idnits 2.17.1 draft-ietf-6lowpan-problem-06.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- ** It looks like you're using RFC 3978 boilerplate. You should update this to the boilerplate described in the IETF Trust License Policy document (see https://trustee.ietf.org/license-info), which is required now. -- Found old boilerplate from RFC 3978, Section 5.1 on line 18. -- Found old boilerplate from RFC 3978, Section 5.5 on line 540. -- Found old boilerplate from RFC 3979, Section 5, paragraph 1 on line 551. -- Found old boilerplate from RFC 3979, Section 5, paragraph 2 on line 558. -- Found old boilerplate from RFC 3979, Section 5, paragraph 3 on line 564. ** This document has an original RFC 3978 Section 5.4 Copyright Line, instead of the newer IETF Trust Copyright according to RFC 4748. ** This document has an original RFC 3978 Section 5.5 Disclaimer, instead of the newer disclaimer which includes the IETF Trust according to RFC 4748. 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 RFC 3978 Section 5.4 Copyright Line does not match the current year == The document doesn't use any RFC 2119 keywords, yet seems to have RFC 2119 boilerplate text. -- The document seems to lack a disclaimer for pre-RFC5378 work, but may have content which was first submitted before 10 November 2008. If you have contacted all the original authors and they are all willing to grant the BCP78 rights to the IETF Trust, then this is fine, and you can ignore this comment. If not, you may need to add the pre-RFC5378 disclaimer. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (November 8, 2006) is 6379 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Unused Reference: 'I-D.ietf-ipv6-2461bis' is defined on line 462, but no explicit reference was found in the text == Unused Reference: 'RFC3756' is defined on line 500, but no explicit reference was found in the text -- Possible downref: Non-RFC (?) normative reference: ref. 'EUI64' == Outdated reference: A later version (-11) exists of draft-ietf-ipv6-2461bis-09 ** Obsolete normative reference: RFC 2460 (Obsoleted by RFC 8200) -- Possible downref: Non-RFC (?) normative reference: ref. 'ieee802.15.4' Summary: 4 errors (**), 0 flaws (~~), 5 warnings (==), 9 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group N. Kushalnagar 3 Internet-Draft Intel Corp 4 Intended status: Standards Track G. Montenegro 5 Expires: May 12, 2007 Microsoft Corporation 6 C. Schumacher 7 Danfoss A/S 8 November 8, 2006 10 6LoWPAN: Overview, Assumptions, Problem Statement and Goals 11 draft-ietf-6lowpan-problem-06.txt 13 Status of this Memo 15 By submitting this Internet-Draft, each author represents that any 16 applicable patent or other IPR claims of which he or she is aware 17 have been or will be disclosed, and any of which he or she becomes 18 aware will be disclosed, in accordance with Section 6 of BCP 79. 20 Internet-Drafts are working documents of the Internet Engineering 21 Task Force (IETF), its areas, and its working groups. Note that 22 other groups may also distribute working documents as Internet- 23 Drafts. 25 Internet-Drafts are draft documents valid for a maximum of six months 26 and may be updated, replaced, or obsoleted by other documents at any 27 time. It is inappropriate to use Internet-Drafts as reference 28 material or to cite them other than as "work in progress." 30 The list of current Internet-Drafts can be accessed at 31 http://www.ietf.org/ietf/1id-abstracts.txt. 33 The list of Internet-Draft Shadow Directories can be accessed at 34 http://www.ietf.org/shadow.html. 36 This Internet-Draft will expire on May 12, 2007. 38 Copyright Notice 40 Copyright (C) The Internet Society (2006). 42 Abstract 44 This document describes the assumptions, problem statement and goals 45 for transmitting IP over IEEE 802.15.4 networks. The set of goals 46 enumerated in this document form an initial set only. 48 Table of Contents 50 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 51 1.1. Requirements notation . . . . . . . . . . . . . . . . . . 3 52 2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 53 3. Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 4 54 4. Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 55 4.1. IP Connectivity . . . . . . . . . . . . . . . . . . . . . 5 56 4.2. Topologies . . . . . . . . . . . . . . . . . . . . . . . . 6 57 4.3. Limited Packet Size . . . . . . . . . . . . . . . . . . . 6 58 4.4. Limited configuration and management . . . . . . . . . . . 7 59 4.5. Service discovery . . . . . . . . . . . . . . . . . . . . 7 60 4.6. Security . . . . . . . . . . . . . . . . . . . . . . . . . 7 61 5. Goals . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 62 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 63 7. Security Considerations . . . . . . . . . . . . . . . . . . . 