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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group Q. Xie 3 Internet-Draft Motorola 4 Expires: December 8, 2004 R. Stewart 5 Cisco 6 M. Stillman 7 Nokia 8 June 9, 2004 10 Endpoint Name Resolution Protocol (ENRP) 11 draft-ietf-rserpool-enrp-08.txt 13 Status of this Memo 15 By submitting this Internet-Draft, I certify that any applicable 16 patent or other IPR claims of which I am aware have been disclosed, 17 and any of which I become aware will be disclosed, in accordance with 18 RFC 3668. 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 23 Internet-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 December 8, 2004. 38 Copyright Notice 40 Copyright (C) The Internet Society (2004). All Rights Reserved. 42 Abstract 44 Endpoint Name Resolution Protocol (ENRP) is designed to work in 45 conjunction with the Aggregate Server Access Protocol (ASAP) to 46 accomplish the functionality of the Reliable Server Pooling 47 (Rserpool) requirements and architecture. Within the operational 48 scope of Rserpool, ENRP defines the procedures and message formats of 49 a distributed, fault-tolerant registry service for storing, 50 bookkeeping, retrieving, and distributing pool operation and 51 membership information. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 56 1.1 Definitions . . . . . . . . . . . . . . . . . . . . . . . 4 57 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . 6 58 3. ENRP Message Definitions . . . . . . . . . . . . . . . . . . 7 59 3.1 PEER_PRESENCE message . . . . . . . . . . . . . . . . . . 7 60 3.2 PEER_NAME_TABLE_REQUEST message . . . . . . . . . . . . . 9 61 3.3 PEER_NAME_TABLE_RESPONSE message . . . . . . . . . . . . . 9 62 3.4 PEER_NAME_UPDATE message . . . . . . . . . . . . . . . . . 11 63 3.5 PEER_LIST_REQUEST message . . . . . . . . . . . . . . . . 12 64 3.6 PEER_LIST_RESPONSE message . . . . . . . . . . . . . . . . 13 65 3.7 PEER_INIT_TAKEOVER message . . . . . . . . . . . . . . . . 14 66 3.8 PEER_INIT_TAKEOVER_ACK message . . . . . . . . . . . . . . 15 67 3.9 PEER_TAKEOVER_SERVER message . . . . . . . . . . . . . . . 15 68 3.10 PEER_OWNERSHIP_CHANGE message . . . . . . . . . . . . . 16 69 3.11 PEER_ERROR message . . . . . . . . . . . . . . . . . . . 18 70 4. ENRP Operation Procedures . . . . . . . . . . . . . . . . . 19 71 4.1 Methods for Communicating amongst ENRP Servers . . . . . . 19 72 4.2 ENRP Server Initialization . . . . . . . . . . . . . . . . 20 73 4.2.1 Generate a Server Identifier . . . . . . . . . . . . . 21 74 4.2.2 Acquire Peer Server List . . . . . . . . . . . . . . . 21 75 4.2.3 Download ENRP Namespace Data from Mentor Peer . . . . 23 76 4.3 Handle PE Registration . . . . . . . . . . . . . . . . . . 25 77 4.3.1 Rules on PE Re-registration . . . . . . . . . . . . . 27 78 4.4 Handle PE De-registration . . . . . . . . . . . . . . . . 28 79 4.5 Pool Handle Translation . . . . . . . . . . . . . . . . . 28 80 4.6 Server Namespace Update . . . . . . . . . . . . . . . . . 29 81 4.6.1 Announcing Addition or Update of PE . . . . . . . . . 29 82 4.6.2 Announcing Removal of PE . . . . . . . . . . . . . . . 30 83 4.7 Detecting and Removing Unreachable PE . . . . . . . . . . 31 84 4.8 Helping PE and PU to Discover Home ENRP Server . . . . . . 32 85 4.9 Maintaining Peer List and Monitoring Peer Status . . . . . 32 86 4.9.1 Discovering New Peer . . . . . . . . . . . . . . . . . 32 87 4.9.2 Server Sending Heartbeat . . . . . . . . . . . . . . . 32 88 4.9.3 Detecting Peer Server Failure . . . . . . . . . . . . 33 89 4.10 Taking-over a Failed Peer Server . . . . . . . . . . . . 33 90 4.10.1 Initiate Server Take-over Arbitration . . . . . . . 33 91 4.10.2 Take-over Target Peer Server . . . . . . . . . . . . 34 92 4.11 Namespace Data Auditing and Re-synchronization . . . . . 35 93 4.11.1 Auditing Procedures . . . . . . . . . . . . . . . . 35 94 4.11.2 PE Checksum Calculation Algorithm . . . . . . . . . 36 95 4.11.3 Re-synchronization Procedures . . . . . . . . . . . 37 96 4.12 Handling Unrecognized Message or Unrecognized 97 Parameter . . . . . . . . . . . . . . . . . . . . . . . 37 99 5. Variables and Thresholds . . . . . . . . . . . . . . . . . . 39 100 5.1 Variables . . . . . . . . . . . . . . . . . . . . . . . . 39 101 5.2 Thresholds . . . . . . . . . . . . . . . . . . . . . . . . 39 102 6. Security Considerations . . . . . . . . . . . . . . . . . . 40 103 6.1 Implementing Security Mechanisms . . . . . . . . . . . . . 41 104 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 43 105 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 44 106 8.1 Normative References . . . . . . . . . . . . . . . . . . . . 44 107 8.2 Informative References . . . . . . . . . . . . . . . . . . . 45 108 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 45 109 Intellectual Property and Copyright Statements . . . . . . . 