destination Up ACK signal to indicate 1188 whether a Destination Up signal (Section 7.9) was successfully 1189 processed. 1191 To construct a Destination Up ACK signal, the Signal Type value in 1192 the signal header is set to DLEP_DEST_UP_ACK in Table 1. 1194 The Destination Up ACK signal MUST contain one of each of the 1195 following data items: 1197 o MAC Address (Section 8.9) 1199 The Destination Up ACK signal MAY contain one of each of the 1200 following data items: 1202 o Status (Section 8.2) 1203 A receiver of a Destination Up ACK signal without a Status data item 1204 MUST behave as if a Status data item with status code 'Success' had 1205 been received. Implementations are free to define retry heuristics 1206 when receiving a Destination Up ACK signal indicating an error. 1208 7.11. Destination Down Signal 1210 A DLEP peer MUST send a Destination Down signal to report when a 1211 destination (a remote node or a multicast group) is no longer 1212 reachable. A Destination Down ACK signal (Section 7.12) MUST be sent 1213 by the recipient of a Destination Down signal to confirm that the 1214 relevant data has been removed from the information base. The sender 1215 of the Destination Down signal is free to define its retry heuristics 1216 in event of a timeout. 1218 To construct a Destination Down signal, the Signal Type value in the 1219 signal header is set to DLEP_DEST_DOWN in Table 1. 1221 The Destination Down signal MUST contain one of each of the following 1222 data items: 1224 o MAC Address (Section 8.9) 1226 7.12. Destination Down ACK Signal 1228 A DLEP participant MUST send a Destination Down ACK signal to 1229 indicate whether a received Destination Down signal (Section 7.11) 1230 was successfully processed. If successfully processed, the sender of 1231 the ACK MUST have removed all entries in the information base that 1232 pertain to the referenced destination. 1234 To construct a Destination Down ACK signal, the Signal Type value in 1235 the signal header is set to DLEP_DEST_DOWN_ACK in Table 1. 1237 The Destination Down ACK signal MUST contain one of each of the 1238 following data items: 1240 o MAC Address (Section 8.9) 1242 The Destination Down ACK signal MAY contain one of each of the 1243 following data items: 1245 o Status (Section 8.2) 1247 A receiver of a Destination Down ACK signal without a Status data 1248 item MUST behave as if a Status data item with status code 'Success' 1249 had been received. Implementations are free to define retry 1250 heuristics when receiving a Destination Down ACK signal indicating an 1251 error. 1253 7.13. Destination Update Signal 1255 A DLEP participant SHOULD send the Destination Update signal when it 1256 detects some change in the information base for a given destination 1257 (remote node or multicast group). Some examples of changes that 1258 would prompt a Destination Update signal are: 1260 o Change in link metrics (e.g., Data Rates) 1262 o Layer 3 addressing change 1264 To construct a Destination Update signal, the Signal Type value in 1265 the signal header is set to DLEP_DEST_UPDATE in Table 1. 1267 The Destination Update signal MUST contain one of each of the 1268 following data items: 1270 o MAC Address (Section 8.9) 1272 The Destination Update signal MAY contain one of each of the 1273 following data items: 1275 o Maximum Data Rate (Receive) (Section 8.14) 1277 o Maximum Data Rate (Transmit) (Section 8.15) 1279 o Current Data Rate (Receive) (Section 8.16) 1281 o Current Data Rate (Transmit) (Section 8.17) 1283 o Latency (Section 8.18) 1285 o Resources (Receive) (Section 8.19) 1287 o Resources (Transmit) (Section 8.20) 1289 o Relative Link Quality (Receive) (Section 8.21) 1291 o Relative Link Quality (Transmit) (Section 8.22) 1293 The Destination Update signal MAY contain one or more of the 1294 following data items, with different values: 1296 o IPv4 Address (Section 8.10) 1297 o IPv6 Address (Section 8.11) 1299 o IPv4 Attached Subnet (Section 8.12) 1301 o IPv6 Attached Subnet (Section 8.13) 1303 7.14. Heartbeat Signal 1305 A Heartbeat signal SHOULD be sent by a DLEP participant every N 1306 seconds, where N is defined in the Heartbeat Interval data item of 1307 the Peer Initialization signal (Section 7.3) or Peer Initialization 1308 ACK signal (Section 7.4). Note that implementations setting the 1309 Heartbeat Interval to 0 effectively set the interval to an infinite 1310 value, therefore, in those cases, this signal SHOULD NOT be sent. 1312 The signal is used by participants to detect when a DLEP session 1313 partner (either the modem or the router) is no longer communicating. 1314 Participants SHOULD allow two (2) heartbeat intervals to expire with 1315 no traffic on the router/modem session before initiating DLEP session 1316 termination procedures. 1318 To construct a Heartbeat signal, the Signal Type value in the signal 1319 header is set to DLEP_PEER_HEARTBEAT in Table 1. 1321 There are no valid data items for the Heartbeat signal. 1323 7.15. Link Characteristics Request Signal 1325 The Link Characteristics Request signal MAY be sent by the router to 1326 request that the modem initiate changes for specific characteristics 1327 of the link. The request can reference either a real destination 1328 (e.g., a remote node), or a logical destination (e.g., a multicast 1329 group) within the network. 1331 The Link Characteristics Request signal MAY contain either a Current 1332 Data Rate (CDRR or CDRT) data item to request a different datarate 1333 than what is currently allocated, a Latency data item to request that 1334 traffic delay on the link not exceed the specified value, or both. A 1335 Link Characteristics ACK signal (Section 7.16) is required to 1336 complete the request. Issuing a Link Characteristics Request with 1337 ONLY the MAC Address data item is a mechanism a peer MAY use to 1338 request metrics (via the Link Characteristics ACK) from its partner. 1340 The sender of a Link Characteristics Request signal MAY attach a 1341 timer to the request using the Link Characteristics ACK Timer data 1342 item. If a Link Characteristics ACK signal is received after the 1343 timer expires, the sender MUST NOT assume that the request succeeded. 1345 Implementations are free to define their retry heuristics in event of 1346 a timeout. 1348 To construct a Link Characteristics Request signal, the Signal Type 1349 value in the signal header is set to DLEP_LINK_CHAR_REQ in Table 1. 1351 The Link Characteristics Request signal MUST contain one of each of 1352 the following data items: 1354 o MAC Address (Section 8.9) 1356 The Link Characteristics Request signal MAY contain one of each of 1357 the following data items: 1359 o Link Characteristics ACK Timer (Section 8.23) 1361 o Current Data Rate (Receive) (Section 8.16) 1363 o Current Data Rate (Transmit) (Section 8.17) 1365 o Latency (Section 8.18) 1367 7.16. Link Characteristics ACK Signal 1369 A DLEP participant MUST send a Link Characteristics ACK signal to 1370 indicate whether a received Link Characteristics Request signal 1371 (Section 7.15) was successfully processed. The Link Characteristics 1372 ACK signal SHOULD contain a complete set of metric data items, and 1373 MUST contain a full set (i.e. those declared in the Peer 1374 Initialization ACK signal (Section 7.4)), if metrics were requested 1375 by only including a MAC address data item. It MUST contain the same 1376 metric types as the request. The values in the metric data items in 1377 the Link Characteristics ACK signal MUST reflect the link 1378 characteristics after the request has been processed. 1380 If an implementation is not able to alter the characteristics of the 1381 link in the manner requested, then a Status data item with status 1382 code 'Request Denied' MUST be added to the signal. 1384 To construct a Link Characteristics Request ACK signal, the Signal 1385 Type value in the signal header is set to DLEP_LINK_CHAR_ACK in 1386 Table 1. 