idnits 2.17.1 draft-ietf-manet-dlep-11.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == Line 276 has weird spacing: '... Shared o ...' == Line 277 has weird spacing: '... Medium o...' -- The document date (May 10, 2015) is 3273 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Downref: Normative reference to an Informational RFC: RFC 5578 -- Obsolete informational reference (is this intentional?): RFC 5246 (Obsoleted by RFC 8446) Summary: 1 error (**), 0 flaws (~~), 3 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Mobile Ad hoc Networks Working Group S. Ratliff 3 Internet-Draft VT iDirect 4 Intended status: Standards Track B. Berry 5 Expires: November 11, 2015 6 S. Jury 7 Cisco Systems 8 D. Satterwhite 9 Broadcom 10 R. Taylor 11 Airbus Defence & Space 12 May 10, 2015 14 Dynamic Link Exchange Protocol (DLEP) 15 draft-ietf-manet-dlep-11 17 Abstract 19 When routing devices rely on modems to effect communications over 20 wireless links, they need timely and accurate knowledge of the 21 characteristics of the link (speed, state, etc.) in order to make 22 forwarding decisions. In mobile or other environments where these 23 characteristics change frequently, manual configurations or the 24 inference of state through routing or transport protocols does not 25 allow the router to make the best decisions. A bidirectional, event- 26 driven communication channel between the router and the modem is 27 necessary. 29 Status of This Memo 31 This Internet-Draft is submitted in full conformance with the 32 provisions of BCP 78 and BCP 79. 34 Internet-Drafts are working documents of the Internet Engineering 35 Task Force (IETF). Note that other groups may also distribute 36 working documents as Internet-Drafts. The list of current Internet- 37 Drafts is at http://datatracker.ietf.org/drafts/current/. 39 Internet-Drafts are draft documents valid for a maximum of six months 40 and may be updated, replaced, or obsoleted by other documents at any 41 time. It is inappropriate to use Internet-Drafts as reference 42 material or to cite them other than as "work in progress." 44 This Internet-Draft will expire on November 11, 2015. 46 Copyright Notice 48 Copyright (c) 2015 IETF Trust and the persons identified as the 49 document authors. All rights reserved. 51 This document is subject to BCP 78 and the IETF Trust's Legal 52 Provisions Relating to IETF Documents 53 (http://trustee.ietf.org/license-info) in effect on the date of 54 publication of this document. Please review these documents 55 carefully, as they describe your rights and restrictions with respect 56 to this document. Code Components extracted from this document must 57 include Simplified BSD License text as described in Section 4.e of 58 the Trust Legal Provisions and are provided without warranty as 59 described in the Simplified BSD License. 61 Table of Contents 63 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 64 1.1. Protocol Overview . . . . . . . . . . . . . . . . . . . . 7 65 1.2. Requirements . . . . . . . . . . . . . . . . . . . . . . 8 66 2. Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 8 67 3. Core Features and Optional Extensions . . . . . . . . . . . . 10 68 3.1. Negotiation of Optional Extensions . . . . . . . . . . . 10 69 3.2. Protocol Extensions . . . . . . . . . . . . . . . . . . . 11 70 3.3. Experimental Signals and Data Items . . . . . . . . . . . 11 71 4. Metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 72 4.1. Mandatory Metrics . . . . . . . . . . . . . . . . . . . . 12 73 5. DLEP Session Flow . . . . . . . . . . . . . . . . . . . . . . 12 74 5.1. DLEP Router session flow - Discovery case . . . . . . . . 13 75 5.2. DLEP Router session flow - Configured case . . . . . . . 13 76 5.3. DLEP Modem session flow . . . . . . . . . . . . . . . . . 14 77 5.4. Common Session Flow . . . . . . . . . . . . . . . . . . . 15 78 6. DLEP Signal Processing . . . . . . . . . . . . . . . . . . . 16 79 6.1. DLEP Signal Header . . . . . . . . . . . . . . . . . . . 16 80 6.2. DLEP Generic Data Item . . . . . . . . . . . . . . . . . 17 81 7. DLEP Signals . . . . . . . . . . . . . . . . . . . . . . . . 17 82 7.1. Peer Discovery Signal . . . . . . . . . . . . . . . . . . 18 83 7.2. Peer Offer Signal . . . . . . . . . . . . . . . . . . . . 19 84 7.3. Peer Initialization Signal . . . . . . . . . . . . . . . 19 85 7.4. Peer Initialization ACK Signal . . . . . . . . . . . . . 20 86 7.5. Peer Update Signal . . . . . . . . . . . . . . . . . . . 22 87 7.6. Peer Update ACK Signal . . . . . . . . . . . . . . . . . 23 88 7.7. Peer Termination Signal . . . . . . . . . . . . . . . . . 24 89 7.8. Peer Termination ACK Signal . . . . . . . . . . . . . . . 25 90 7.9. Destination Up Signal . . . . . . . . . . . . . . . . . . 25 91 7.10. Destination Up ACK Signal . . . . . . . . . . . . . . . . 26 92 7.11. Destination Down Signal . . . . . . . . . . . . . . . . . 27 93 7.12. Destination Down ACK Signal . . . . . . . . . . . . . . . 27 94 7.13. Destination Update Signal . . . . . . . . . . . . . . . . 28 95 7.14. Heartbeat Signal . . . . . . . . . . . . . . . . . . . . 29 96 7.15. Link Characteristics Request Signal . . . . . . . . . . . 29 97 7.16. Link Characteristics ACK Signal . . . . . . . . . . . . . 30 98 8. DLEP Data Items . . . . . . . . . . . . . . . . . . . . . . . 31 99 8.1. DLEP Version . . . . . . . . . . . . . . . . . . . . . . 32 100 8.2. Status . . . . . . . . . . . . . . . . . . . . . . . . . 33 101 8.3. IPv4 Connection Point . . . . . . . . . . . . . . . . . . 34 102 8.4. IPv6 Connection Point . . . . . . . . . . . . . . . . . . 35 103 8.5. Peer Type . . . . . . . . . . . . . . . . . . . . . . . . 36 104 8.6. Heartbeat Interval . . . . . . . . . . . . . . . . . . . 36 105 8.7. Extensions Supported . . . . . . . . . . . . . . . . . . 37 106 8.8. Experimental Definition . . . . . . . . . . . . . . . . . 38 107 8.9. MAC Address . . . . . . . . . . . . . . . . . . . . . . . 38 108 8.10. IPv4 Address . . . . . . . . . . . . . . . . . . . . . . 39 109 8.11. IPv6 Address . . . . . . . . . . . . . . . . . . . . . . 40 110 8.12. IPv4 Attached Subnet . . . . . . . . . . . . . . . . . . 40 111 8.13. IPv6 Attached Subnet . . . . . . . . . . . . . . . . . . 41 112 8.14. Maximum Data Rate (Receive) . . . . . . . . . . . . . . . 42 113 8.15. Maximum Data Rate (Transmit) . . . . . . . . . . . . . . 42 114 8.16. Current Data Rate (Receive) . . . . . . . . . . . . . . . 43 115 8.17. Current Data Rate (Transmit) . . . . . . . . . . . . . . 44 116 8.18. Latency . . . . . . . . . . . . . . . . . . . . . . . . . 45 117 8.19. Resources (Receive) . . . . . . . . . . . . . . . . . . . 45 118 8.20. Resources (Transmit) . . . . . . . . . . . . . . . . . . 46 119 8.21. Relative Link Quality (Receive) . . . . . . . . . . . . . 47 120 8.22. Relative Link Quality (Transmit) . . . . . . . . . . . . 47 121 8.23. Link Characteristics ACK Timer . . . . . . . . . . . . . 48 122 9. Credit-Windowing . . . . . . . . . . . . . . . . . . . . . . 48 123 9.1. Credit-Windowing Signals . . . . . . . . . . . . . . . . 49 124 9.1.1. Destination Up Signal . . . . . . . . . . . . . . . . 49 125 9.1.2. Destination Up ACK Signal . . . . . . . . . . . . . . 49 126 9.1.3. Destination Update Signal . . . . . . . . . . . . . . 49 127 9.2. Credit-Windowing Data Items . . . . . . . . . . . . . . . 50 128 9.2.1. Credit Grant . . . . . . . . . . . . . . . . . . . . 50 129 9.2.2. Credit Window Status . . . . . . . . . . . . . . . . 51 130 9.2.3. Credit Request . . . . . . . . . . . . . . . . . . . 52 131 10. Security Considerations . . . . . . . . . . . . . . . . . . . 52 132 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 53 133 11.1. Registrations . . . . . . . . . . . . . . . . . . . . . 53 134 11.2. Expert Review: Evaluation Guidelines . . . . . . . . . . 53 135 11.3. Signal Type Registration . . . . . . . . . . . . . . . . 53 136 11.4. DLEP Data Item Registrations . . . . . . . . . . . . . . 54 137 11.5. DLEP Status Code Registrations . . . . . . . . . . . . . 55 138 11.6. DLEP Extensions Registrations . . . . . . . . . . . . . 56 139 11.7. DLEP Well-known Port . . . . . . . . . . . . . . . . . . 56 140 11.8. DLEP Multicast Address . . . . . . . . . . . . . . . . . 56 141 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 56 142 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 57 143 13.1. Normative References . . . . . . . . . . . . . . . . . . 57 144 13.2. Informative References . . . . . . . . . . . . . . . . . 57 145 Appendix A. Peer Level Signal Flows . . . . . . . . . . . . . . 57 146 A.1. Discovery . . . . . . . . . . . . . . . . . . . . . . . . 57 147 A.2. Session Initialization . . . . . . . . . . . . . . . . . 57 148 A.3. Session Initialization - Refused . . . . . . . . . . . . 58 149 A.4. Router Changes IP Addresses . . . . . . . . . . . . . . . 59 150 A.5. Modem Changes Session-wide Metrics . . . . . . . . . . . 59 151 A.6. Router Terminates Session . . . . . . . . . . . . . . . . 59 152 A.7. Modem Terminates Session . . . . . . . . . . . . . . . . 60 153 A.8. Session Heartbeats . . . . . . . . . . . . . . . . . . . 60 154 A.9. Router Detects a Heartbeat timeout . . . . . . . . . . . 61 155 A.10. Modem Detects a Heartbeat timeout . . . . . . . . . . . . 62 156 Appendix B. Destination Specific Signal Flows . . . . . . . . . 62 157 B.1. Common Destination Signaling . . . . . . . . . . . . . . 62 158 B.2. Multicast Destination Signaling . . . . . . . . . . . . . 63 159 B.3. Link Characteristics Request . . . . . . . . . . . . . . 63 160 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 64 162 1. Introduction 164 There exist today a collection of modem devices that control links of 165 variable datarate and quality. Examples of these types of links 166 include line-of-sight (LOS) terrestrial radios, satellite terminals, 167 and cable/DSL modems. Fluctuations in speed and quality of these 168 links can occur due to configuration, or on a moment-to-moment basis, 169 due to physical phenomena like multipath interference, obstructions, 170 rain fade, etc. It is also quite possible that link quality and 171 datarate varies with respect to individual destinations on a link, 172 and with the type of traffic being sent. As an example, consider the 173 case of an 802.11g access point, serving 2 associated laptop 174 computers. In this environment, the answer to the question "What is 175 the datarate on the 802.11g link?" is "It depends on which associated 176 laptop we're talking about, and on what kind of traffic is being 177 sent." While the first laptop, being physically close to the access 178 point, may have a datarate of 54Mbps for unicast traffic, the other 179 laptop, being relatively far away, or obstructed by some object, can 180 simultaneously have a datarate of only 32Mbps for unicast. However, 181 for multicast traffic sent from the access point, all traffic is sent 182 at the base transmission rate (which is configurable, but depending 183 on the model of the access point, is usually 24Mbps or less). 185 In addition to utilizing variable datarate links, mobile networks are 186 challenged by the notion that link connectivity will come and go over 187 time, without an effect on a router's interface state (Up or Down). 188 Effectively utilizing a relatively short-lived connection is 189 problematic in IP routed networks, as routing protocols tend to rely 190 on interface state and independent timers at OSI Layer 3 to maintain 191 network convergence (e.g., HELLO messages and/or recognition of DEAD 192 routing adjacencies). These dynamic connections can be better 193 utilized with an event-driven paradigm, where acquisition of a new 194 neighbor (or loss of an existing one) is signaled, as opposed to a 195 paradigm driven by timers and/or interface state. 