46 111 1. Introduction 113 ENRP is designed to work in conjunction with ASAP [1] to accomplish 114 the functionality of Rserpool as defined by its requirements [2] and 115 architecture [3]. 117 Within the operation scope of Rserpool, ENRP defines the procedures 118 and message formats of a distributed fault-tolerant registry service 119 for storing, bookkeeping, retrieving, and distributing pool operation 120 and membership information. 122 Whenever appropriate, in the rest of this document we will refer to 123 this Rserpool registry service as ENRP namespace, or simply 124 namespace. 126 1.1 Definitions 128 This document uses the following terms: 130 Operation scope: See [3]; 132 Pool (or server pool): See [3]; 134 Pool handle (or pool name): See [3]; 136 Pool element (PE): See [3]; 138 Pool user (PU): See [3]; 140 Pool element handle: See [3]; 142 ENRP namespace (or namespace): See [3]; 144 ENRP namespace server (or ENRP server): See [3]; 146 ENRP client channel: The communication channel through which a PE 147 requests for ENRP namespace service. The ENRP client channel is 148 usually defined by the transport address of the home ENRP server 149 and a well known port number; 151 ENRP server channel: Defined by a well known multicast IP address and 152 a well known port number. All ENRP servers in an operation scope 153 can send multicast messages to other servers through this channel. 154 PEs are also allowed to multicast on this channel occasionally; 156 Home ENRP server: The ENRP server to which a PE or PU currently 157 belongs. A PE MUST only have one home ENRP server at any given 158 time and both the PE and its home ENRP server MUST keep track of 159 this master/slave relationship between them. A PU SHOULD select 160 one of the available ENRP servers as its home ENRP server, but the 161 ENRP server does not need to know, nor does it need to keep track 162 of this relationship. 164 2. Conventions 166 The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, 167 SHOULD NOT, RECOMMENDED, NOT RECOMMENDED, MAY, and OPTIONAL, when 168 they appear in this document, are to be interpreted as described in 169 [5]. 171 3. ENRP Message Definitions 173 In this section, we defines the format of all ENRP messages. These 174 are messages sent and received amongst ENRP servers in an operation 175 scope. Messages sent and received between a PE/PU and an ENRP server 176 are part of ASAP and are defined in [1]. A common format, defined in 177 [10], is used for all ENRP and ASAP messages. 179 Most ENRP messages contains a combination of fixed fields and TLV 180 parameters. The TLV parameters are also defined in [10]. 182 All messages, as well as their fields/parameters described below, 183 MUST be transmitted in network byte order (a.k.a. Big Endian, i.e., 184 the most significant byte first). 186 For ENRP, the following message types are defined: 188 Type Message Name 189 ----- ------------------------- 190 0x0 - (reserved by IETF) 191 0x1 - PEER_PRESENCE 192 0x2 - PEER_NAME_TABLE_REQUEST 193 0x3 - PEER_NAME_TABLE_RESPONSE 194 0x4 - PEER_NAME_UPDATE 195 0x5 - PEER_LIST_REQUEST 196 0x6 - PEER_LIST_RESPONSE 197 0x7 - PEER_INIT_TAKEOVER 198 0x8 - PEER_INIT_TAKEOVER_ACK 199 0x9 - PEER_TAKEOVER_SERVER 200 0xa - PEER_OWNERSHIP_CHANGE 201 0xb - PEER_ERROR 202 0xc-0xFF - (reserved by IETF) 204 3.1 PEER_PRESENCE message 206 This ENRP message is used to announce (periodically) the presence of 207 an ENRP server, or to probe the status of a peer ENRP sever. 209 0 1 2 3 210 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 1 211 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 212 | Type = 0x1 |0|0|0|0|0|0|0|R| Message Length = 0xC | 213 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 214 | Sender Server's ID | 215 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 216 | Receiver Server's ID | 217 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 218 : PE Checksum Param : 219 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 220 : Server Information Param (optional) : 221 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 223 R (reply_required) flag: 1 bit 225 Set to '1' if the sender requires a response to this message, 226 otherwise set to '0'. 228 Sender Server's ID: 32 bit (unsigned integer) 230 This is the ID of the ENRP server which sends the message. 232 Receiver Server's ID: 32 bit (unsigned integer) 234 This is the ID of the ENRP server to which the message is 235 intended. If the message is not intended to an individual 236 server (e.g., the message is multicasted to a group of 237 servers), this field MUST be set with all 0's. 239 PE Checksum Parameter: 241 This is a TLV that contains the latest PE checksum of the ENRP 242 server who sends the PEER_PRESENCE. This parameter SHOULD be 243 included for namespace consistency auditing. See Section 244 4.11.1 for details. 