1388 The Link Characteristics ACK signal MUST contain one of each of the 1389 following data items: 1391 o MAC Address (Section 8.9) 1392 The Link Characteristics ACK signal SHOULD contain one of each of the 1393 following data items: 1395 o Maximum Data Rate (Receive) (Section 8.14) 1397 o Maximum Data Rate (Transmit) (Section 8.15) 1399 o Current Data Rate (Receive) (Section 8.16) 1401 o Current Data Rate (Transmit) (Section 8.17) 1403 o Latency (Section 8.18) 1405 The Link Characteristics ACK signal MAY contain one of each of the 1406 following data items: 1408 o Resources (Receive) (Section 8.19) 1410 o Resources (Transmit) (Section 8.20) 1412 o Relative Link Quality (Receive) (Section 8.21) 1414 o Relative Link Quality (Transmit) (Section 8.22) 1416 o Status (Section 8.2) 1418 A receiver of a Link Characteristics ACK signal without a Status data 1419 item MUST behave as if a Status data item with status code 'Success' 1420 had been received. 1422 8. DLEP Data Items 1424 Following is the list of MANDATORY data items that must be recognized 1425 by a DLEP compliant implementation. As mentioned before, not all 1426 data items need be used during a session, but an implementation MUST 1427 correctly process these data items when correctly associated with a 1428 signal. 1430 The DLEP data items are: 1432 +------------+--------------------------------------+---------------+ 1433 | Data Item | Description | Section | 1434 +------------+--------------------------------------+---------------+ 1435 | TBD | DLEP Version | Section 8.1 | 1436 | TBD | Status | Section 8.2 | 1437 | TBD | IPv4 Connection Point | Section 8.3 | 1438 | TBD | IPv6 Connection Point | Section 8.4 | 1439 | TBD | Peer Type | Section 8.5 | 1440 | TBD | Heartbeat Interval | Section 8.6 | 1441 | TBD | Extensions Supported | Section 8.7 | 1442 | TBD | Experimental Definition | Section 8.8 | 1443 | TBD | MAC Address | Section 8.9 | 1444 | TBD | IPv4 Address | Section 8.10 | 1445 | TBD | IPv6 Address | Section 8.11 | 1446 | TBD | IPv4 Attached Subnet | Section 8.12 | 1447 | TBD | IPv6 Attached Subnet | Section 8.13 | 1448 | TBD | Maximum Data Rate (Receive) MDRR) | Section 8.14 | 1449 | TBD | Maximum Data Rate (Transmit) (MDRT) | Section 8.15 | 1450 | TBD | Current Data Rate (Receive) (CDRR) | Section 8.16 | 1451 | TBD | Current Data Rate (Transmit) (CDRT) | Section 8.17 | 1452 | TBD | Latency | Section 8.18 | 1453 | TBD | Resources (Receive) (RESR) | Section 8.19 | 1454 | TBD | Resources (Transmit) (REST) | Section 8.20 | 1455 | TBD | Relative Link Quality (Receive) | Section 8.21 | 1456 | | (RLQR) | | 1457 | TBD | Relative Link Quality (Transmit) | Section 8.22 | 1458 | | (RLQT) | | 1459 | TBD | Link Characteristics ACK Timer | Section 8.23 | 1460 +------------+--------------------------------------+---------------+ 1462 Table 2: DLEP Data Item Values 1464 8.1. DLEP Version 1466 The DLEP Version data item MUST appear in the Peer Discovery 1467 (Section 7.1), Peer Offer (Section 7.2), Peer Initialization 1468 (Section 7.3) and Peer Initialization ACK (Section 7.4) signals. The 1469 Version data item is used to indicate the version of the protocol 1470 running in the originator. A DLEP implementation SHOULD use this 1471 information to decide if the potential session partner is running at 1472 a supported level. 1474 The DLEP Version data item contains the following fields: 1476 0 1 2 3 1477 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 1478 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1479 | Data Item Type| Length | Major Version | 1480 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1481 | Minor Version | 1482 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1484 Data Item Type: TBD 1486 Length: 4 1488 Major Version: The major version of the DLEP protocol, expressed as 1489 an 16-bit unsigned integer. 1491 Minor Version: The minor version of the DLEP protocol, expressed as 1492 an 16-bit unsigned integer. 1494 Support of this draft is indicated by setting the Major Version to 1495 '1', and the Minor Version to '0' (i.e. Version 1.0). 1497 8.2. Status 1499 The Status data item MAY appear in the Peer Initialization ACK 1500 (Section 7.4), Peer Termination (Section 7.7), Peer Termination ACK 1501 (Section 7.8), Peer Update ACK (Section 7.6), Destination Up ACK 1502 (Section 7.10), Destination Down ACK (Section 7.12) and Link 1503 Characteristics ACK (Section 7.16) signals. For the Peer Termination 1504 Signal (Section 7.7), the Status data item indicates a reason for the 1505 termination. For all acknowledgement signals, the Status data item 1506 is used to indicate the success or failure of the previously received 1507 signal. 1509 The status data item includes an optional Text field that can be used 1510 to provide a textual description of the status. The use of the Text 1511 field is entirely up to the receiving implementation, i.e., it could 1512 be output to a log file or discarded. If no Text field is supplied 1513 with the Status data item, the Length field MUST be set to 1. 1515 The Status data item contains the following fields: 1517 0 1 2 3 1518 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 1519 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1520 | Data Item Type| Length | Code | Text... 1521 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1523 Data Item Type: TBD 1524 Length: 1 + Length of text 1526 Status Code: One of the codes defined below. 1528 Text: UTF-8 encoded string, describing an problem, used for 1529 implementation defined purposes. Since this field is used for a 1530 description of the problem, implementations SHOULD limit 1531 characters in this field to printable characters. Implementations 1532 receiving this data item SHOULD check for printable characters in 1533 the field. 1535 An implementation MUST NOT assume the Text field is NUL-terminated. 1537 +----------------+-------+------------------------------------------+ 1538 | Status Code | Value | Reason | 1539 +----------------+-------+------------------------------------------+ 1540 | Success | 0 | The signal was processed successfully. | 1541 | Unknown Signal | TBD | The signal was not recognized by the | 1542 | | | implementation. | 1543 | Invalid Data | TBD | One or more data items in the signal are | 1544 | | | invalid, unexpected or duplicated. | 1545 | Unexpected | TBD | The signal was not expected while the | 1546 | Signal | | machine was in this state, e.g., a Peer | 1547 | | | Initialization signal after session | 1548 | | | establishment. | 1549 | Request Denied | TBD | The receiver has not completed the | 1550 | | | request. | 1551 | Timed Out | TBD | The request could not be completed in | 1552 | | | the time allowed. | 1553 | Invalid | TBD | The destination provided in the signal | 1554 | Destination | | does not match a previously announced | 1555 | | | destination. For example, in the Link | 1556 | | | Characteristic Request ACK signal | 1557 | | | (Section 7.16). | 1558 +----------------+-------+------------------------------------------+ 1560 8.3. IPv4 Connection Point 1562 The IPv4 Connection Point data item MAY appear in the Peer Offer 1563 signal (Section 7.2). The IPv4 Connection Point data item indicates 1564 the IPv4 address and, optionally, the TCP port number on the DLEP 1565 modem available for connections. If provided, the receiver MUST use 1566 this information to perform the TCP connect to the DLEP server. 1568 The IPv4 Connection Point data item contains the following fields: 1570 0 1 2 3 1571 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 1572 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1573 | Data Item Type| Length | IPv4 Address | 1574 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1575 | IPv4 Address | TCP Port Number (optional) | 1576 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1578 Data Item Type: TBD 1580 Length: 4 (or 6 if TCP Port included) 1582 IPv4 Address: The IPv4 address listening on the DLEP modem. 1584 TCP Port Number: TCP Port number on the DLEP modem. 1586 If the Length field is 6, the port number specified MUST be used to 1587 establish the TCP session. If the TCP Port Number is omitted, i.e. 1588 the Length field is 4, the receiver MUST use the DLEP well-known port 1589 number (Section 11.7) to establish the TCP connection. 