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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 12, 2015 5 S. Jury 6 Cisco Systems 7 D. Satterwhite 8 Broadcom 9 R. Taylor 10 Airbus Defence & Space 11 May 11, 2015 13 Dynamic Link Exchange Protocol (DLEP) 14 draft-ietf-manet-dlep-12 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 forwarding 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 12, 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 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) . . . . . . . . . . . . . . 42 113 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) . . . . . . . . . . . . . . . . . . . 45 117 8.20. Resources (Transmit) . . . . . . . . . . . . . . . . . . 46 118 8.21. Relative Link Quality (Receive) . . . . . . . . . . . . . 47 119 8.22. Relative Link Quality (Transmit) . . . . . . . . . . . . 47 120 8.23. Link Characteristics ACK Timer . . . . . . . . . . . . . 48 121 9. Credit-Windowing . . . . . . . . . . . . . . . . . . . . . . 48 122 9.1. Credit-Windowing Signals . . . . . . . . . . . . . . . . 49 123 9.1.1. Destination Up Signal . . . . . . . . . . . . . . . . 49 124 9.1.2. Destination Up ACK Signal . . . . . . . . . . . . . . 49 125 9.1.3. Destination Update Signal . . . . . . . . . . . . . . 49 126 9.2. Credit-Windowing Data Items . . . . . . . . . . . . . . . 50 127 9.2.1. Credit Grant . . . . . . . . . . . . . . . . . . . . 50 128 9.2.2. Credit Window Status . . . . . . . . . . . . . . . . 51 129 9.2.3. Credit Request . . . . . . . . . . . . . . . . . . . 52 130 10. Security Considerations . . . . . . . . . . . . . . . . . . . 52 131 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 53 132 11.1. Registrations . . . . . . . . . . . . . . . . . . . . . 53 133 11.2. Expert Review: Evaluation Guidelines . . . . . . . . . . 53 134 11.3. Signal Type Registration . . . . . . . . . . . . . . . . 53 135 11.4. DLEP Data Item Registrations . . . . . . . . . . . . . . 54 136 11.5. DLEP Status Code Registrations . . . . . . . . . . . . . 55 137 11.6. DLEP Extensions Registrations . . . . . . . . . . . . . 56 138 11.7. DLEP Well-known Port . . . . . . . . . . . . . . . . . . 56 139 11.8. DLEP Multicast Address . . . . . . . . . . . . . . . . . 56 140 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 56 141 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 . . . . . . . . . . . . . . . . . 57 147 A.3. Session Initialization - Refused . . . . . . . . . . . . 58 148 A.4. Router Changes IP Addresses . . . . . . . . . . . . . . . 59 149 A.5. Modem Changes Session-wide Metrics . . . . . . . . . . . 59 150 A.6. Router Terminates Session . . . . . . . . . . . . . . . . 59 151 A.7. Modem Terminates Session . . . . . . . . . . . . . . . . 60 152 A.8. Session Heartbeats . . . . . . . . . . . . . . . . . . . 60 153 A.9. Router Detects a Heartbeat timeout . . . . . . . . . . . 61 154 A.10. Modem Detects a Heartbeat timeout . . . . . . . . . . . . 62 155 Appendix B. Destination Specific Signal Flows . . . . . . . . . 62 156 B.1. Common Destination Signaling . . . . . . . . . . . . . . 62 157 B.2. Multicast Destination Signaling . . . . . . . . . . . . . 63 158 B.3. Link Characteristics Request . . . . . . . . . . . . . . 63 159 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 64 161 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 varies with respect to individual destinations on a link, 171 and with the type of traffic being sent. As an example, consider the 172 case of an 802.11g access point, serving 2 associated laptop 173 computers. In this environment, the answer to the question "What is 174 the datarate on the 802.11g 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 or serial attachment, with existing 201 protocols and techniques, routing software cannot be aware of 202 convergence events occurring on the radio link (e.g., acquisition or 203 loss of a potential routing neighbor), nor can the router be aware of 204 the actual capacity of the link. This lack of awareness, along with 205 the 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 is 338 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", "MAY", and "OPTIONAL" in this 345 document are to be interpreted as described in BCP 14, RFC 2119 346 [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 As mentioned in the introduction section of this document, DLEP 500 allows for metrics to be sent within two contexts - metrics for a 501 specific destination within the network (e.g., a specific router), 502 and 'modem-wide' (those that apply to all destinations accessed via 503 the modem). Most metrics can be further subdivided into transmit and 504 receive metrics. Metrics supplied on DLEP Peer signals are, by 505 definition, modem-wide; metrics supplied on Destination signals are, 506 by definition, used for the specific logical destination only. 508 DLEP modem implementations MUST announce all supported metric items, 509 and provide default values for those metrics, in the Peer 510 Initialization ACK signal (Section 7.4). In order to introduce a new 511 metric type, DLEP modem implementations MUST terminate the session 512 with the router (via the Peer Terminate signal (Section 7.7)), and 513 re-establish the session. 515 It is left to implementations to choose sensible default values based 516 on their specific characteristics. Modems having static (non- 517 changing) link metric characteristics MAY report metrics only once 518 for a given destination (or once on a modem-wide basis, if all 519 connections via the modem are of this static nature). 521 The approach of allowing for different contexts for metric data 522 increases both the flexibility and the complexity of using metric 523 data. This document details the mechanism whereby the data is 524 transmitted, however, the specific algorithms (precedence, etc.) for 525 utilizing the dual-context metrics is out of scope and not addressed 526 by this document. 528 4.1. Mandatory Metrics 530 As mentioned above, DLEP modem implementations MUST announce all 531 supported metric items during session initialization. However, an 532 implementation MUST include the following list of metrics: 534 o Maximum Data Rate (Receive) (Section 8.14) 536 o Maximum Data Rate (Transmit) (Section 8.15) 538 o Current Data Rate (Receive) (Section 8.16) 540 o Current Data Rate (Transmit) (Section 8.17) 542 o Latency (Section 8.18) 544 5. DLEP Session Flow 546 For routers supporting DLEP, support of Discovery is optional. 547 Discovery is initiated in the DLEP modem by sending the Peer 548 Discovery Signal (Section 7.1) to a well-known multicast address. 549 However, support for receipt and processing of the signal is optional 550 in the router (see Appendix A and B for flow diagrams of the 551 discovery signal). Due to the optional (on the router) support for 552 discovery, normal session flow is described for both the 'Discovery 553 case', and the 'Configured case'. Again, for modem implementations 554 of DLEP, support of Discovery is mandatory; therefore, that is the 555 only case to be described. 557 5.1. DLEP Router session flow - Discovery case 559 If the DLEP router implementation is utilizing the optional discovery 560 mechanism, then the implementation will initialize a UDP socket, 561 binding it to an arbitrary port. This UDP socket is used to send the 562 Peer Discovery signal (Section 7.1) to the DLEP link-local multicast 563 address and port (TBD). The implementation then waits on receipt of 564 a Peer Offer signal (Section 7.2), which MAY contain the unicast 565 address and port for TCP-based communication with a DLEP modem, via 566 the IPv4 Connection Point data item (Section 8.3) or the IPv6 567 Connection Point data item (Section 8.4). The Peer Offer signal MAY 568 contain multiple IP Connection Point data items. If more than one IP 569 Connection Point data items is in the Peer Offer, router 570 implementations MAY use their own heuristics to determine the best 571 address/port combination. If no IP Connection Point data items are 572 included in the Peer Offer signal, the receiver MUST use the origin 573 address of the signal as the IP address, and the DLEP well-known port 574 number (Section 11.7) to establish the TCP connection. At this 575 point, the router implementation MAY either destroy the UDP socket, 576 or continue to issue Peer Discovery signals to the link-local 577 address/port combination. In either case, the TCP session 578 initialization occurs as in the configured case. 580 5.2. DLEP Router session flow - Configured case 582 When a DLEP router implementation has the address and port 583 information for a TCP connection to a modem (obtained either via 584 configuration or via the discovery process described above), the 585 router will initialize and bind a TCP socket. This socket is used to 586 connect to the DLEP modem software. After a successful TCP connect, 587 the router implementation MUST issue a Peer Initialization signal 588 (Section 7.3) to the DLEP modem. After sending the Peer 589 Initialization, the router implementation MUST wait for receipt of a 590 Peer Initialization ACK signal (Section 7.4) from the modem. Receipt 591 of the Peer Initialization ACK signal containing a Status data item 592 (Section 8.2) with value 'Success', indicates that the modem has 593 received and processed the Peer Initialization, and the session MUST 594 transition to the 'in session' state. At this point, signals 595 regarding destinations in the network, and/or Peer Update signals 596 (Section 7.5), can flow on the DLEP session between modem and router, 597 and Heartbeat signals can begin to flow, if Heartbeats are used. The 598 'in session' state is maintained until one of the following 599 conditions occur: 601 o The session is explicitly terminated (using Peer Termination), or 603 o The session times out, based on supplied timeout values. 605 5.3. DLEP Modem session flow 607 DLEP modem implementations MUST support the discovery mechanism. 608 Therefore, the normal flow is as follows: 610 The implementation will initialize a UDP socket, binding that socket 611 to the DLEP link-local multicast address (TBD) and the DLEP well- 612 known port number (also TBD). The implementation will then 613 initialize a TCP socket, on a unicast address and port. This socket 614 is used to listen for incoming TCP connection requests. 616 When the modem implementation receives a Peer Discovery signal 617 (Section 7.1) on the UDP socket, it responds by issuing a Peer Offer 618 signal (Section 7.2) to the sender of the Peer Discovery signal. The 619 Peer Offer signal MAY contain the unicast address and port of the 620 listening TCP socket, as described above. A DLEP modem 621 implementation MAY respond with ALL address/port combinations that 622 have an active TCP listen posted. Anything other than Peer Discovery 623 signals received on the UDP socket MUST be silently dropped. 625 When the DLEP modem implementation accepts a connection via TCP, it 626 MUST wait for receipt of a Peer Initialization signal (Section 7.3), 627 sent by the router. Upon receipt and successful parsing of a Peer 628 Initialization signal, the modem MUST respond with a Peer 629 Initialization ACK signal (Section 7.4). The Peer Initialization ACK 630 signal MUST contain metric data items for ALL supported metrics. If 631 an additional metric is to be introduced, the DLEP session between 632 router and modem MUST be terminated and restarted, and the new metric 633 described in a Peer Initialization ACK signal. Once the Peer 634 Initialization signal (Section 7.3) and Peer Initialization ACK 635 signal (Section 7.4) have been exchanged, the session is transitioned 636 to the 'in session' state. As in the router case, when the 'in 637 session' state is reached, signals regarding destinations in the 638 network, and/or Peer Update signals (Section 7.5), can flow on the 639 DLEP session between modem and router, and Heartbeat signals can 640 begin to flow, if Heartbeats are used. The 'in session' state 641 persists until the session is explicitly terminated (using Peer 642 Termination), or it times out (based on timeout values). 