10 64 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11 65 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 66 9.1. Normative References . . . . . . . . . . . . . . . . . . . 11 67 9.2. Informative References . . . . . . . . . . . . . . . . . . 11 68 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12 69 Intellectual Property and Copyright Statements . . . . . . . . . . 13 71 1. Introduction 73 Low-power wireless personal area networks (LoWPANs) comprise devices 74 that conform to the IEEE 802.15.4-2003 standard by the IEEE 75 [ieee802.15.4]. IEEE 802.15.4 devices are characterized by short 76 range, low bit rate, low power and low cost. Many of the devices 77 employing IEEE 802.15.4 radios will be limited in their computational 78 power, memory, and/or energy availability. 80 This document gives an overview of LoWPANs and describes how they 81 benefit from IP and in particular IPv6 networking. It describes 82 LoWPAN requirements with regards to the IP layer and above, and 83 spells out the underlying assumptions of IP for LoWPANs. Finally, it 84 describes problems associated with enabling IP communication with 85 devices in a LoWPAN, and defines goals to address these in a 86 prioritized manner. Admittedly, not all items on this list may be 87 necessarily appropriate tasks for the IETF. Nevertheless, they are 88 documented here to give a general overview of the larger problem. 89 This is useful both to structure work within the IETF as well as to 90 understand better how to coordinate with external organizations. 92 1.1. Requirements notation 94 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 95 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 96 document are to be interpreted as described in [RFC2119]. 98 2. Overview 100 A LoWPAN is a simple low cost communication network that allows 101 wireless connectivity in applications with limited power and relaxed 102 throughput requirements. A LoWPAN typically includes devices that 103 work together to connect the physical environment to real-world 104 applications, e.g., wireless sensors. LoWPANs conform to the IEEE 105 802.15.4-2003 standard. [ieee802.15.4]. 107 Some of the characteristics of LoWPANs are: 109 1. Small packet size. Given that the maximum physical layer packet 110 is 127 bytes, the resulting maximum frame size at the media 111 access control layer is 102 octets. Link-layer security imposes 112 further overhead, which in the maximum case (21 octets of 113 overhead in the AES-CCM-128 case, versus 9 and 13 for AES-CCM-32 114 and AES-CCM-64, respectively) leaves 81 octets for data packets. 116 2. Support for both 16-bit short or IEEE 64-bit extended media 117 access control addresses. 119 3. Low bandwidth. Data rates of 250 kbps, 40 kbps and 20 kbps for 120 each of the currently defined physical layers (2.4 GHz, 915 MHz 121 and 868 MHz, respectively). 123 4. Topologies include star and mesh operation. 125 5. Low power. Typically, some or all devices are battery operated. 127 6. Low cost. These devices are typically associated with sensors, 128 switches, etc. This drives some of the other characteristics 129 such as low processing, low memory, etc. Numerical values for 130 "low" elided on purpose since costs tend to change over time. 132 7. Large number of devices expected to be deployed during the life- 133 time of the technology. This number is expected to dwarf the 134 number of deployed personal computers, for example. 136 8. Location of the devices is typically not predefined, as they 137 tend to be deployed in an ad-hoc fashion. Furthermore, 138 sometimes the location of these devices may not be easily 139 accessible. Additionally, these devices may move to new 140 locations. 142 9. Devices within LoWPANs tend to be unreliable due to variety of 143 reasons: uncertain radio connectivity, battery drain, device 144 lockups, physical tampering, etc. 146 10. In many environments, devices connected to a LoWPAN may sleep 147 for long periods of time in order to conserve energy, and are 148 unable to communicate during these sleep periods. 150 The following sections take into account these characteristics in 151 describing the assumptions, problems statement and goals for LoWPANs, 152 and, in particular, for 6LoWPANs (IPv6-based LoWPAN networks). 154 3. Assumptions 156 Given the small packet size of LoWPANs, this document presumes 157 applications typically send small amounts of data. However, the 158 protocols themselves do not restrict bulk data transfers. 160 LoWPANs as described in this document are based on IEEE 802.15.4- 161 2003. It is possible that the specification may undergo changes in 162 the future and may change some of the requirements mentioned above. 