246 Server Information Parameter: 248 If present, contains the server information of the sender of 249 this message (Server Information Parameter is defined in [10]). 250 This parameter is optional. However, if this message is sent 251 in response to a received "reply required" PEER_PRESENCE from a 252 peer, the sender then MUST include its server information. 254 Note, at startup an ENRP server MUST pick a randomly generated, 255 non-zero 32-bit unsigned integer as its ID and MUST use this same ID 256 for its entire life. 258 3.2 PEER_NAME_TABLE_REQUEST message 260 An ENRP server sends this message to one of its peers to request a 261 copy of the namespace data. This message is normally used during 262 server initialization or namespace re-synchronization. 264 0 1 2 3 265 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 1 266 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 267 | Type = 0x2 |0|0|0|0|0|0|0|W| Message Length = 0xC | 268 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 269 | Sender Server's ID | 270 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 271 | Receiver Server's ID | 272 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 274 W (oWn-children-only) flag: 1 bit 276 Set to '1' if the sender of this message is only requesting 277 information about the PEs owned by the message receiver. 278 Otherwise, set to '0'. 280 Sender Server's ID: 282 See Section 3.1. 284 Receiver Server's ID: 286 See Section 3.1. 288 3.3 PEER_NAME_TABLE_RESPONSE message 289 0 1 2 3 290 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 1 291 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 292 | Type = 0x3 |0|0|0|0|0|0|R|M| Message Length | 293 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 294 | Sender Server's ID | 295 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 296 | Receiver Server's ID | 297 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 298 : : 299 : Pool entry #1 (see below) : 300 : : 301 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 302 : : 303 : ... : 304 : : 305 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 306 : : 307 : Pool entry #n (see below) : 308 : : 309 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 311 R (Reject) flag: 1 bit 313 MUST be set to '1' if the sender of this message is rejecting a 314 namespace request. In such a case, this message MUST be sent 315 with no pool entries included. 317 M (More_to_send) flag: 1 bit 319 Set to '1' if the sender has more pool entries to sent in 320 subsequent PEER_NAME_TABLE_RESPONSE messages, otherwise, set to 321 '0'. 323 Message Length: 16 bits (unsigned integer) 325 Indicates the entire length of the message in number of octets. 327 Note, the value in Message Length field will NOT cover any 328 padding at the end of this message. 330 Sender Server's ID: 332 See Section 3.1. 334 Receiver Server's ID: 336 See Section 3.1. 338 Pool entry #1-#n: 340 If R flag is '0', at least one pool entry SHOULD be present in 341 the message. Each pool entry MUST start with a pool handle 342 parameter as defined in section 3.1.7, followed by one or more 343 pool element parameters, i.e.: 345 +---------------------------+ 346 : Pool handle : 347 +---------------------------+ 348 : PE #1 : 349 +---------------------------+ 350 : PE #2 : 351 +---------------------------+ 352 : ... : 353 +---------------------------+ 354 : PE #n : 355 +---------------------------+ 357 3.4 PEER_NAME_UPDATE message 359 0 1 2 3 360 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 1 361 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 362 | Type = 0x4 |0|0|0|0|0|0|0|0| Message Length | 363 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 364 | Update Action | (reserved) | 365 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 366 | Sender Server's ID | 367 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 368 | Receiver Server's ID | 369 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 370 : Pool handle : 371 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 372 : Pool Element : 373 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 375 Message Length: 16 bits (unsigned integer) 377 Indicates the entire length of the message in number of octets. 379 Note, the value in Message Length field will NOT cover any 380 padding at the end of this message. 382 Update Action: 16 bits (unsigned integer) 384 This field indicates what act is requested to the specified PE. 385 It MUST take one of the following values: 387 0x0 - ADD_PE: add or update the specified PE in the ENRP 388 namespace 390 0x1 - DEL_PE: delete the specified PE from the ENRP namespace. 392 Other values are reserved by IETF and MUST not be used. 394 Reserved: 16 bits 396 MUST be set to 0's by sender and ignored by the receiver. 398 Sender Server's ID: 400 See Section 3.1. 402 Receiver Server's ID: 404 See Section 3.1. 