idnits 2.17.1 draft-ietf-stox-im-13.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 -- The document date (March 5, 2015) is 3339 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) -- Possible downref: Non-RFC (?) normative reference: ref. 'XEP-0071' Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group P. Saint-Andre 3 Internet-Draft &yet 4 Intended status: Standards Track A. Houri 5 Expires: September 6, 2015 IBM 6 J. Hildebrand 7 Cisco Systems, Inc. 8 March 5, 2015 10 Interworking between the Session Initiation Protocol (SIP) and the 11 Extensible Messaging and Presence Protocol (XMPP): Instant Messaging 12 draft-ietf-stox-im-13 14 Abstract 16 This document defines a bidirectional protocol mapping for the 17 exchange of single instant messages between the Session Initiation 18 Protocol (SIP) and the Extensible Messaging and Presence Protocol 19 (XMPP). 21 Status of This Memo 23 This Internet-Draft is submitted in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF). Note that other groups may also distribute 28 working documents as Internet-Drafts. The list of current Internet- 29 Drafts is at http://datatracker.ietf.org/drafts/current/. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 This Internet-Draft will expire on September 6, 2015. 38 Copyright Notice 40 Copyright (c) 2015 IETF Trust and the persons identified as the 41 document authors. All rights reserved. 43 This document is subject to BCP 78 and the IETF Trust's Legal 44 Provisions Relating to IETF Documents 45 (http://trustee.ietf.org/license-info) in effect on the date of 46 publication of this document. Please review these documents 47 carefully, as they describe your rights and restrictions with respect 48 to this document. Code Components extracted from this document must 49 include Simplified BSD License text as described in Section 4.e of 50 the Trust Legal Provisions and are provided without warranty as 51 described in the Simplified BSD License. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 56 2. Intended Audience . . . . . . . . . . . . . . . . . . . . . . 3 57 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 58 4. XMPP to SIP . . . . . . . . . . . . . . . . . . . . . . . . . 4 59 5. SIP to XMPP . . . . . . . . . . . . . . . . . . . . . . . . . 6 60 6. Message Size . . . . . . . . . . . . . . . . . . . . . . . . 8 61 7. Content Types . . . . . . . . . . . . . . . . . . . . . . . . 9 62 8. Internationalization Considerations . . . . . . . . . . . . . 9 63 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 64 10. Security Considerations . . . . . . . . . . . . . . . . . . . 10 65 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 66 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 12 67 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 69 1. Introduction 71 In order to help ensure interworking between instant messaging (IM) 72 systems that conform to the instant messaging / presence requirements 73 [RFC2779], it is important to clearly define protocol mappings 74 between such systems. Within the IETF, work has proceeded on two 75 instant messaging technologies: 77 o Various extensions to the Session Initiation Protocol ([RFC3261]) 78 for instant messaging, in particular the MESSAGE method extension 79 [RFC3428]. 81 o The Extensible Messaging and Presence Protocol (XMPP), which 82 consists of a formalization of the core XML streaming protocols 83 developed originally by the Jabber open-source community; the 84 relevant specifications are [RFC6120] for the XML streaming layer 85 and [RFC6121] for basic presence and instant messaging extensions. 87 One approach to helping ensure interworking between these protocols 88 is to map each protocol to the abstract semantics described in 89 [RFC3860]; that is the approach taken by 90 [I-D.ietf-simple-cpim-mapping] and [RFC3922]. By contrast, the 91 approach taken in this document is to directly map semantics from one 92 protocol to another (i.e., from SIP/SIMPLE to XMPP and vice-versa), 93 since that is how existing systems solve the interworking problem. 