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Found 'MUST not' in this paragraph: Serial Number: A 32-bit monotonically increasing, cardinal which wraps from 2^32-1 to 0. It denotes the logical version of a cache. A cache increments the value by one when it successfully updates its data from a parent cache or from primary RPKI data. As a cache is rcynicing, new incoming data, and implicit deletes, are marked with the new serial but MUST not be sent until the fetch is complete. A serial number is not commensurate between caches, nor need it be maintained across resets of the cache server. See [RFC1982] on DNS Serial Number Arithmetic for too much detail on serial number arithmetic. -- The document date (March 3, 2009) is 5505 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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-13) exists of draft-ietf-sidr-arch-04 == Outdated reference: A later version (-09) exists of draft-ietf-sidr-repos-struct-01 Summary: 2 errors (**), 0 flaws (~~), 4 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group R. Bush 3 Internet-Draft Internet Initiative Japan, Inc. 4 Intended status: Standards Track March 3, 2009 5 Expires: September 4, 2009 7 The RPKI/Router Protocol 8 draft-ymbk-rpki-rtr-protocol-00 10 Status of this Memo 12 This Internet-Draft is submitted to IETF in full conformance with the 13 provisions of BCP 78 and BCP 79. This document may not be modified, 14 and derivative works of it may not be created, and it may not be 15 published except as an Internet-Draft. 17 Internet-Drafts are working documents of the Internet Engineering 18 Task Force (IETF), its areas, and its working groups. Note that 19 other groups may also distribute working documents as Internet- 20 Drafts. 22 Internet-Drafts are draft documents valid for a maximum of six months 23 and may be updated, replaced, or obsoleted by other documents at any 24 time. It is inappropriate to use Internet-Drafts as reference 25 material or to cite them other than as "work in progress." 27 The list of current Internet-Drafts can be accessed at 28 http://www.ietf.org/ietf/1id-abstracts.txt. 30 The list of Internet-Draft Shadow Directories can be accessed at 31 http://www.ietf.org/shadow.html. 33 This Internet-Draft will expire on September 4, 2009. 35 Copyright Notice 37 Copyright (c) 2009 IETF Trust and the persons identified as the 38 document authors. All rights reserved. 40 This document is subject to BCP 78 and the IETF Trust's Legal 41 Provisions Relating to IETF Documents in effect on the date of 42 publication of this document (http://trustee.ietf.org/license-info). 43 Please review these documents carefully, as they describe your rights 44 and restrictions with respect to this document. 46 Abstract 48 In order to formally validate the origin ASes of BGP announcements, 49 routers need a simple but reliable mechanism to receive RPKI 50 [I-D.ietf-sidr-arch] or analogous prefix origin data from a trusted 51 cache. This document describes a protocol to deliver validated 52 prefix origin data to routers over ssh. 54 Requirements Language 56 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 57 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 58 document are to be interpreted as described in RFC 2119 [RFC2119]. 60 Table of Contents 62 1. Items that Need Work . . . . . . . . . . . . . . . . . . . . . 3 63 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 64 3. Deployment Structure . . . . . . . . . . . . . . . . . . . . . 3 65 4. Operational Overview . . . . . . . . . . . . . . . . . . . . . 4 66 5. Protocol Data Units (PDUs) . . . . . . . . . . . . . . . . . . 4 67 5.1. Serial Notify . . . . . . . . . . . . . . . . . . . . . . 4 68 5.2. Serial Query . . . . . . . . . . . . . . . . . . . . . . . 5 69 5.3. Reset Query . . . . . . . . . . . . . . . . . . . . . . . 5 70 5.4. Cache Response . . . . . . . . . . . . . . . . . . . . . . 5 71 5.5. IPv4 Prefix . . . . . . . . . . . . . . . . . . . . . . . 6 72 5.6. IPv6 Prefix . . . . . . . . . . . . . . . . . . . . . . . 6 73 5.7. End of Data . . . . . . . . . . . . . . . . . . . . . . . 7 74 5.8. Cache Reset . . . . . . . . . . . . . . . . . . . . . . . 7 75 5.9. Fields of a PDU . . . . . . . . . . . . . . . . . . . . . 7 76 6. Protocol Sequences . . . . . . . . . . . . . . . . . . . . . . 8 77 6.1. Start or Restart . . . . . . . . . . . . . . . . . . . . . 