1591 8.4. IPv6 Connection Point 1593 The IPv6 Connection Point data item MAY appear in the Peer Offer 1594 signal (Section 7.2). The IPv6 Connection Point data item indicates 1595 the IPv6 address and, optionally, the TCP port number on the DLEP 1596 modem available for connections. If provided, the receiver MUST use 1597 this information to perform the TCP connect to the DLEP server. 1599 The IPv6 Connection Point data item contains the following fields: 1601 0 1 2 3 1602 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 1603 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1604 | Data Item Type| Length | IPv6 Address | 1605 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1606 | IPv6 Address | 1607 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1608 | IPv6 Address | 1609 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1610 | IPv6 Address | 1611 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1612 | IPv6 Address | TCP Port Number (optional) | 1613 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1615 Data Item Type: TBD 1617 Length: 16 (or 18 if TCP Port included) 1618 IPv6 Address: The IPv6 address listening on the DLEP modem. 1620 TCP Port Number: TCP Port number on the DLEP modem. 1622 If the Length field is 18, the port number specified MUST be used to 1623 establish the TCP session. If the TCP Port Number is omitted, i.e. 1624 the Length field is 16, the receiver MUST use the DLEP well-known 1625 port number (Section 11.7) to establish the TCP connection. 1627 8.5. Peer Type 1629 The Peer Type data item MAY appear in the Peer Discovery 1630 (Section 7.1), Peer Offer (Section 7.2), Peer Initialization 1631 (Section 7.3) and Peer Initialization ACK (Section 7.4) signals. The 1632 Peer Type data item is used by the router and modem to give 1633 additional information as to its type. The peer type is a string and 1634 is envisioned to be used for informational purposes (e.g., as output 1635 in a display command). 1637 The Peer Type data item contains the following fields: 1639 0 1 2 3 1640 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 1641 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1642 | Data Item Type| Length | Peer Type | 1643 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1645 Data Item Type: TBD 1647 Length: Length of peer type string. 1649 Peer Type: UTF-8 encoded string. For example, a satellite modem 1650 might set this variable to "Satellite terminal". Since this data 1651 item is intended to provide additional information for display 1652 commands, sending implementations SHOULD limit the data to 1653 printable characters, and receiving implmentations SHOULD check 1654 the data for printable characters. 1656 An implementation MUST NOT assume the Peer Type field is NUL- 1657 terminated. 1659 8.6. Heartbeat Interval 1661 The Heartbeat Interval data item MUST appear in both the Peer 1662 Initialization (Section 7.3) and Peer Initialization ACK 1663 (Section 7.4) signals to indicate the Heartbeat timeout window to be 1664 used by the sender. 1666 The Interval is used to specify a period (in seconds) for Heartbeat 1667 signals (Section 7.14). By specifying an Interval value of 0, 1668 implementations MAY indicate the desire to disable Heartbeat signals 1669 entirely (i.e., the Interval is set to an infinite value). However, 1670 it is strongly recommended that implementations use non-0 timer 1671 values. Implementations MUST implement heuristics such that DLEP 1672 signals sent/received reset the timer interval. 1674 A DLEP session will be considered inactive, and MUST be torn down, 1675 via the Peer Termination procedure, by an implementation detecting 1676 that two (2) Heartbeat intervals have transpired without receipt of 1677 any DLEP signals. 1679 The Heartbeat Interval data item contains the following fields: 1681 0 1 2 3 1682 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 1683 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1684 | Data Item Type| Length | Interval | 1685 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1687 Data Item Type: TBD 1689 Length: 2 1691 Interval: 0 = Do NOT use heartbeats on this DLEP session. Non-zero 1692 = Interval, in seconds, for heartbeat signals. 1694 8.7. Extensions Supported 1696 The Extensions Supported data item MAY be used in both the Peer 1697 Initialization and Peer Initialization ACK signals. The Extensions 1698 Supported data item is used by the router and modem to negotiate 1699 additional optional functionality they are willing to support. The 1700 Extensions List is a concatenation of the types of each supported 1701 extension, found in the IANA DLEP Extensions repository. 1703 The Extensions Supported data item contains the following fields: 1705 0 1 2 3 1706 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 1707 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1708 | Data Item Type| Length | Extensions List | 1709 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1711 Data Item Type: TBD 1713 Length: Number of Extensions supported. 1715 Extension List: A list of extensions supported, identified by their 1716 1-octet value as listed in the extensions registry. 1718 8.8. Experimental Definition 1720 The Experimental Definition data item MAY be used in both the Peer 1721 Initialization and Peer Initialization ACK signals. The Experimental 1722 Definition data item is used by the router and modem to indicate the 1723 formats to be used for experimental signals and data items for the 1724 given peer session. The formats are identified by using a string 1725 that matches the 'name' given to the experiment. 1727 The Experimental Definition item contains the following fields: 1729 0 1 2 3 1730 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 1731 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1732 | Data Item Type| Length | Experiment Name | 1733 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1735 Data Item Type: TBD 1737 Length: Length of the name string for the Experiment. 1739 Experiment Name: UTF-8 encoded string, containing the name of the 1740 experiment being implemented. 1742 An implementation receiving this data item MUST compare the received 1743 string to a list of experiments that it supports. 1745 An implementation MUST NOT assume the Experiment Name field is NUL- 1746 terminated. 1748 8.9. MAC Address 1750 The MAC address data item MUST appear in all destination-oriented 1751 signals (i.e., Destination Up (Section 7.9), Destination Up ACK 1752 (Section 7.10), Destination Down (Section 7.11), Destination Down ACK 1753 (Section 7.12), Destination Update (Section 7.13), Link 1754 Characteristics Request (Section 7.15), and Link Characteristics ACK 1755 (Section 7.16)). The MAC Address data item contains the address of 1756 the destination on the remote node. The MAC address MAY be either a 1757 physical or a virtual destination, and MAY be expressed in EUI-48 or 1758 EUI-64 format. Examples of a virtual destination would be a 1759 multicast MAC address, or the broadcast MAC (FF:FF:FF:FF:FF:FF). 1761 0 1 2 3 1762 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 1763 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1764 | Data Item Type| Length | MAC Address | 1765 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1766 | MAC Address | 1767 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1768 | MAC Address | 1769 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1771 Data Item Type: TBD 1773 Length: 6 for EUI-48 format, or 8 for EUI-64 format 1775 MAC Address: MAC Address of the destination. 1777 8.10. IPv4 Address 1779 The IPv4 Address data item MAY appear in the Peer Update 1780 (Section 7.5), Destination Up (Section 7.9) and Destination Update 1781 (Section 7.13) signals. When included in Destination signals, this 1782 data item contains the IPv4 address of the destination. When 1783 included in the Peer Update signal, this data item contains the IPv4 1784 address of the peer. In either case, the data item also contains an 1785 indication of whether this is a new or existing address, or is a 1786 deletion of a previously known address. 