406 Pool handle: 408 Specifies to which the PE belongs. 410 Pool Element: 412 Specifies the PE. 414 3.5 PEER_LIST_REQUEST message 416 This ENRP message is used to request a copy of the current known ENRP 417 peer server list. This message is normally sent from a newly started 418 ENRP server to an existing ENRP server as part of the initialization 419 process of the new server. 421 0 1 2 3 422 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 1 423 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 424 | Type = 0x5 |0|0|0|0|0|0|0|0| Message Length = 0xC | 425 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 426 | Sender Server's ID | 427 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 428 | Receiver Server's ID | 429 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 431 Sender Server's ID: 433 See Section 3.1. 435 Receiver Server's ID: 437 See Section 3.1. 439 3.6 PEER_LIST_RESPONSE message 441 This message is used to respond a PEER_LIST_REQUEST. 443 0 1 2 3 444 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 1 445 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 446 | Type = 0x6 |0|0|0|0|0|0|0|R| Message Length | 447 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 448 | Sender Server's ID | 449 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 450 | Receiver Server's ID | 451 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 452 : Server Info Param of Peer #1 : 453 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 454 : ... : 455 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 456 : Server Info Param of Peer #n : 457 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 459 R (Reject) flag: 1 bit 461 MUST be set to '1' if the sender of this message is rejecting a 462 peer list request. In such a case, this message MUST be sent 463 with no peer server ID included. 465 Message Length: 16 bits (unsigned integer) 467 Indicates the entire length of the message in number of octets. 469 Note, the value in Message Length field will NOT cover any 470 padding at the end of this message. 472 Sender Server's ID: 474 See Section 3.1. 476 Receiver Server's ID: 478 See Section 3.1. 480 Server Information Parameter of Peer #1-#n: 482 Each contains a Server Information Parameter of a peer known to 483 the sender. The Server Information Parameter is defined in 484 [10]. 486 3.7 PEER_INIT_TAKEOVER message 488 This message is used by an ENRP server (the takeover initiator) to 489 declare its intention of taking over a specific peer ENRP server. 491 0 1 2 3 492 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 1 493 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 494 | Type = 0x7 |0|0|0|0|0|0|0|0| Message Length | 495 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 496 | Sender Server's ID | 497 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 498 | Receiver Server's ID | 499 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 500 | Target Server's ID | 501 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 503 Sender Server's ID: 505 See Section 3.1. 507 Receiver Server's ID: 509 See Section 3.1. 511 Target Server's ID: 513 Contains the 32-bit server ID of the peer ENRP that is the 514 target of this takeover attempt. 516 3.8 PEER_INIT_TAKEOVER_ACK message 518 This message is used to acknowledge the takeover initiator that the 519 sender of this message received the PEER_INIT_TAKEOVER message and 520 that it does not object to the takeover. 522 0 1 2 3 523 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 1 524 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 525 | Type = 0x8 |0|0|0|0|0|0|0|0| Message Length | 526 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 527 | Sender Server's ID | 528 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 529 | Receiver Server's ID | 530 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 531 | Target Server's ID | 532 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 534 Sender Server's ID: 536 See Section 3.1. 538 Receiver Server's ID: 540 See Section 3.1. 542 Target Server's ID: 544 Contains the 32-bit server ID of the peer ENRP that is the 545 target of this takeover attempt. 547 3.9 PEER_TAKEOVER_SERVER message 549 This message is used by the takeover initiator to declare that a 550 takeover is underway. 552 0 1 2 3 553 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 1 554 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 555 | Type = 0x9 |0|0|0|0|0|0|0|0| Message Length | 556 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 557 | Sender Server's ID | 558 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 559 | Receiver Server's ID | 560 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 561 | Target Server's ID | 562 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 564 Sender Server's ID: 566 See Section 3.1. 