95 Both XMPP and IM-capable SIP systems enable entities to exchange 96 "instant messages". The term "instant message" usually refers to a 97 message sent between two entities for delivery in close to real time 98 (rather than a message that is stored and forwarded to the intended 99 recipient upon request). This document covers single messages only 100 (sometimes called "page-mode" messaging), since they form the lowest 101 common denominator for IM. Separate documents cover "session-mode" 102 instant messaging in the form of one-to-one chat sessions 103 [I-D.ietf-stox-chat], as well as multi-party chat sessions 104 [I-D.ietf-stox-groupchat]. In particular, session-mode instant 105 messaging supports several features that are not part of page-mode 106 instant messaging, such as a higher level of assurance regarding end- 107 to-end message delivery. 109 The architectural assumptions underlying such direct mappings are 110 provided in [RFC7247], including mapping of addresses and error 111 conditions. The mappings specified in this document cover basic 112 instant messaging functionality, i.e., the exchange of a single 113 instant message between a SIP user and an XMPP user in either 114 direction. Mapping of more advanced functionality is out of scope 115 for this document, but other documents in this "series" cover such 116 topics. 118 2. Intended Audience 120 The documents in this series are intended for use by software 121 developers who have an existing system based on one of these 122 technologies (e.g., SIP), and would like to enable communication from 123 that existing system to systems based on the other technology (e.g., 124 XMPP). We assume that readers are familiar with the core 125 specifications for both SIP [RFC3261] and XMPP [RFC6120], with the 126 base document for this series [RFC7247], and with the following IM- 127 related specifications: 129 o Session Initiation Protocol (SIP) Extension for Instant Messaging 130 [RFC3428] 132 o Extensible Messaging and Presence Protocol: Instant Messaging and 133 Presence [RFC6121] 135 Note well that not all protocol-compliant messages are shown (such as 136 SIP 100 TRYING messages), in order to focus the reader on the 137 essential aspects of the protocol flows. 139 3. Terminology 141 A number of terms used here are explained in [RFC3261], [RFC3428], 142 [RFC6120], and [RFC6121]. 144 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 145 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 146 "OPTIONAL" in this document are to be interpreted as described in 147 [RFC2119]. 149 4. XMPP to SIP 151 As described in [RFC6121], a single instant message is an XML 152 stanza of type "normal" sent over an XML stream (since 153 "normal" is the default for the 'type' attribute of the 154 stanza, the attribute is often omitted). 156 When the XMPP user Juliet wants to send an 157 instant message to Romeo, she interacts with her XMPP client, which 158 generates an XMPP stanza. The syntax of the 159 stanza, including required and optional elements and attributes, is 160 defined in [RFC6121] (for single instant messages, Section 5.1 of 161 [RFC6121] recommends that the value of the 'to' address be a "bare 162 JID" of the form "localpart@domainpart"). The following is an 163 example of such a stanza: 165 Example 1: XMPP user sends message 167 | 169 | Art thou not Romeo, and a Montague? 170 | 172 Upon receiving such a message stanza, the XMPP server needs to 173 determine the identity of the domainpart in the 'to' address, which 174 it does by following the procedures explained in Section 5 of 175 [RFC7247]. If the domain is a SIP domain, the XMPP server will hand 176 off the message stanza to an XMPP-to-SIP gateway that natively 177 communicates with IM-aware SIP servers. 