1788 The IPv4 Address data item contains the following fields: 1790 0 1 2 3 1791 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 1792 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1793 | Data Item Type| Length | Add/Drop | IPv4 Address | 1794 | | | Indicator | | 1795 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1796 | IPv4 Address | 1797 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1799 Data Item Type: TBD 1801 Length: 5 1803 Add/Drop: Value indicating whether this is a new or existing address 1804 (1), or a withdrawal of an address (0). Values other than 0 or 1 1805 MUST be considered as invalid. 1807 IPv4 Address: The IPv4 address of the destination or peer. 1809 8.11. IPv6 Address 1811 The IPv6 Address data item MAY appear in the Peer Update 1812 (Section 7.5), Destination Up (Section 7.9) and Destination Update 1813 (Section 7.13) signals. When included in Destination signals, this 1814 data item contains the IPv6 address of the destination. When 1815 included in the Peer Update signal, this data item contains the IPv6 1816 address of the peer. In either case, the data item also contains an 1817 indication of whether this is a new or existing address, or is a 1818 deletion of a previously known address. 1820 The IPv6 Address data item contains the following fields: 1822 0 1 2 3 1823 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 1824 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1825 | Data Item Type| Length | Add/Drop | IPv6 Address | 1826 | | | Indicator | | 1827 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1828 | IPv6 Address | 1829 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1830 | IPv6 Address | 1831 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1832 | IPv6 Address | 1833 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1834 | IPv6 Address | 1835 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1837 Data Item Type: TBD 1839 Length: 17 1841 Add/Drop: Value indicating whether this is a new or existing address 1842 (1), or a withdrawal of an address (0). Values other than 0 or 1 1843 MUST be considered as invalid. 1845 IPv6 Address: IPv6 Address of the destination or peer. 1847 8.12. IPv4 Attached Subnet 1849 The DLEP IPv4 Attached Subnet allows a device to declare that it has 1850 an IPv4 subnet (e.g., a stub network) attached, or that it has become 1851 aware of an IPv4 subnet being present at a remote destination. The 1852 IPv4 Attached Subnet data item MAY appear in the Destination Up 1853 (Section 7.9) and Destination Update (Section 7.13) signals. Once an 1854 IPv4 Subnet has been declared on a device, the declaration can NOT be 1855 withdrawn without terminating the destination (via the Destination 1856 Down signal (Section 7.11)) and re-issuing the Destination Up signal. 1858 The DLEP IPv4 Attached Subnet data item contains the following 1859 fields: 1861 0 1 2 3 1862 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 1863 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1864 |Data Item Type | Length | IPv4 Attached Subnet | 1865 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1866 | IPv4 Attached Subnet | Prefix Len. | 1867 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1869 Data Item Type: TBD 1871 Length: 5 1873 IPv4 Subnet: The IPv4 subnet reachable at the destination. 1875 Prefix Length: Length of the prefix (1-32) for the IPv4 subnet. A 1876 prefix length outside the speficied range MUST be considered as 1877 invalid. 1879 8.13. IPv6 Attached Subnet 1881 The DLEP IPv6 Attached Subnet allows a device to declare that it has 1882 an IPv6 subnet (e.g., a stub network) attached, or that it has become 1883 aware of an IPv6 subnet being present at a remote destination. The 1884 IPv6 Attached Subnet data item MAY appear in the Destination Up 1885 (Section 7.9) and Destination Update (Section 7.13) signals. As in 1886 the case of the IPv4 attached Subnet data item above, once an IPv6 1887 attached subnet has been declared, it can NOT be withdrawn without 1888 terminating the destination (via the Destination Down signal 1889 (Section 7.11)) and re-issuing the Destination Up signal. 1891 The DLEP IPv6 Attached Subnet data item contains the following 1892 fields: 1894 0 1 2 3 1895 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 1896 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1897 | Data Item Type| Length | IPv6 Attached Subnet | 1898 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1899 | IPv6 Attached Subnet | 1900 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1901 | IPv6 Attached Subnet | 1902 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1903 | IPv6 Attached Subnet | 1904 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1905 | IPv6 Attached Subnet | Prefix Len. | 1906 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1908 Data Item Type: TBD 1910 Length: 17 1912 IPv4 Subnet: The IPv6 subnet reachable at the destination. 1914 Prefix Length: Length of the prefix (1-128) for the IPv6 subnet. A 1915 prefix length outside the specified range MUST be considered as 1916 invalid. 1918 8.14. Maximum Data Rate (Receive) 1920 The Maximum Data Rate (Receive) (MDRR) data item MUST appear in the 1921 Peer Initialization ACK signal (Section 7.4), and MAY appear in the 1922 Peer Update (Section 7.5), Destination Up (Section 7.9), Destination 1923 Update (Section 7.13) and Link Characteristics ACK (Section 7.16) 1924 signals to indicate the maximum theoretical data rate, in bits per 1925 second, that can be achieved while receiving data on the link. 1927 The Maximum Data Rate (Receive) data item contains the following 1928 fields: 1930 0 1 2 3 1931 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 1932 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1933 | Data Item Type| Length | MDRR (bps) | 1934 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1935 | MDRR (bps) | 1936 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1937 | MDRR (bps) | 1938 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1940 Data Item Type: TBD 1941 Length: 8 1943 Maximum Data Rate (Receive): A 64-bit unsigned integer, representing 1944 the maximum theoretical data rate, in bits per second (bps), that 1945 can be achieved while receiving on the link. 1947 8.15. Maximum Data Rate (Transmit) 1949 The Maximum Data Rate (Transmit) (MDRT) data item MUST appear in the 1950 Peer Initialization ACK signal (Section 7.4), and MAY appear in the 1951 Peer Update (Section 7.5), Destination Up (Section 7.9), Destination 1952 Update (Section 7.13) and Link Characteristics ACK (Section 7.16) 1953 signals to indicate the maximum theoretical data rate, in bits per 1954 second, that can be achieved while transmitting data on the link. 1956 The Maximum Data Rate (Transmit) data item contains the following 1957 fields: 1959 0 1 2 3 1960 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 1961 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1962 | Data Item Type| Length | MDRT (bps) | 1963 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1964 | MDRT (bps) | 1965 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1966 | MDRT (bps) | 1967 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1969 Data Item Type: TBD 1971 Length: 8 1973 Maximum Data Rate (Transmit): A 64-bit unsigned integer, 1974 representing the maximum theoretical data rate, in bits per second 1975 (bps), that can be achieved while transmitting on the link. 1977 8.16. Current Data Rate (Receive) 1979 The Current Data Rate (Receive) (CDRR) data item MUST appear in the 1980 Peer Initialization ACK signal (Section 7.4), and MAY appear in the 1981 Peer Update (Section 7.5), Destination Up (Section 7.9), Destination 1982 Update (Section 7.13) and Link Characteristics ACK (Section 7.16) 1983 signals to indicate the rate at which the link is currently operating 1984 for receiving traffic. 