644 5.4. Common Session Flow 646 In order to maintain the session between router and modem, periodic 647 Heartbeat signals (Section 7.14) MAY be exchanged. These signals are 648 intended to keep the session alive, and to verify bidirectional 649 connectivity between the two participants. If heartbeat signals are 650 exchanged, they do not begin until the DLEP peer session has entered 651 the 'in session' state. Each DLEP peer is responsible for the 652 creation of heartbeat signals. Receipt of any DLEP signal SHOULD 653 reset the heartbeat interval timer (i.e., valid DLEP signals take the 654 place of, and obviate the need for, Heartbeat signals). 656 DLEP also provides a Peer Update signal (Section 7.5), intended to 657 communicate some change in status (e.g., a change of layer 3 address 658 parameters, or a modem-wide link change). 660 In addition to the local (Peer level) signals above, the participants 661 will transmit DLEP signals concerning destinations in the network. 662 These signals trigger creation/maintenance/deletion of destinations 663 in the information base of the recipient. For example, a modem will 664 inform its attached router of the presence of a new destination via 665 the Destination Up signal (Section 7.9). Receipt of a Destination Up 666 causes the router to allocate the necessary resources, creating an 667 entry in the information base with the specifics (i.e. MAC Address, 668 Latency, Data Rate, etc.) of the destination. The loss of a 669 destination is communicated via the Destination Down signal 670 (Section 7.11), and changes in status to the destination (e.g., 671 varying link quality, or addressing changes) are communicated via the 672 Destination Update signal (Section 7.13). The information on a given 673 destination will persist in the router's information base until (1) a 674 Destination Down signal is received, indicating that the modem has 675 lost contact with the remote node, or (2) the router/modem session 676 terminates, indicating that the router has lost contact with its own 677 local modem. 679 Metrics can be expressed within the context of a specific destination 680 via the Destination Update signal, or on a modem-wide basis via the 681 Peer Update signal. In cases where metrics are provided at peer 682 level, the receiver MUST propagate the metrics to all destinations in 683 its information base that are accessed via the originator. A DLEP 684 participant MAY send metrics both in a router/modem session context 685 (via the Peer Update signal) and a specific destination context (via 686 Destination Update) at any time. The heuristics for applying 687 received metrics is left to implementations. 689 In addition to receiving metrics about the link, DLEP provides a 690 signal allowing a router to request a different datarate, or latency, 691 from the modem. This signal is referred to as the Link 692 Characteristics Request signal (Section 7.15), and gives the router 693 the ability to deal with requisite increases (or decreases) of 694 allocated datarate/latency in demand-based schemes in a more 695 deterministic manner. 697 6. DLEP Signal Processing 699 Communication between DLEP peers consists of a bidirectional stream 700 of signals (messages), each signal consisting of a signal header and 701 an unordered list of data items. Signal headers consist of Type and 702 Length information, while data items are encoded as TLV (Type-Length- 703 Value) structures. In this document, the data items following the 704 signal header are described as being 'contained in' the signal. 706 All integer values structures MUST be in network byte-order. 708 There is no restriction on the order of data items following a 709 signal, and the multiplicity of duplicate data items is defined by 710 the definition of the signal declared by the type in the signal 711 header. 713 If an unrecognized, or unexpected signal is received, or a received 714 signal contains unrecognized, invalid, or disallowed duplicate data 715 items, the receiving peer MUST terminate the session by issuing a 716 Peer Termination signal (Section 7.7) with a Status data item 717 (Section 8.2) containing the most relevant status code, and then 718 close the TCP connection. 720 6.1. DLEP Signal Header 722 The DLEP signal header contains the following fields: 724 0 1 2 725 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 726 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 727 | Signal Type | Length | 728 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 730 Figure 3: DLEP Signal Header 732 Signal Type: One of the DLEP Signal Type values defined in this 733 document. 735 Length: The length, expressed as a 16-bit unsigned integer, of all 736 of the DLEP data items associated with this signal. This length 737 does not include the length of the header itself 739 The DLEP Signal Header is immediately followed by one or more DLEP 740 data items, encoded in TLVs, as defined in this document. 742 6.2. DLEP Generic Data Item 744 All DLEP data items contain the following fields: 746 0 1 2 3 747 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 1 748 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 749 | Data Item Type| Length | Value... | 750 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 752 Figure 4: DLEP Generic Data Item 754 Data Item Type: An 8-bit unsigned integer field specifying the data 755 item being sent. 757 Length: The length, expressed as an 8-bit unsigned integer, of the 758 value field of the data item. 760 Value: A field of length which contains data specific to a 761 particular data item. 763 7. DLEP Signals 765 As mentioned above, all DLEP signals begin with the DLEP signal 766 header structure. Therefore, in the following descriptions of 767 specific signals, this header structure is assumed, and will not be 768 replicated. 770 Following is the set of MANDATORY signals that must be recognized by 771 a DLEP compliant implementation. As mentioned before, not all 772 signals may be used during a session, but an implementation MUST 773 correctly process these signals when received. 775 The mandatory DLEP signals are: 777 +--------+--------------------+----------------------+--------------+ 778 | Signal | Description | Mnemonic | Section | 779 +--------+--------------------+----------------------+--------------+ 780 | TBD | Peer Discovery | DLEP_PEER_DISCOVERY | Section 7.1 | 781 | TBD | Peer Offer | DLEP_PEER_OFFER | Section 7.2 | 782 | TBD | Peer | DLEP_PEER_INIT | Section 7.3 | 783 | | Initialization | | | 784 | TBD | Peer | DLEP_PEER_INIT_ACK | Section 7.4 | 785 | | Initialization ACK | | | 786 | TBD | Peer Update | DLEP_PEER_UPDATE | Section 7.5 | 787 | TBD | Peer Update ACK | DLEP_PEER_UPDATE_ACK | Section 7.6 | 788 | TBD | Peer Termination | DLEP_PEER_TERM | Section 7.7 | 789 | TBD | Peer Termination | DLEP_PEER_TERM_ACK | Section 7.8 | 790 | | ACK | | | 791 | TBD | Destination Up | DLEP_DEST_UP | Section 7.9 | 792 | TBD | Destination Up ACK | DLEP_DEST_UP_ACK | Section 7.10 | 793 | TBD | Destination Down | DLEP_DEST_DOWN | Section 7.11 | 794 | TBD | Destination Down | DLEP_DEST_DOWN_ACK | Section 7.12 | 795 | | ACK | | | 796 | TBD | Destination Update | DLEP_DEST_UPDATE | Section 7.13 | 797 | TBD | Heartbeat | DLEP_PEER_HEARTBEAT | Section 7.14 | 798 | TBD | Link | DLEP_LINK_CHAR_REQ | Section 7.15 | 799 | | Characteristics | | | 800 | | Request | | | 801 | TBD | Link | DLEP_LINK_CHAR_ACK | Section 7.16 | 802 | | Characteristics | | | 803 | | ACK | | | 804 +--------+--------------------+----------------------+--------------+ 806 Table 1: DLEP Signal Values 808 7.1. Peer Discovery Signal 810 A Peer Discovery signal SHOULD be sent by a router to discover DLEP 811 modems in the network. The Peer Offer signal (Section 7.2) is 812 required to complete the discovery process. Implementations MAY 813 implement their own retry heuristics in cases where it is determined 814 the Peer Discovery signal has timed out. 816 To construct a Peer Discovery signal, the Signal Type value in the 817 signal header is set to DLEP_PEER_DISCOVERY in Table 1. 819 The Peer Discovery signal MUST contain the following data item: 821 o DLEP Version (Section 8.1) 823 The Peer Discovery signal MAY contain the following data item: 825 o Peer Type (Section 8.5) 827 7.2. Peer Offer Signal 829 A Peer Offer signal MUST be sent by a DLEP modem in response to a 830 valid Peer Discovery signal (Section 7.1). 832 The Peer Offer signal MUST be sent to the unicast address of the 833 originator of the Peer Discovery signal. 835 To construct a Peer Offer signal, the Signal Type value in the signal 836 header is set to DLEP_PEER_OFFER in Table 1. 838 The Peer Offer signal MUST contain the following data item: 840 o DLEP Version (Section 8.1) 842 The Peer Offer signal MAY contain the following data item: 844 o Peer Type (Section 8.5) 846 The Peer Offer signal MAY contain one or more of any of the following 847 data items, with different values: 849 o IPv4 Connection Point (Section 8.3) 851 o IPv6 Connection Point (Section 8.4) 853 The IP Connection Point data items indicate the unicast address the 854 receiver of Peer Offer MUST use when connecting the DLEP TCP session. 855 If multiple IP Connection Point data items are present in the Peer 856 Offer signal, implementations MAY use their own heuristics to select 857 the address to connect to. If no IP Connection Point data items are 858 included in the Peer Offer signal, the receiver MUST use the origin 859 address of the signal as the IP address, and the DLEP well-known port 860 number (Section 11.7) to establish the TCP connection. 862 7.3. Peer Initialization Signal 864 A Peer Initialization signal MUST be sent by a router as the first 865 signal of the DLEP TCP session. It is sent by the router after a TCP 866 connect to an address/port combination that was obtained either via 867 receipt of a Peer Offer, or from a priori configuration. 869 If any optional extensions are supported by the implementation, they 870 MUST be enumerated in the Extensions Supported data item. If an 871 Extensions Supported data item does NOT exist in a Peer 872 Initialization signal, the receiver of the signal MUST conclude that 873 there is NO support for extensions in the sender. 875 If any experimental signals or data items are used by the 876 implementation, they MUST be enumerated in one or more Experimental 877 Definition data items. If there are no Experimental Definition data 878 items in a Peer Initialization signal, the receiver of the signal 879 MUST conclude that NO experimental definitions are in use by the 880 sender. 882 Implementations supporting the Heartbeat Interval (Section 8.6) 883 should understand that heartbeats are NOT fully established until 884 receipt of Peer Initialization ACK Signal (Section 7.4), and should 885 therefore implement their own timeout and retry heurestics for this 886 signal. 888 To construct a Peer Initialization signal, the Signal Type value in 889 the signal header is set to DLEP_PEER_INIT in Table 1. 891 The Peer Initialization signal MUST contain one of each of the 892 following data items: 894 o DLEP Version (Section 8.1) 896 o Heartbeat Interval (Section 8.6) 898 The Peer Initialization signal MAY contain one of each of the 899 following data items: 901 o Peer Type (Section 8.5) 903 o Extensions Supported (Section 8.7) 905 The Peer Initialization signal MAY contain one or more of any of the 906 following data items, with different values: 908 o Experimental Definition (Section 8.8) 910 A Peer Initialization signal MUST be acknowledged by the receiver 911 issuing a Peer Initialization ACK signal (Section 7.4). 913 7.4. Peer Initialization ACK Signal 915 A Peer Initialization ACK signal MUST be sent in response to a 916 received Peer Initialization signal (Section 7.3). The Peer 917 Initialization ACK signal completes the DLEP session establishment; 918 the sender of the signal should transition to an 'in-session' state 919 when the signal is sent, and the receiver should transition to the 920 'in-session' state upon receipt (and successful parsing) of an 921 acceptable Peer Initialization ACK signal. 