8 78 6.2. Typical Exchange . . . . . . . . . . . . . . . . . . . . . 9 79 6.3. Cache has Reset . . . . . . . . . . . . . . . . . . . . . 9 80 7. SSH Transport . . . . . . . . . . . . . . . . . . . . . . . . 10 81 8. Router-Cache Setup . . . . . . . . . . . . . . . . . . . . . . 10 82 9. Deployment Scenarios . . . . . . . . . . . . . . . . . . . . . 11 83 10. Security Considerations . . . . . . . . . . . . . . . . . . . 12 84 11. Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 85 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 86 13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13 87 14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14 88 14.1. Normative References . . . . . . . . . . . . . . . . . . . 14 89 14.2. Informative References . . . . . . . . . . . . . . . . . . 14 90 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 14 92 1. Items that Need Work 94 Errors - Need to figure out what kinds of errors there might be and 95 then how to report and handle them. 97 2. Introduction 99 In order to formally validate the origin ASes of BGP announcements, 100 routers need a simple but reliable mechanism to receive RPKI 101 [I-D.ietf-sidr-arch] or analogous formally validated prefix origin 102 data from a trusted cache. This document describes a protocol to 103 deliver validated prefix origin data to routers over ssh. 105 Section 3 describes the deployment structure and Section 4 then 106 presents an operational overview. The binary payloads of the 107 protocol are formally described in Section 5, and the expected PDU 108 sequences are described in Section 6. And the transport protocol is 109 described in Section 7. Section 8 details how routers and caches are 110 configured to connect and authenticate. Section 9 describes likely 111 deployment scenarios. The traditional security and IANA 112 considerations end the document. 114 3. Deployment Structure 116 Deployment of the RPKI to reach routers has a three level structure 117 as follows: 119 Global RPKI: The authoritative data of the RPKI are published in a 120 distributed set of servers, RPKI publication repositories, e.g. 121 the IANA, RIRs, NIRs, and ISPs, see [I-D.ietf-sidr-repos-struct]. 123 Local Caches: A local set of one or more collected and verified non- 124 authoritative caches. A relying party, e.g. router or other 125 client, MUST have a formally authenticated trust relationship 126 with, and a secure transport channel to, any non-authoritative 127 cache(s) it uses. 129 Routers: A router fetches data from a local cache using the protocol 130 described in this document. It is said to be a client of the 131 cache. There are mechanisms for the router to assure itself of 132 the authenticity of the cache and to authenticate itself to the 133 cache. 135 4. Operational Overview 137 A router establishes and keeps open an authenticated connection to a 138 cache with which it has an client/server relationship. It is 139 configured with a semi-ordered list of caches, and establishes a 140 connection to the highest preference cache that accepts one. 142 Periodically, the router sends to the cache the serial number of the 143 highest numbered data record it has received from that cache, i.e. 144 the router's current serial number. When a router establishes a new 145 connection to a cache, or wishes to reset a current relationship, it 146 sends a Reset Query. 148 The Cache responds with all data records which have serial numbers 149 greater than that in the router's query. This may be the null set, 150 in which case the End of Data PDU is still sent. Note that 'greater' 151 must take wrap-around into account, see [RFC1982]. 153 When the router has received all data records from the cache, it sets 154 its current serial number to that of the serial number in the End of 155 Data PDU. 157 5. Protocol Data Units (PDUs) 159 The exchanges between the cache and the router are sequences of 160 exchanges of the following PDUs according to the rules described in 161 Section 6. 163 5.1. Serial Notify 165 The cache notifies the router that the cache has new data. 167 0 8 16 24 31 168 .-------------------------------------------. 169 | Protocol | PDU | | 170 | Version | Type | reserved = zero | 171 | 0 | 0 | | 172 +-------------------------------------------+ 173 | | 174 | Serial Number | 175 | | 176 `-------------------------------------------' 178 5.2. Serial Query 180 Serial Query: The router sends Serial Query to ask the cache for all 181 payload PDUs which have serial numbers higher than the serial number 182 in the Serial Query. 