179 The XMPP-to-SIP gateway is then responsible for translating the XMPP 180 message stanza into a SIP MESSAGE request from the XMPP user to the 181 SIP user: 183 Example 2: XMPP user sends message (SIP transformation) 185 | MESSAGE sip:romeo@example.net SIP/2.0 186 | Via: SIP/2.0/TCP x2s.example.com;branch=z9hG4bK776sgdkse 187 | Max-Forwards: 70 188 | To: sip:romeo@example.net 189 | From: ;tag=12345 190 | Call-ID: D9AA95FD-2BD5-46E2-AF0F-6CFAA96BDDFA 191 | CSeq: 1 MESSAGE 192 | Content-Type: text/plain 193 | Content-Length: 35 194 | 195 | Art thou not Romeo, and a Montague? 197 The destination SIP server is responsible for delivering the message 198 to the intended recipient, and the recipient is responsible for 199 generating a response (e.g., 200 OK). 201 Example 3: SIP user agent indicates receipt of message 203 | SIP/2.0 200 OK 204 | Via: SIP/2.0/TCP x2s.example.com;branch=z9hG4bK776sgdkse 205 | From: sip:juliet@example.com;tag=12345 206 | To: sip:romeo@example.net;tag=vwxyz 207 | Call-ID: D9AA95FD-2BD5-46E2-AF0F-6CFAA96BDDFA 208 | CSeq: 1 MESSAGE 209 | Content-Length: 0 211 As described in [RFC3428], a downstream proxy could fork a MESSAGE 212 request, but it would return only one 200 OK to the gateway. 214 Note: This document does not specify handling of the 200 OK by the 215 XMPP-to-SIP gateway (e.g., to enable message acknowledgements). 216 See [I-D.ietf-stox-chat] for a mapping of message acknowledgements 217 in the context of one-to-one chat sessions. 219 The mapping of XMPP syntax to SIP syntax MUST be as shown in the 220 following table. 222 Table 1: Message syntax mapping from XMPP to SIP 224 +-----------------------------+--------------------------+ 225 | XMPP Element or Attribute | SIP Header or Contents | 226 +-----------------------------+--------------------------+ 227 | | body of MESSAGE | 228 | | Subject | 229 | | Call-ID | 230 | from | From (1) | 231 | id | transaction identifer | 232 | to | To or Request-URI | 233 | type | (no mapping) (2) | 234 | xml:lang | Content-Language | 235 +-----------------------------+--------------------------+ 237 1. As shown in the foregoing example and described in [RFC7247], the 238 XMPP-to-SIP gateway MUST map the bare JID 239 ("localpart@domainpart") of the XMPP sender to the SIP From 240 header and include the resourcepart of the full JID as the GRUU 241 portion [RFC5627] of the SIP URI. 243 2. Because there is no SIP header field that matches the meaning of 244 the XMPP message 'type' values ("normal", "chat", "groupchat", 245 "headline", "error"), no general mapping is possible here. 247 5. SIP to XMPP 249 As described in [RFC3428], a single instant message is a SIP MESSAGE 250 request sent from a SIP user agent to an intended recipient who is 251 most generally referenced by an Instant Message URI of the form 252 but who might be referenced by a SIP or SIPS URI of 253 the form or . 255 When the SIP user Romeo wants to send an 256 instant message to Juliet, he interacts with his SIP user agent, 257 which generates a SIP MESSAGE request. The syntax of the MESSAGE 258 request is defined in [RFC3428]. The following is an example of such 259 a request: 261 Example 4: SIP user sends message 263 | MESSAGE sip:juliet@example.com SIP/2.0 264 | Via: SIP/2.0/TCP s2x.example.net;branch=z9hG4bKeskdgs677 265 | Max-Forwards: 70 266 | To: sip:juliet@example.com 267 | From: sip:romeo@example.net;tag=vwxyz 268 | Call-ID: 9E97FB43-85F4-4A00-8751-1124FD4C7B2E 269 | CSeq: 1 MESSAGE 270 | Content-Type: text/plain 271 | Content-Length: 44 272 | 273 | Neither, fair saint, if either thee dislike. 