923 All supported metric data items MUST be included in the Peer 924 Initialization ACK signal, with default values to be used on a 925 'modem-wide' basis. This can be viewed as the modem 'declaring' all 926 supported metrics at DLEP session initialization. Receipt of any 927 DLEP signal containing a metric data item NOT included in the Peer 928 Initialization ACK signal MUST be treated as an error, resulting in 929 the termination of the DLEP session between router and modem. 931 If any optional extensions are supported by the modem, they MUST be 932 enumerated in the Extensions Supported data item. If an Extensions 933 Supported data item does NOT exist in a Peer Initialization ACK 934 signal, the receiver of the signal MUST conclude that there is NO 935 support for extensions in the sender. 937 If any experimental signals or data items are used by the 938 implementation, they MUST be enumerated in one or more Experimental 939 Definition data items. If there are no Experimental Definition data 940 items in a Peer Initialization ACK signal, the receiver of the signal 941 MUST conclude that NO experimental definitions are in use by the 942 sender. 944 After the Peer Initialization/Peer Initialization ACK signals have 945 been successfully exchanged, implementations MUST only use extensions 946 and experimental definitions that are supported by BOTH peers. 948 To construct a Peer Initialization ACK signal, the Signal Type value 949 in the signal header is set to DLEP_PEER_INIT_ACK in Table 1. 951 The Peer Initialization ACK signal MUST contain one of each of the 952 following data items: 954 o DLEP Version (Section 8.1) 956 o Heartbeat Interval (Section 8.6) 958 o Maximum Data Rate (Receive) (Section 8.14) 960 o Maximum Data Rate (Transmit) (Section 8.15) 962 o Current Data Rate (Receive) (Section 8.16) 964 o Current Data Rate (Transmit) (Section 8.17) 966 o Latency (Section 8.18) 967 The Peer Initialization ACK signal MUST contain one of each of the 968 following data items, if the data item will be used during the 969 lifetime of the session: 971 o Resources (Receive) (Section 8.19) 973 o Resources (Transmit) (Section 8.20) 975 o Relative Link Quality (Receive) (Section 8.21) 977 o Relative Link Quality (Transmit) (Section 8.22) 979 The Peer Initialization ACK signal MAY contain one of each of the 980 following data items: 982 o Status (Section 8.2) 984 o Peer Type (Section 8.5) 986 o Extensions Supported (Section 8.7) 988 The Peer Initialization ACK signal MAY contain one or more of any of 989 the following data items, with different values: 991 o Experimental Definition (Section 8.8) 993 7.5. Peer Update Signal 995 A Peer Update signal MAY be sent by a DLEP peer to indicate local 996 Layer 3 address changes, or metric changes on a modem-wide basis. 997 For example, addition of an IPv4 address to the router MAY prompt a 998 Peer Update signal to its attached DLEP modems. Also, for example, a 999 modem that changes its Maximum Data Rate (Receive) for all 1000 destinations MAY reflect that change via a Peer Update signal to its 1001 attached router(s). 1003 Concerning Layer 3 addresses, if the modem is capable of 1004 understanding and forwarding this information (via proprietary 1005 mechanisms), the address update would prompt any remote DLEP modems 1006 (DLEP-enabled modems in a remote node) to issue a Destination Update 1007 signal (Section 7.13) to their local routers with the new (or 1008 deleted) addresses. Modems that do not track Layer 3 addresses 1009 SHOULD silently parse and ignore the Peer Update signal. Modems that 1010 track Layer 3 addresses MUST acknowledge the Peer Update with a Peer 1011 Update ACK signal (Section 7.6). 1013 If metrics are supplied with the Peer Update signal (e.g., Maximum 1014 Data Rate), these metrics are considered to be modem-wide, and 1015 therefore MUST be applied to all destinations in the information base 1016 associated with the router/modem session. 1018 Supporting implementations are free to employ heuristics to 1019 retransmit Peer Update signals. The sending of Peer Update signals 1020 for Layer 3 address changes SHOULD cease when either participant 1021 (router or modem) determines that the other implementation does NOT 1022 support Layer 3 address tracking. 1024 To construct a Peer Update signal, the Signal Type value in the 1025 signal header is set to DLEP_PEER_UPDATE in Table 1. 1027 The Peer Update signal MAY contain one of each of the following data 1028 items: 1030 o Maximum Data Rate (Receive) (Section 8.14) 1032 o Maximum Data Rate (Transmit) (Section 8.15) 1034 o Current Data Rate (Receive) (Section 8.16) 1036 o Current Data Rate (Transmit) (Section 8.17) 1038 o Latency (Section 8.18) 1040 o Resources (Receive) (Section 8.19) 1042 o Resources (Transmit) (Section 8.20) 1044 o Relative Link Quality (Receive) (Section 8.21) 1046 o Relative Link Quality (Transmit) (Section 8.22) 1048 The Peer Update signal MAY contain one or more of the following data 1049 items, with different values: 1051 o IPv4 Address (Section 8.10) 1053 o IPv6 Address (Section 8.11) 1055 A Peer Update signal MUST be acknowledged by the receiver issuing a 1056 Peer Update ACK signal (Section 7.6). 1058 7.6. Peer Update ACK Signal 1060 A Peer Update ACK signal MUST be sent by implementations to indicate 1061 whether a Peer Update signal (Section 7.5) was successfully received. 1063 To construct a Peer Update ACK signal, the Signal Type value in the 1064 signal header is set to DLEP_PEER_UPDATE_ACK in Table 1. 1066 The Peer Update ACK signal MAY contain one of each of the following 1067 data items: 1069 o Status (Section 8.2) 1071 A receiver of a Peer Update ACK signal without a Status data item 1072 MUST behave as if a Status data item with code 'Success' had been 1073 received. 1075 7.7. Peer Termination Signal 1077 A Peer Termination signal MUST be sent by a DLEP participant when the 1078 router/modem session needs to be terminated. Implementations 1079 receiving a Peer Termination signal MUST send a Peer Termination ACK 1080 signal (Section 7.8) to confirm the termination process. 1082 The receiver of a Peer Termination signal MUST release all resources 1083 allocated for the router/modem session, and MUST eliminate all 1084 destinations in the information base accessible via the router/modem 1085 pair represented by the session. Router and modem state machines are 1086 returned to the 'discovery' state. No Destination Down signals 1087 (Section 7.11) are sent. 1089 The sender of a Peer Termination signal is free to define its 1090 heuristics in event of a timeout. It may resend the Peer Termination 1091 or free resources and return to the 'discovery' state. 1093 To construct a Peer Termination signal, the Signal Type value in the 1094 signal header is set to DLEP_PEER_TERM in Table 1. 1096 The Peer Termination signal MAY contain one of each of the following 1097 data items: 1099 o Status (Section 8.2) 1101 A receiver of a Peer Termination signal without a Status data item 1102 MUST behave as if a Status data item with status code 'Success', 1103 implying graceful termination, had been received. 1105 A Peer Termination signal MUST be acknowledged by the receiver 1106 issuing a Peer Termination ACK signal (Section 7.8). 1108 7.8. Peer Termination ACK Signal 1110 A Peer Termination ACK signal MUST be sent by a DLEP peer in response 1111 to a received Peer Termination signal (Section 7.7). Receipt of a 1112 Peer Termination ACK signal completes the teardown of the router/ 1113 modem session. 1115 To construct a Peer Termination ACK signal, the Signal Type value in 1116 the signal header is set to DLEP_PEER_TERM_ACK in Table 1. 1118 The Peer Termination ACK signal MAY contain one of each of the 1119 following data items: 1121 o Status (Section 8.2) 1123 A receiver of a Peer Termination ACK signal without a Status data 1124 item MUST behave as if a Status data item with status code 'Success', 1125 implying graceful termination, had been received. 1127 7.9. Destination Up Signal 1129 A Destination Up signal can be sent either by the modem, to indicate 1130 that a new remote node has been detected, or by the router, to 1131 indicate the presence of a new logical destination (e.g., a Multicast 1132 group) in the network. 1134 A Destination Up signal MUST be acknowledged by the receiver issuing 1135 a Destination Up ACK signal (Section 7.10). The sender of the 1136 Destination Up signal is free to define its retry heuristics in event 1137 of a timeout. When a Destination Up signal is received and 1138 successfully processed, the receiver should add knowledge of the new 1139 destination to its information base, indicating that the destination 1140 is accessible via the modem/router pair. 1142 To construct a Destination Up signal, the Signal Type value in the 1143 signal header is set to DLEP_DEST_UP in Table 1. 1145 The Destination Up signal MUST contain one of each of the following 1146 data items: 1148 o MAC Address (Section 8.9) 1150 The Destination Up signal MAY contain one of each of the following 1151 data items: 1153 o Maximum Data Rate (Receive) (Section 8.14) 1155 o Maximum Data Rate (Transmit) (Section 8.15) 1156 o Current Data Rate (Receive) (Section 8.16) 1158 o Current Data Rate (Transmit) (Section 8.17) 1160 o Latency (Section 8.18) 1162 o Resources (Receive) (Section 8.19) 1164 o Resources (Transmit) (Section 8.20) 1166 o Relative Link Quality (Receive) (Section 8.21) 1168 o Relative Link Quality (Transmit) (Section 8.22) 1170 The Destination Up signal MAY contain one or more of the following 1171 data items, with different values: 1173 o IPv4 Address (Section 8.10) 1175 o IPv6 Address (Section 8.11) 1177 o IPv4 Attached Subnet (Section 8.12) 1179 o IPv6 Attached Subnet (Section 8.13) 1181 If the sender has IPv4 and/or IPv6 address information for a 1182 destination it SHOULD include the relevant data items in the 1183 Destination Up signal, reducing the need for the receiver to probe 1184 for any address. 1186 7.10. Destination Up ACK Signal 1188 A DLEP participant MUST send a Destination Up ACK signal to indicate 1189 whether a Destination Up signal (Section 7.9) was successfully 1190 processed. 1192 To construct a Destination Up ACK signal, the Signal Type value in 1193 the signal header is set to DLEP_DEST_UP_ACK in Table 1. 1195 The Destination Up ACK signal MUST contain one of each of the 1196 following data items: 1198 o MAC Address (Section 8.9) 1200 The Destination Up ACK signal MAY contain one of each of the 1201 following data items: 1203 o Status (Section 8.2) 1204 A receiver of a Destination Up ACK signal without a Status data item 1205 MUST behave as if a Status data item with status code 'Success' had 1206 been received. Implementations are free to define retry heurestics 1207 when receiving a Destination Up ACK signal indicating an error. 1209 7.11. Destination Down Signal 1211 A DLEP peer MUST send a Destination Down signal to report when a 1212 destination (a remote node or a multicast group) is no longer 1213 reachable. A Destination Down ACK signal (Section 7.12) MUST be sent 1214 by the recipient of a Destination Down signal to confirm that the 1215 relevant data has been removed from the information base. The sender 1216 of the Destination Down signal is free to define its retry heuristics 1217 in event of a timeout. 1219 To construct a Destination Down signal, the Signal Type value in the 1220 signal header is set to DLEP_DEST_DOWN in Table 1. 1222 The Destination Down signal MUST contain one of each of the following 1223 data items: 1225 o MAC Address (Section 8.9) 1227 7.12. Destination Down ACK Signal 1229 A DLEP participant MUST send a Destination Down ACK signal to 1230 indicate whether a received Destination Down signal (Section 7.11) 1231 was successfully processed. If successfully processed, the sender of 1232 the ACK MUST have removed all entries in the information base that 1233 pertain to the referenced destination. 1235 To construct a Destination Down ACK signal, the Signal Type value in 1236 the signal header is set to DLEP_DEST_DOWN_ACK in Table 1. 1238 The Destination Down ACK signal MUST contain one of each of the 1239 following data items: 1241 o MAC Address (Section 8.9) 1243 The Destination Down ACK signal MAY contain one of each of the 1244 following data items: 1246 o Status (Section 8.2) 1248 A receiver of a Destination Down ACK signal without a Status data 1249 item MUST behave as if a Status data item with status code 'Success' 1250 had been received. Implementations are free to define retry 1251 heurestics when receiving a Destination Down ACK signal indicating an 1252 error. 