1986 When used in the Link Characteristics Request signal (Section 7.15), 1987 CDRR represents the desired receive rate, in bits per second, on the 1988 link. 1990 The Current Data Rate (Receive) data item contains the following 1991 fields: 1993 0 1 2 3 1994 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 1995 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1996 | Data Item Type| Length | CDRR (bps) | 1997 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1998 | CDRR (bps) | 1999 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2000 | CDRR (bps) | 2001 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2003 Data Item Type: TBD 2005 Length: 8 2007 Current Data Rate (Receive): A 64-bit unsigned integer, representing 2008 the current data rate, in bits per second, that can currently be 2009 achieved while receiving traffic on the link. 2011 If there is no distinction between current and maximum receive data 2012 rates, current data rate receive MUST be set equal to the maximum 2013 data rate receive. 2015 8.17. Current Data Rate (Transmit) 2017 The Current Data Rate Transmit (CDRT) data item MUST appear in the 2018 Peer Initialization ACK signal (Section 7.4), and MAY appear in the 2019 Peer Update (Section 7.5), Destination Up (Section 7.9), Destination 2020 Update (Section 7.13), and Link Characteristics ACK (Section 7.16) 2021 signals to indicate the rate at which the link is currently operating 2022 for transmitting traffic. 2024 When used in the Link Characteristics Request signal (Section 7.15), 2025 CDRT represents the desired transmit rate, in bits per second, on the 2026 link. 2028 The Current Data Rate (Transmit) data item contains the following 2029 fields: 2031 0 1 2 3 2032 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 2033 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2034 | Data Item Type| Length | CDRT (bps) | 2035 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2036 | CDRT (bps) | 2037 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2038 | CDRT (bps) | 2039 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2041 Data Item Type: TBD 2043 Length: 8 2045 Current Data Rate (Transmit): A 64-bit unsigned integer, 2046 representing the current data rate, in bits per second, that can 2047 currently be achieved while transmitting traffic on the link. 2049 If there is no distinction between current and maximum transmit data 2050 rates, current data rate transmit MUST be set equal to the maximum 2051 data rate transmit. 2053 8.18. Latency 2055 The Latency data item MUST appear in the Peer Initialization ACK 2056 signal (Section 7.4), and MAY appear in the Peer Update 2057 (Section 7.5), Destination Up (Section 7.9), Destination Update 2058 (Section 7.13), and Link Characteristics ACK (Section 7.16) signals 2059 to indicate the amount of latency, in microseconds, on the link. 2061 When used in the Link Characteristics Request signal (Section 7.15), 2062 Latency represents the maximum latency desired on the link. 2064 The Latency value is reported as delay. The calculation of latency 2065 is implementation dependent. For example, the latency may be a 2066 running average calculated from the internal queuing. 2068 0 1 2 3 2069 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 2070 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2071 | Data Item Type| Length | Latency | 2072 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2073 | Latency (cont.) | 2074 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2075 | Latency (cont.) | 2076 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2078 Data Item Type: TBD 2079 Length: 8 2081 Latency: A 64-bit unsigned integer, representing the transmission 2082 delay, in microseconds, that a packet encounters as it is 2083 transmitted over the link. 2085 8.19. Resources (Receive) 2087 The Resources (Receive) (RESR) data item MAY appear in the Peer 2088 Initialization ACK signal (Section 7.4), Peer Update (Section 7.5), 2089 Destination Up (Section 7.9), Destination Update (Section 7.13) and 2090 Link Characteristics ACK (Section 7.16) signals to indicate the 2091 amount of resources for reception (with 0 meaning 'no resources 2092 available', and 100 meaning 'all resources available') at the 2093 destination. The list of resources that might be considered is 2094 beyond the scope of this document, and is left to implementations to 2095 decide. 2097 The Resources (Receive) data item contains the following fields: 2099 0 1 2 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 2101 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2102 | Data Item Type| Length | RESR | 2103 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2105 Data Item Type: TBD 2107 Length: 1 2109 Resources (Receive): An 8-bit integer percentage, 0-100, 2110 representing the amount of resources allocated to receiving data. 2111 Any value greater than 100 MUST be considered as invalid. 2113 If a device cannot calculate RESR, this data item SHOULD NOT be 2114 issued. 2116 8.20. Resources (Transmit) 2118 The Resources (Transmit) (REST) data item MAY appear in the Peer 2119 Initialization ACK signal (Section 7.4), Peer Update (Section 7.5), 2120 Destination Up (Section 7.9), Destination Update (Section 7.13) and 2121 Link Characteristics ACK (Section 7.16) signals to indicate the 2122 amount of resources for transmission (with 0 meaning 'no resources 2123 available', and 100 meaning 'all resources available') at the 2124 destination. The list of resources that might be considered is 2125 beyond the scope of this document, and is left to implementations to 2126 decide. 2128 The Resources (Transmit) data item contains the following fields: 2130 0 1 2 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 2132 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2133 | Data Item Type| Length | REST | 2134 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2136 Data Item Type: TBD 2138 Length: 1 2140 Resources (Transmit): An 8-bit integer percentage, 0-100, 2141 representing the amount of resources allocated to transmitting 2142 data. Any value greater than 100 MUST be considered as invalid. 2144 If a device cannot calculate REST, this data item SHOULD NOT be 2145 issued. 2147 8.21. Relative Link Quality (Receive) 2149 The Relative Link Quality (Receive) (RLQR) data item MAY appear in 2150 the Peer Initialization ACK signal (Section 7.4), Peer Update 2151 (Section 7.5), Destination Up (Section 7.9), Destination Update 2152 (Section 7.13) and Link Characteristics ACK (Section 7.16) signals to 2153 indicate the quality of the link for receiving data. 2155 The Relative Link Quality (Receive) data item contains the following 2156 fields: 2158 0 1 2 2159 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 2160 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2161 | Data Item Type| Length | RLQR | 2162 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2164 Data Item Type: TBD 2166 Length: 1 2168 Relative Link Quality (Receive): A non-dimensional 8-bit integer, 2169 0-100, representing relative link quality. A value of 100 2170 represents a link of the highest quality. Any value greater than 2171 100 MUST be considered as invalid. 2173 If a device cannot calculate the RLQR, this data item SHOULD NOT be 2174 issued. 2176 8.22. Relative Link Quality (Transmit) 2178 The Relative Link Quality (Transmit) (RLQT) data item MAY appear in 2179 the Peer Initialization ACK signal (Section 7.4), Peer Update 2180 (Section 7.5), Destination Up (Section 7.9), Destination Update 2181 (Section 7.13) and Link Characteristics ACK (Section 7.16) signals to 2182 indicate the quality of the link for transmitting data. 2184 The Relative Link Quality (Transmit) data item contains the following 2185 fields: 2187 0 1 2 2188 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 2189 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2190 | Data Item Type| Length | RLQT | 2191 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2193 Data Item Type: TBD 2195 Length: 1 2197 Relative Link Quality (Transmit): A non-dimensional 8-bit integer, 2198 0-100, representing relative link quality. A value of 100 2199 represents a link of the highest quality. Any value greater than 2200 100 MUST be considered as invalid. 