164 Some of these assumptions are based on the limited capabilities of 165 devices within LoWPANs. As devices become more powerful, and consume 166 less power, some of the requirements mentioned above may be somewhat 167 relaxed. 169 While some LoWPAN devices are expected to be extremely limited (the 170 so-called "Reduced Function Devices" or RFDs), more capable "Full 171 Function Devices" (FFDs) will also be present, albeit in much smaller 172 numbers. FFDs will typically have more resources and may be mains 173 powered. Accordingly, FFDs will aid RFDs by providing functions such 174 as network coordination, packet forwarding, interfacing with other 175 types of networks, etc. 177 The application of IP technology is assumed to provide the following 178 benefits: 180 1. The pervasive nature of IP networks allows use of existing 181 infrastructure. 182 2. IP-based technologies already exist, are well known and proven to 183 be working. 184 3. An admittedly non-technical but important consideration is that 185 intellectual property conditions for IP networking technology are 186 either more favorable or at least better understood than 187 proprietary and newer solutions. 188 4. Tools for diagnostics, management and commissioning of IP 189 networks already exist. 190 5. IP-based devices can be connected readily to other IP-based 191 networks, without the need for intermediate entities like 192 translation gateways or proxies. 194 4. Problems 196 Based on the characteristics defined in the overview section, the 197 following sections elaborate on the main problems with IP for 198 LoWPANs. 200 4.1. IP Connectivity 202 The requirement for IP connectivity within a LoWPAN is driven by the 203 following: 205 1. The many devices in a LoWPAN make network auto configuration and 206 statelessness highly desirable. And for this, IPv6 has ready 207 solutions. 209 2. The large number of devices poses the need for a large address 210 space, well met by IPv6. 211 3. Given the limited packet size of LoWPANs, the IPv6 address format 212 allows subsuming of IEEE 802.15.4 addresses if so desired. 213 4. Simple interconnectivity to other IP networks including the 214 Internet. 216 However, given the limited packet size, headers for IPv6 and layers 217 above must be compressed whenever possible. 219 4.2. Topologies 221 LoWPANs must support various topologies including mesh and star. 223 Mesh topologies imply multi-hop routing, to a desired destination. 224 In this case, intermediate devices act as packet forwarders at the 225 link layer (akin to routers at the network layer). Typically these 226 are "full function devices" that have more capabilities in terms of 227 power, computation, etc. The requirements on the routing protocol 228 are: 230 1. Given the minimal packet size of LoWPANs, the routing protocol 231 must impose low (or no) overhead on data packets, hopefully 232 independently of the number of hops. 233 2. The routing protocols should have low routing overhead (low 234 chattiness) balanced with topology changes and power 235 conservation. 236 3. The computation and memory requirements in the routing protocol 237 should be minimal to satisfy the low cost and low power 238 objectives. Thus, storage and maintenance of large routing 239 tables is detrimental. 240 4. Support for network topologies in which either FFDs or RFDs may 241 be battery or mains-powered. This implies the appropriate 242 considerations for routing in the presence of sleeping nodes. 244 As with mesh topologies, star topologies include provisioning a 245 subset of devices with packet forwarding functionality. If, in 246 addition to IEEE 802.15.4, these devices use other kinds of network 247 interfaces such as ethernet or IEEE 802.11, the goal is to seamlessly 248 integrate the networks built over those different technologies. 249 This, of course, is a primary motivation to use IP to begin with. 251 4.3. Limited Packet Size 253 Applications within LoWPANs are expected to originate small packets. 254 Adding all layers for IP connectivity should still allow transmission 255 in one frame without incurring excessive fragmentation and 256 reassembly. Furthermore, protocols must be designed or chosen so 257 that the individual "control/protocol packets" fit within a single 258 802.15.4 frame. Along these lines, IPv6's requirement of sub-IP 259 reassembly (see Section 5) may pose challenges for low-end LoWPAN 260 devices that do not have enough RAM or storage for a 1280-octet 261 packet. 263 4.4. Limited configuration and management 265 As alluded to above, devices within LoWPANs are expected to be 266 deployed in exceedingly large numbers. Additionally, they are 267 expected to have limited display and input capabilities. 