197 Another complicating factor for mobile networks are the different 198 methods of physically connecting the modem devices to the router. 199 Modems can be deployed as an interface card in a router's chassis, or 200 as a standalone device connected to the router via Ethernet or serial 201 link. In the case of Ethernet or serial attachment, with existing 202 protocols and techniques, routing software cannot be aware of 203 convergence events occurring on the radio link (e.g., acquisition or 204 loss of a potential routing neighbor), nor can the router be aware of 205 the actual capacity of the link. This lack of awareness, along with 206 the variability in datarate, leads to a situation where finding the 207 (current) best route through the network to a given destination is 208 difficult to establish and properly maintain. This is especially 209 true of demand-based access schemes such as Demand Assigned Multiple 210 Access (DAMA) implementations used on some satellite systems. With a 211 DAMA-based system, additional datarate may be available, but will not 212 be used unless the network devices emit traffic at a rate higher than 213 the currently established rate. Increasing the traffic rate does not 214 guarantee additional datarate will be allocated; rather, it may 215 result in data loss and additional retransmissions on the link. 217 Addressing the challenges listed above, the co-authors have developed 218 the Dynamic Link Exchange Protocol, or DLEP. The DLEP protocol runs 219 between a router and its attached modem devices, allowing the modem 220 to communicate link characteristics as they change, and convergence 221 events (acquisition and loss of potential routing destinations). The 222 following diagrams are used to illustrate the scope of DLEP packets. 224 |-------Local Node-------| |-------Remote Node------| 225 | | | | 226 +--------+ +-------+ +-------+ +--------+ 227 | Router |=======| Modem |{~~~~~~~~}| Modem |=======| Router | 228 | | | Device| | Device| | | 229 +--------+ +-------+ +-------+ +--------+ 230 | | | Link | | | 231 |-DLEP--| | Protocol | |-DLEP--| 232 | | | (e.g. | | | 233 | | | 802.11) | | | 235 Figure 1: DLEP Network 237 In Figure 1, when the local modem detects the presence of a remote 238 node, it (the local modem) sends a signal to its router via the DLEP 239 protocol. The signal consists of an indication of what change has 240 occurred on the link (e.g., presence of a remote node detected), 241 along with a collection of DLEP-defined Data Items that further 242 describe the change. Upon receipt of the signal, the local router 243 may take whatever action it deems appropriate, such as initiating 244 discovery protocols, and/or issuing HELLO messages to converge the 245 network. On a continuing, as-needed basis, the modem devices use 246 DLEP to report any characteristics of the link (datarate, latency, 247 etc.) that have changed. DLEP is independent of the link type and 248 topology supported by the modem. Note that the DLEP protocol is 249 specified to run only on the local link between router and modem. 250 Some over the air signaling may be necessary between the local and 251 remote modem in order to provide some parameters in DLEP signals 252 between the local modem and local router, but DLEP does not specify 253 how such over the air signaling is carried out. Over the air 254 signaling is purely a matter for the modem implementer. 256 Figure 2 shows how DLEP can support a configuration where routers are 257 connected with different link types. In this example, Modem A 258 implements a point-to-point link, and Modem B is connected via a 259 shared medium. In both cases, the DLEP protocol is used to report 260 the characteristics of the link (datarate, latency, etc.) to routers. 261 The modem is also able to use the DLEP session to notify the router 262 when the remote node is lost, shortening the time required to re- 263 converge the network. 265 +--------+ +--------+ 266 +----+ Modem A| | Modem A+---+ 267 | | Device | <===== // ======> | Device | | 268 | +--------+ P-2-P Link +--------+ | 269 +---+----+ +---+----+ 270 | Router | | Router | 271 | | | | 272 +---+----+ +---+----+ 273 | +--------+ +--------+ | 274 +-----+ Modem B| | Modem B| | 275 | Device | o o o o o o o o | Device +--+ 276 +--------+ o Shared o +--------+ 277 o Medium o 278 o o 279 o o 280 o o 281 o 282 +--------+ 283 | Modem B| 284 | Device | 285 +---+----+ 286 | 287 | 288 +---+----+ 289 | Router | 290 | | 291 +--------+ 293 Figure 2: DLEP Network with Multiple Modem Devices 295 1.1. Protocol Overview 297 As mentioned earlier, DLEP defines a set of signals used by modems 298 and their attached routers. The signals are used to communicate 299 events that occur on the physical link(s) managed by the modem: for 300 example, a remote node entering or leaving the network, or that the 301 link has changed. Associated with these signals are a set of data 302 items - information that describes the remote node (e.g., address 303 information), and/or the characteristics of the link to the remote 304 node. 306 The protocol is defined as a collection of type-length-value (TLV) 307 based formats, specifying the signals that are exchanged between a 308 router and a modem, and the data items associated with the signal. 309 This document specifies transport of DLEP signals and data items via 310 the TCP transport, with a UDP-based discovery mechanism. Other 311 transports for the protocol are possible, but are outside the scope 312 of this document. 314 DLEP uses a session-oriented paradigm between the modem device and 315 its associated router. If multiple modem devices are attached to a 316 router (as in Figure 2), or the modem supports multiple connections 317 (via multiple logical or physical interfaces), then separate DLEP 318 sessions exist for each modem or connection. This router/modem 319 session provides a carrier for information exchange concerning 320 'destinations' that are available via the modem device. A 321 'destination' can be either physical (as in the case of a specific 322 far-end router), or a logical destination (as in a Multicast group). 323 As such, all of the destination-level exchanges in DLEP can be 324 envisioned as building an information base concerning the remote 325 nodes, and the link characteristics to those nodes. 327 Multicast traffic destined for the variable-quality network (the 328 network accessed via the DLEP modem) is handled in IP networks by 329 deriving a Layer 2 MAC address based on the Layer 3 address. 330 Leveraging on this scheme, multicast traffic is supported in DLEP 331 simply by treating the derived MAC address as any other 'destination' 332 (albeit a logical one) in the network. To support these logical 333 destinations, one of the DLEP participants (typically, the router) 334 informs the other as to the existence of the logical destination. 335 The modem, once it is aware of the existence of this logical 336 destination, reports link characteristics just as it would for any 337 other destination in the network. The specific algorithms a modem 338 would use to derive metrics on multicast (or logical) destinations is 339 outside the scope of this specification, and is left to specific 340 implementations to decide. 342 1.2. Requirements 344 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 345 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 346 document are to be interpreted as described in BCP 14, RFC 2119 347 [RFC2119]. 349 2. Assumptions 351 Routers and modems that exist as part of the same node (e.g., that 352 are locally connected) can use a discovery technique to locate each 353 other, thus avoiding a priori configuration. The router is 354 responsible for initializing the discovery process, using the Peer 355 Discovery signal (Section 7.1). 357 DLEP uses a session-oriented paradigm. A router and modem form a 358 session by completing the discovery and initialization process. This 359 router-modem session persists unless or until it either (1) times 360 out, based on the timeout values supplied, or (2) is explicitly torn 361 down by one of the participants. Note that while use of timers in 362 DLEP is optional, it is strongly recommended that implementations 363 choose to run with timers enabled. 365 DLEP assumes that the MAC address for delivering data traffic is the 366 MAC specified in the Destination Up signal (Section 7.9). No 367 manipulation or substitution is performed; the MAC address supplied 368 in Destination Up is used as the OSI Layer 2 Destination MAC address. 369 DLEP also assumes that MAC addresses MUST be unique within the 370 context of a router-modem session. Additionally, DLEP can support 371 MAC addresses in either EUI-48 or EUI-64 format, with the restriction 372 that ALL MAC addresses for a given DLEP session MUST be in the same 373 format, and MUST be consistent with the MAC address format of the 374 connected modem (e.g., if the modem is connected to the router with 375 an EUI-48 MAC, all destination addresses via that modem MUST be 376 expressed in EUI-48 format). 378 DLEP uses UDP multicast for single-hop discovery, and TCP for 379 transport of the control signals. Therefore, DLEP assumes that the 380 modem and router have topologically consistent IP addresses assigned. 381 It is recommended that DLEP implementations utilize IPv6 link-local 382 addresses to reduce the administrative burden of address assignment. 384 Destinations can be identified by either the router or the modem, and 385 represent a specific destination (e.g., an address) that exists on 386 the link(s) managed by the modem. A destination MUST contain a MAC 387 address, it MAY optionally include a Layer 3 address (or addresses). 388 Note that since a destination is a MAC address, the MAC could 389 reference a logical destination, as in a derived multicast MAC 390 address, as well as a physical device. As destinations are 391 discovered, DLEP routers and modems build an information base on 392 destinations accessible via the modem. 394 The DLEP signals concerning destinations thus become the way for 395 routers and modems to maintain, and notify each other about, an 396 information base representing the physical and logical (e.g., 397 multicast) destinations accessible via the modem device. The 398 information base would contain addressing information (i.e. MAC 399 address, and OPTIONALLY, Layer 3 addresses), link characteristics 400 (metrics), and OPTIONALLY, flow control information (credits). 402 DLEP assumes that any signal not understood by a receiver MUST result 403 in an error indication being sent to the originator, and also MUST 404 result in termination of the session between the DLEP peers. Any 405 DLEP data item not understood by a receiver MUST also result in 406 termination of the session. 408 DLEP assumes that security on the session (e.g., authentication of 409 session partners, encryption of traffic, or both) is dealt with by 410 the underlying transport mechanism (e.g., by using a transport such 411 as TLS [RFC5246]). 413 This document specifies an implementation of the DLEP signals and 414 data items running over the TCP transport. It is assumed that DLEP 415 running over other transport mechanisms would be documented 416 separately. 