568 Receiver Server's ID: 570 See Section 3.1. 572 Target Server's ID: 574 Contains the 32-bit server ID of the peer ENRP that is the 575 target of this takeover operation. 577 3.10 PEER_OWNERSHIP_CHANGE message 579 This message is used by the ENRP server, normally after a successful 580 takeover, to declare that it is now the new home ENRP server of the 581 listed PEs in the listed pools. 583 0 1 2 3 584 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 1 585 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 586 | Type = 0xa |0|0|0|0|0|0|0|0| Message Length | 587 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 588 | Sender Server's ID | 589 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 590 | Receiver Server's ID | 591 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 592 : Pool handle #1 : 593 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 594 : PE Identifier Param #1 of pool #1 : 595 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 596 : ... : 597 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 598 : PE Identifier Param #k of pool #1 : 599 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 600 : : 601 : ... : 602 : : 603 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 604 : Pool handle #M : 605 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 606 : PE Identifier Param #1 of pool #M : 607 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 608 : ... : 609 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 610 : PE Identifier Param #n of pool #M : 611 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 613 Sender Server's ID: 615 See Section 3.1. 617 Receiver Server's ID: 619 See Section 3.1. 621 Pool handles and PE Identifier parameters: 623 Each listed pool handle is followed by a list of PE Identifier 624 parameters, indicating that the sender of this message is 625 taking ownership of the listed PEs in the pool. 627 3.11 PEER_ERROR message 629 This message is used by an ENRP server to report an operation error 630 to one of its peers. 632 0 1 2 3 633 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 1 634 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 635 | Type = 0xb |0|0|0|0|0|0|0|0| Message Length | 636 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 637 | Sender Server's ID | 638 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 639 | Receiver Server's ID | 640 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 641 : Operation Error Parameter : 642 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 644 Sender Server's ID: 646 See Section 3.1. 648 Receiver Server's ID: 650 See Section 3.1. 652 Operation Error Parameter: 654 This parameter, defined in [10], indicates the type of error(s) 655 being reported. 657 4. ENRP Operation Procedures 659 In this section, we discuss the operation procedures defined by ENRP. 660 An ENRP server MUST following these procedures when sending, 661 receiving, or processing ENRP messages. 663 Many of the Rserpool events call for both server-to-server and PU/ 664 PE-to-server message exchanges. Only the message exchanges and 665 activities between an ENRP server and its peer(s) are considered 666 within the ENRP scope and are defined in this document. 668 Procedures for exchanging messages between a PE/PU and ENRP servers 669 are defined in [1]. 671 4.1 Methods for Communicating amongst ENRP Servers 673 Within an Rserpool operation scope, ENRP servers need to communicate 674 with each other in order to exchange information such as the pool 675 membership changes, namespace data synchronization, etc. 677 Two types of communications are used amongst ENRP servers: 679 o point-to-point message exchange from one ENPR server to a specific 680 peer server, and 682 o announcements from one server to all its peer servers in the 683 operation scope. 685 Point-to-point communication is always carried out over an SCTP 686 association between the sending server and the receiving server. 688 Announcements are communicated out with one of the following two 689 approaches: 691 1. The sending server sends the announcement message to a well-known 692 RSERPOOL IP multicast channel that its peer servers subscribe to. 694 Note: Because IP multicast is not reliable, this approach does 695 not guarantee that all the peers will receive the announcement 696 message. Moreover, since IP multicast is not secure, this 697 approach cannot provide any security to the communication. 699 2. The sending server sends multiple copies of the announcement, one 700 to each of its peer servers, over a set of point-to-point SCTP 701 associations between the sending server and the peers. 703 This approach guarantees the reliable reception of the message. 704 When needed, data security can be achieved by using IP security 705 mechanisms such as IPsec [9] or TLS [8]. 