275 Section 5 of [RFC3428] stipulates that a SIP User Agent presented 276 with an im: URI should resolve it to a sip: or sips: URI. Therefore 277 we assume that the Request-URI of a request received by an IM-capable 278 SIP-to-XMPP gateway will contain a sip: or sips: URI. Upon receiving 279 the MESSAGE, the SIP server needs to determine the identity of the 280 domain portion of the Request-URI or To header, which it does by 281 following the procedures explained in Section 5 of [RFC7247]. If the 282 domain is an XMPP domain, the SIP server will hand off the MESSAGE to 283 an associated SIP-to-XMPP gateway that natively communicates with 284 XMPP servers. 286 The SIP-to-XMPP gateway is then responsible for translating the 287 request into an XMPP message stanza from the SIP user to the XMPP 288 user and returning a SIP "200 OK" message to the sender: 290 Example 5: SIP user sends message (XMPP transformation) 292 | 294 | Neither, fair saint, if either thee dislike. 295 | 297 Note that the stanza handling rules specified in [RFC6121] allow the 298 receiving XMPP server to deliver a message stanza whose 'to' address 299 is a bare JID ("localpart@domainpart") to multiple connected devices. 300 This is similar to the "forking" of messages in SIP. 302 The mapping of SIP syntax to XMPP syntax MUST be as shown in the 303 following table. 305 Table 2: Message syntax mapping from SIP to XMPP 307 +--------------------------+-----------------------------+ 308 | SIP Header or Contents | XMPP Element or Attribute | 309 +--------------------------+-----------------------------+ 310 | Call-ID | | 311 | Content-Language | xml:lang | 312 | CSeq | (no mapping) | 313 | From | from (1) | 314 | Subject | | 315 | Request-URI or To | to | 316 | body of MESSAGE | | 317 | transaction identifier | id | 318 +--------------------------+-----------------------------+ 320 1. As shown in the foregoing example and described in [RFC7247], if 321 the IM-capable SIP-to-XMPP gateway has information about the GRUU 322 [RFC5627] of the particular endpoint that sent the SIP message 323 then it MUST map the sender's address to a full JID 324 ("localpart@domainpart/resourcepart") in the 'from' attribute of 325 the XMPP stanza and include the GRUU as the resourcepart. 327 When transforming SIP pager-mode messages, an IM-capable SIP-to-XMPP 328 gateway MUST specify no XMPP 'type' attribute or, equivalently, a 329 'type' attribute whose value is "normal" [RFC6121]. 331 See Section 7 of this document about the handling of SIP message 332 bodies that contain content types other than plain text. 334 6. Message Size 336 [RFC3428] specifies that (outside of a media session) the size of a 337 MESSAGE request is not allowed to exceed 1300 bytes. Although in 338 practice XMPP instant messages do not often exceed that size, neither 339 [RFC6120] nor [RFC6121] sets an upper limit on the size of XMPP 340 stanzas. However, XMPP server deployments usually do limit the size 341 of stanzas in order to help prevent denial of service attacks, and 342 [RFC6120] states that if a server sets a maximum stanza size then the 343 limit is not allowed to be less than 10,000 bytes. Because of this 344 mismatch, an XMPP-to-SIP gateway SHOULD return a 345 stanza error if an XMPP user attempts to send an XMPP message stanza 346 that would result in a SIP MESSAGE greater than 1300 bytes. Although 347 such a gateway might decide to "upgrade" from page mode to session 348 mode using the Message Session Relay Protocol (MSRP) and thus 349 treating the instant message as part of a chat session as described 350 in [I-D.ietf-stox-chat], such behavior is application-specific and 351 this document provides no guidelines for how to complete such an 352 upgrade. 354 7. Content Types 356 SIP requests of type MESSAGE are allowed to contain essentially any 357 content type. The recommended procedures for SIP-to-XMPP gateways to 358 use in handling these content types are as follows. 360 An IM-aware SIP-to-XMPP gateway MUST process SIP messages that 361 contain message bodies of type "text/plain" and MUST encapsulate such 362 message bodies as the XML character data of the XMPP element. 