418 3. Core Features and Optional Extensions 420 DLEP has a core set of signals and data items that MUST be processed 421 without error by an implementation in order to guarantee 422 interoperability and therefore make the implementation DLEP 423 compliant. This document defines the core set of signals and data 424 items, listing them as 'mandatory'. It should be noted that some 425 core signals and data items might not be used during the lifetime of 426 a single DLEP session, but a compliant implementation MUST support 427 them. 429 While this document represents the best efforts of the working group 430 to be functionally complete, it is recognized that extensions to DLEP 431 will in all likelihood be necessary as more link types are used. To 432 support future extension of DLEP, this document describes an 433 extension negotiation capability to be used during session 434 initialization via the Extensions Supported data item, documented in 435 Section 8.7 of this document. 437 All extensions are considered OPTIONAL. Only the DLEP functionality 438 listed as 'mandatory' is required by implementation in order to be 439 DLEP compliant. 441 This specification defines one extension, Credit windowing, exposed 442 via the Extensions Supported mechanism that implementations MAY 443 choose to implement, or to omit. 445 3.1. Negotiation of Optional Extensions 447 Optional extensions supported by an implementation MUST be declared 448 to potential DLEP peers using the Extensions Supported data item 449 (Section 8.7) during the session initialization sequence. Once both 450 peers have exchanged initialization signals, an implementation MUST 451 NOT emit any signal or data item associated with an optional 452 extension that was not specified in the received initialization 453 signal from its peer. 455 3.2. Protocol Extensions 457 If/when protocol extensions are required, they should be standardized 458 either as an update to this document, or as an additional stand-alone 459 specification. The requests for IANA-controlled registries in this 460 document contain sufficient reserved space, both in terms of DLEP 461 signals and DLEP data items, to accommodate future extensions to the 462 protocol and the data transferred. 464 3.3. Experimental Signals and Data Items 466 This document requests numbering space in both the DLEP signal and 467 data item registries for experimental items. The intent is to allow 468 for experimentation with either (1) new signals, (2) new data items, 469 or (3) both new signals and new data items, while still retaining the 470 documented DLEP behavior. If a given experiment proves successful, 471 it SHOULD be documented as an update to this document, or as a stand- 472 alone specification. 474 Use of the experimental signals, data items, or behaviors MUST be 475 announced by inclusion of an Experimental Definition data item 476 (Section 8.8) with a value agreed upon (a priori) between the 477 participating peers. The exact mechanism for a priori communication 478 of the experimental definition formats is beyond the scope of this 479 document. 481 Multiple Experimental Definition data items MAY appear in the Peer 482 Initialization/Peer Initialization ACK sequence. However, use of 483 multiple experiments in a single peer session could lead to 484 interoperability issues or unexpected results (e.g., redefinition of 485 experimental signals and/or data items), and is therefore 486 discouraged. It is left to implementations to determine the correct 487 processing path (e.g., a decision on whether to terminate the peer 488 session, or to establish a precedence of the conflicting definitions) 489 if such conflicts arise. 491 4. Metrics 493 DLEP includes the ability for the router and modem to communicate 494 metrics that reflect the characteristics (e.g., datarate, latency) of 495 the variable-quality link in use. DLEP does NOT specify how a given 496 metric value is to be calculated, rather, the protocol assumes that 497 metrics have been calculated with a 'best effort', incorporating all 498 pertinent data that is available to the modem device. 500 As mentioned in the introduction section of this document, DLEP 501 allows for metrics to be sent within two contexts - metrics for a 502 specific destination within the network (e.g., a specific router), 503 and 'modem-wide' (those that apply to all destinations accessed via 504 the modem). Most metrics can be further subdivided into transmit and 505 receive metrics. Metrics supplied on DLEP Peer signals are, by 506 definition, modem-wide; metrics supplied on Destination signals are, 507 by definition, used for the specific logical destination only. 509 DLEP modem implementations MUST announce all supported metric items, 510 and provide default values for those metrics, in the Peer 511 Initialization ACK signal (Section 7.4). In order to introduce a new 512 metric type, DLEP modem implementations MUST terminate the session 513 with the router (via the Peer Terminate signal (Section 7.7)), and 514 re-establish the session. 516 It is left to implementations to choose sensible default values based 517 on their specific characteristics. Modems having static (non- 518 changing) link metric characteristics MAY report metrics only once 519 for a given destination (or once on a modem-wide basis, if all 520 connections via the modem are of this static nature). 522 The approach of allowing for different contexts for metric data 523 increases both the flexibility and the complexity of using metric 524 data. This document details the mechanism whereby the data is 525 transmitted, however, the specific algorithms (precedence, etc.) for 526 utilizing the dual-context metrics is out of scope and not addressed 527 by this document. 529 4.1. Mandatory Metrics 531 As mentioned above, DLEP modem implementations MUST announce all 532 supported metric items during session initialization. However, an 533 implementation MUST include the following list of metrics: 535 o Maximum Data Rate (Receive) (Section 8.14) 537 o Maximum Data Rate (Transmit) (Section 8.15) 539 o Current Data Rate (Receive) (Section 8.16) 541 o Current Data Rate (Transmit) (Section 8.17) 543 o Latency (Section 8.18) 545 5. DLEP Session Flow 547 For routers supporting DLEP, support of Discovery is optional. 548 Discovery is initiated in the DLEP modem by sending the Peer 549 Discovery Signal (Section 7.1) to a well-known multicast address. 550 However, support for receipt and processing of the signal is optional 551 in the router (see Appendix A and B for flow diagrams of the 552 discovery signal). Due to the optional (on the router) support for 553 discovery, normal session flow is described for both the 'Discovery 554 case', and the 'Configured case'. Again, for modem implementations 555 of DLEP, support of Discovery is mandatory; therefore, that is the 556 only case to be described. 558 5.1. DLEP Router session flow - Discovery case 560 If the DLEP router implementation is utilizing the optional discovery 561 mechanism, then the implementation will initialize a UDP socket, 562 binding it to an arbitrary port. This UDP socket is used to send the 563 Peer Discovery signal (Section 7.1) to the DLEP link-local multicast 564 address and port (TBD). The implementation then waits on receipt of 565 a Peer Offer signal (Section 7.2), which MAY contain the unicast 566 address and port for TCP-based communication with a DLEP modem, via 567 the IPv4 Connection Point data item (Section 8.3) or the IPv6 568 Connection Point data item (Section 8.4). The Peer Offer signal MAY 569 contain multiple IP Connection Point data items. If more than one IP 570 Connection Point data items is in the Peer Offer, router 571 implementations MAY use their own heuristics to determine the best 572 address/port combination. If no IP Connection Point data items are 573 included in the Peer Offer signal, the receiver MUST use the origin 574 address of the signal as the IP address, and the DLEP well-known port 575 number (Section 11.7) to establish the TCP connection. At this 576 point, the router implementation MAY either destroy the UDP socket, 577 or continue to issue Peer Discovery signals to the link-local 578 address/port combination. In either case, the TCP session 579 initialization occurs as in the configured case. 581 5.2. DLEP Router session flow - Configured case 583 When a DLEP router implementation has the address and port 584 information for a TCP connection to a modem (obtained either via 585 configuration or via the discovery process described above), the 586 router will initialize and bind a TCP socket. This socket is used to 587 connect to the DLEP modem software. After a successful TCP connect, 588 the router implementation MUST issue a Peer Initialization signal 589 (Section 7.3) to the DLEP modem. After sending the Peer 590 Initialization, the router implementation MUST wait for receipt of a 591 Peer Initialization ACK signal (Section 7.4) from the modem. Receipt 592 of the Peer Initialization ACK signal containing a Status data item 593 (Section 8.2) with value 'Success', indicates that the modem has 594 received and processed the Peer Initialization, and the session MUST 595 transition to the 'in session' state. At this point, signals 596 regarding destinations in the network, and/or Peer Update signals 597 (Section 7.5), can flow on the DLEP session between modem and router, 598 and Heartbeat signals can begin to flow, if Heartbeats are used. The 599 'in session' state is maintained until one of the following 600 conditions occur: 602 o The session is explicitly terminated (using Peer Termination), or 604 o The session times out, based on supplied timeout values. 606 5.3. DLEP Modem session flow 608 DLEP modem implementations MUST support the discovery mechanism. 609 Therefore, the normal flow is as follows: 611 The implementation will initialize a UDP socket, binding that socket 612 to the DLEP link-local multicast address (TBD) and the DLEP well- 613 known port number (also TBD). The implementation will then 614 initialize a TCP socket, on a unicast address and port. This socket 615 is used to listen for incoming TCP connection requests. 617 When the modem implementation receives a Peer Discovery signal 618 (Section 7.1) on the UDP socket, it responds by issuing a Peer Offer 619 signal (Section 7.2) to the sender of the Peer Discovery signal. The 620 Peer Offer signal MAY contain the unicast address and port of the 621 listening TCP socket, as described above. A DLEP modem 622 implementation MAY respond with ALL address/port combinations that 623 have an active TCP listen posted. Anything other than Peer Discovery 624 signals received on the UDP socket MUST be silently dropped. 626 When the DLEP modem implementation accepts a connection via TCP, it 627 MUST wait for receipt of a Peer Initialization signal (Section 7.3), 628 sent by the router. Upon receipt and successful parsing of a Peer 629 Initialization signal, the modem MUST respond with a Peer 630 Initialization ACK signal (Section 7.4). The Peer Initialization ACK 631 signal MUST contain metric data items for ALL supported metrics. If 632 an additional metric is to be introduced, the DLEP session between 633 router and modem MUST be terminated and restarted, and the new metric 634 described in a Peer Initialization ACK signal. Once the Peer 635 Initialization signal (Section 7.3) and Peer Initialization ACK 636 signal (Section 7.4) have been exchanged, the session is transitioned 637 to the 'in session' state. As in the router case, when the 'in 638 session' state is reached, signals regarding destinations in the 639 network, and/or Peer Update signals (Section 7.5), can flow on the 640 DLEP session between modem and router, and Heartbeat signals can 641 begin to flow, if Heartbeats are used. The 'in session' state 642 persists until the session is explicitly terminated (using Peer 643 Termination), or it times out (based on timeout values). 