184 0 8 16 24 31 185 .-------------------------------------------. 186 | Protocol | PDU | | 187 | Version | Type | reserved = zero | 188 | 0 | 1 | | 189 +-------------------------------------------+ 190 | | 191 | Serial Number | 192 | | 193 `-------------------------------------------' 195 5.3. Reset Query 197 Reset Query: The router tells the cache that it wants to receive the 198 total active, current, non-withdrawn, database. 200 0 8 16 24 31 201 .-------------------------------------------. 202 | Protocol | PDU | | 203 | Version | Type | reserved = zero | 204 | 0 | 2 | | 205 `-------------------------------------------' 207 5.4. Cache Response 209 The cache responds with zero or more payload PDUs, the set of all 210 data records it has with serial numbers greater than that sent by the 211 client router, or all data records if the cache received a Reset 212 Query. 214 0 8 16 24 31 215 .-------------------------------------------. 216 | Protocol | PDU | | 217 | Version | Type | reserved = zero | 218 | 0 | 3 | | 219 `-------------------------------------------' 221 5.5. IPv4 Prefix 223 0 8 16 24 31 224 .-------------------------------------------. 225 | Protocol | PDU | | 226 | Version | Type | Color | 227 | 0 | 4 | | 228 +-------------------------------------------+ 229 | Announce | Prefix | Max | Data | 230 | Withdraw | Length | Length | Source | 231 | 0/1 | 0..32 | 0..32 | RPKI/IRR | 232 +-------------------------------------------+ 233 | | 234 | IPv4 prefix | 235 | | 236 +-------------------------------------------+ 237 | | 238 | Autonomous System Number | 239 | | 240 `-------------------------------------------' 242 5.6. IPv6 Prefix 244 0 8 16 24 31 245 .-------------------------------------------. 246 | Protocol | PDU | | 247 | Version | Type | Color | 248 | 0 | 6 | | 249 +-------------------------------------------+ 250 | Announce | Prefix | Max | Data | 251 | Withdraw | Length | Length | Source | 252 | 0/1 | 0..128 | 0..128 | RPKI/IRR | 253 +-------------------------------------------+ 254 | | 255 +--- ---+ 256 | | 257 +--- IPv6 prefix ---+ 258 | | 259 +--- ---+ 260 | | 261 +-------------------------------------------+ 262 | | 263 | Autonomous System Number | 264 | | 265 `-------------------------------------------' 267 5.7. End of Data 269 End of Data: Cache tells router it has no more data for the request. 271 0 8 16 24 31 272 .-------------------------------------------. 273 | Protocol | PDU | | 274 | Version | Type | reserved = zero | 275 | 0 | 9 | | 276 +-------------------------------------------+ 277 | | 278 | Serial Number | 279 | | 280 `-------------------------------------------' 282 5.8. Cache Reset 284 The cache may respond to a Serial Query informing the router that the 285 cache's serial number is no longer commensurate with that of the 286 router. 288 0 8 16 24 31 289 .-------------------------------------------. 290 | Protocol | PDU | | 291 | Version | Type | reserved = zero | 292 | 0 | 10 | | 293 `-------------------------------------------' 295 5.9. Fields of a PDU 297 PDUs contain the following data elements: 299 Protocol Version: A cardinal, currently 0, denoting the version of 300 this protocol. 302 Serial Number: The serial number of the RPKI Cache when this ROA was 303 received from the cache's up-stream cache server or gathered from 304 the global RPKI. A cache increments its serial number when 305 completing an rcynic from a parent cache. See [RFC1982] on DNS 306 Serial Number Arithmetic for too much detail on serial number 307 arithmetic. 309 Color: An arbitrary 16 bit field that might be used in some way. 311 Announce/Withdraw: Whether this PDU announces a new right to 312 announce the prefix or withdraws a previously announced right. 313 The allowed values are 0 for withdraw and 1 for announce. A 314 withdraw effectively deletes all previously announced IPvX Prefix 315 PDUs with the exact same Prefix, Length, Max-Len, ASN, Data 316 Source, and Color. 318 Prefix Length: A cardinal denoting the shortest prefix allowed for 319 the prefix. 321 Max Length: A cardinal denoting the longest prefix allowed by the 322 prefix. This MUST NOT be less than the Prefix Length element. 324 Data Source: A cardinal denoting the source of the data, e.g. for 325 RPKI data, it is 0, for IRR data it is 1. 