1254 7.13. Destination Update Signal 1256 A DLEP participant SHOULD send the Destination Update signal when it 1257 detects some change in the information base for a given destination 1258 (remote node or multicast group). Some examples of changes that 1259 would prompt a Destination Update signal are: 1261 o Change in link metrics (e.g., Data Rates) 1263 o Layer 3 addressing change 1265 To construct a Destination Update signal, the Signal Type value in 1266 the signal header is set to DLEP_DEST_UPDATE in Table 1. 1268 The Destination Update signal MUST contain one of each of the 1269 following data items: 1271 o MAC Address (Section 8.9) 1273 The Destination Update signal MAY contain one of each of the 1274 following data items: 1276 o Maximum Data Rate (Receive) (Section 8.14) 1278 o Maximum Data Rate (Transmit) (Section 8.15) 1280 o Current Data Rate (Receive) (Section 8.16) 1282 o Current Data Rate (Transmit) (Section 8.17) 1284 o Latency (Section 8.18) 1286 o Resources (Receive) (Section 8.19) 1288 o Resources (Transmit) (Section 8.20) 1290 o Relative Link Quality (Receive) (Section 8.21) 1292 o Relative Link Quality (Transmit) (Section 8.22) 1294 The Destination Update signal MAY contain one or more of the 1295 following data items, with different values: 1297 o IPv4 Address (Section 8.10) 1298 o IPv6 Address (Section 8.11) 1300 o IPv4 Attached Subnet (Section 8.12) 1302 o IPv6 Attached Subnet (Section 8.13) 1304 7.14. Heartbeat Signal 1306 A Heartbeat signal SHOULD be sent by a DLEP participant every N 1307 seconds, where N is defined in the Heartbeat Interval data item of 1308 the Peer Initialization signal (Section 7.3) or Peer Initialization 1309 ACK signal (Section 7.4). Note that implementations setting the 1310 Heartbeat Interval to 0 effectively set the interval to an infinite 1311 value, therefore, in those cases, this signal SHOULD NOT be sent. 1313 The signal is used by participants to detect when a DLEP session 1314 partner (either the modem or the router) is no longer communicating. 1315 Participants SHOULD allow two (2) heartbeat intervals to expire with 1316 no traffic on the router/modem session before initiating DLEP session 1317 termination procedures. 1319 To construct a Heartbeat signal, the Signal Type value in the signal 1320 header is set to DLEP_PEER_HEARTBEAT in Table 1. 1322 There are no valid data items for the Heartbeat signal. 1324 7.15. Link Characteristics Request Signal 1326 The Link Characteristics Request signal MAY be sent by the router to 1327 request that the modem initiate changes for specific characteristics 1328 of the link. The request can reference either a real destination 1329 (e.g., a remote node), or a logical destination (e.g., a multicast 1330 group) within the network. 1332 The Link Characteristics Request signal MAY contain either a Current 1333 Data Rate (CDRR or CDRT) data item to request a different datarate 1334 than what is currently allocated, a Latency data item to request that 1335 traffic delay on the link not exceed the specified value, or both. A 1336 Link Characteristics ACK signal (Section 7.16) is required to 1337 complete the request. Issuing a Link Characteristics Request with 1338 ONLY the MAC Address data item is a mechanism a peer MAY use to 1339 request metrics (via the Link Characteristics ACK) from its partner. 1341 The sender of a Link Characteristics Request signal MAY attach a 1342 timer to the request using the Link Characteristics ACK Timer data 1343 item. If a Link Characteristics ACK signal is received after the 1344 timer expires, the sender MUST NOT assume that the request succeeded. 1346 Implementations are free to define their retry heuristics in event of 1347 a timeout. 1349 To construct a Link Characteristics Request signal, the Signal Type 1350 value in the signal header is set to DLEP_LINK_CHAR_REQ in Table 1. 1352 The Link Characteristics Request signal MUST contain one of each of 1353 the following data items: 1355 o MAC Address (Section 8.9) 1357 The Link Characteristics Request signal MAY contain one of each of 1358 the following data items: 1360 o Link Characteristics ACK Timer (Section 8.23) 1362 o Current Data Rate (Receive) (Section 8.16) 1364 o Current Data Rate (Transmit) (Section 8.17) 1366 o Latency (Section 8.18) 1368 7.16. Link Characteristics ACK Signal 1370 A DLEP participant MUST send a Link Characteristics ACK signal to 1371 indicate whether a received Link Characteristics Request signal 1372 (Section 7.15) was successfully processed. The Link Characteristics 1373 ACK signal SHOULD contain a complete set of metric data items, and 1374 MUST contain a full set (i.e. those declared in the Peer 1375 Initialization ACK signal (Section 7.4)), if metrics were requested 1376 by only including a MAC address data item. It MUST contain the same 1377 metric types as the request. The values in the metric data items in 1378 the Link Characteristics ACK signal MUST reflect the link 1379 characteristics after the request has been processed. 1381 If an implementation is not able to alter the characteristics of the 1382 link in the manner requested, then a Status data item with status 1383 code 'Request Denied' MUST be added to the signal. 1385 To construct a Link Characteristics Request ACK signal, the Signal 1386 Type value in the signal header is set to DLEP_LINK_CHAR_ACK in 1387 Table 1. 1389 The Link Characteristics ACK signal MUST contain one of each of the 1390 following data items: 1392 o MAC Address (Section 8.9) 1393 The Link Characteristics ACK signal SHOULD contain one of each of the 1394 following data items: 1396 o Maximum Data Rate (Receive) (Section 8.14) 1398 o Maximum Data Rate (Transmit) (Section 8.15) 1400 o Current Data Rate (Receive) (Section 8.16) 1402 o Current Data Rate (Transmit) (Section 8.17) 1404 o Latency (Section 8.18) 1406 The Link Characteristics ACK signal MAY contain one of each of the 1407 following data items: 1409 o Resources (Receive) (Section 8.19) 1411 o Resources (Transmit) (Section 8.20) 1413 o Relative Link Quality (Receive) (Section 8.21) 1415 o Relative Link Quality (Transmit) (Section 8.22) 1417 o Status (Section 8.2) 1419 A receiver of a Link Characteristics ACK signal without a Status data 1420 item MUST behave as if a Status data item with status code 'Success' 1421 had been received. 1423 8. DLEP Data Items 1425 Following is the list of MANDATORY data items that must be recognized 1426 by a DLEP compliant implementation. As mentioned before, not all 1427 data items need be used during a session, but an implementation MUST 1428 correctly process these data items when correctly associated with a 1429 signal. 1431 The DLEP data items are: 1433 +------------+--------------------------------------+---------------+ 1434 | Data Item | Description | Section | 1435 +------------+--------------------------------------+---------------+ 1436 | TBD | DLEP Version | Section 8.1 | 1437 | TBD | Status | Section 8.2 | 1438 | TBD | IPv4 Connection Point | Section 8.3 | 1439 | TBD | IPv6 Connection Point | Section 8.4 | 1440 | TBD | Peer Type | Section 8.5 | 1441 | TBD | Heartbeat Interval | Section 8.6 | 1442 | TBD | Extensions Supported | Section 8.7 | 1443 | TBD | Experimental Definition | Section 8.8 | 1444 | TBD | MAC Address | Section 8.9 | 1445 | TBD | IPv4 Address | Section 8.10 | 1446 | TBD | IPv6 Address | Section 8.11 | 1447 | TBD | IPv4 Attached Subnet | Section 8.12 | 1448 | TBD | IPv6 Attached Subnet | Section 8.13 | 1449 | TBD | Maximum Data Rate (Receive) MDRR) | Section 8.14 | 1450 | TBD | Maximum Data Rate (Transmit) (MDRT) | Section 8.15 | 1451 | TBD | Current Data Rate (Receive) (CDRR) | Section 8.16 | 1452 | TBD | Current Data Rate (Transmit) (CDRT) | Section 8.17 | 1453 | TBD | Latency | Section 8.18 | 1454 | TBD | Resources (Receive) (RESR) | Section 8.19 | 1455 | TBD | Resources (Transmit) (REST) | Section 8.20 | 1456 | TBD | Relative Link Quality (Receive) | Section 8.21 | 1457 | | (RLQR) | | 1458 | TBD | Relative Link Quality (Transmit) | Section 8.22 | 1459 | | (RLQT) | | 1460 | TBD | Link Characteristics ACK Timer | Section 8.23 | 1461 +------------+--------------------------------------+---------------+ 1463 Table 2: DLEP Data Item Values 1465 8.1. DLEP Version 1467 The DLEP Version data item MUST appear in the Peer Discovery 1468 (Section 7.1), Peer Offer (Section 7.2), Peer Initialization 1469 (Section 7.3) and Peer Initialization ACK (Section 7.4) signals. The 1470 Version data item is used to indicate the version of the protocol 1471 running in the originator. A DLEP implementation SHOULD use this 1472 information to decide if the potential session partner is running at 1473 a supported level. 1475 The DLEP Version data item contains the following fields: 1477 0 1 2 3 1478 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 1479 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1480 | Data Item Type| Length | Major Version | 1481 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1482 | Minor Version | 1483 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1485 Data Item Type: TBD 1487 Length: 4 1489 Major Version: The major version of the DLEP protocol, expressed as 1490 an 16-bit unsigned integer. 1492 Minor Version: The minor version of the DLEP protocol, expressed as 1493 an 16-bit unsigned integer. 1495 Support of this draft is indicated by setting the Major Version to 1496 '1', and the Minor Version to '0' (i.e. Version 1.0). 1498 8.2. Status 1500 The Status data item MAY appear in the Peer Initialization ACK 1501 (Section 7.4), Peer Termination (Section 7.7), Peer Termination ACK 1502 (Section 7.8), Peer Update ACK (Section 7.6), Destination Up ACK 1503 (Section 7.10), Destination Down ACK (Section 7.12) and Link 1504 Characteristics ACK (Section 7.16) signals as part of an 1505 acknowledgement from either the modem or the router, to indicate the 1506 success or failure of the previously received signal. 1508 The status data item includes an optional Text field that can be used 1509 to provide a textual description of the status. The use of the Text 1510 field is entirely up to the receiving implementation, i.e., it could 1511 be output to a log file or discarded. If no Text field is supplied 1512 with the Status data item, the Length field MUST be set to 1. 1514 The Status data item contains the following fields: 1516 0 1 2 3 1517 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 1518 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1519 | Data Item Type| Length | Code | Text... 1520 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1522 Data Item Type: TBD 1524 Length: 1 + Length of text 1525 Status Code: One of the codes defined below. 1527 Text: UTF-8 encoded string, describing an problem, used for 1528 implementation defined purposes. Since this field is used for a 1529 description of the problem, implementations SHOULD limit 1530 characters in this field to printable characters. Implementations 1531 receiving this data item SHOULD check for printable characters in 1532 the field. 1534 An implementation MUST NOT assume the Text field is NUL-terminated. 1536 +----------------+-------+------------------------------------------+ 1537 | Status Code | Value | Reason | 1538 +----------------+-------+------------------------------------------+ 1539 | Success | 0 | The signal was processed successfully. | 1540 | Unknown Signal | TBD | The signal was not recognized by the | 1541 | | | implementation. | 1542 | Invalid Data | TBD | One or more data items in the signal are | 1543 | | | invalid, unexpected or duplicated. | 1544 | Unexpected | TBD | The signal was not expected while the | 1545 | Signal | | machine was in this state, e.g., a Peer | 1546 | | | Initialization signal after session | 1547 | | | establishment. | 1548 | Request Denied | TBD | The receiver has not completed the | 1549 | | | request. | 1550 | Timed Out | TBD | The request could not be completed in | 1551 | | | the time allowed. | 1552 | Invalid | TBD | The destination provided in the signal | 1553 | Destination | | does not match a previously announced | 1554 | | | destination. For example, in the Link | 1555 | | | Characteristic Request ACK signal | 1556 | | | (Section 7.16). | 1557 +----------------+-------+------------------------------------------+ 1559 8.3. IPv4 Connection Point 1561 The IPv4 Connection Point data item MAY appear in the Peer Offer 1562 signal (Section 7.2). The IPv4 Connection Point data item indicates 1563 the IPv4 address and, optionally, the TCP port number on the DLEP 1564 modem available for connections. If provided, the receiver MUST use 1565 this information to perform the TCP connect to the DLEP server. 