268 Furthermore, the location of some of these devices may be hard to 269 reach. Accordingly, protocols used in LoWPANs should have minimal 270 configuration, preferably work "out of the box", be easy to 271 bootstrap, and enable the network to self heal given the inherent 272 unreliable characteristic of these devices. Network management 273 should have little overhead yet be powerful enough to control dense 274 deployment of devices. 276 4.5. Service discovery 278 LoWPANs require simple service discovery network protocols to 279 discover, control and maintain services provided by devices. In some 280 cases, especially in dense deployments, abstraction of several nodes 281 to provide a service may be beneficial. In order to enable such 282 features, new protocols may have to be designed. 284 4.6. Security 286 IEEE 802.15.4 mandates link-layer security based on AES, but it omits 287 any details about topics like bootstrapping, key management and 288 security at higher layers. Of course, a complete security solution 289 for LoWPAN devices must consider application needs very carefully. 290 Please refer to the security consideration section below for a more 291 detailed discussion and in-depth security requirements. 293 5. Goals 295 The goals mentioned below are general and not limited to IETF 296 activities. As such, they may not only refer to work that can be 297 done within the IETF (e.g., specification required to transmit IP, 298 profile of best practices for transmitting IP packets, and associated 299 upper level protocols, etc). They also point at work more relevant 300 to other standards bodies (e.g., desirable changes to or profiles 301 relevant to IEEE 802.15.4, W3C, etc). When the goals fall under the 302 IETF's purview, they serve to point out what those efforts should 303 strive to accomplish, regardless of whether they are pursued within 304 one (or more) new (or existing) working groups. When the goals do 305 not fall under the purview of the IETF, documenting them here serves 306 as input to other organizations [liaison]. 308 Note that a common underlying goal is to reduce packet overhead, 309 bandwidth consumption, processing requirements and power consumption. 311 The following are the goals according to priority for LoWPANs: 313 1. Fragmentation and Reassembly layer: As mentioned in the overview, 314 the protocol data units may be as small 81 bytes. This is 315 obviously far below the minimum IPv6 packet size of 1280 octets, 316 and in keeping with section 5 of the IPv6 specification 317 [RFC2460], a fragmentation and reassembly adaptation layer must 318 be provided at the layer below IP. 320 2. Header Compression: Given that in the worst case the maximum size 321 available for transmitting IP packets over IEEE 802.15.4 frame is 322 81 octets, and that the IPv6 header is 40 octets long, (without 323 optional headers), this leaves only 41 octets for upper-layer 324 protocols, like UDP and TCP. UDP uses 8 octets in the header and 325 TCP uses 20 octets. This leaves 33 octets for data over UDP and 326 21 octets for data over TCP. Additionally, as pointed above, 327 there is also a need for a fragmentation and reassembly layer, 328 which will use even more octets leaving very few octets for data. 329 Thus if one were to use the protocols as is, it would lead to 330 excessive fragmentation and reassembly even when data packets are 331 just 10s of octets long. This points to the need for header 332 compression. As there is much published and in-progress 333 standardization work on header compression, the 6LoWPAN community 334 needs to investigate using existing header compression 335 techniques, and, if necessary, specify new ones. 337 3. Address Autoconfiguration: [I-D.ietf-ipv6-rfc2462bis] specifies 338 methods for creating IPv6 stateless address auto configuration. 339 Stateless auto configuration (as compared to stateful) is 340 attractive for 6LoWPANs, because it reduces the configuration 341 overhead on the hosts. There is a need for a method to generate 342 an "interface identifier" from the EUI-64 [EUI64] assigned to the 343 IEEE 802.15.4 device. 345 4. Mesh Routing Protocol: A routing protocol to support a multi-hop 346 mesh network is necessary. There is much published work on ad- 347 hoc multi hop routing for devices. Some examples include 348 [RFC3561], [RFC3626], [RFC3684], all experimental. Also, these 349 protocols are designed to use IP-based addresses that have large 350 overheads. For example, the AODV [RFC3561] routing protocol uses 351 48 octets for a route request based on IPv6 addressing. Given 352 the packet-size constraints, transmitting this packet without 353 fragmentation and reassembly may be difficult. Thus, care should 354 be taken when using existing routing protocols (or designing new 355 ones) so that the routing packets fit within a single IEEE 356 802.15.4 frame. 