327 Prefix: The IPv4 or IPv6 prefix of the ROA. 329 Autonomous System Number: ASN allowed to announce this prefix, a 32 330 bit cardinal. 332 6. Protocol Sequences 334 The sequences of PDU transmissions fall into three conversations as 335 follows: 337 6.1. Start or Restart 339 Cache Router 340 ~ ~ 341 | <----- Reset Query -------- | R requests data 342 | | 343 | ----- Cache Response -----> | C tells R C's serial 344 | ------- IPvX Prefix ------> | C sends zero or more 345 | ------- IPvX Prefix ------> | IPv4 and IPv6 Prefix 346 | ------- IPvX Prefix ------> | Payload PDUs 347 | ------ End of Data ------> | C sends End of Data 348 ~ ~ 350 When a transport session is first established, the router sends a 351 Reset Query and the cache responds with a data sequence of all data 352 it contains. 354 This Reset Query sequence is also used in response to the cache 355 sending a Cache Reset, the router choosing a new cache, or the router 356 fearing it has otherwise lost its way. 358 To limit the length of time a cache must keep withdraws, a router 359 MUST send either a Serial Query or a Reset Query no less frequently 360 than once an hour. This also acts as a keep alive at the application 361 layer. 363 6.2. Typical Exchange 365 Cache Router 366 ~ ~ 367 | -------- Notify ----------> | (optional) 368 | | 369 | <----- Serial Query ------- | R requests data 370 | | 371 | ----- Cache Response -----> | C tells R C's serial 372 | ------- IPvX Prefix ------> | C sends zero or more 373 | ------- IPvX Prefix ------> | IPv4 and IPv6 Prefix 374 | ------- IPvX Prefix ------> | Payload PDUs 375 | ------ End of Data ------> | C sends End of Data 377 The cache server SHOULD send a notify PDU with its current serial 378 number when the cache's serial changes, with the expectation that the 379 router MAY then issue a serial query earlier than it otherwise might. 380 This is analogous to DNS NOTIFY in [RFC1996]. The cache SHOULD rate 381 limit Serial Notifies to no more frequently than one per minute. 383 When the transport layer is up and either a timer has gone off in the 384 router, or the cache has sent a Notify, the router queries for new 385 data by sending a Serial Query, and the router sends all data newer 386 than the serial in the Serial Query. 388 To limit the length of time a cache must keep old withdraws, a router 389 MUST send either a Serial Query or a Reset Query no less frequently 390 than once an hour. 392 6.3. Cache has Reset 394 Cache Router 395 ~ ~ 396 | <----- Serial Query ------ | R requests data 397 | ------- Cache Reset ------> | C has lost serial 398 | | 399 | <------ Reset Query ------- | R requests new data 400 | | 401 | ----- Cache Response -----> | C tells R C's serial 402 | ------- IPvX Prefix ------> | C sends zero or more 403 | ------- IPvX Prefix ------> | IPv4 and IPv6 Prefix 404 | ------- IPvX Prefix ------> | Payload PDUs 405 | ------ End of Data ------> | C sends End of Data 406 ~ ~ 408 The cache may respond to a Serial Query informing the router that the 409 cache's serial number is no longer commensurate with that of the 410 router. The most likely cause is that the cache was completely 411 restarted when or since the transport session to the router was down. 412 When a router receives this, the router SHOULD attempt to connect to 413 any more preferred caches in its cache list. If there are no more 414 preferred caches it MUST issue a Reset Query and get an entire new 415 load from the cache 417 7. SSH Transport 419 The transport layer session between a router and a cache carries the 420 binary Protocol Data Units (PDUs) in a persistent SSH session. 422 To run over SSH, the client router first establishes an SSH transport 423 connection using the SSH transport protocol, and the client and 424 server exchange keys for message integrity and encryption. The 425 client then invokes the "ssh-userauth" service to authenticate the 426 application, as described in the SSH authentication protocol RFC 4252 427 [RFC4252]. Once the application has been successfully authenticated, 428 the client invokes the "ssh-connection" service, also known as the 429 SSH connection protocol. 431 After the ssh-connection service is established, the client opens a 432 channel of type "session", which results in an SSH session. 434 Once the SSH session has been established, the application invokes 435 the application transport as an SSH subsystem called "rpki-rtr". 