707 In order to maximize inter-operability of ENRP servers, the following 708 rules MUST be followed: 710 1. At the startup time, a new ENRP server SHOULD make a decision on 711 whether it will enable IP multicast for ENRP announcements. This 712 decision should be based on factors such as the availability of 713 IP multicast and the security requirements from the user of 714 Rserpool. 716 2. If an ENRP server disables multicast, it then: 718 A. MUST NOT subscribe to the well-known server multicast 719 channel, i.e., it only receives peer announcements over SCTP 720 associations, and 722 B. MUST transmit all its out-going announcements over 723 point-to-point SCTP associations with its peers. 725 3. If an ENRP server enables itself to use multicast, it then: 727 A. MUST subscribe to the well-known server multicast channel to 728 ready itself for receiving peers' multicast announcements, 730 B. MUST also be prepared to receive peer announcements over 731 point-to-point SCTP associations from peers. 733 C. MUST track internally which peers are multicast-enabled and 734 which are not. Note: A peer is always assumed to be 735 multicast-disabled until/unless an ENRP message of any type 736 is received from that peer over the well-known server 737 multicast channel. 739 D. when sending out an announcement, MUST send a copy to the 740 well-known server multicast channel AND a copy to each of the 741 peers that are marked as multicast-disabled over a 742 point-to-point SCTP association. 744 4.2 ENRP Server Initialization 746 This section describes the steps a new ENRP server needs to take in 747 order to join the other existing ENRP servers, or to initiate the 748 namespace service if it is the first ENRP server started in the 749 operation scope. 751 4.2.1 Generate a Server Identifier 753 A new ENRP server MUST generate a non-zero, 32-bit server Id that is 754 as unique as possible in the operation scope and this server Id MUST 755 remain unchanged for the lifetime of the server. Normally, a good 756 32-bit random number will be good enough as the server Id ([12] 757 provides some information on randomness guidelines). 759 Note, there is a very remote chance (about 1 in 4 billion) that two 760 ENRP servers in an operation scope will generate the same server Id 761 and hence cause a server Id conflict in the pool. However, no severe 762 consequence of such a conflict has been identified. 764 4.2.2 Acquire Peer Server List 766 At startup, the ENRP server (initiating server) will first attempt to 767 learn all existing peer ENRP servers in the same operation scope, or 768 to determine that it is along in the scope. 770 The initiating server uses an existing peer server to bootstrap 771 itself into service. We call this peer server the mentor server. 773 4.2.2.1 Find the mentor server 775 If the initiating server is told about an existing peer server 776 through some administrative means (such as DNS query, configuration 777 database, startup scripts, etc), the initiating server SHOULD then 778 use this peer server as its mentor server and SHOULD skip the 779 remaining steps in this subsection. 781 If multiple existing peer servers are specified, the initiating 782 server SHOULD pick one of them as its mentor peer server, keep the 783 others as its backup mentor peers, and skip the remaining steps in 784 this subsection. 786 If no existing peer server is specified to the initiating server AND 787 if multicast is available in the operation scope, the following 788 mentor peer discovery procedures SHOULD be followed: 790 1. The initiating server SHOULD first join the well-known ENRP 791 server multicast channel. 793 2. Then the initiating server SHOULD send a PEER_PRESENCE message, 794 with the 'Reply_required' flag set, over the multicast channel. 795 Upon the reception of this PEER_PRESENCE message, a peer server 796 MUST send a PEER_PRESENCE, without the 'Reply_required' flag, 797 back to the initiating server. 799 3. When the first response to its original PEER_PRESENCE arrives, 800 the initiating server SHOULD take the sender of this received 801 response as its mentor peer server. This completes the discovery 802 of the mentor peer server. 804 If responses are also received from other peers (a likely event 805 when multiple peers exist in the operation scope at the time the 806 new server started), the initiating server SHOULD keep a list of 807 those responded as its backup mentor peers (see below). 809 4. If no response to its PEER_PRESENCE message are received after 810 TIMEOUT-SERVER-HUNT seconds, the initiating server SHOULD repeat 811 steps 2) and 3) for up to MAX-NUMBER-SERVER-HUNT times. After 812 that, if there is still no response, the initiating server MUST 813 assume that it is alone in the operation scope. 815 5. If the initiating server determined that it is alone in the 816 scope, it MUST skip the procedures in Section 4.2.2.2 and Section 817 4.2.3 and MUST consider its initialization completed and start 818 offering ENRP services. 