358 5. Network Management: One of the points of transmitting IPv6 359 packets, is to reuse existing protocols as much as possible. 360 Network management functionality is critical for LoWPANs. 361 [RFC3411] specifies SNMPv3 protocol operations. SNMP 362 functionality may be translated "as is" to LoWPANs. However, 363 further investigation is required to determine if it is suitable, 364 or if an appropriate adaption is in order. This adaptation could 365 include limiting the data types and simplifying the Basic 366 Encoding Rules so as to reduce the size and complexity of the 367 ASN.1 parser, thereby reducing the memory and processing needs to 368 better fit into the limited memory and power of LoWPAN devices. 370 6. Implementation Considerations: It may be the case that 371 transmitting IP over IEEE 802.15.4 would become more beneficial 372 if implemented in a "certain" way. Accordingly, implementation 373 considerations are to be documented. 375 7. Application and higher layer Considerations: As header 376 compression becomes more prevalent, overall performance will 377 depend even more on efficiency of application protocols. 378 Heavyweight protocols based on XML such as SOAP [SOAP], may not 379 be suitable for LoWPANs. As such, more compact encodings (and 380 perhaps protocols) may become necessary. The goal here is to 381 specify or suggest modifications to existing protocols so that 382 they are suitable for LoWPANs. Furthermore, application level 383 interoperability specifications may also become necessary in the 384 future and may thus be specified. 386 8. Security Considerations: Security threats at different layers 387 must be clearly understood and documented. Bootstrapping of 388 devices into a secure network could also be considered given the 389 location, limited display, high density and ad-hoc deployment of 390 devices. 392 6. IANA Considerations 394 This document contains no IANA considerations. 396 7. Security Considerations 398 IPv6 over LoWPAN (6LoWPAN) applications often require confidentiality 399 and integrity protection. This can be provided at the application, 400 transport, network, and/or at the link layer (i.e., within the 401 6LoWPAN set of specifications). In all these cases, prevailing 402 constraints will influence the choice of a particular protocol. Some 403 of the more relevant constraints are small code size, low power 404 operation, low complexity, and small bandwidth requirements. 406 Given these constraints, first, a threat model for 6LoWPAN devices 407 needs to be developed in order to weigh any risks against the cost of 408 their mitigations while making meaningful assumptions and 409 simplifications. Some examples for threats that should be considered 410 are man-in-the-middle attacks and denial of service attacks. 412 A separate set of security considerations apply to bootstrapping a 413 6LoWPAN device into the network (e.g., for initial key 414 establishment). This generally involves application level exchanges 415 or out-of-band techniques for the initial key establishment, and may 416 rely on application- specific trust models; thus, it is considered 417 extraneous to 6LoWPAN and is not addressed in these specifications. 418 In order to be able to select (or design) this next set of protocols, 419 there needs to be a common model of the keying material created by 420 the initial key establishment. 422 Beyond initial key establishment, protocols for subsequent key 423 management as well as to secure the data traffic do fall under the 424 purview of 6LoWPAN. Here, the different alternatives (TLS, IKE/ 425 IPsec, etc.) must be evaluated in light of the 6LoWPAN constraints. 427 One argument for using link layer security is that most IEEE 802.15.4 428 devices already have support for AES link-layer security. AES is a 429 block cipher operating on blocks of fixed length, i.e., 128 bits. To 430 encrypt longer messages, several modes of operation may be used. The 431 earliest modes described, such as ECB, CBC, OFB and CFB provide only 432 confidentiality, and this does not ensure message integrity. Other 433 modes have been designed which ensure both confidentiality and 434 message integrity, such as CCM* mode. 6LoWPAN networks can operate in 435 any of the previous modes, but it is desirable to utilize the most 436 secure modes available for link-layer security (e.g., CCM*), and 437 build upon it. 439 For network layer security, two models are applicable: end-to-end 440 security, e.g. using IPsec transport mode, or security that is 441 limited to the wireless portion of the network, e.g. using a security 442 gateway and IPsec tunnel mode. The disadvantage of the latter is the 443 larger header size, which is significant at the 6LoWPAN frame MTUs. 445 To simplify 6LoWPAN implementations, it is beneficial to identify the 446 relevant security model, and to identify a preferred set of cipher 447 suites that are appropriate given the constraints. 