1567 The IPv4 Connection Point data item contains the following fields: 1569 0 1 2 3 1570 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 1571 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1572 | Data Item Type| Length | IPv4 Address | 1573 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1574 | IPv4 Address | TCP Port Number (optional) | 1575 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1577 Data Item Type: TBD 1579 Length: 4 (or 6 if TCP Port included) 1581 IPv4 Address: The IPv4 address listening on the DLEP modem. 1583 TCP Port Number: TCP Port number on the DLEP modem. 1585 If the Length field is 6, the port number specified MUST be used to 1586 establish the TCP session. If the TCP Port Number is omitted, i.e. 1587 the Length field is 4, the receiver MUST use the DLEP well-known port 1588 number (Section 11.7) to establish the TCP connection. 1590 8.4. IPv6 Connection Point 1592 The IPv6 Connection Point data item MAY appear in the Peer Offer 1593 signal (Section 7.2). The IPv6 Connection Point data item indicates 1594 the IPv6 address and, optionally, the TCP port number on the DLEP 1595 modem available for connections. If provided, the receiver MUST use 1596 this information to perform the TCP connect to the DLEP server. 1598 The IPv6 Connection Point data item contains the following fields: 1600 0 1 2 3 1601 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 1602 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1603 | Data Item Type| Length | IPv6 Address | 1604 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1605 | IPv6 Address | 1606 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1607 | IPv6 Address | 1608 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1609 | IPv6 Address | 1610 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1611 | IPv6 Address | TCP Port Number (optional) | 1612 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1614 Data Item Type: TBD 1616 Length: 16 (or 18 if TCP Port included) 1617 IPv6 Address: The IPv6 address listening on the DLEP modem. 1619 TCP Port Number: TCP Port number on the DLEP modem. 1621 If the Length field is 18, the port number specified MUST be used to 1622 establish the TCP session. If the TCP Port Number is omitted, i.e. 1623 the Length field is 16, the receiver MUST use the DLEP well-known 1624 port number (Section 11.7) to establish the TCP connection. 1626 8.5. Peer Type 1628 The Peer Type data item MAY appear in the Peer Discovery 1629 (Section 7.1), Peer Offer (Section 7.2), Peer Initialization 1630 (Section 7.3) and Peer Initialization ACK (Section 7.4) signals. The 1631 Peer Type data item is used by the router and modem to give 1632 additional information as to its type. The peer type is a string and 1633 is envisioned to be used for informational purposes (e.g., as output 1634 in a display command). 1636 The Peer Type data item contains the following fields: 1638 0 1 2 3 1639 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 1640 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1641 | Data Item Type| Length | Peer Type | 1642 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1644 Data Item Type: TBD 1646 Length: Length of peer type string. 1648 Peer Type: UTF-8 encoded string. For example, a satellite modem 1649 might set this variable to "Satellite terminal". Since this data 1650 item is intended to provide additional information for display 1651 commands, sending implementations SHOULD limit the data to 1652 printable characters, and receiving implmentations SHOULD check 1653 the data for printable characters. 1655 An implementation MUST NOT assume the Peer Type field is NUL- 1656 terminated. 1658 8.6. Heartbeat Interval 1660 The Heartbeat Interval data item MUST appear in both the Peer 1661 Initialization (Section 7.3) and Peer Initialization ACK 1662 (Section 7.4) signals to indicate the Heartbeat timeout window to be 1663 used by the sender. 1665 The Interval is used to specify a period (in seconds) for Heartbeat 1666 signals (Section 7.14). By specifying an Interval value of 0, 1667 implementations MAY indicates the desire to disable Heartbeat signals 1668 entirely (i.e., the Interval is set to an infinite value). However, 1669 it is strongly recommended that implementations use non 0 timer 1670 values. Implementations MUST implement heuristics such that DLEP 1671 signals sent/received reset the timer interval. 1673 A DLEP session will be considered inactive, and MUST be torn down, 1674 via the Peer Termination procedure, by an implementation detecting 1675 that two (2) Heartbeat intervals have transpired without receipt of 1676 any DLEP signals. 1678 The Heartbeat Interval data item contains the following fields: 1680 0 1 2 3 1681 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 1682 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1683 | Data Item Type| Length | Interval | 1684 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1686 Data Item Type: TBD 1688 Length: 2 1690 Interval: 0 = Do NOT use heartbeats on this DLEP session. Non-zero 1691 = Interval, in seconds, for heartbeat signals. 1693 8.7. Extensions Supported 1695 The Extensions Supported data item MAY be used in both the Peer 1696 Initialization and Peer Initialization ACK signals. The Extensions 1697 Supported data item is used by the router and modem to negotiate 1698 additional optional functionality they are willing to support. The 1699 Extensions List is a concatenation of the types of each supported 1700 extension, found in the IANA DLEP Extensions repository. 1702 The Extensions Supported data item contains the following fields: 1704 0 1 2 3 1705 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 1706 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1707 | Data Item Type| Length | Extensions List | 1708 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1710 Data Item Type: TBD 1712 Length: Number of Extensions supported. 1714 Extension List: A list of extensions supported, identified by their 1715 1-octet value as listed in the extensions registry. 1717 8.8. Experimental Definition 1719 The Experimental Definition data item MAY be used in both the Peer 1720 Initialization and Peer Initialization ACK signals. The Experimental 1721 Definition data item is used by the router and modem to indicate the 1722 formats to be used for experimental signals and data items for the 1723 given peer session. The formats are identified by using a string 1724 that matches the 'name' given to the experiment. 1726 The Experimental Definition item contains the following fields: 1728 0 1 2 3 1729 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 1730 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1731 | Data Item Type| Length | Experiment Name | 1732 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1734 Data Item Type: TBD 1736 Length: Length of the name string for the Experiment. 1738 Experiment Name: UTF-8 encoded string, containing the name of the 1739 experiment being implemented. 1741 An implementation receiving this data item MUST compare the received 1742 string to a list of experiments that it supports. 1744 An implementation MUST NOT assume the Experiment Name field is NUL- 1745 terminated. 1747 8.9. MAC Address 1749 The MAC address data item MUST appear in all destination-oriented 1750 signals (i.e., Destination Up (Section 7.9), Destination Up ACK 1751 (Section 7.10), Destination Down (Section 7.11), Destination Down ACK 1752 (Section 7.12), Destination Update (Section 7.13), Link 1753 Characteristics Request (Section 7.15), and Link Characteristics ACK 1754 (Section 7.16)). The MAC Address data item contains the address of 1755 the destination on the remote node. The MAC address MAY be either a 1756 physical or a virtual destination, and MAY be expressed in EUI-48 or 1757 EUI-64 format. Examples of a virtual destination would be a 1758 multicast MAC address, or the broadcast MAC (FF:FF:FF:FF:FF:FF). 1760 0 1 2 3 1761 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 1762 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1763 | Data Item Type| Length | MAC Address | 1764 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1765 | MAC Address | 1766 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1767 | MAC Address | 1768 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1770 Data Item Type: TBD 1772 Length: 6 for EUI-48 format, or 8 for EUI-64 format 1774 MAC Address: MAC Address of the destination. 1776 8.10. IPv4 Address 1778 The IPv4 Address data item MAY appear in the Peer Update 1779 (Section 7.5), Destination Up (Section 7.9) and Destination Update 1780 (Section 7.13) signals. When included in Destination signals, this 1781 data item contains the IPv4 address of the destination. When 1782 included in the Peer Update signal, this data item contains the IPv4 1783 address of the peer. In either case, the data item also contains an 1784 indication of whether this is a new or existing address, or is a 1785 deletion of a previously known address. 1787 The IPv4 Address data item contains the following fields: 1789 0 1 2 3 1790 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 1791 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1792 | Data Item Type| Length | Add/Drop | IPv4 Address | 1793 | | | Indicator | | 1794 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1795 | IPv4 Address | 1796 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1798 Data Item Type: TBD 1800 Length: 5 1802 Add/Drop: Value indicating whether this is a new or existing address 1803 (1), or a withdrawal of an address (0). 1805 IPv4 Address: The IPv4 address of the destination or peer. 1807 8.11. IPv6 Address 1809 The IPv6 Address data item MAY appear in the Peer Update 1810 (Section 7.5), Destination Up (Section 7.9) and Destination Update 1811 (Section 7.13) signals. When included in Destination signals, this 1812 data item contains the IPv6 address of the destination. When 1813 included in the Peer Update signal, this data item contains the IPv6 1814 address of the peer. In either case, the data item also contains an 1815 indication of whether this is a new or existing address, or is a 1816 deletion of a previously known address. 1818 The IPv6 Address data item contains the following fields: 1820 0 1 2 3 1821 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 1822 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1823 | Data Item Type| Length | Add/Drop | IPv6 Address | 1824 | | | Indicator | | 1825 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1826 | IPv6 Address | 1827 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1828 | IPv6 Address | 1829 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1830 | IPv6 Address | 1831 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1832 | IPv6 Address | 1833 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1835 Data Item Type: TBD 1837 Length: 17 1839 Add/Drop: Value indicating whether this is a new or existing address 1840 (1), or a withdrawal of an address (0). 1842 IPv6 Address: IPv6 Address of the destination or peer. 1844 8.12. IPv4 Attached Subnet 1846 The DLEP IPv4 Attached Subnet allows a device to declare that it has 1847 an IPv4 subnet (e.g., a stub network) attached, and MAY appear in the 1848 Destination Up (Section 7.9) and Destination Update (Section 7.13) 1849 signals. Once an IPv4 Subnet has been declared on a device, the 1850 declaration can NOT be withdrawn without terminating the destination 1851 (via the Destination Down signal (Section 7.11)) and re-issuing the 1852 Destination Up signal. 