645 5.4. Common Session Flow 647 In order to maintain the session between router and modem, periodic 648 Heartbeat signals (Section 7.14) MAY be exchanged. These signals are 649 intended to keep the session alive, and to verify bidirectional 650 connectivity between the two participants. If heartbeat signals are 651 exchanged, they do not begin until the DLEP peer session has entered 652 the 'in session' state. Each DLEP peer is responsible for the 653 creation of heartbeat signals. Receipt of any DLEP signal SHOULD 654 reset the heartbeat interval timer (i.e., valid DLEP signals take the 655 place of, and obviate the need for, Heartbeat signals). 657 DLEP also provides a Peer Update signal (Section 7.5), intended to 658 communicate some change in status (e.g., a change of layer 3 address 659 parameters, or a modem-wide link change). 661 In addition to the local (Peer level) signals above, the participants 662 will transmit DLEP signals concerning destinations in the network. 663 These signals trigger creation/maintenance/deletion of destinations 664 in the information base of the recipient. For example, a modem will 665 inform its attached router of the presence of a new destination via 666 the Destination Up signal (Section 7.9). Receipt of a Destination Up 667 causes the router to allocate the necessary resources, creating an 668 entry in the information base with the specifics (i.e. MAC Address, 669 Latency, Data Rate, etc.) of the destination. The loss of a 670 destination is communicated via the Destination Down signal 671 (Section 7.11), and changes in status to the destination (e.g., 672 varying link quality, or addressing changes) are communicated via the 673 Destination Update signal (Section 7.13). The information on a given 674 destination will persist in the router's information base until (1) a 675 Destination Down signal is received, indicating that the modem has 676 lost contact with the remote node, or (2) the router/modem session 677 terminates, indicating that the router has lost contact with its own 678 local modem. 680 Metrics can be expressed within the context of a specific destination 681 via the Destination Update signal, or on a modem-wide basis via the 682 Peer Update signal. In cases where metrics are provided at peer 683 level, the receiver MUST propagate the metrics to all destinations in 684 its information base that are accessed via the originator. A DLEP 685 participant MAY send metrics both in a router/modem session context 686 (via the Peer Update signal) and a specific destination context (via 687 Destination Update) at any time. The heuristics for applying 688 received metrics is left to implementations. 690 In addition to receiving metrics about the link, DLEP provides a 691 signal allowing a router to request a different datarate, or latency, 692 from the modem. This signal is referred to as the Link 693 Characteristics Request signal (Section 7.15), and gives the router 694 the ability to deal with requisite increases (or decreases) of 695 allocated datarate/latency in demand-based schemes in a more 696 deterministic manner. 698 6. DLEP Signal Processing 700 Communication between DLEP peers consists of a bidirectional stream 701 of signals (messages), each signal consisting of a signal header and 702 an unordered list of data items. Signal headers consist of Type and 703 Length information, while data items are encoded as TLV (Type-Length- 704 Value) structures. In this document, the data items following the 705 signal header are described as being 'contained in' the signal. 707 All integer values structures MUST be in network byte-order. 709 There is no restriction on the order of data items following a 710 signal, and the multiplicity of duplicate data items is defined by 711 the definition of the signal declared by the type in the signal 712 header. 714 If an unrecognized, or unexpected signal is received, or a received 715 signal contains unrecognized, invalid, or disallowed duplicate data 716 items, the receiving peer MUST terminate the session by issuing a 717 Peer Termination signal (Section 7.7) with a Status data item 718 (Section 8.2) containing the most relevant status code, and then 719 close the TCP connection. 721 6.1. DLEP Signal Header 723 The DLEP signal header contains the following fields: 725 0 1 2 726 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 727 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 728 | Signal Type | Length | 729 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 731 Figure 3: DLEP Signal Header 733 Signal Type: One of the DLEP Signal Type values defined in this 734 document. 736 Length: The length, expressed as a 16-bit unsigned integer, of all 737 of the DLEP data items associated with this signal. This length 738 does not include the length of the header itself 740 The DLEP Signal Header is immediately followed by one or more DLEP 741 data items, encoded in TLVs, as defined in this document. 743 6.2. DLEP Generic Data Item 745 All DLEP data items contain the following fields: 747 0 1 2 3 748 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 1 749 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 750 | Data Item Type| Length | Value... | 751 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 753 Figure 4: DLEP Generic Data Item 755 Data Item Type: An 8-bit unsigned integer field specifying the data 756 item being sent. 758 Length: The length, expressed as an 8-bit unsigned integer, of the 759 value field of the data item. 761 Value: A field of length which contains data specific to a 762 particular data item. 764 7. DLEP Signals 766 As mentioned above, all DLEP signals begin with the DLEP signal 767 header structure. Therefore, in the following descriptions of 768 specific signals, this header structure is assumed, and will not be 769 replicated. 771 Following is the set of MANDATORY signals that must be recognized by 772 a DLEP compliant implementation. As mentioned before, not all 773 signals may be used during a session, but an implementation MUST 774 correctly process these signals when received. 776 The mandatory DLEP signals are: 778 +--------+--------------------+----------------------+--------------+ 779 | Signal | Description | Mnemonic | Section | 780 +--------+--------------------+----------------------+--------------+ 781 | TBD | Peer Discovery | DLEP_PEER_DISCOVERY | Section 7.1 | 782 | TBD | Peer Offer | DLEP_PEER_OFFER | Section 7.2 | 783 | TBD | Peer | DLEP_PEER_INIT | Section 7.3 | 784 | | Initialization | | | 785 | TBD | Peer | DLEP_PEER_INIT_ACK | Section 7.4 | 786 | | Initialization ACK | | | 787 | TBD | Peer Update | DLEP_PEER_UPDATE | Section 7.5 | 788 | TBD | Peer Update ACK | DLEP_PEER_UPDATE_ACK | Section 7.6 | 789 | TBD | Peer Termination | DLEP_PEER_TERM | Section 7.7 | 790 | TBD | Peer Termination | DLEP_PEER_TERM_ACK | Section 7.8 | 791 | | ACK | | | 792 | TBD | Destination Up | DLEP_DEST_UP | Section 7.9 | 793 | TBD | Destination Up ACK | DLEP_DEST_UP_ACK | Section 7.10 | 794 | TBD | Destination Down | DLEP_DEST_DOWN | Section 7.11 | 795 | TBD | Destination Down | DLEP_DEST_DOWN_ACK | Section 7.12 | 796 | | ACK | | | 797 | TBD | Destination Update | DLEP_DEST_UPDATE | Section 7.13 | 798 | TBD | Heartbeat | DLEP_PEER_HEARTBEAT | Section 7.14 | 799 | TBD | Link | DLEP_LINK_CHAR_REQ | Section 7.15 | 800 | | Characteristics | | | 801 | | Request | | | 802 | TBD | Link | DLEP_LINK_CHAR_ACK | Section 7.16 | 803 | | Characteristics | | | 804 | | ACK | | | 805 +--------+--------------------+----------------------+--------------+ 807 Table 1: DLEP Signal Values 809 7.1. Peer Discovery Signal 811 A Peer Discovery signal SHOULD be sent by a router to discover DLEP 812 modems in the network. The Peer Offer signal (Section 7.2) is 813 required to complete the discovery process. Implementations MAY 814 implement their own retry heuristics in cases where it is determined 815 the Peer Discovery signal has timed out. 817 To construct a Peer Discovery signal, the Signal Type value in the 818 signal header is set to DLEP_PEER_DISCOVERY in Table 1. 820 The Peer Discovery signal MUST contain the following data item: 822 o DLEP Version (Section 8.1) 824 The Peer Discovery signal MAY contain the following data item: 826 o Peer Type (Section 8.5) 828 7.2. Peer Offer Signal 830 A Peer Offer signal MUST be sent by a DLEP modem in response to a 831 valid Peer Discovery signal (Section 7.1). 833 The Peer Offer signal MUST be sent to the unicast address of the 834 originator of the Peer Discovery signal. 836 To construct a Peer Offer signal, the Signal Type value in the signal 837 header is set to DLEP_PEER_OFFER in Table 1. 839 The Peer Offer signal MUST contain the following data item: 841 o DLEP Version (Section 8.1) 843 The Peer Offer signal MAY contain the following data item: 845 o Peer Type (Section 8.5) 847 The Peer Offer signal MAY contain one or more of any of the following 848 data items, with different values: 850 o IPv4 Connection Point (Section 8.3) 852 o IPv6 Connection Point (Section 8.4) 854 The IP Connection Point data items indicate the unicast address the 855 receiver of Peer Offer MUST use when connecting the DLEP TCP session. 856 If multiple IP Connection Point data items are present in the Peer 857 Offer signal, implementations MAY use their own heuristics to select 858 the address to connect to. If no IP Connection Point data items are 859 included in the Peer Offer signal, the receiver MUST use the origin 860 address of the signal as the IP address, and the DLEP well-known port 861 number (Section 11.7) to establish the TCP connection. 863 7.3. Peer Initialization Signal 865 A Peer Initialization signal MUST be sent by a router as the first 866 signal of the DLEP TCP session. It is sent by the router after a TCP 867 connect to an address/port combination that was obtained either via 868 receipt of a Peer Offer, or from a priori configuration. 870 If any optional extensions are supported by the implementation, they 871 MUST be enumerated in the Extensions Supported data item. If an 872 Extensions Supported data item does NOT exist in a Peer 873 Initialization signal, the receiver of the signal MUST conclude that 874 there is NO support for extensions in the sender. 876 If any experimental signals or data items are used by the 877 implementation, they MUST be enumerated in one or more Experimental 878 Definition data items. If there are no Experimental Definition data 879 items in a Peer Initialization signal, the receiver of the signal 880 MUST conclude that NO experimental definitions are in use by the 881 sender. 883 Implementations supporting the Heartbeat Interval (Section 8.6) 884 should understand that heartbeats are NOT fully established until 885 receipt of Peer Initialization ACK Signal (Section 7.4), and should 886 therefore implement their own timeout and retry heurestics for this 887 signal. 889 To construct a Peer Initialization signal, the Signal Type value in 890 the signal header is set to DLEP_PEER_INIT in Table 1. 892 The Peer Initialization signal MUST contain one of each of the 893 following data items: 895 o DLEP Version (Section 8.1) 897 o Heartbeat Interval (Section 8.6) 899 The Peer Initialization signal MAY contain one of each of the 900 following data items: 902 o Peer Type (Section 8.5) 904 o Extensions Supported (Section 8.7) 906 The Peer Initialization signal MAY contain one or more of any of the 907 following data items, with different values: 909 o Experimental Definition (Section 8.8) 911 A Peer Initialization signal MUST be acknowledged by the receiver 912 issuing a Peer Initialization ACK signal (Section 7.4). 