2202 If a device cannot calculate the RLQT, this data item SHOULD NOT be 2203 issued. 2205 8.23. Link Characteristics ACK Timer 2207 The Link Characteristics ACK Timer data item MAY appear in the Link 2208 Characteristics Request signal (Section 7.15) to indicate the desired 2209 number of seconds the sender will wait for a response to the request. 2210 If this data item is omitted, implementations supporting the Link 2211 Characteristics Request SHOULD choose a default value. 2213 The Link Characteristics ACK Timer data item contains the following 2214 fields: 2216 0 1 2 2217 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 2218 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2219 | Data Item Type| Length | Interval | 2220 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2222 Data Item Type: TBD 2223 Length: 1 2225 Interval: 0 = Do NOT use timeouts for this Link Characteristics 2226 request. Non-zero = Interval, in seconds, to wait before 2227 considering this Link Characteristics Request lost. 2229 9. Credit-Windowing 2231 DLEP includes an OPTIONAL Protocol Extension for a credit-windowing 2232 scheme analogous to the one documented in [RFC5578]. In this scheme, 2233 traffic between the router and modem is treated as two unidirectional 2234 windows. This document identifies these windows as the 'Modem 2235 Receive Window' (MRW), and the 'Router Receive Window' (RRW). 2237 If the OPTIONAL credit-windowing extension is used, credits MUST be 2238 granted by the receiver on a given window - that is, on the 'Modem 2239 Receive Window' (MRW), the modem is responsible for granting credits 2240 to the router, allowing it (the router) to send data to the modem. 2241 Likewise, the router is responsible for granting credits on the RRW, 2242 which allows the modem to send data to the router. 2244 Credits are managed on a destination-specific basis; that is, 2245 separate credit counts are maintained for each destination requiring 2246 the service. Credits do not apply to the DLEP session that exists 2247 between routers and modems. 2249 Credits represent the number of octets, or an increment in the number 2250 of octets, that MAY be sent on the given window. When the number of 2251 available credits reaches 0, a sender MUST stop sending data, until 2252 additional credits are supplied. 2254 If a peer is able to support the OPTIONAL credit-windowing extension 2255 then it MUST include an Extensions Supported data item (Section 8.7) 2256 including the value DLEP_EXT_CREDITS (value TBD) in the appropriate 2257 Peer Initialization or Peer Initialization ACK signal. 2259 9.1. Credit-Windowing Signals 2261 The credit-windowing extension introduces no additional DLEP signals. 2262 However, if a peer has advertised during session initialization that 2263 it supports the credit-windowing extension then the following DLEP 2264 signals MAY contain additional credit-windowing data items: 2266 9.1.1. Destination Up Signal 2268 The Destination Up signal MAY contain one of each of the following 2269 data items: 2271 o Credit Grant (Section 9.2.1) 2273 If the Destination Up signal does not contain the Credit Grant data 2274 item, credits MUST NOT be used for that destination. 2276 9.1.2. Destination Up ACK Signal 2278 If the corresponding Destination Up signal contained the Credit Grant 2279 data item, the Destination Up ACK signal MUST contain one of each of 2280 the following data items: 2282 o Credit Window Status (Section 9.2.2) 2284 9.1.3. Destination Update Signal 2286 If the corresponding Destination Up signal contained the Credit Grant 2287 data item, the Destination Update signal MUST contain one of each of 2288 the following data items: 2290 o Credit Window Status (Section 9.2.2) 2292 If the corresponding Destination Up signal contained the Credit Grant 2293 data item, the Destination Update signal MAY contain one of each of 2294 the following data items: 2296 o Credit Grant (Section 9.2.1) 2298 o Credit Request (Section 9.2.3) 2300 9.2. Credit-Windowing Data Items 2302 The credit-windowing extension introduces 3 additional data items. 2303 If a peer has advertised during session initialization that it 2304 supports the credit-windowing extension then it MUST correctly 2305 process the following data items. 2307 +------------+-----------------------+----------------+ 2308 | Data Item | Description | Section | 2309 +------------+-----------------------+----------------+ 2310 | TBD | Credit Grant | Section 9.2.1 | 2311 | TBD | Credit Window Status | Section 9.2.2 | 2312 | TBD | Credit Request | Section 9.2.3 | 2313 +------------+-----------------------+----------------+ 2315 9.2.1. Credit Grant 2317 The Credit Grant data item is sent from a DLEP participant to grant 2318 an increment to credits on a window. The Credit Grant data item MAY 2319 appear in the Destination Up (Section 7.9) and Destination Update 2320 (Section 7.13) signals. The value in a Credit Grant data item 2321 represents an increment to be added to any existing credits available 2322 on the window. Upon successful receipt and processing of a Credit 2323 Grant data item, the receiver MUST respond with a signal containing a 2324 Credit Window Status data item to report the updated aggregate values 2325 for synchronization purposes, and if initializing a new credit 2326 window, granting initial credits. 2328 In the Destination Up signal, when credits are desired, the 2329 originating peer MUST set the initial credit value of the window it 2330 controls (i.e., the Modem Receive Window, or Router Receive Window) 2331 to an initial, non-zero value. If the receiver of a Destination Up 2332 signal with a Credit Grant data item supports credits, the receiver 2333 MUST either reject the use of credits for this destination, via a 2334 Destination Up ACK response containing a Status data item 2335 (Section 8.2) with a status code of 'Request Denied', or set the 2336 initial value from the data contained in the Credit Window Status 2337 data item. If the initialization completes successfully, the 2338 receiver MUST respond to the Destination Up signal with a Destination 2339 Up ACK signal that contains a Credit Window Status data item, 2340 initializing its receive window. 2342 The Credit Grant data item contains the following fields: 2344 0 1 2 3 2345 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 2346 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2347 | Data Item Type| Length | Credit Increment | 2348 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2349 | Credit Increment | 2350 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2351 | Credit Increment | 2352 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2354 Data Item Type: TBD 2356 Length: 8 2358 Reserved: A 64-bit unsigned integer representing the additional 2359 credits to be assigned to the credit window. 2361 Since credits can only be granted by the receiver on a window, the 2362 applicable credit window (either the MRW or the RRW) is derived from 2363 the sender of the grant. The Credit Increment MUST NOT cause the 2364 window to overflow; if this condition occurs, implementations MUST 2365 set the credit window to the maximum value contained in a 64-bit 2366 quantity. 2368 9.2.2. Credit Window Status 2370 If the credit-window extension is supported by the DLEP participants 2371 (both the router and the modem), the Credit Window Status data item 2372 MUST be sent by the participant receiving a Credit Grant for a given 2373 destination. 