1854 The DLEP IPv4 Attached Subnet data item contains the following 1855 fields: 1857 0 1 2 3 1858 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 1859 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1860 |Data Item Type | Length | IPv4 Attached Subnet | 1861 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1862 | IPv4 Attached Subnet | Subnet Mask | 1863 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1865 Data Item Type: TBD 1867 Length: 5 1869 IPv4 Subnet: The IPv4 subnet reachable at the destination. 1871 Subnet Mask: A subnet mask (0-32) to be applied to the IPv4 subnet. 1873 8.13. IPv6 Attached Subnet 1875 The DLEP IPv6 Attached Subnet allows a device to declare that it has 1876 an IPv6 subnet (e.g., a stub network) attached, and MAY appear in the 1877 Destination Up (Section 7.9) and Destination Update (Section 7.13) 1878 signals. As in the case of the IPv4 attached Subnet data item above, 1879 once an IPv6 attached subnet has been declared, it can NOT be 1880 withdrawn without terminating the destination (via the Destination 1881 Down signal (Section 7.11)) and re-issuing the Destination Up signal. 1883 The DLEP IPv6 Attached Subnet data item contains the following 1884 fields: 1886 0 1 2 3 1887 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 1888 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1889 | Data Item Type| Length | IPv6 Attached Subnet | 1890 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1891 | IPv6 Attached Subnet | 1892 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1893 | IPv6 Attached Subnet | 1894 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1895 | IPv6 Attached Subnet | 1896 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1897 | IPv6 Attached Subnet | Subnet Mask | 1898 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1900 Data Item Type: TBD 1901 Length: 17 1903 IPv4 Subnet: The IPv6 subnet reachable at the destination. 1905 Subnet Mask: A subnet mask (0-128) to be applied to the IPv6 subnet. 1907 8.14. Maximum Data Rate (Receive) 1909 The Maximum Data Rate (Receive) (MDRR) data item MUST appear in the 1910 Peer Initialization ACK signal (Section 7.4), and MAY appear in the 1911 Peer Update (Section 7.5), Destination Up (Section 7.9), Destination 1912 Update (Section 7.13) and Link Characteristics ACK (Section 7.16) 1913 signals to indicate the maximum theoretical data rate, in bits per 1914 second, that can be achieved while receiving data on the link. 1916 The Maximum Data Rate (Receive) data item contains the following 1917 fields: 1919 0 1 2 3 1920 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 1921 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1922 | Data Item Type| Length | MDRR (bps) | 1923 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1924 | MDRR (bps) | 1925 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1926 | MDRR (bps) | 1927 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1929 Data Item Type: TBD 1931 Length: 8 1933 Maximum Data Rate (Receive): A 64-bit unsigned integer, representing 1934 the maximum theoretical data rate, in bits per second (bps), that 1935 can be achieved while receiving on the link. 1937 8.15. Maximum Data Rate (Transmit) 1939 The Maximum Data Rate (Transmit) (MDRT) data item MUST appear in the 1940 Peer Initialization ACK signal (Section 7.4), and MAY appear in the 1941 Peer Update (Section 7.5), Destination Up (Section 7.9), Destination 1942 Update (Section 7.13) and Link Characteristics ACK (Section 7.16) 1943 signals to indicate the maximum theoretical data rate, in bits per 1944 second, that can be achieved while transmitting data on the link. 1946 The Maximum Data Rate (Transmit) data item contains the following 1947 fields: 1949 0 1 2 3 1950 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1951 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1952 | Data Item Type| Length | MDRT (bps) | 1953 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1954 | MDRT (bps) | 1955 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1956 | MDRT (bps) | 1957 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1959 Data Item Type: TBD 1961 Length: 8 1963 Maximum Data Rate (Transmit): A 64-bit unsigned integer, 1964 representing the maximum theoretical data rate, in bits per second 1965 (bps), that can be achieved while transmitting on the link. 1967 8.16. Current Data Rate (Receive) 1969 The Current Data Rate (Receive) (CDRR) data item MUST appear in the 1970 Peer Initialization ACK signal (Section 7.4), and MAY appear in the 1971 Peer Update (Section 7.5), Destination Up (Section 7.9), Destination 1972 Update (Section 7.13) and Link Characteristics ACK (Section 7.16) 1973 signals to indicate the rate at which the link is currently operating 1974 for receiving traffic. 1976 When used in the Link Characteristics Request signal (Section 7.15), 1977 CDRR represents the desired receive rate, in bits per second, on the 1978 link. 1980 The Current Data Rate (Receive) data item contains the following 1981 fields: 1983 0 1 2 3 1984 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 1985 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1986 | Data Item Type| Length | CDRR (bps) | 1987 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1988 | CDRR (bps) | 1989 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1990 | CDRR (bps) | 1991 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1993 Data Item Type: TBD 1995 Length: 8 1996 Current Data Rate (Receive): A 64-bit unsigned integer, representing 1997 the current data rate, in bits per second, that can currently be 1998 achieved while receiving traffic on the link. 2000 If there is no distinction between current and maximum receive data 2001 rates, current data rate receive MUST be set equal to the maximum 2002 data rate receive. 2004 8.17. Current Data Rate (Transmit) 2006 The Current Data Rate Transmit (CDRT) data item MUST appear in the 2007 Peer Initialization ACK signal (Section 7.4), and MAY appear in the 2008 Peer Update (Section 7.5), Destination Up (Section 7.9), Destination 2009 Update (Section 7.13), and Link Characteristics ACK (Section 7.16) 2010 signals to indicate the rate at which the link is currently operating 2011 for transmitting traffic. 2013 When used in the Link Characteristics Request signal (Section 7.15), 2014 CDRT represents the desired transmit rate, in bits per second, on the 2015 link. 2017 The Current Data Rate (Transmit) data item contains the following 2018 fields: 2020 0 1 2 3 2021 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 2022 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2023 | Data Item Type| Length | CDRT (bps) | 2024 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2025 | CDRT (bps) | 2026 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2027 | CDRT (bps) | 2028 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2030 Data Item Type: TBD 2032 Length: 8 2034 Current Data Rate (Transmit): A 64-bit unsigned integer, 2035 representing the current data rate, in bits per second, that can 2036 currently be achieved while transmitting traffic on the link. 2038 If there is no distinction between current and maximum transmit data 2039 rates, current data rate transmit MUST be set equal to the maximum 2040 data rate transmit. 2042 8.18. Latency 2044 The Latency data item MUST appear in the Peer Initialization ACK 2045 signal (Section 7.4), and MAY appear in the Peer Update 2046 (Section 7.5), Destination Up (Section 7.9), Destination Update 2047 (Section 7.13), and Link Characteristics ACK (Section 7.16) signals 2048 to indicate the amount of latency, in microseconds, on the link. 2050 When used in the Link Characteristics Request signal (Section 7.15), 2051 Latency represents the maximum latency desired on the link. 2053 The Latency value is reported as delay. The calculation of latency 2054 is implementation dependent. For example, the latency may be a 2055 running average calculated from the internal queuing. 2057 0 1 2 3 2058 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 2059 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2060 | Data Item Type| Length | Latency | 2061 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2062 | Latency (cont.) | 2063 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2064 | Latency (cont.) | 2065 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2067 Data Item Type: TBD 2069 Length: 8 2071 Latency: A 64-bit unsigned integer, representing the transmission 2072 delay, in microseconds, that a packet encounters as it is 2073 transmitted over the link. 2075 8.19. Resources (Receive) 2077 The Resources (Receive) (RESR) data item MAY appear in the Peer 2078 Initialization ACK signal (Section 7.4), Peer Update (Section 7.5), 2079 Destination Up (Section 7.9), Destination Update (Section 7.13) and 2080 Link Characteristics ACK (Section 7.16) signals to indicate the 2081 amount of resources for reception (with 0 meaning 'no resources 2082 available', and 100 meaning 'all resources available') at the 2083 destination. The list of resources that might be considered is 2084 beyond the scope of this document, and is left to implementations to 2085 decide. 2087 The Resources (Receive) data item contains the following fields: 2089 0 1 2 2090 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 2091 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2092 | Data Item Type| Length | RESR | 2093 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2095 Data Item Type: TBD 2097 Length: 1 2099 Resources (Receive): An 8-bit integer percentage, 0-100, 2100 representing the amount of resources allocated to receiving data. 2102 If a device cannot calculate RESR, this data item SHOULD NOT be 2103 issued. 2105 8.20. Resources (Transmit) 2107 The Resources (Transmit) (REST) data item MAY appear in the Peer 2108 Initialization ACK signal (Section 7.4), Peer Update (Section 7.5), 2109 Destination Up (Section 7.9), Destination Update (Section 7.13) and 2110 Link Characteristics ACK (Section 7.16) signals to indicate the 2111 amount of resources for transmission (with 0 meaning 'no resources 2112 available', and 100 meaning 'all resources available') at the 2113 destination. The list of resources that might be considered is 2114 beyond the scope of this document, and is left to implementations to 2115 decide. 2117 The Resources (Transmit) data item contains the following fields: 2119 0 1 2 2120 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 2121 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2122 | Data Item Type| Length | REST | 2123 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2125 Data Item Type: TBD 2127 Length: 1 2129 Resources (Transmit): An 8-bit integer percentage, 0-100, 2130 representing the amount of resources allocated to transmitting 2131 data. 2133 If a device cannot calculate REST, this data item SHOULD NOT be 2134 issued. 2136 8.21. Relative Link Quality (Receive) 2138 The Relative Link Quality (Receive) (RLQR) data item MAY appear in 2139 the Peer Initialization ACK signal (Section 7.4), Peer Update 2140 (Section 7.5), Destination Up (Section 7.9), Destination Update 2141 (Section 7.13) and Link Characteristics ACK (Section 7.16) signals to 2142 indicate the quality of the link for receiving data. 2144 The Relative Link Quality (Receive) data item contains the following 2145 fields: 2147 0 1 2 2148 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 2149 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2150 | Data Item Type| Length | RLQR | 2151 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2153 Data Item Type: TBD 2155 Length: 1 2157 Relative Link Quality (Receive): A non-dimensional 8-bit integer, 2158 1-100, representing relative link quality. A value of 100 2159 represents a link of the highest quality. 2161 If a device cannot calculate the RLQR, this data item SHOULD NOT be 2162 issued. 