914 7.4. Peer Initialization ACK Signal 916 A Peer Initialization ACK signal MUST be sent in response to a 917 received Peer Initialization signal (Section 7.3). The Peer 918 Initialization ACK signal completes the DLEP session establishment; 919 the sender of the signal should transition to an 'in-session' state 920 when the signal is sent, and the receiver should transition to the 921 'in-session' state upon receipt (and successful parsing) of an 922 acceptable Peer Initialization ACK signal. 924 All supported metric data items MUST be included in the Peer 925 Initialization ACK signal, with default values to be used on a 926 'modem-wide' basis. This can be viewed as the modem 'declaring' all 927 supported metrics at DLEP session initialization. Receipt of any 928 DLEP signal containing a metric data item NOT included in the Peer 929 Initialization ACK signal MUST be treated as an error, resulting in 930 the termination of the DLEP session between router and modem. 932 If any optional extensions are supported by the modem, they MUST be 933 enumerated in the Extensions Supported data item. If an Extensions 934 Supported data item does NOT exist in a Peer Initialization ACK 935 signal, the receiver of the signal MUST conclude that there is NO 936 support for extensions in the sender. 938 If any experimental signals or data items are used by the 939 implementation, they MUST be enumerated in one or more Experimental 940 Definition data items. If there are no Experimental Definition data 941 items in a Peer Initialization ACK signal, the receiver of the signal 942 MUST conclude that NO experimental definitions are in use by the 943 sender. 945 After the Peer Initialization/Peer Initialization ACK signals have 946 been successfully exchanged, implementations MUST only use extensions 947 and experimental definitions that are supported by BOTH peers. 949 To construct a Peer Initialization ACK signal, the Signal Type value 950 in the signal header is set to DLEP_PEER_INIT_ACK in Table 1. 952 The Peer Initialization ACK signal MUST contain one of each of the 953 following data items: 955 o DLEP Version (Section 8.1) 957 o Heartbeat Interval (Section 8.6) 959 o Maximum Data Rate (Receive) (Section 8.14) 961 o Maximum Data Rate (Transmit) (Section 8.15) 963 o Current Data Rate (Receive) (Section 8.16) 965 o Current Data Rate (Transmit) (Section 8.17) 967 o Latency (Section 8.18) 968 The Peer Initialization ACK signal MUST contain one of each of the 969 following data items, if the data item will be used during the 970 lifetime of the session: 972 o Resources (Receive) (Section 8.19) 974 o Resources (Transmit) (Section 8.20) 976 o Relative Link Quality (Receive) (Section 8.21) 978 o Relative Link Quality (Transmit) (Section 8.22) 980 The Peer Initialization ACK signal MAY contain one of each of the 981 following data items: 983 o Status (Section 8.2) 985 o Peer Type (Section 8.5) 987 o Extensions Supported (Section 8.7) 989 The Peer Initialization ACK signal MAY contain one or more of any of 990 the following data items, with different values: 992 o Experimental Definition (Section 8.8) 994 7.5. Peer Update Signal 996 A Peer Update signal MAY be sent by a DLEP peer to indicate local 997 Layer 3 address changes, or metric changes on a modem-wide basis. 998 For example, addition of an IPv4 address to the router MAY prompt a 999 Peer Update signal to its attached DLEP modems. Also, for example, a 1000 modem that changes its Maximum Data Rate (Receive) for all 1001 destinations MAY reflect that change via a Peer Update signal to its 1002 attached router(s). 1004 Concerning Layer 3 addresses, if the modem is capable of 1005 understanding and forwarding this information (via proprietary 1006 mechanisms), the address update would prompt any remote DLEP modems 1007 (DLEP-enabled modems in a remote node) to issue a Destination Update 1008 signal (Section 7.13) to their local routers with the new (or 1009 deleted) addresses. Modems that do not track Layer 3 addresses 1010 SHOULD silently parse and ignore the Peer Update signal. Modems that 1011 track Layer 3 addresses MUST acknowledge the Peer Update with a Peer 1012 Update ACK signal (Section 7.6). 1014 If metrics are supplied with the Peer Update signal (e.g., Maximum 1015 Data Rate), these metrics are considered to be modem-wide, and 1016 therefore MUST be applied to all destinations in the information base 1017 associated with the router/modem session. 1019 Supporting implementations are free to employ heuristics to 1020 retransmit Peer Update signals. The sending of Peer Update signals 1021 for Layer 3 address changes SHOULD cease when either participant 1022 (router or modem) determines that the other implementation does NOT 1023 support Layer 3 address tracking. 1025 To construct a Peer Update signal, the Signal Type value in the 1026 signal header is set to DLEP_PEER_UPDATE in Table 1. 1028 The Peer Update signal MAY contain one of each of the following data 1029 items: 1031 o Maximum Data Rate (Receive) (Section 8.14) 1033 o Maximum Data Rate (Transmit) (Section 8.15) 1035 o Current Data Rate (Receive) (Section 8.16) 1037 o Current Data Rate (Transmit) (Section 8.17) 1039 o Latency (Section 8.18) 1041 o Resources (Receive) (Section 8.19) 1043 o Resources (Transmit) (Section 8.20) 1045 o Relative Link Quality (Receive) (Section 8.21) 1047 o Relative Link Quality (Transmit) (Section 8.22) 1049 The Peer Update signal MAY contain one or more of the following data 1050 items, with different values: 1052 o IPv4 Address (Section 8.10) 1054 o IPv6 Address (Section 8.11) 1056 A Peer Update signal MUST be acknowledged by the receiver issuing a 1057 Peer Update ACK signal (Section 7.6). 1059 7.6. Peer Update ACK Signal 1061 A Peer Update ACK signal MUST be sent by implementations to indicate 1062 whether a Peer Update signal (Section 7.5) was successfully received. 1064 To construct a Peer Update ACK signal, the Signal Type value in the 1065 signal header is set to DLEP_PEER_UPDATE_ACK in Table 1. 1067 The Peer Update ACK signal MAY contain one of each of the following 1068 data items: 1070 o Status (Section 8.2) 1072 A receiver of a Peer Update ACK signal without a Status data item 1073 MUST behave as if a Status data item with code 'Success' had been 1074 received. 1076 7.7. Peer Termination Signal 1078 A Peer Termination signal MUST be sent by a DLEP participant when the 1079 router/modem session needs to be terminated. Implementations 1080 receiving a Peer Termination signal MUST send a Peer Termination ACK 1081 signal (Section 7.8) to confirm the termination process. 1083 The receiver of a Peer Termination signal MUST release all resources 1084 allocated for the router/modem session, and MUST eliminate all 1085 destinations in the information base accessible via the router/modem 1086 pair represented by the session. Router and modem state machines are 1087 returned to the 'discovery' state. No Destination Down signals 1088 (Section 7.11) are sent. 1090 The sender of a Peer Termination signal is free to define its 1091 heuristics in event of a timeout. It may resend the Peer Termination 1092 or free resources and return to the 'discovery' state. 1094 To construct a Peer Termination signal, the Signal Type value in the 1095 signal header is set to DLEP_PEER_TERM in Table 1. 1097 The Peer Termination signal MAY contain one of each of the following 1098 data items: 1100 o Status (Section 8.2) 1102 A receiver of a Peer Termination signal without a Status data item 1103 MUST behave as if a Status data item with status code 'Success', 1104 implying graceful termination, had been received. 1106 A Peer Termination signal MUST be acknowledged by the receiver 1107 issuing a Peer Termination ACK signal (Section 7.8). 1109 7.8. Peer Termination ACK Signal 1111 A Peer Termination ACK signal MUST be sent by a DLEP peer in response 1112 to a received Peer Termination signal (Section 7.7). Receipt of a 1113 Peer Termination ACK signal completes the teardown of the router/ 1114 modem session. 1116 To construct a Peer Termination ACK signal, the Signal Type value in 1117 the signal header is set to DLEP_PEER_TERM_ACK in Table 1. 1119 The Peer Termination ACK signal MAY contain one of each of the 1120 following data items: 1122 o Status (Section 8.2) 1124 A receiver of a Peer Termination ACK signal without a Status data 1125 item MUST behave as if a Status data item with status code 'Success', 1126 implying graceful termination, had been received. 1128 7.9. Destination Up Signal 1130 A Destination Up signal can be sent either by the modem, to indicate 1131 that a new remote node has been detected, or by the router, to 1132 indicate the presence of a new logical destination (e.g., a Multicast 1133 group) in the network. 1135 A Destination Up signal MUST be acknowledged by the receiver issuing 1136 a Destination Up ACK signal (Section 7.10). The sender of the 1137 Destination Up signal is free to define its retry heuristics in event 1138 of a timeout. When a Destination Up signal is received and 1139 successfully processed, the receiver should add knowledge of the new 1140 destination to its information base, indicating that the destination 1141 is accessible via the modem/router pair. 1143 To construct a Destination Up signal, the Signal Type value in the 1144 signal header is set to DLEP_DEST_UP in Table 1. 1146 The Destination Up signal MUST contain one of each of the following 1147 data items: 1149 o MAC Address (Section 8.9) 1151 The Destination Up signal MAY contain one of each of the following 1152 data items: 1154 o Maximum Data Rate (Receive) (Section 8.14) 1156 o Maximum Data Rate (Transmit) (Section 8.15) 1157 o Current Data Rate (Receive) (Section 8.16) 1159 o Current Data Rate (Transmit) (Section 8.17) 1161 o Latency (Section 8.18) 1163 o Resources (Receive) (Section 8.19) 1165 o Resources (Transmit) (Section 8.20) 1167 o Relative Link Quality (Receive) (Section 8.21) 1169 o Relative Link Quality (Transmit) (Section 8.22) 1171 The Destination Up signal MAY contain one or more of the following 1172 data items, with different values: 1174 o IPv4 Address (Section 8.10) 1176 o IPv6 Address (Section 8.11) 1178 o IPv4 Attached Subnet (Section 8.12) 1180 o IPv6 Attached Subnet (Section 8.13) 1182 If the sender has IPv4 and/or IPv6 address information for a 1183 destination it SHOULD include the relevant data items in the 1184 Destination Up signal, reducing the need for the receiver to probe 1185 for any address. 1187 7.10. Destination Up ACK Signal 1189 A DLEP participant MUST send a Destination Up ACK signal to indicate 1190 whether a Destination Up signal (Section 7.9) was successfully 1191 processed. 1193 To construct a Destination Up ACK signal, the Signal Type value in 1194 the signal header is set to DLEP_DEST_UP_ACK in Table 1. 1196 The Destination Up ACK signal MUST contain one of each of the 1197 following data items: 1199 o MAC Address (Section 8.9) 1201 The Destination Up ACK signal MAY contain one of each of the 1202 following data items: 1204 o Status (Section 8.2) 1205 A receiver of a Destination Up ACK signal without a Status data item 1206 MUST behave as if a Status data item with status code 'Success' had 1207 been received. Implementations are free to define retry heurestics 1208 when receiving a Destination Up ACK signal indicating an error. 