2375 The Credit Window Status data item contains the following fields: 2377 0 1 2 3 2378 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 2379 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2380 | Data Item Type| Length | Modem Receive Window Value | 2381 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2382 | Modem Receive Window Value | 2383 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2384 | Modem Receive Window Value | Router Receive Window Value | 2385 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2386 | Router Receive Window Value | 2387 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2388 | Router Receive Window Value | 2389 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2391 Data Item Type: TBD 2393 Length: 16 2395 Modem Receive Window Value: A 64-bit unsigned integer, indicating 2396 the current number of credits available on the Modem Receive 2397 Window, for the destination referred to by the signal. 2399 Router Receive Window Value: A 64-bit unsigned integer, indicating 2400 the current number of credits available on the Router Receive 2401 Window, for the destination referred to by the signal. 2403 9.2.3. Credit Request 2405 The Credit Request data item MAY be sent from either DLEP 2406 participant, via the Destination Update signal (Section 7.13), to 2407 indicate the desire for the partner to grant additional credits in 2408 order for data transfer to proceed on the session. If the 2409 corresponding Destination Up signal (Section 7.9) for this session 2410 did NOT contain a Credit Window Status data item, indicating that 2411 credits are to be used on the session, then the Credit Request data 2412 item MUST be silently dropped by the receiver. 2414 The Credit Request data item contains the following fields: 2416 0 1 2 2417 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 2418 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2419 | Data Item Type| Length | Reserved, MUST| 2420 | | | be set to 0 | 2421 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2423 Data Item Type: TBD 2425 Length: 1 2427 Reserved: This field is currently unused and MUST be set to 0. 2429 10. Security Considerations 2431 The protocol does not contain any mechanisms for security (e.g., 2432 authentication or encryption). The protocol assumes that any 2433 security would be implemented in the underlying transport (for 2434 example, by use of TLS or some other mechanism), and is therefore 2435 outside the scope of this document. 2437 11. IANA Considerations 2439 This section specifies requests to IANA. 2441 11.1. Registrations 2443 This specification defines: 2445 o A new repository for DLEP signals, with sixteen values currently 2446 assigned. 2448 o Reservation of numbering space for Experimental DLEP signals. 2450 o A new repository for DLEP data items, with twenty-six values 2451 currently assigned. 2453 o Reservation of numbering space in the data items repository for 2454 experimental data items. 2456 o A new repository for DLEP status codes, with seven currently 2457 assigned. 2459 o A new repository for DLEP extensions, with one value currently 2460 assigned. 2462 o A request for allocation of a well-known port for DLEP TCP and UDP 2463 communication. 2465 o A request for allocation of a multicast IP address for DLEP 2466 discovery. 2468 11.2. Expert Review: Evaluation Guidelines 2470 No additional guidelines for expert review are anticipated. 2472 11.3. Signal Type Registration 2474 A new repository must be created with the values of the DLEP signals. 2476 All signal values are in the range [0..255]. 2478 Valid signals are: 2480 o Peer Discovery 2482 o Peer Offer 2484 o Peer Initialization 2486 o Peer Initialization ACK 2488 o Peer Update 2490 o Peer Update ACK 2492 o Peer Termination 2494 o Peer Termination ACK 2496 o Destination Up 2498 o Destination Up ACK 2500 o Destination Down 2502 o Destination Down ACK 2504 o Destination Update 2506 o Heartbeat 2507 o Link Characteristics Request 2509 o Link Characteristics ACK 2511 It is also requested that the repository contain space for 2512 experimental signal types. 2514 11.4. DLEP Data Item Registrations 2516 A new repository for DLEP data items must be created. 2518 All data item values are in the range [0..255]. 2520 Valid data items are: 2522 o DLEP Version 2524 o Status 2526 o IPv4 Connection Point 2528 o IPv6 Connection Point 2530 o Peer Type 2532 o Heartbeat Interval 2534 o Extensions Supported 2536 o Experimental Definition 2538 o MAC Address 2540 o IPv4 Address 2542 o IPv6 Address 2544 o IPv4 Attached Subnet 2546 o IPv6 Attached Subnet 2548 o Maximum Data Rate (Receive) 2550 o Maximum Data Rate (Transmit) 2552 o Current Data Rate (Receive) 2554 o Current Data Rate (Transmit) 2555 o Latency 2557 o Resources (Receive) 2559 o Resources (Transmit) 2561 o Relative Link Quality (Receive) 2563 o Relative Link Quality (Transmit) 2565 o Link Characteristics ACK Timer 2567 o Credit Window Status 2569 o Credit Grant 2571 o Credit Request 2573 It is also requested that the registry allocation contain space for 2574 experimental data items. 2576 11.5. DLEP Status Code Registrations 2578 A new repository for DLEP status codes must be created. 2580 All status codes are in the range [0..255]. 2582 Valid status codes are: 2584 o Success (value 0) 2586 o Unknown Signal 2588 o Invalid Data 2590 o Unexpected Signal 2592 o Request Denied 2594 o Timed Out 2596 o Invalid Destination 2598 11.6. DLEP Extensions Registrations 2600 A new repository for DLEP extensions must be created. 2602 All extension values are in the range [0..255]. 2604 Valid extensions are: 2606 o DLEP_EXT_CREDITS - Credit windowing 2608 11.7. DLEP Well-known Port 2610 It is requested that IANA allocate a well-known port number for DLEP 2611 communication. 2613 11.8. DLEP Multicast Address 2615 It is requested that IANA allocate a multicast address for DLEP 2616 discovery signals. 2618 12. Acknowledgements 2620 We would like to acknowledge and thank the members of the DLEP design 2621 team, who have provided invaluable insight. The members of the 2622 design team are: Teco Boot, Bow-Nan Cheng, John Dowdell, and Henning 2623 Rogge. 2625 We would also like to acknowledge the influence and contributions of 2626 Greg Harrison, Chris Olsen, Martin Duke, Subir Das, Jaewon Kang, 2627 Vikram Kaul, Nelson Powell and Victoria Mercieca. 2629 13. References 2631 13.1. Normative References 2633 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 2634 Requirement Levels", BCP 14, RFC 2119, March 1997. 2636 13.2. Informative References 2638 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 2639 (TLS) Protocol Version 1.2", RFC 5246, August 2008. 2641 [RFC5578] Berry, B., Ratliff, S., Paradise, E., Kaiser, T., and M. 2642 Adams, "PPP over Ethernet (PPPoE) Extensions for Credit 2643 Flow and Link Metrics", RFC 5578, February 2010. 2645 Appendix A. Peer Level Signal Flows 2647 A.1. Discovery 2648 Router Modem Signal Description 2649 ======================================================================== 2651 | Router initiates discovery, starts 2652 | a timer, send Peer Discovery 2653 |-------Peer Discovery---->|| signal. 2655 ~ ~ ~ ~ ~ ~ ~ Router discovery timer expires 2656 without receiving Peer Offer. 2658 | Router sends another Peer 2659 |-------Peer Discovery---------->| Discovery signal. 2660 | 2661 | Modem receives Peer Discovery 2662 | signal. 2663 | 2664 | Modem sends Peer Offer with 2665 |<--------Peer Offer-------------| Connection Point information. 2666 : 2667 : Router MAY cancel discovery timer 2668 : and stop sending Peer Discovery 2669 : signals. 2671 A.2. Session Initialization 2673 Router Modem Signal Description 2674 ======================================================================== 2676 | Router connects to discovered or 2677 | pre-configured Modem Connection 2678 |---------TCP connect----------> Point. 2679 | 2680 | Router sends Peer Initialization 2681 |-------Peer Initialization----->| signal. 2682 | 2683 | Modem receives Peer Initialization 2684 | signal. 2685 | 2686 | Modem sends Peer Initialization 2687 | ACK, with compatible extensions, 2688 |<----Peer Initialization ACK----| and Success status data item. 2689 | | 2690 |<<============================>>| Session established. Heartbeats 2691 : : begin. 2693 A.3. Session Initialization - Refused 2695 Router Modem Signal Description 2696 ======================================================================== 2698 | Router connects to discovered or 2699 | pre-configured Modem Connection 2700 |---------TCP connect----------> Point. 