436 Subsystem support is a feature of SSH version 2 (SSHv2) and is not 437 included in SSHv1. Running this protocol as an SSH subsystem avoids 438 the need for the application to recognize shell prompts or skip over 439 extraneous information, such as a system message that is sent at 440 shell start-up. 442 It is assumed that the router and cache have exchanged keys out of 443 band by some reasonably secured means. 445 8. Router-Cache Setup 447 A cache has the public authentication data for each router it is 448 configured to support. 450 When a router or cache peers with multiple serving caches, it must 451 have the name of each server and authentication data for each. In 452 addition, the list has a non-unique preference value for each server 453 in order of preference. The client router or cache attempts to 454 establish a session with each potential serving cache in priority 455 order, and then starts to load data from the highest preference cache 456 to which it can connect and authenticate. The router's list of 457 caches has the following elements: 459 Preference: A cardinal denoting the router's preference to use that 460 cache, the lower the value the more preferred. 462 Name: The IP Address or fully qualified domain name of the cache. 464 Key: The public ssh key of the cache. 466 MyKey: The private ssh key of this client. 468 As caches can not be rigorously synchronous, a client which changes 469 servers can not combine data from different parent caches. 470 Therefore, when a lower preference cache becomes available, if 471 resources allow, it would be prudent for the client to start a new 472 buffer for that cache's data, and only switch to those data when that 473 buffer is fully up to date. 475 9. Deployment Scenarios 477 For illustration, we present three likely deployment scenarios. 479 Small End Site: The small multi-homed end site may wish to outsource 480 the RPKI cache to one or more of their upstream ISPs. They would 481 exchange authentication material with the ISP using some out of 482 band mechanism, and their router(s) would connect to one or more 483 up-streams' caches. The ISPs would likely deploy caches intended 484 for customer use separately from the caches with which their own 485 BGP speakers peer. 487 Large End Site: A larger multi-homed end site might run one or more 488 caches, arranging them in a hierarchy of client caches, each 489 fetching from a serving cache which is closer to the global RPKI. 490 They might configure fall-back peerings to up-stream ISP caches. 492 ISP Backbone: A large ISP would likely have one or more redundant 493 caches in each major PoP, and these caches would fetch from each 494 other in an ISP-dependent topology so as not to place undue load 495 on the global RPKI publication infrastructure. 497 Experience with large DNS cache deployments has shown that complex 498 topologies are ill-advised as it is easy to make errors in the graph, 499 e.g. not maintaining a loop-free condition. 501 Of course, these are illustrations and there are other possible 502 deployment strategies. It is expected that minimizing load on the 503 global RPKI servers will be a major consideration. 505 To keep load on global RPKI services from unnecessary peaks, it is 506 recommended that primary caches which load from the distributed 507 global RPKI not do so all at the same times, e.g. on the hour. 508 Choose a random time, perhaps the ISP's AS number modulo 60 and 509 jitter the inter-fetch timing. 511 10. Security Considerations 513 As this document describes a security protocol, many aspects of 514 security interest are described in the relevant sections. This 515 section points out issues which may not be obvious in other sections. 517 Cache Validation: In order for a collection of caches as described 518 in Section 9 to guarantee a consistent view, they need to be given 519 consistent trust anchors to use in their internal validation 520 process. Distribution of a consistent trust anchor is assumed to 521 be out of band. 523 Cache Peer Identification: As the router initiates an ssh transport 524 session to a cache which it identifies by either IP address or 525 fully qualified domain name, a DNS or address spoofing attack 526 could make the correct cache unreachable. No session would be 527 established, as the authorization keys would not match. 