1210 7.11. Destination Down Signal 1212 A DLEP peer MUST send a Destination Down signal to report when a 1213 destination (a remote node or a multicast group) is no longer 1214 reachable. A Destination Down ACK signal (Section 7.12) MUST be sent 1215 by the recipient of a Destination Down signal to confirm that the 1216 relevant data has been removed from the information base. The sender 1217 of the Destination Down signal is free to define its retry heuristics 1218 in event of a timeout. 1220 To construct a Destination Down signal, the Signal Type value in the 1221 signal header is set to DLEP_DEST_DOWN in Table 1. 1223 The Destination Down signal MUST contain one of each of the following 1224 data items: 1226 o MAC Address (Section 8.9) 1228 7.12. Destination Down ACK Signal 1230 A DLEP participant MUST send a Destination Down ACK signal to 1231 indicate whether a received Destination Down signal (Section 7.11) 1232 was successfully processed. If successfully processed, the sender of 1233 the ACK MUST have removed all entries in the information base that 1234 pertain to the referenced destination. 1236 To construct a Destination Down ACK signal, the Signal Type value in 1237 the signal header is set to DLEP_DEST_DOWN_ACK in Table 1. 1239 The Destination Down ACK signal MUST contain one of each of the 1240 following data items: 1242 o MAC Address (Section 8.9) 1244 The Destination Down ACK signal MAY contain one of each of the 1245 following data items: 1247 o Status (Section 8.2) 1249 A receiver of a Destination Down ACK signal without a Status data 1250 item MUST behave as if a Status data item with status code 'Success' 1251 had been received. Implementations are free to define retry 1252 heurestics when receiving a Destination Down ACK signal indicating an 1253 error. 1255 7.13. Destination Update Signal 1257 A DLEP participant SHOULD send the Destination Update signal when it 1258 detects some change in the information base for a given destination 1259 (remote node or multicast group). Some examples of changes that 1260 would prompt a Destination Update signal are: 1262 o Change in link metrics (e.g., Data Rates) 1264 o Layer 3 addressing change 1266 To construct a Destination Update signal, the Signal Type value in 1267 the signal header is set to DLEP_DEST_UPDATE in Table 1. 1269 The Destination Update signal MUST contain one of each of the 1270 following data items: 1272 o MAC Address (Section 8.9) 1274 The Destination Update signal MAY contain one of each of the 1275 following data items: 1277 o Maximum Data Rate (Receive) (Section 8.14) 1279 o Maximum Data Rate (Transmit) (Section 8.15) 1281 o Current Data Rate (Receive) (Section 8.16) 1283 o Current Data Rate (Transmit) (Section 8.17) 1285 o Latency (Section 8.18) 1287 o Resources (Receive) (Section 8.19) 1289 o Resources (Transmit) (Section 8.20) 1291 o Relative Link Quality (Receive) (Section 8.21) 1293 o Relative Link Quality (Transmit) (Section 8.22) 1295 The Destination Update signal MAY contain one or more of the 1296 following data items, with different values: 1298 o IPv4 Address (Section 8.10) 1299 o IPv6 Address (Section 8.11) 1301 o IPv4 Attached Subnet (Section 8.12) 1303 o IPv6 Attached Subnet (Section 8.13) 1305 7.14. Heartbeat Signal 1307 A Heartbeat signal SHOULD be sent by a DLEP participant every N 1308 seconds, where N is defined in the Heartbeat Interval data item of 1309 the Peer Initialization signal (Section 7.3) or Peer Initialization 1310 ACK signal (Section 7.4). Note that implementations setting the 1311 Heartbeat Interval to 0 effectively set the interval to an infinite 1312 value, therefore, in those cases, this signal SHOULD NOT be sent. 1314 The signal is used by participants to detect when a DLEP session 1315 partner (either the modem or the router) is no longer communicating. 1316 Participants SHOULD allow two (2) heartbeat intervals to expire with 1317 no traffic on the router/modem session before initiating DLEP session 1318 termination procedures. 1320 To construct a Heartbeat signal, the Signal Type value in the signal 1321 header is set to DLEP_PEER_HEARTBEAT in Table 1. 1323 There are no valid data items for the Heartbeat signal. 1325 7.15. Link Characteristics Request Signal 1327 The Link Characteristics Request signal MAY be sent by the router to 1328 request that the modem initiate changes for specific characteristics 1329 of the link. The request can reference either a real destination 1330 (e.g., a remote node), or a logical destination (e.g., a multicast 1331 group) within the network. 1333 The Link Characteristics Request signal MAY contain either a Current 1334 Data Rate (CDRR or CDRT) data item to request a different datarate 1335 than what is currently allocated, a Latency data item to request that 1336 traffic delay on the link not exceed the specified value, or both. A 1337 Link Characteristics ACK signal (Section 7.16) is required to 1338 complete the request. Issuing a Link Characteristics Request with 1339 ONLY the MAC Address data item is a mechanism a peer MAY use to 1340 request metrics (via the Link Characteristics ACK) from its partner. 1342 The sender of a Link Characteristics Request signal MAY attach a 1343 timer to the request using the Link Characteristics ACK Timer data 1344 item. If a Link Characteristics ACK signal is received after the 1345 timer expires, the sender MUST NOT assume that the request succeeded. 1347 Implementations are free to define their retry heuristics in event of 1348 a timeout. 1350 To construct a Link Characteristics Request signal, the Signal Type 1351 value in the signal header is set to DLEP_LINK_CHAR_REQ in Table 1. 1353 The Link Characteristics Request signal MUST contain one of each of 1354 the following data items: 1356 o MAC Address (Section 8.9) 1358 The Link Characteristics Request signal MAY contain one of each of 1359 the following data items: 1361 o Link Characteristics ACK Timer (Section 8.23) 1363 o Current Data Rate (Receive) (Section 8.16) 1365 o Current Data Rate (Transmit) (Section 8.17) 1367 o Latency (Section 8.18) 1369 7.16. Link Characteristics ACK Signal 1371 A DLEP participant MUST send a Link Characteristics ACK signal to 1372 indicate whether a received Link Characteristics Request signal 1373 (Section 7.15) was successfully processed. The Link Characteristics 1374 ACK signal SHOULD contain a complete set of metric data items, and 1375 MUST contain a full set (i.e. those declared in the Peer 1376 Initialization ACK signal (Section 7.4)), if metrics were requested 1377 by only including a MAC address data item. It MUST contain the same 1378 metric types as the request. The values in the metric data items in 1379 the Link Characteristics ACK signal MUST reflect the link 1380 characteristics after the request has been processed. 1382 If an implementation is not able to alter the characteristics of the 1383 link in the manner requested, then a Status data item with status 1384 code 'Request Denied' MUST be added to the signal. 1386 To construct a Link Characteristics Request ACK signal, the Signal 1387 Type value in the signal header is set to DLEP_LINK_CHAR_ACK in 1388 Table 1. 1390 The Link Characteristics ACK signal MUST contain one of each of the 1391 following data items: 1393 o MAC Address (Section 8.9) 1394 The Link Characteristics ACK signal SHOULD contain one of each of the 1395 following data items: 1397 o Maximum Data Rate (Receive) (Section 8.14) 1399 o Maximum Data Rate (Transmit) (Section 8.15) 1401 o Current Data Rate (Receive) (Section 8.16) 1403 o Current Data Rate (Transmit) (Section 8.17) 1405 o Latency (Section 8.18) 1407 The Link Characteristics ACK signal MAY contain one of each of the 1408 following data items: 1410 o Resources (Receive) (Section 8.19) 1412 o Resources (Transmit) (Section 8.20) 1414 o Relative Link Quality (Receive) (Section 8.21) 1416 o Relative Link Quality (Transmit) (Section 8.22) 1418 o Status (Section 8.2) 1420 A receiver of a Link Characteristics ACK signal without a Status data 1421 item MUST behave as if a Status data item with status code 'Success' 1422 had been received. 1424 8. DLEP Data Items 1426 Following is the list of MANDATORY data items that must be recognized 1427 by a DLEP compliant implementation. As mentioned before, not all 1428 data items need be used during a session, but an implementation MUST 1429 correctly process these data items when correctly associated with a 1430 signal. 1432 The DLEP data items are: 1434 +------------+--------------------------------------+---------------+ 1435 | Data Item | Description | Section | 1436 +------------+--------------------------------------+---------------+ 1437 | TBD | DLEP Version | Section 8.1 | 1438 | TBD | Status | Section 8.2 | 1439 | TBD | IPv4 Connection Point | Section 8.3 | 1440 | TBD | IPv6 Connection Point | Section 8.4 | 1441 | TBD | Peer Type | Section 8.5 | 1442 | TBD | Heartbeat Interval | Section 8.6 | 1443 | TBD | Extensions Supported | Section 8.7 | 1444 | TBD | Experimental Definition | Section 8.8 | 1445 | TBD | MAC Address | Section 8.9 | 1446 | TBD | IPv4 Address | Section 8.10 | 1447 | TBD | IPv6 Address | Section 8.11 | 1448 | TBD | IPv4 Attached Subnet | Section 8.12 | 1449 | TBD | IPv6 Attached Subnet | Section 8.13 | 1450 | TBD | Maximum Data Rate (Receive) MDRR) | Section 8.14 | 1451 | TBD | Maximum Data Rate (Transmit) (MDRT) | Section 8.15 | 1452 | TBD | Current Data Rate (Receive) (CDRR) | Section 8.16 | 1453 | TBD | Current Data Rate (Transmit) (CDRT) | Section 8.17 | 1454 | TBD | Latency | Section 8.18 | 1455 | TBD | Resources (Receive) (RESR) | Section 8.19 | 1456 | TBD | Resources (Transmit) (REST) | Section 8.20 | 1457 | TBD | Relative Link Quality (Receive) | Section 8.21 | 1458 | | (RLQR) | | 1459 | TBD | Relative Link Quality (Transmit) | Section 8.22 | 1460 | | (RLQT) | | 1461 | TBD | Link Characteristics ACK Timer | Section 8.23 | 1462 +------------+--------------------------------------+---------------+ 1464 Table 2: DLEP Data Item Values 1466 8.1. DLEP Version 1468 The DLEP Version data item MUST appear in the Peer Discovery 1469 (Section 7.1), Peer Offer (Section 7.2), Peer Initialization 1470 (Section 7.3) and Peer Initialization ACK (Section 7.4) signals. The 1471 Version data item is used to indicate the version of the protocol 1472 running in the originator. A DLEP implementation SHOULD use this 1473 information to decide if the potential session partner is running at 1474 a supported level. 1476 The DLEP Version data item contains the following fields: 1478 0 1 2 3 1479 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 1480 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1481 | Data Item Type| Length | Major Version | 1482 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1483 | Minor Version | 1484 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1486 Data Item Type: TBD 1488 Length: 4 1490 Major Version: The major version of the DLEP protocol, expressed as 1491 an 16-bit unsigned integer. 1493 Minor Version: The minor version of the DLEP protocol, expressed as 1494 an 16-bit unsigned integer. 1496 Support of this draft is indicated by setting the Major Version to 1497 '1', and the Minor Version to '0' (i.e. Version 1.0). 1499 8.2. Status 1501 The Status data item MAY appear in the Peer Initialization ACK 1502 (Section 7.4), Peer Termination (Section 7.7), Peer Termination ACK 1503 (Section 7.8), Peer Update ACK (Section 7.6), Destination Up ACK 1504 (Section 7.10), Destination Down ACK (Section 7.12) and Link 1505 Characteristics ACK (Section 7.16) signals as part of an 1506 acknowledgement from either the modem or the router, to indicate the 1507 success or failure of the previously received signal. 