2701 | 2702 | Router sends Peer Initialization 2703 |-------Peer Initialization----->| signal. 2704 | 2705 | Modem receives Peer Initialization 2706 | signal, and will not support the 2707 | advertised version, experiment or 2708 | extensions. 2709 | 2710 | Modem sends Peer Initialization 2711 | ACK, with 'Request Denied' status 2712 |<----Peer Initialization ACK----| data item. 2713 | | 2714 | <---- TCP shutdown (send)-----| Modem closes TCP connection. 2715 | 2716 | Router receives negative Peer 2717 | Initialization ACK, closes 2718 |---------TCP close-----------> TCP connection. 2719 | 2720 ||------------------------------|| Session not started. 2722 A.4. Router Changes IP Addresses 2724 Router Modem Signal Description 2725 ======================================================================== 2727 | Router sends Peer Update signal to 2728 |--------Peer Update------------>| announce change of IP address 2729 | 2730 | Modem receives Peer Update signal 2731 | and updates internal state. 2732 | 2733 |<-------Peer Update ACK---------| Modem sends Peer Update ACK. 2735 A.5. Modem Changes Session-wide Metrics 2736 Router Modem Signal Description 2737 ======================================================================== 2739 | Modem sends Peer Update signal to 2740 | announce change of modem-wide 2741 |<--------Peer Update------------| metrics 2742 | 2743 | Router receives Peer Update signal 2744 | and updates internal state. 2745 | 2746 |-------Peer Update ACK--------->| Router sends Peer Update ACK. 2748 A.6. Router Terminates Session 2750 Router Modem Signal Description 2751 ======================================================================== 2753 | Router sends Peer Termination 2754 |-------Peer Termination-------->| signal with Status data item. 2755 | | 2756 |-------TCP shutdown (send)---> | Router stops sending signals. 2757 | 2758 | Modem receives Peer Termination, 2759 | stops counting received heartbeats 2760 | and stops sending heartbeats. 2761 | 2762 | Modem sends Peer Termination ACK 2763 |<-----Peer Termination ACK------| with Status 'Success'. 2764 | | 2765 | <----TCP shutdown (send)------| Modem stops sending signals. 2766 | 2767 ||------------------------------|| Session terminated. 2769 A.7. Modem Terminates Session 2770 Router Modem Signal Description 2771 ======================================================================== 2773 | Modem sends Peer Termination 2774 |<------Peer Termination---------| signal with Status data item. 2775 | | 2776 | <----TCP shutdown (send)------| Modem stops sending signals. 2777 | 2778 | Router receives Peer Termination, 2779 | stops counting received heartbeats 2780 | and stops sending heartbeats. 2781 | 2782 | Router sends Peer Termination ACK 2783 |------Peer Termination ACK----->| with Status 'Success'. 2784 | | 2785 |-------TCP shutdown (send)---> | Router stops sending signals. 2786 | 2787 ||------------------------------|| Session terminated. 2789 A.8. Session Heartbeats 2790 Router Modem Signal Description 2791 ======================================================================== 2793 |----------Heartbeat------------>| Router sends heartbeat signal 2794 | 2795 | Modem resets heartbeats missed 2796 | counter. 2798 ~ ~ ~ ~ ~ ~ ~ 2800 |----------[Any signal]--------->| When the Modem receives any signal 2801 | from the Router. 2802 | 2803 | Modem resets heartbeats missed 2804 | counter. 2806 ~ ~ ~ ~ ~ ~ ~ 2808 |<---------Heartbeat-------------| Modem sends heartbeat signal 2809 | 2810 | Router resets heartbeats missed 2811 | counter. 2813 ~ ~ ~ ~ ~ ~ ~ 2815 |<---------[Any signal]----------| When the Router receives any 2816 | signal from the Modem. 2817 | 2818 | Modem resets heartbeats missed 2819 | counter. 2821 A.9. Router Detects a Heartbeat timeout 2823 Router Modem Signal Description 2824 ======================================================================== 2826 ||<----------------------| Router misses a heartbeat 2828 | ||<----------------------| Router misses too many heartbeats 2829 | 2830 | 2831 |-------Peer Termination-------->| Router sends Peer Termination 2832 | signal with 'Timeout' Status 2833 | data item. 2834 : 2835 : Termination proceeds as above. 2837 A.10. Modem Detects a Heartbeat timeout 2839 Router Modem Signal Description 2840 ======================================================================== 2842 |---------------------->|| Modem misses a heartbeat 2844 |---------------------->|| | Modem misses too many heartbeats 2845 | 2846 | 2847 |<-------Peer Termination--------| Modem sends Peer Termination 2848 | signal with 'Timeout' Status 2849 | data item. 2850 : 2851 : Termination proceeds as above. 2853 Appendix B. Destination Specific Signal Flows 2855 B.1. Common Destination Signaling 2857 Router Modem Signal Description 2858 ======================================================================== 2860 | Modem detects a new logical 2861 | destination is reachable, and 2862 |<-------Destination Up----------| sends Destination Up signal. 2863 | 2864 |--------Destination Up ACK----->| Router sends Destination Up ACK. 2866 ~ ~ ~ ~ ~ ~ ~ 2867 | Modem detects change in logical 2868 | destination metrics, and sends 2869 |<-------Destination Update------| Destination Update signal. 2871 ~ ~ ~ ~ ~ ~ ~ 2872 | Modem detects change in logical 2873 | destination metrics, and sends 2874 |<-------Destination Update------| Destination Update signal. 2876 ~ ~ ~ ~ ~ ~ ~ 2877 | Modem detects logical destination 2878 | is no longer reachable, and sends 2879 |<-------Destination Down--------| Destination Down signal. 2880 | 2881 | Router receives Destination Down, 2882 | updates internal state, and sends 2883 |--------Destination Down ACK--->| Destination Down ACK signal. 2885 B.2. Multicast Destination Signaling 2887 Router Modem Signal Description 2888 ======================================================================== 2890 | Router detects a new multicast 2891 | destination is in use, and sends 2892 |--------Destination Up--------->| Destination Up signal. 2893 | 2894 | Modem updates internal state to 2895 | monitor multicast destination, and 2896 |<-------Destination Up ACK------| sends Destination Up ACK. 2898 ~ ~ ~ ~ ~ ~ ~ 2899 | Modem detects change in multicast 2900 | destination metrics, and sends 2901 |<-------Destination Update------| Destination Update signal. 2903 ~ ~ ~ ~ ~ ~ ~ 2904 | Modem detects change in multicast 2905 | destination metrics, and sends 2906 |<-------Destination Update------| Destination Update signal. 2908 ~ ~ ~ ~ ~ ~ ~ 2909 | Router detects multicast 2910 | destination is no longer in use, 2911 |--------Destination Down------->| and sends Destination Down signal. 2912 | 2913 | Modem receives Destination Down, 2914 | updates internal state, and sends 2915 |<-------Destination Down ACK----| Destination Down ACK signal. 2917 B.3. Link Characteristics Request 2918 Router Modem Signal Description 2919 ======================================================================== 2921 Destination has already been 2922 ~ ~ ~ ~ ~ ~ ~ announced by either peer. 2924 | Router requires different 2925 | Characteristics for the 2926 | destination, and sends Link 2927 |--Link Characteristics Request->| Characteristics Request signal. 2928 | 2929 | Modem attempts to adjust link 2930 | status to meet the received 2931 | request, and sends a Link 2932 | Characteristics Request ACK 2933 |<---Link Char. Request ACK------| signal with the new values. 2935 Authors' Addresses 2937 Stan Ratliff 2938 VT iDirect 2939 13861 Sunrise Valley Drive, Suite 300 2940 Herndon, VA 20171 2941 USA 2943 Email: sratliff@idirect.net 2945 Bo Berry 2947 Shawn Jury 2948 Cisco Systems 2949 170 West Tasman Drive 2950 San Jose, CA 95134 2951 USA 2953 Email: sjury@cisco.com 2955 Darryl Satterwhite 2956 Broadcom 2958 Email: dsatterw@broadcom.com 2959 Rick Taylor 2960 Airbus Defence & Space 2961 Quadrant House 2962 Celtic Springs 2963 Coedkernew 2964 Newport NP10 8FZ 2965 UK 2967 Email: rick.taylor@airbus.com