449 8. Acknowledgements 451 Thanks to Geoff Mulligan, Soohong Daniel Park, Samita Chakrabarti and 452 Brijesh Kumar for their comments and help in shaping this document. 454 9. References 456 9.1. Normative References 458 [EUI64] "GUIDELINES FOR 64-BIT GLOBAL IDENTIFIER (EUI-64) 459 REGISTRATION AUTHORITY", IEEE http://standards.ieee.org/ 460 regauth/oui/tutorials/EUI64.html. 462 [I-D.ietf-ipv6-2461bis] 463 Narten, T., "Neighbor Discovery for IP version 6 (IPv6)", 464 draft-ietf-ipv6-2461bis-09 (work in progress), 465 October 2006. 467 [I-D.ietf-ipv6-rfc2462bis] 468 Thomson, S., "IPv6 Stateless Address Autoconfiguration", 469 draft-ietf-ipv6-rfc2462bis-08 (work in progress), 470 May 2005. 472 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 473 Requirement Levels", BCP 14, RFC 2119, March 1997. 475 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 476 (IPv6) Specification", RFC 2460, December 1998. 478 [ieee802.15.4] 479 IEEE Computer Society, "IEEE Std. 802.15.4-2003", 480 October 2003. 482 9.2. Informative References 484 [RFC3411] Harrington, D., Presuhn, R., and B. Wijnen, "An 485 Architecture for Describing Simple Network Management 486 Protocol (SNMP) Management Frameworks", STD 62, RFC 3411, 487 December 2002. 489 [RFC3561] Perkins, C., Belding-Royer, E., and S. Das, "Ad hoc On- 490 Demand Distance Vector (AODV) Routing", RFC 3561, 491 July 2003. 493 [RFC3626] Clausen, T. and P. Jacquet, "Optimized Link State Routing 494 Protocol (OLSR)", RFC 3626, October 2003. 496 [RFC3684] Ogier, R., Templin, F., and M. Lewis, "Topology 497 Dissemination Based on Reverse-Path Forwarding (TBRPF)", 498 RFC 3684, February 2004. 500 [RFC3756] Nikander, P., Kempf, J., and E. Nordmark, "IPv6 Neighbor 501 Discovery (ND) Trust Models and Threats", RFC 3756, 502 May 2004. 504 [SOAP] "SOAP", W3C http://www.w3c.org/2000/xp/Group/. 506 [liaison] "LIASONS", 507 IETF http://www.ietf.org/liaisonActivities.html. 509 Authors' Addresses 511 Nandakishore Kushalnagar 512 Intel Corp 514 Email: nandakishore.kushalnagar@intel.com 516 Gabriel Montenegro 517 Microsoft Corporation 519 Email: gabriel_montenegro_2000@yahoo.com 521 Christian Peter Pii Schumacher 522 Danfoss A/S 524 Email: schumacher@danfoss.com 526 Full Copyright Statement 528 Copyright (C) The Internet Society (2006). 530 This document is subject to the rights, licenses and restrictions 531 contained in BCP 78, and except as set forth therein, the authors 532 retain all their rights. 534 This document and the information contained herein are provided on an 535 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 536 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET 537 ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, 538 INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE 539 INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 540 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 542 Intellectual Property 544 The IETF takes no position regarding the validity or scope of any 545 Intellectual Property Rights or other rights that might be claimed to 546 pertain to the implementation or use of the technology described in 547 this document or the extent to which any license under such rights 548 might or might not be available; nor does it represent that it has 549 made any independent effort to identify any such rights. Information 550 on the procedures with respect to rights in RFC documents can be 551 found in BCP 78 and BCP 79. 553 Copies of IPR disclosures made to the IETF Secretariat and any 554 assurances of licenses to be made available, or the result of an 555 attempt made to obtain a general license or permission for the use of 556 such proprietary rights by implementers or users of this 557 specification can be obtained from the IETF on-line IPR repository at 558 http://www.ietf.org/ipr. 560 The IETF invites any interested party to bring to its attention any 561 copyrights, patents or patent applications, or other proprietary 562 rights that may cover technology that may be required to implement 563 this standard. Please address the information to the IETF at 564 ietf-ipr@ietf.org. 566 Acknowledgment 568 Funding for the RFC Editor function is provided by the IETF 569 Administrative Support Activity (IASA).