1509 The status data item includes an optional Text field that can be used 1510 to provide a textual description of the status. The use of the Text 1511 field is entirely up to the receiving implementation, i.e., it could 1512 be output to a log file or discarded. If no Text field is supplied 1513 with the Status data item, the Length field MUST be set to 1. 1515 The Status data item contains the following fields: 1517 0 1 2 3 1518 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1519 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1520 | Data Item Type| Length | Code | Text... 1521 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1523 Data Item Type: TBD 1525 Length: 1 + Length of text 1526 Status Code: One of the codes defined below. 1528 Text: UTF-8 encoded string, describing an problem, used for 1529 implementation defined purposes. Since this field is used for a 1530 description of the problem, implementations SHOULD limit 1531 characters in this field to printable characters. Implementations 1532 receiving this data item SHOULD check for printable characters in 1533 the field. 1535 An implementation MUST NOT assume the Text field is NUL-terminated. 1537 +----------------+-------+------------------------------------------+ 1538 | Status Code | Value | Reason | 1539 +----------------+-------+------------------------------------------+ 1540 | Success | 0 | The signal was processed successfully. | 1541 | Unknown Signal | TBD | The signal was not recognized by the | 1542 | | | implementation. | 1543 | Invalid Data | TBD | One or more data items in the signal are | 1544 | | | invalid, unexpected or duplicated. | 1545 | Unexpected | TBD | The signal was not expected while the | 1546 | Signal | | machine was in this state, e.g., a Peer | 1547 | | | Initialization signal after session | 1548 | | | establishment. | 1549 | Request Denied | TBD | The receiver has not completed the | 1550 | | | request. | 1551 | Timed Out | TBD | The request could not be completed in | 1552 | | | the time allowed. | 1553 | Invalid | TBD | The destination provided in the signal | 1554 | Destination | | does not match a previously announced | 1555 | | | destination. For example, in the Link | 1556 | | | Characteristic Request ACK signal | 1557 | | | (Section 7.16). | 1558 +----------------+-------+------------------------------------------+ 1560 8.3. IPv4 Connection Point 1562 The IPv4 Connection Point data item MAY appear in the Peer Offer 1563 signal (Section 7.2). The IPv4 Connection Point data item indicates 1564 the IPv4 address and, optionally, the TCP port number on the DLEP 1565 modem available for connections. If provided, the receiver MUST use 1566 this information to perform the TCP connect to the DLEP server. 1568 The IPv4 Connection Point data item contains the following fields: 1570 0 1 2 3 1571 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1572 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1573 | Data Item Type| Length | IPv4 Address | 1574 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1575 | IPv4 Address | TCP Port Number (optional) | 1576 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1578 Data Item Type: TBD 1580 Length: 4 (or 6 if TCP Port included) 1582 IPv4 Address: The IPv4 address listening on the DLEP modem. 1584 TCP Port Number: TCP Port number on the DLEP modem. 1586 If the Length field is 6, the port number specified MUST be used to 1587 establish the TCP session. If the TCP Port Number is omitted, i.e. 1588 the Length field is 4, the receiver MUST use the DLEP well-known port 1589 number (Section 11.7) to establish the TCP connection. 1591 8.4. IPv6 Connection Point 1593 The IPv6 Connection Point data item MAY appear in the Peer Offer 1594 signal (Section 7.2). The IPv6 Connection Point data item indicates 1595 the IPv6 address and, optionally, the TCP port number on the DLEP 1596 modem available for connections. If provided, the receiver MUST use 1597 this information to perform the TCP connect to the DLEP server. 1599 The IPv4 Connection Point data item contains the following fields: 1601 0 1 2 3 1602 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1603 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1604 | Data Item Type| Length | IPv6 Address | 1605 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1606 | IPv6 Address | 1607 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1608 | IPv6 Address | 1609 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1610 | IPv6 Address | 1611 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1612 | IPv6 Address | TCP Port Number (optional) | 1613 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1615 Data Item Type: TBD 1617 Length: 16 (or 18 if TCP Port included) 1618 IPv6 Address: The IPv6 address listening on the DLEP modem. 1620 TCP Port Number: TCP Port number on the DLEP modem. 1622 If the Length field is 18, the port number specified MUST be used to 1623 establish the TCP session. If the TCP Port Number is omitted, i.e. 1624 the Length field is 16, the receiver MUST use the DLEP well-known 1625 port number (Section 11.7) to establish the TCP connection. 1627 8.5. Peer Type 1629 The Peer Type data item MAY appear in the Peer Discovery 1630 (Section 7.1), Peer Offer (Section 7.2), Peer Initialization 1631 (Section 7.3) and Peer Initialization ACK (Section 7.4) signals. The 1632 Peer Type data item is used by the router and modem to give 1633 additional information as to its type. The peer type is a string and 1634 is envisioned to be used for informational purposes (e.g., as output 1635 in a display command). 1637 The Peer Type data item contains the following fields: 1639 0 1 2 3 1640 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1641 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1642 | Data Item Type| Length | Peer Type | 1643 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1645 Data Item Type: TBD 1647 Length: Length of peer type string. 1649 Peer Type: UTF-8 encoded string. For example, a satellite modem 1650 might set this variable to "Satellite terminal". Since this data 1651 item is intended to provide additional information for display 1652 commands, sending implementations SHOULD limit the data to 1653 printable characters, and receiving implmentations SHOULD check 1654 the data for printable characters. 1656 An implementation MUST NOT assume the Peer Type field is NUL- 1657 terminated. 1659 8.6. Heartbeat Interval 1661 The Heartbeat Interval data item MUST appear in both the Peer 1662 Initialization (Section 7.3) and Peer Initialization ACK 1663 (Section 7.4) signals to indicate the Heartbeat timeout window to be 1664 used by the sender. 1666 The Interval is used to specify a period (in seconds) for Heartbeat 1667 signals (Section 7.14). By specifying an Interval value of 0, 1668 implementations MAY indicates the desire to disable Heartbeat signals 1669 entirely (i.e., the Interval is set to an infinite value). However, 1670 it is strongly recommended that implementations use non 0 timer 1671 values. Implementations MUST implement heuristics such that DLEP 1672 signals sent/received reset the timer interval. 1674 A DLEP session will be considered inactive, and MUST be torn down, 1675 via the Peer Termination procedure, by an implementation detecting 1676 that two (2) Heartbeat intervals have transpired without receipt of 1677 any DLEP signals. 1679 The Heartbeat Interval data item contains the following fields: 1681 0 1 2 3 1682 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1683 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1684 | Data Item Type| Length | Interval | 1685 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1687 Data Item Type: TBD 1689 Length: 2 1691 Interval: 0 = Do NOT use heartbeats on this DLEP session. Non-zero 1692 = Interval, in seconds, for heartbeat signals. 1694 8.7. Extensions Supported 1696 The Extensions Supported data item MAY be used in both the Peer 1697 Initialization and Peer Initialization ACK signals. The Extensions 1698 Supported data item is used by the router and modem to negotiate 1699 additional optional functionality they are willing to support. The 1700 Extensions List is a concatenation of the types of each supported 1701 extension, found in the IANA DLEP Extensions repository. 1703 The Extensions Supported data item contains the following fields: 1705 0 1 2 3 1706 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1707 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1708 | Data Item Type| Length | Extensions List | 1709 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1711 Data Item Type: TBD 1713 Length: Number of Extensions supported. 1715 Extension List: A list of extensions supported, identified by their 1716 1-octet value as listed in the extensions registry. 1718 8.8. Experimental Definition 1720 The Experimental Definition data item MAY be used in both the Peer 1721 Initialization and Peer Initialization ACK signals. The Experimental 1722 Definition data item is used by the router and modem to indicate the 1723 formats to be used for experimental signals and data items for the 1724 given peer session. The formats are identified by using a string 1725 that matches the 'name' given to the experiment. 1727 The Experimental Definition item contains the following fields: 1729 0 1 2 3 1730 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1731 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1732 | Data Item Type| Length | Experiment Name | 1733 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1735 Data Item Type: TBD 1737 Length: Length of the name string for the Experiment. 1739 Experiment Name: UTF-8 encoded string, containing the name of the 1740 experiment being implemented. 1742 An implementation receiving this data item MUST compare the received 1743 string to a list of experiments that it supports. 1745 An implementation MUST NOT assume the Experiment Name field is NUL- 1746 terminated. 1748 8.9. MAC Address 1750 The MAC address data item MUST appear in all destination-oriented 1751 signals (i.e., Destination Up (Section 7.9), Destination Up ACK 1752 (Section 7.10), Destination Down (Section 7.11), Destination Down ACK 1753 (Section 7.12), Destination Update (Section 7.13), Link 1754 Characteristics Request (Section 7.15), and Link Characteristics ACK 1755 (Section 7.16)). The MAC Address data item contains the address of 1756 the destination on the remote node. The MAC address MAY be either a 1757 physical or a virtual destination, and MAY be expressed in EUI-48 or 1758 EUI-64 format. Examples of a virtual destination would be a 1759 multicast MAC address, or the broadcast MAC (FF:FF:FF:FF:FF:FF). 1761 0 1 2 3 1762 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1763 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1764 | Data Item Type| Length | MAC Address | 1765 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1766 | MAC Address | 1767 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1768 | MAC Address | 1769 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1771 Data Item Type: TBD 1773 Length: 6 for EUI-48 format, or 8 for EUI-64 format 1775 MAC Address: MAC Address of the destination. 1777 8.10. IPv4 Address 1779 The IPv4 Address data item MAY appear in the Peer Update 1780 (Section 7.5), Destination Up (Section 7.9) and Destination Update 1781 (Section 7.13) signals. When included in Destination signals, this 1782 data item contains the IPv4 address of the destination. When 1783 included in the Peer Update signal, this data item contains the IPv4 1784 address of the peer. In either case, the data item also contains an 1785 indication of whether this is a new or existing address, or is a 1786 deletion of a previously known address. 