529 Transport Security: The RPKI relies on object, not server or 530 transport, trust. I.e. the IANA root trust anchor is distributed 531 to all caches through some out of band means, and can then be used 532 by each cache to validate certificates and ROAs all the way down 533 the tree. The inter-cache relationships are based on this object 534 security model, hence the inter-cache transport can be lightly 535 protected. 537 But this protocol document assumes that the routers can not do the 538 validation cryptography. Hence the last link, from cache to 539 router, is secured by server authentication and transport level 540 security. This is dangerous, as server authentication and 541 transport have very different threat models than object security. 543 So the strength of the trust relationship and the transport 544 between the router(s) and the cache(s) are critical. You're 545 betting your routing on this. 547 While we can not say the cache must be on the same LAN, if only 548 due to the issue of an enterprise wanting to off-load the cache 549 task to their upstream ISP(s), locality, trust, and control are 550 very critical issues here. The cache(s) really SHOULD be as 551 close, in the sense of controlled and protected (against DDoS, 552 MITM) transport, to the router(s) as possible. It also SHOULD be 553 topologically close so that a minimum of validated routing data 554 are needed to bootstrap a router's access to a cache. 556 11. Glossary 558 The following terms are used with special meaning: 560 Global RPKI: The authoritative data of the RPKI are published in a 561 distributed set of servers at the IANA, RIRs, NIRs, and ISPs, see 562 [I-D.ietf-sidr-repos-struct]. 564 Non-authorative Cache: A coalesced copy of the RPKI which is 565 periodically fetched/refreshed directly or indirectly from the 566 global RPKI using the [rcynic] protocol/tools 568 Cache: The rcynic system is used to gather the distributed data of 569 the RPKI into a validated cache. Trusting this cache further is a 570 matter between the provider of the cache and a relying party. 572 Serial Number: A 32-bit monotonically increasing, cardinal which 573 wraps from 2^32-1 to 0. It denotes the logical version of a 574 cache. A cache increments the value by one when it successfully 575 updates its data from a parent cache or from primary RPKI data. 576 As a cache is rcynicing, new incoming data, and implicit deletes, 577 are marked with the new serial but MUST not be sent until the 578 fetch is complete. A serial number is not commensurate between 579 caches, nor need it be maintained across resets of the cache 580 server. See [RFC1982] on DNS Serial Number Arithmetic for too 581 much detail on serial number arithmetic. 583 12. IANA Considerations 585 This document request the IANA to create a registry for PDU types. 587 In addition, a registry for Version Numbers would be needed if new 588 Version Number is defined in a new RFC. 590 Note to RFC Editor: this section may be replaced on publication as an 591 RFC. 593 13. Acknowledgments 595 The author wishes to thank Rob Austein, Steve Bellovin, Rex Fernando, 596 Russ Housley, Pradosh Mohapatra. Megumi Ninomiya, Robert Raszuk, 597 John Scudder, Ruediger Volk, David Ward, and Bert Wijnen. 599 14. References 601 14.1. Normative References 603 [RFC1982] Elz, R. and R. Bush, "Serial Number Arithmetic", RFC 1982, 604 August 1996. 606 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 607 Requirement Levels", BCP 14, RFC 2119, March 1997. 609 [RFC4252] Ylonen, T. and C. Lonvick, "The Secure Shell (SSH) 610 Authentication Protocol", RFC 4252, January 2006. 612 [rcynic] Austein, R., "rcynic protocol", 613 . 615 14.2. Informative References 617 [I-D.ietf-sidr-arch] 618 Lepinski, M. and S. Kent, "An Infrastructure to Support 619 Secure Internet Routing", draft-ietf-sidr-arch-04 (work in 620 progress), November 2008. 622 [I-D.ietf-sidr-repos-struct] 623 Huston, G., Loomans, R., and G. Michaelson, "A Profile for 624 Resource Certificate Repository Structure", 625 draft-ietf-sidr-repos-struct-01 (work in progress), 626 October 2008. 628 [RFC1996] Vixie, P., "A Mechanism for Prompt Notification of Zone 629 Changes (DNS NOTIFY)", RFC 1996, August 1996. 631 Author's Address 633 Randy Bush 634 Internet Initiative Japan, Inc. 635 5147 Crystal Springs 636 Bainbridge Island, Washington 98110 637 US 639 Phone: +1 206 780 0431 x1 640 Email: randy@psg.com