2164 8.22. Relative Link Quality (Transmit) 2166 The Relative Link Quality (Transmit) (RLQT) data item MAY appear in 2167 the Peer Initialization ACK signal (Section 7.4), Peer Update 2168 (Section 7.5), Destination Up (Section 7.9), Destination Update 2169 (Section 7.13) and Link Characteristics ACK (Section 7.16) signals to 2170 indicate the quality of the link for transmitting data. 2172 The Relative Link Quality (Transmit) data item contains the following 2173 fields: 2175 0 1 2 2176 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 2177 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2178 | Data Item Type| Length | RLQT | 2179 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2181 Data Item Type: TBD 2183 Length: 1 2184 Relative Link Quality (Transmit): A non-dimensional 8-bit integer, 2185 1-100, representing relative link quality. A value of 100 2186 represents a link of the highest quality. 2188 If a device cannot calculate the RLQT, this data item SHOULD NOT be 2189 issued. 2191 8.23. Link Characteristics ACK Timer 2193 The Link Characteristics ACK Timer data item MAY appear in the Link 2194 Characteristics Request signal (Section 7.15) to indicate the desired 2195 number of seconds to the sender will wait for a response to the 2196 request. If this data item is omitted, implementations supporting 2197 the Link Characteristics Request SHOULD choose a default value. 2199 The Link Characteristics ACK Timer data item contains the following 2200 fields: 2202 0 1 2 2203 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 2204 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2205 | Data Item Type| Length | Interval | 2206 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2208 Data Item Type: TBD 2210 Length: 1 2212 Interval: 0 = Do NOT use timeouts for this Link Characteristics 2213 request. Non-zero = Interval, in seconds, to wait before 2214 considering this Link Characteristics Request has been lost. 2216 9. Credit-Windowing 2218 DLEP includes an OPTIONAL Protocol Extension for a credit-windowing 2219 scheme analogous to the one documented in [RFC5578]. In this scheme, 2220 traffic between the router and modem is treated as two unidirectional 2221 windows. This document identifies these windows as the 'Modem 2222 Receive Window' (MRW), and the 'Router Receive Window' (RRW). 2224 If the OPTIONAL credit-windowing extension is used, credits MUST be 2225 granted by the receiver on a given window - that is, on the 'Modem 2226 Receive Window' (MRW), the modem is responsible for granting credits 2227 to the router, allowing it (the router) to send data to the modem. 2228 Likewise, the router is responsible for granting credits on the RRW, 2229 which allows the modem to send data to the router. 2231 Credits are managed on a destination-specific basis; that is, 2232 separate credit counts are maintained for each destination requiring 2233 the service. Credits do not apply to the DLEP session that exists 2234 between routers and modems. 2236 If a peer is able to support the OPTIONAL credit-windowing extension 2237 then it MUST include a Extensions Supported data item (Section 8.7) 2238 including the value DLEP_EXT_CREDITS (value TBD) in the appropriate 2239 Peer Initialization or Peer Initialization ACK signal. 2241 9.1. Credit-Windowing Signals 2243 The credit-windowing extension introduces no additional DLEP signals. 2244 However, if a peer has advertised during session initialization that 2245 it supports the credit-windowing extension then the following DLEP 2246 signals MAY contain additional credit-windowing data items: 2248 9.1.1. Destination Up Signal 2250 The Destination Up signal MAY contain one of each of the following 2251 data items: 2253 o Credit Grant (Section 9.2.1) 2255 If the Destination Up signal does not contain the Credit Grant data 2256 item, credits MUST NOT be used for that destination. 2258 9.1.2. Destination Up ACK Signal 2260 If the corresponding Destination Up signal contained the Credit Grant 2261 data item, the Destination Up ACK signal MUST contain one of each of 2262 the following data items: 2264 o Credit Window Status (Section 9.2.2) 2266 9.1.3. Destination Update Signal 2268 If the corresponding Destination Up signal contained the Credit Grant 2269 data item, the Destination Update signal MUST contain one of each of 2270 the following data items: 2272 o Credit Window Status (Section 9.2.2) 2274 If the corresponding Destination Up signal contained the Credit Grant 2275 data item, the Destination Update signal MAY contain one of each of 2276 the following data items: 2278 o Credit Grant (Section 9.2.1) 2279 o Credit Request (Section 9.2.3) 2281 9.2. Credit-Windowing Data Items 2283 The credit-windowing extension introduces 3 additional data items. 2284 If a peer has advertised during session initialization that it 2285 supports the credit-windowing extension then it MUST correctly 2286 process the following data items without error. 2288 +------------+-----------------------+----------------+ 2289 | Data Item | Description | Section | 2290 +------------+-----------------------+----------------+ 2291 | TBD | Credit Grant | Section 9.2.1 | 2292 | TBD | Credit Window Status | Section 9.2.2 | 2293 | TBD | Credit Request | Section 9.2.3 | 2294 +------------+-----------------------+----------------+ 2296 9.2.1. Credit Grant 2298 The Credit Grant data item is sent from a DLEP participant to grant 2299 an increment to credits on a window. The Credit Grant data item MAY 2300 appear in the Destination Up (Section 7.9) and Destination Update 2301 (Section 7.13) signals. The value in a Credit Grant data item 2302 represents an increment to be added to any existing credits available 2303 on the window. Upon successful receipt and processing of a Credit 2304 Grant data item, the receiver MUST respond with a signal containing a 2305 Credit Window Status data item to report the updated aggregate values 2306 for synchronization purposes, and if initializing a new credit 2307 window, granting initial credits. 2309 In the Destination Up signal, when credits are desired, the 2310 originating peer MUST set the initial credit value of the window it 2311 controls (i.e., the Modem Receive Window, or Router Receive Window) 2312 to an initial, non-zero value. If the receiver of a Destination Up 2313 signal with a Credit Grant data item supports credits, the receiver 2314 MUST either reject the use of credits for this destination, via a 2315 Destination Up ACK response containing a Status data item 2316 (Section 8.2) with a status code of 'Request Denied', or set the 2317 initial value from the data contained in the Credit Window Status 2318 data item. If the initialization completes successfully, the 2319 receiver MUST respond to the Destination Up signal with a Destination 2320 Up ACK signal that contains a Credit Window Status data item, 2321 initializing its receive window. 2323 The Credit Grant data item contains the following fields: 2325 0 1 2 3 2326 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 2327 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2328 | Data Item Type| Length | Credit Increment | 2329 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2330 | Credit Increment | 2331 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2332 | Credit Increment | 2333 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2335 Data Item Type: TBD 2337 Length: 8 2339 Reserved: A 64-bit unsigned integer representing the additional 2340 credits to be assigned to the credit window. 2342 Since credits can only be granted by the receiver on a window, the 2343 applicable credit window (either the MRW or the RRW) is derived from 2344 the sender of the grant. The Credit Increment MUST NOT cause the 2345 window to overflow; if this condition occurs, implementations MUST 2346 set the credit window to the maximum value contained in a 64-bit 2347 quantity. 2349 9.2.2. Credit Window Status 2351 If the credit-window extension is supported by the DLEP participants 2352 (both the router and the modem), the Credit Window Status data item 2353 MUST be sent by the participant receiving a Credit Grant for a given 2354 destination. 2356 The Credit Window Status data item contains the following fields: 2358 0 1 2 3 2359 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 2360 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2361 | Data Item Type| Length | Modem Receive Window Value | 2362 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2363 | Modem Receive Window Value | 2364 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2365 | Modem Receive Window Value | Router Receive Window Value | 2366 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2367 | Router Receive Window Value | 2368 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2369 | Router Receive Window Value | 2370 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2372 Data Item Type: TBD 2373 Length: 16 2375 Modem Receive Window Value: A 64-bit unsigned integer, indicating 2376 the current number of credits available on the Modem Receive 2377 Window, for the destination referred to by the signal. 2379 Router Receive Window Value: A 64-bit unsigned integer, indicating 2380 the current number of credits available on the Router Receive 2381 Window, for the destination referred to by the signal. 2383 9.2.3. Credit Request 2385 The Credit Request data item MAY be sent from either DLEP 2386 participant, via the Destination Update signal (Section 7.13), to 2387 indicate the desire for the partner to grant additional credits in 2388 order for data transfer to proceed on the session. If the 2389 corresponding Destination Up signal (Section 7.9) for this session 2390 did NOT contain a Credit Window Status data item, indicating that 2391 credits are to be used on the session, then the Credit Request data 2392 item MUST be silently dropped by the receiver. 2394 The Credit Request data item contains the following fields: 2396 0 1 2 2397 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 2398 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2399 | Data Item Type| Length | Reserved, MUST| 2400 | | | be set to 0 | 2401 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2403 Data Item Type: TBD 2405 Length: 1 2407 Reserved: This field is currently unused and MUST be set to 0. 2409 10. Security Considerations 2411 The protocol does not contain any mechanisms for security (e.g., 2412 authentication or encryption). The protocol assumes that any 2413 security would be implemented in the underlying transport (for 2414 example, by use of TLS or some other mechanism), and is therefore 2415 outside the scope of this document. 2417 11. IANA Considerations 2419 This section specifies requests to IANA. 2421 11.1. Registrations 2423 This specification defines: 2425 o A new repository for DLEP signals, with sixteen values currently 2426 assigned. 2428 o Reservation of numbering space for Experimental DLEP signals. 2430 o A new repository for DLEP data items, with twenty-six values 2431 currently assigned. 2433 o Reservation of numbering space in the data items repository for 2434 experimental data items. 2436 o A new repository for DLEP status codes, with seven currently 2437 assigned. 2439 o A new repository for DLEP extensions, with one value currently 2440 assigned. 2442 o A request for allocation of a well-known port for DLEP TCP and UDP 2443 communication. 2445 o A request for allocation of a multicast IP address for DLEP 2446 discovery. 2448 11.2. Expert Review: Evaluation Guidelines 2450 No additional guidelines for expert review are anticipated. 2452 11.3. Signal Type Registration 2454 A new repository must be created with the values of the DLEP signals. 2456 All signal values are in the range [0..255]. 2458 Valid signals are: 2460 o Peer Discovery 2462 o Peer Offer 2464 o Peer Initialization 2465 o Peer Initialization ACK 2467 o Peer Update 2469 o Peer Update ACK 2471 o Peer Termination 2473 o Peer Termination ACK 2475 o Destination Up 2477 o Destination Up ACK 2479 o Destination Down 2481 o Destination Down ACK 2483 o Destination Update 2485 o Heartbeat 2487 o Link Characteristics Request 2489 o Link Characteristics ACK 2491 It is also requested that the repository contain space for 2492 experimental signal types. 2494 11.4. DLEP Data Item Registrations 2496 A new repository for DLEP data items must be created. 2498 All data item values are in the range [0..255]. 