364 An IM-aware SIP-to-XMPP gateway SHOULD process SIP messages that 365 contain message bodies of type "text/html"; if so, a gateway MUST 366 transform the "text/html" content into XHTML content that conforms to 367 the XHTML-IM Integration Set specified in [XEP-0071]. 369 Although an IM-aware SIP-to-XMPP gateway MAY process SIP messages 370 that contain message bodies of types other than "text/plain" and 371 "text/html", the handling of such content types is a matter of 372 implementation. 374 8. Internationalization Considerations 376 Both XMPP and SIP support the UTF-8 encoding [RFC3629] of Unicode 377 characters [UNICODE] within messages, along with tagging of the 378 language for a particular message (in XMPP via the 'xml:lang' 379 attribute and in SIP via the Content-Language header). Gateways MUST 380 map these language tagging mechanisms if they are present in the 381 original message. Several examples follow, using the "XML Notation" 382 [RFC3987] for Unicode characters outside the ASCII range. 384 Example 6: SIP user sends message 386 | MESSAGE sip:juliet@example.com SIP/2.0 387 | Via: SIP/2.0/TCP s2x.example.net;branch=z9hG4bKeskdgs677 388 | Max-Forwards: 70 389 | To: sip:juliet@example.com 390 | From: sip:romeo@example.net;tag=vwxyz 391 | Call-ID: 5A37A65D-304B-470A-B718-3F3E6770ACAF 392 | CSeq: 1 MESSAGE 393 | Content-Type: text/plain 394 | Content-Length: 45 395 | Content-Language: cs 396 | 397 | Nic z ob쎩ho, m쎡 d쒛vo spanil쎡, 398 | nenavid쎭얡-li jedno nebo druh쎩. 400 Example 7: SIP user sends message (XMPP transformation) 402 | 405 | 406 | Nic z ob쎩ho, m쎡 d쒛vo spanil쎡, 407 | nenavid쎭얡-li jedno nebo druh쎩. 408 | 409 | 411 9. IANA Considerations 413 This document requests no actions of IANA. 415 10. Security Considerations 417 Detailed security considerations for instant messaging protocols are 418 given in [RFC2779], for SIP-based instant messaging in [RFC3428] (see 419 also [RFC3261]), and for XMPP-based instant messaging in [RFC6121] 420 (see also [RFC6120]). The security considerations provided in 421 [RFC7247] also apply. 423 This document specifies methods for exchanging "page-mode" instant 424 messages through a gateway that translates between SIP and XMPP, and 425 [I-D.ietf-stox-chat] specifies such methods for "session-mode" 426 instant messaging between MSRP and XMPP. Such a gateway MUST be 427 compliant with the minimum security requirements of the textual chat 428 protocols for which it translates (i.e., SIP or MSRP and XMPP). 430 The addition of gateways to the security model of instant messaging 431 specified in [RFC2779] introduces some new risks. In particular, 432 end-to-end security properties (especially confidentiality and 433 integrity) between instant messaging clients that interface through a 434 gateway can be provided only if common formats are supported. 435 Specification of those common formats is out of scope for this 436 document. For instant messages, it is possible to use [RFC3862] and 437 [RFC3923], but those methods are not widely implemented. A more 438 widely implemented albeit unstandardized method for interoperable 439 end-to-end encryption would be Off-the-Record Messaging [OTR]. 441 11. References 443 11.1. Normative References 445 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 446 Requirement Levels", BCP 14, RFC 2119, March 1997. 448 [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, 449 A., Peterson, J., Sparks, R., Handley, M., and E. 450 Schooler, "SIP: Session Initiation Protocol", RFC 3261, 451 June 2002. 453 [RFC3428] Campbell, B., Rosenberg, J., Schulzrinne, H., Huitema, C., 454 and D. Gurle, "Session Initiation Protocol (SIP) Extension 455 for Instant Messaging", RFC 3428, December 2002. 