1788 The IPv4 Address data item contains the following fields: 1790 0 1 2 3 1791 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1792 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1793 | Data Item Type| Length | Add/Drop | IPv4 Address | 1794 | | | Indicator | | 1795 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1796 | IPv4 Address | 1797 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1799 Data Item Type: TBD 1801 Length: 5 1803 Add/Drop: Value indicating whether this is a new or existing address 1804 (1), or a withdrawal of an address (0). 1806 IPv4 Address: The IPv4 address of the destination or peer. 1808 8.11. IPv6 Address 1810 The IPv6 Address data item MAY appear in the Peer Update 1811 (Section 7.5), Destination Up (Section 7.9) and Destination Update 1812 (Section 7.13) signals. When included in Destination signals, this 1813 data item contains the IPv6 address of the destination. When 1814 included in the Peer Update signal, this data item contains the IPv6 1815 address of the peer. In either case, the data item also contains an 1816 indication of whether this is a new or existing address, or is a 1817 deletion of a previously known address. 1819 The IPv6 Address data item contains the following fields: 1821 0 1 2 3 1822 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 1823 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1824 | Data Item Type| Length | Add/Drop | IPv6 Address | 1825 | | | Indicator | | 1826 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1827 | IPv6 Address | 1828 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1829 | IPv6 Address | 1830 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1831 | IPv6 Address | 1832 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1833 | IPv6 Address | 1834 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1836 Data Item Type: TBD 1838 Length: 17 1840 Add/Drop: Value indicating whether this is a new or existing address 1841 (1), or a withdrawal of an address (0). 1843 IPv6 Address: IPv6 Address of the destination or peer. 1845 8.12. IPv4 Attached Subnet 1847 The DLEP IPv4 Attached Subnet allows a device to declare that it has 1848 an IPv4 subnet (e.g., a stub network) attached, and MAY appear in the 1849 Destination Up (Section 7.9) and Destination Update (Section 7.13) 1850 signals. Once an IPv4 Subnet has been declared on a device, the 1851 declaration can NOT be withdrawn without terminating the destination 1852 (via the Destination Down signal (Section 7.11)) and re-issuing the 1853 Destination Up signal. 1855 The DLEP IPv4 Attached Subnet data item contains the following 1856 fields: 1858 0 1 2 3 1859 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 1860 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1861 |Data Item Type | Length | IPv4 Attached Subnet | 1862 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1863 | IPv4 Attached Subnet | Subnet Mask | 1864 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1866 Data Item Type: TBD 1868 Length: 5 1870 IPv4 Subnet: The IPv4 subnet reachable at the destination. 1872 Subnet Mask: A subnet mask (0-32) to be applied to the IPv4 subnet. 1874 8.13. IPv6 Attached Subnet 1876 The DLEP IPv6 Attached Subnet allows a device to declare that it has 1877 an IPv6 subnet (e.g., a stub network) attached, and MAY appear in the 1878 Destination Up (Section 7.9) and Destination Update (Section 7.13) 1879 signals. As in the case of the IPv4 attached Subnet data item above, 1880 once an IPv6 attached subnet has been declared, it can NOT be 1881 withdrawn without terminating the destination (via the Destination 1882 Down signal (Section 7.11)) and re-issuing the Destination Up signal. 1884 The DLEP IPv6 Attached Subnet data item contains the following 1885 fields: 1887 0 1 2 3 1888 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 1889 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1890 | Data Item Type| Length | IPv6 Attached Subnet | 1891 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1892 | IPv6 Attached Subnet | 1893 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1894 | IPv6 Attached Subnet | 1895 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1896 | IPv6 Attached Subnet | 1897 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1898 | IPv6 Attached Subnet | Subnet Mask | 1899 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1901 Data Item Type: TBD 1902 Length: 17 1904 IPv4 Subnet: The IPv6 subnet reachable at the destination. 1906 Subnet Mask: A subnet mask (0-128) to be applied to the IPv6 subnet. 1908 8.14. Maximum Data Rate (Receive) 1910 The Maximum Data Rate (Receive) (MDRR) data item MUST appear in the 1911 Peer Initialization ACK signal (Section 7.4), and MAY appear in the 1912 Peer Update (Section 7.5), Destination Up (Section 7.9), Destination 1913 Update (Section 7.13) and Link Characteristics ACK (Section 7.16) 1914 signals to indicate the maximum theoretical data rate, in bits per 1915 second, that can be achieved while receiving data on the link. 1917 The Maximum Data Rate (Receive) data item contains the following 1918 fields: 1920 0 1 2 3 1921 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 1922 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1923 | Data Item Type| Length | MDRR (bps) | 1924 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1925 | MDRR (bps) | 1926 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1927 | MDRR (bps) | 1928 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1930 Data Item Type: TBD 1932 Length: 8 1934 Maximum Data Rate (Receive): A 64-bit unsigned integer, representing 1935 the maximum theoretical data rate, in bits per second (bps), that 1936 can be achieved while receiving on the link. 1938 8.15. Maximum Data Rate (Transmit) 1940 The Maximum Data Rate (Transmit) (MDRT) data item MUST appear in the 1941 Peer Initialization ACK signal (Section 7.4), and MAY appear in the 1942 Peer Update (Section 7.5), Destination Up (Section 7.9), Destination 1943 Update (Section 7.13) and Link Characteristics ACK (Section 7.16) 1944 signals to indicate the maximum theoretical data rate, in bits per 1945 second, that can be achieved while transmitting data on the link. 1947 The Maximum Data Rate (Transmit) data item contains the following 1948 fields: 1950 0 1 2 3 1951 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 1952 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1953 | Data Item Type| Length | MDRT (bps) | 1954 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1955 | MDRT (bps) | 1956 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1957 | MDRT (bps) | 1958 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1960 Data Item Type: TBD 1962 Length: 8 1964 Maximum Data Rate (Transmit): A 64-bit unsigned integer, 1965 representing the maximum theoretical data rate, in bits per second 1966 (bps), that can be achieved while transmitting on the link. 1968 8.16. Current Data Rate (Receive) 1970 The Current Data Rate (Receive) (CDRR) data item MUST appear in the 1971 Peer Initialization ACK signal (Section 7.4), and MAY appear in the 1972 Peer Update (Section 7.5), Destination Up (Section 7.9), Destination 1973 Update (Section 7.13) and Link Characteristics ACK (Section 7.16) 1974 signals to indicate the rate at which the link is currently operating 1975 for receiving traffic. 1977 When used in the Link Characteristics Request signal (Section 7.15), 1978 CDRR represents the desired receive rate, in bits per second, on the 1979 link. 1981 The Current Data Rate (Receive) data item contains the following 1982 fields: 1984 0 1 2 3 1985 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1986 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1987 | Data Item Type| Length | CDRR (bps) | 1988 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1989 | CDRR (bps) | 1990 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1991 | CDRR (bps) | 1992 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1994 Data Item Type: TBD 1996 Length: 8 1997 Current Data Rate (Receive): A 64-bit unsigned integer, representing 1998 the current data rate, in bits per second, that can currently be 1999 achieved while receiving traffic on the link. 2001 If there is no distinction between current and maximum receive data 2002 rates, current data rate receive MUST be set equal to the maximum 2003 data rate receive. 2005 8.17. Current Data Rate (Transmit) 2007 The Current Data Rate Transmit (CDRT) data item MUST appear in the 2008 Peer Initialization ACK signal (Section 7.4), and MAY appear in the 2009 Peer Update (Section 7.5), Destination Up (Section 7.9), Destination 2010 Update (Section 7.13), and Link Characteristics ACK (Section 7.16) 2011 signals to indicate the rate at which the link is currently operating 2012 for transmitting traffic. 2014 When used in the Link Characteristics Request signal (Section 7.15), 2015 CDRT represents the desired transmit rate, in bits per second, on the 2016 link. 2018 The Current Data Rate (Transmit) data item contains the following 2019 fields: 2021 0 1 2 3 2022 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 2023 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2024 | Data Item Type| Length | CDRT (bps) | 2025 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2026 | CDRT (bps) | 2027 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2028 | CDRT (bps) | 2029 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2031 Data Item Type: TBD 2033 Length: 8 2035 Current Data Rate (Transmit): A 64-bit unsigned integer, 2036 representing the current data rate, in bits per second, that can 2037 currently be achieved while transmitting traffic on the link. 2039 If there is no distinction between current and maximum transmit data 2040 rates, current data rate transmit MUST be set equal to the maximum 2041 data rate transmit. 2043 8.18. Latency 2045 The Latency data item data item MUST appear in the Peer 2046 Initialization ACK signal (Section 7.4), and MAY appear in the Peer 2047 Update (Section 7.5), Destination Up (Section 7.9), Destination 2048 Update (Section 7.13), and Link Characteristics ACK (Section 7.16) 2049 signals to indicate the amount of latency, in microseconds, on the 2050 link. 2052 When used in the Link Characteristics Request signal (Section 7.15), 2053 Latency represents the maximum latency desired on the link. 2055 The Latency value is reported as delay. The calculation of latency 2056 is implementation dependent. For example, the latency may be a 2057 running average calculated from the internal queuing. 2059 0 1 2 3 2060 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 2061 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2062 | Data Item Type| Length | Latency | 2063 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2064 | Latency (cont.) | 2065 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2067 Data Item Type: TBD 2069 Length: 4 2071 Latency: A 32-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 [RFC5578] Berry, B., Ratliff, S., Paradise, E., Kaiser, T., and M. 2617 Adams, "PPP over Ethernet (PPPoE) Extensions for Credit 2618 Flow and Link Metrics", RFC 5578, February 2010. 2620 13.2. Informative References 2622 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 2623 (TLS) Protocol Version 1.2", RFC 5246, August 2008. 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