2500 Valid data items are: 2502 o DLEP Version 2504 o Status 2506 o IPv4 Connection Point 2508 o IPv6 Connection Point 2510 o Peer Type 2512 o Heartbeat Interval 2513 o Extensions Supported 2515 o Experimental Definition 2517 o MAC Address 2519 o IPv4 Address 2521 o IPv6 Address 2523 o IPv4 Attached Subnet 2525 o IPv6 Attached Subnet 2527 o Maximum Data Rate (Receive) 2529 o Maximum Data Rate (Transmit) 2531 o Current Data Rate (Receive) 2533 o Current Data Rate (Transmit) 2535 o Latency 2537 o Resources (Receive) 2539 o Resources (Transmit) 2541 o Relative Link Quality (Receive) 2543 o Relative Link Quality (Transmit) 2545 o Link Characteristics ACK Timer 2547 o Credit Window Status 2549 o Credit Grant 2551 o Credit Request 2553 It is also requested that the registry allocation contain space for 2554 experimental data items. 2556 11.5. DLEP Status Code Registrations 2558 A new repository for DLEP status codes must be created. 2560 All status codes are in the range [0..255]. 2562 Valid status codes are: 2564 o Success (value 0) 2566 o Unknown Signal 2568 o Invalid Data 2570 o Unexpected Signal 2572 o Request Denied 2574 o Timed Out 2576 o Invalid Destination 2578 11.6. DLEP Extensions Registrations 2580 A new repository for DLEP extensions must be created. 2582 All extension values are in the range [0..255]. 2584 Valid extensions are: 2586 o DLEP_EXT_CREDITS - Credit windowing 2588 11.7. DLEP Well-known Port 2590 It is requested that IANA allocate a well-known port number for DLEP 2591 communication. 2593 11.8. DLEP Multicast Address 2595 It is requested that IANA allocate a multicast address for DLEP 2596 discovery signals. 2598 12. Acknowledgements 2600 We would like to acknowledge and thank the members of the DLEP design 2601 team, who have provided invaluable insight. The members of the 2602 design team are: Teco Boot, Bow-Nan Cheng, John Dowdell, and Henning 2603 Rogge. 2605 We would also like to acknowledge the influence and contributions of 2606 Greg Harrison, Chris Olsen, Martin Duke, Subir Das, Jaewon Kang, 2607 Vikram Kaul, Nelson Powell and Victoria Mercieca. 2609 13. References 2611 13.1. Normative References 2613 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 2614 Requirement Levels", BCP 14, RFC 2119, March 1997. 2616 13.2. Informative References 2618 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 2619 (TLS) Protocol Version 1.2", RFC 5246, August 2008. 2621 [RFC5578] Berry, B., Ratliff, S., Paradise, E., Kaiser, T., and M. 2622 Adams, "PPP over Ethernet (PPPoE) Extensions for Credit 2623 Flow and Link Metrics", RFC 5578, February 2010. 2625 Appendix A. Peer Level Signal Flows 2627 A.1. Discovery 2629 Router Modem Signal Description 2630 ======================================================================== 2632 | Router initiates discovery, starts 2633 | a timer, send Peer Discovery 2634 |-------Peer Discovery---->|| signal. 2636 ~ ~ ~ ~ ~ ~ ~ Router discovery timer expires 2637 without receiving Peer Offer. 2639 | Router sends another Peer 2640 |-------Peer Discovery---------->| Discovery signal. 2641 | 2642 | Modem receives Peer Discovery 2643 | signal. 2644 | 2645 | Modem sends Peer Offer with 2646 |<--------Peer Offer-------------| Connection Point information. 2647 : 2648 : Router MAY cancel discovery timer 2649 : and stop sending Peer Discovery 2650 : signals. 2652 A.2. Session Initialization 2653 Router Modem Signal Description 2654 ======================================================================== 2656 | Router connects to discovered or 2657 | pre-configured Modem Connection 2658 |---------TCP connect----------> Point. 2659 | 2660 | Router sends Peer Initialization 2661 |-------Peer Initialization----->| signal. 2662 | 2663 | Modem receives Peer Initialization 2664 | signal. 2665 | 2666 | Modem sends Peer Initialization 2667 | ACK, with compatible extensions, 2668 |<----Peer Initialization ACK----| and Success status data item. 2669 | | 2670 |<<============================>>| Session established. Heartbeats 2671 : : begin. 2673 A.3. Session Initialization - Refused 2675 Router Modem Signal Description 2676 ======================================================================== 2678 | Router connects to discovered or 2679 | pre-configured Modem Connection 2680 |---------TCP connect----------> Point. 2681 | 2682 | Router sends Peer Initialization 2683 |-------Peer Initialization----->| signal. 2684 | 2685 | Modem receives Peer Initialization 2686 | signal, and will not support the 2687 | advertised version, experiment or 2688 | extensions. 2689 | 2690 | Modem sends Peer Initialization 2691 | ACK, with 'Request Denied' status 2692 |<----Peer Initialization ACK----| data item. 2693 | | 2694 | <---- TCP shutdown (send)-----| Modem closes TCP connection. 2695 | 2696 | Router receives negative Peer 2697 | Initialization ACK, closes 2698 |---------TCP close-----------> TCP connection. 2699 | 2700 ||------------------------------|| Session not started. 2702 A.4. Router Changes IP Addresses 2704 Router Modem Signal Description 2705 ======================================================================== 2707 | Router sends Peer Update signal to 2708 |--------Peer Update------------>| announce change of IP address 2709 | 2710 | Modem receives Peer Update signal 2711 | and updates internal state. 2712 | 2713 |<-------Peer Update ACK---------| Modem sends Peer Update ACK. 2715 A.5. Modem Changes Session-wide Metrics 2717 Router Modem Signal Description 2718 ======================================================================== 2720 | Modem sends Peer Update signal to 2721 | announce change of modem-wide 2722 |<--------Peer Update------------| metrics 2723 | 2724 | Router receives Peer Update signal 2725 | and updates internal state. 2726 | 2727 |-------Peer Update ACK--------->| Router sends Peer Update ACK. 2729 A.6. Router Terminates Session 2731 Router Modem Signal Description 2732 ======================================================================== 2734 | Router sends Peer Termination 2735 |-------Peer Termination-------->| signal with Status data item. 2736 | | 2737 |-------TCP shutdown (send)---> | Router stops sending signals. 2738 | 2739 | Modem receives Peer Termination, 2740 | stops counting received heartbeats 2741 | and stops sending heartbeats. 2742 | 2743 | Modem sends Peer Termination ACK 2744 |<-----Peer Termination ACK------| with Status 'Success'. 2745 | | 2746 | <----TCP shutdown (send)------| Modem stops sending signals. 2747 | 2748 ||------------------------------|| Session terminated. 2750 A.7. Modem Terminates Session 2752 Router Modem Signal Description 2753 ======================================================================== 2755 | Modem sends Peer Termination 2756 |<------Peer Termination---------| signal with Status data item. 2757 | | 2758 | <----TCP shutdown (send)------| Modem stops sending signals. 2759 | 2760 | Router receives Peer Termination, 2761 | stops counting received heartbeats 2762 | and stops sending heartbeats. 2763 | 2764 | Router sends Peer Termination ACK 2765 |------Peer Termination ACK----->| with Status 'Success'. 2766 | | 2767 |-------TCP shutdown (send)---> | Router stops sending signals. 2768 | 2769 ||------------------------------|| Session terminated. 2771 A.8. Session Heartbeats 2772 Router Modem Signal Description 2773 ======================================================================== 2775 |----------Heartbeat------------>| Router sends heartbeat signal 2776 | 2777 | Modem resets heartbeats missed 2778 | counter. 2780 ~ ~ ~ ~ ~ ~ ~ 2782 |----------[Any signal]--------->| When the Modem receives any signal 2783 | from the Router. 2784 | 2785 | Modem resets heartbeats missed 2786 | counter. 2788 ~ ~ ~ ~ ~ ~ ~ 2790 |<---------Heartbeat-------------| Modem sends heartbeat signal 2791 | 2792 | Router resets heartbeats missed 2793 | counter. 2795 ~ ~ ~ ~ ~ ~ ~ 2797 |<---------[Any signal]----------| When the Router receives any 2798 | signal from the Modem. 2799 | 2800 | Modem resets heartbeats missed 2801 | counter. 2803 A.9. Router Detects a Heartbeat timeout 2805 Router Modem Signal Description 2806 ======================================================================== 2808 ||<----------------------| Router misses a heartbeat 2810 | ||<----------------------| Router misses too many heartbeats 2811 | 2812 | 2813 |-------Peer Termination-------->| Router sends Peer Termination 2814 | signal with 'Timeout' Status 2815 | data item. 2816 : 2817 : Termination proceeds as above. 2819 A.10. Modem Detects a Heartbeat timeout 2821 Router Modem Signal Description 2822 ======================================================================== 2824 |---------------------->|| Modem misses a heartbeat 2826 |---------------------->|| | Modem misses too many heartbeats 2827 | 2828 | 2829 |<-------Peer Termination--------| Modem sends Peer Termination 2830 | signal with 'Timeout' Status 2831 | data item. 2832 : 2833 : Termination proceeds as above. 2835 Appendix B. Destination Specific Signal Flows 2837 B.1. Common Destination Signaling 2839 Router Modem Signal Description 2840 ======================================================================== 2842 | Modem detects a new logical 2843 | destination is reachable, and 2844 |<-------Destination Up----------| sends Destination Up signal. 2845 | 2846 |--------Destination Up ACK----->| Router sends Destination Up ACK. 2848 ~ ~ ~ ~ ~ ~ ~ 2849 | Modem detects change in logical 2850 | destination metrics, and sends 2851 |<-------Destination Update------| Destination Update signal. 2853 ~ ~ ~ ~ ~ ~ ~ 2854 | Modem detects change in logical 2855 | destination metrics, and sends 2856 |<-------Destination Update------| Destination Update signal. 2858 ~ ~ ~ ~ ~ ~ ~ 2859 | Modem detects logical destination 2860 | is no longer reachable, and sends 2861 |<-------Destination Down--------| Destination Down signal. 2862 | 2863 | Router receives Destination Down, 2864 | updates internal state, and sends 2865 |--------Destination Down ACK--->| Destination Down ACK signal. 2867 B.2. Multicast Destination Signaling 2869 Router Modem Signal Description 2870 ======================================================================== 2872 | Router detects a new multicast 2873 | destination is in use, and sends 2874 |--------Destination Up--------->| Destination Up signal. 2875 | 2876 | Modem updates internal state to 2877 | monitor multicast destination, and 2878 |<-------Destination Up ACK------| sends Destination Up ACK. 2880 ~ ~ ~ ~ ~ ~ ~ 2881 | Modem detects change in multicast 2882 | destination metrics, and sends 2883 |<-------Destination Update------| Destination Update signal. 2885 ~ ~ ~ ~ ~ ~ ~ 2886 | Modem detects change in multicast 2887 | destination metrics, and sends 2888 |<-------Destination Update------| Destination Update signal. 2890 ~ ~ ~ ~ ~ ~ ~ 2891 | Router detects multicast 2892 | destination is no longer in use, 2893 |--------Destination Down------->| and sends Destination Down signal. 2894 | 2895 | Modem receives Destination Down, 2896 | updates internal state, and sends 2897 |<-------Destination Down ACK----| Destination Down ACK signal. 2899 B.3. Link Characteristics Request 2900 Router Modem Signal Description 2901 ======================================================================== 2903 Destination has already been 2904 ~ ~ ~ ~ ~ ~ ~ announced by either peer. 2906 | Router requires different 2907 | Characteristics for the 2908 | destination, and sends Link 2909 |--Link Characteristics Request->| Characteristics Request signal. 2910 | 2911 | Modem attempts to adjust link 2912 | status to meet the received 2913 | request, and sends a Link 2914 | Characteristics Request ACK 2915 |<---Link Char. Request ACK------| signal with the new values. 2917 Authors' Addresses 2919 Stan Ratliff 2920 VT iDirect 2921 13861 Sunrise Valley Drive, Suite 300 2922 Herndon, VA 20171 2923 USA 2925 Email: sratliff@idirect.net 2927 Bo Berry 2929 Shawn Jury 2930 Cisco Systems 2931 170 West Tasman Drive 2932 San Jose, CA 95134 2933 USA 2935 Email: sjury@cisco.com 2937 Darryl Satterwhite 2938 Broadcom 2940 Email: dsatterw@broadcom.com 2941 Rick Taylor 2942 Airbus Defence & Space 2943 Quadrant House 2944 Celtic Springs 2945 Coedkernew 2946 Newport NP10 8FZ 2947 UK 2949 Email: rick.taylor@airbus.com