457 [RFC5627] Rosenberg, J., "Obtaining and Using Globally Routable User 458 Agent URIs (GRUUs) in the Session Initiation Protocol 459 (SIP)", RFC 5627, October 2009. 461 [RFC6120] Saint-Andre, P., "Extensible Messaging and Presence 462 Protocol (XMPP): Core", RFC 6120, March 2011. 464 [RFC6121] Saint-Andre, P., "Extensible Messaging and Presence 465 Protocol (XMPP): Instant Messaging and Presence", RFC 466 6121, March 2011. 468 [RFC7247] Saint-Andre, P., Houri, A., and J. Hildebrand, 469 "Interworking between the Session Initiation Protocol 470 (SIP) and the Extensible Messaging and Presence Protocol 471 (XMPP): Architecture, Addresses, and Error Handling", RFC 472 7247, May 2014. 474 [XEP-0071] 475 Saint-Andre, P., "XHTML-IM", XSF XEP 0071, November 2012. 477 11.2. Informative References 479 [I-D.ietf-simple-cpim-mapping] 480 Rosenberg, J. and B. Campbell, "CPIM Mapping of SIMPLE 481 Presence and Instant Messaging", draft-ietf-simple-cpim- 482 mapping-01 (work in progress), June 2002. 484 [I-D.ietf-stox-chat] 485 Saint-Andre, P. and S. Loreto, "Interworking between the 486 Session Initiation Protocol (SIP) and the Extensible 487 Messaging and Presence Protocol (XMPP): One-to-One Text 488 Chat Sessions", draft-ietf-stox-chat-11 (work in 489 progress), March 2015. 491 [I-D.ietf-stox-groupchat] 492 Saint-Andre, P., Corretge, S., and S. Loreto, 493 "Interworking between the Session Initiation Protocol 494 (SIP) and the Extensible Messaging and Presence Protocol 495 (XMPP): Groupchat", draft-ietf-stox-groupchat-11 (work in 496 progress), March 2015. 498 [OTR] Ian Goldberg, , "Off-the-Record Messaging", . 501 [RFC2779] Day, M., Aggarwal, S., and J. Vincent, "Instant Messaging 502 / Presence Protocol Requirements", RFC 2779, February 503 2000. 505 [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO 506 10646", STD 63, RFC 3629, November 2003. 508 [RFC3860] Peterson, J., "Common Profile for Instant Messaging 509 (CPIM)", RFC 3860, August 2004. 511 [RFC3862] Klyne, G. and D. Atkins, "Common Presence and Instant 512 Messaging (CPIM): Message Format", RFC 3862, August 2004. 514 [RFC3922] Saint-Andre, P., "Mapping the Extensible Messaging and 515 Presence Protocol (XMPP) to Common Presence and Instant 516 Messaging (CPIM)", RFC 3922, October 2004. 518 [RFC3923] Saint-Andre, P., "End-to-End Signing and Object Encryption 519 for the Extensible Messaging and Presence Protocol 520 (XMPP)", RFC 3923, October 2004. 522 [RFC3987] Duerst, M. and M. Suignard, "Internationalized Resource 523 Identifiers (IRIs)", RFC 3987, January 2005. 525 [UNICODE] The Unicode Consortium, "The Unicode Standard, Version 526 7.0.0", 2014, 527 . 529 Appendix A. Acknowledgements 531 The authors wish to thank the following individuals for their 532 feedback: Mary Barnes, Dave Cridland, Dave Crocker, Adrian Georgescu, 533 Christer Holmberg, Saul Ibarra Corretge, Olle Johansson, Paul 534 Kyzivat, Salvatore Loreto, Daniel-Constantin Mierla, and Tory Patnoe. 536 Special thanks to Ben Campbell for his detailed and insightful 537 reviews. 539 Francis Dupont reviewed the document on behalf of the General Area 540 Review Team. 542 Spencer Dawkins, Stephen Farrell, and Barry Leiba provided helpful 543 input during IESG review. 545 The authors gratefully acknowledge the assistance of Markus Isomaki 546 and Yana Stamcheva as the working group chairs and Gonzalo Camarillo 547 and Alissa Cooper as the sponsoring Area Directors. 549 Peter Saint-Andre wishes to acknowledge Cisco Systems, Inc., for 550 employing him during his work on earlier versions of this document. 552 Authors' Addresses 554 Peter Saint-Andre 555 &yet 557 Email: peter@andyet.com 558 URI: https://andyet.com/ 560 Avshalom Houri 561 IBM 562 Rorberg Building, Pekris 3 563 Rehovot 76123 564 Israel 566 Email: avshalom@il.ibm.com 568 Joe Hildebrand 569 Cisco Systems, Inc. 570 1899 Wynkoop Street, Suite 600 571 Denver, CO 80202 572 USA 574 Email: jhildebr@cisco.com