820 Note, if multicast is not available (or not allowed for reasons such 821 as security concerns) in the operation scope, at least one peer 822 server MUST be specified to the initiating server through 823 administrative means, unless the initiation server is the first 824 server to start in the operation scope. 826 Note, if the administratively specified mentor peer(s) fails, the 827 initiating server SHOULD use the auto-discover procedure defined in 828 steps 1-5 above. 830 4.2.2.2 Request complete server list from mentor peer 832 Once the initiating server finds its mentor peer server (by either 833 discovery or administrative means), the initiating server MUST send a 834 PEER_LIST_REQUEST message to the mentor peer server to request a copy 835 of the complete server list maintained by the mentor peer (see 836 Section 4.9 for maintaining server list). 838 Upon the reception of this request, the mentor peer server SHOULD 839 reply with a PEER_LIST_RESPONSE message and include in the message 840 body all existing ENRP servers known by the mentor peer. 842 Upon the reception of the PEER_LIST_RESPONSE message from the mentor 843 peer, the initiating server MUST use the server information carried 844 in the message to initialize its own peer list. 846 However, if the mentor itself is in the process of startup and not 847 ready to provide a peer server list (for example, the mentor peer is 848 waiting for a response to its own PEER_LIST_REQUEST to another 849 server), it MUST reject the request by the initiating server and 850 respond with a PEER_LIST_RESPONSE message with the R flag set to '1', 851 and with no server information included in the response. 853 In the case where its PEER_LIST_REQUEST is rejected by the mentor 854 peer, the initiating server SHOULD either wait for a few seconds and 855 re-send the PEER_LIST_REQUEST to the mentor server, or if there is a 856 backup mentor peer available, select another mentor peer server and 857 send the PEER_LIST_REQUEST to the new mentor server. 859 4.2.3 Download ENRP Namespace Data from Mentor Peer 861 After a peer list download is completed, the initiating server MUST 862 request a copy of the current namespace data from its mentor peer 863 server, by taking the following steps: 865 1. The initiating server MUST first send a PEER_NAME_TABLE_REQUEST 866 message to the mentor peer, with W flag set to '0', indicating 867 that the entire namespace is requested. 869 2. Upon the reception of this message, the mentor peer MUST start a 870 download session in which a copy of the current namespace data 871 maintained by the mentor peer is sent to the initiating server in 872 one or more PEER_NAME_TABLE_RESPONSE messages (Note, the mentor 873 server may find it particularly desirable to use multiple 874 PEER_NAME_TABLE_RESPONSE messages to send the namespace when the 875 namespace is large, especially when forming and sending out a 876 single response containing a large namespace may interrupt its 877 other services). 879 If more than one PEER_NAME_TABLE_RESPONSE message are used during 880 the download, the mentor peer MUST use the M flag in each 881 PEER_NAME_TABLE_RESPONSE message to indicate whether this message 882 is the last one for the download session. In particular, the 883 mentor peer MUST set the M flag to '1' in the outbound 884 PEER_NAME_TABLE_RESPONSE if there is more data to be transferred 885 and MUST keep track of the progress of the current download 886 session. The mentor peer MUST set the M flag to '0' in the last 887 PEER_NAME_TABLE_RESPONSE for the download session and close the 888 download session (i.e., removing any internal record of the 889 session) after sending out the last message. 891 3. During the downloading, every time the initiating server receives 892 a PEER_NAME_TABLE_RESPONSE message, it MUST transfer the data 893 entries carried in the message into its local namespace database, 894 and then check whether or not this message is the last one for 895 the download session. 897 If the M flag is set to '1' in the just processed 898 PEER_NAME_TABLE_RESPONSE message, the initiating server MUST send 899 another PEER_NAME_TABLE_REQUEST message to the mentor peer to 900 request for the next PEER_NAME_TABLE_RESPONSE message. 902 4. When unpacking the data entries from a PEER_NAME_TABLE_RESPONSE 903 message into its local namespace database, the initiating server 904 MUST handle each pool entry carried in the message using the 905 following rules: 907 A. If the pool does not exist in the local namespace, the 908 initiating server MUST creates the pool in the local 909 namespace and add the PE(s) in the pool entry to the pool. 911 When creating the pool, the initiation server MUST set the 912 overall member selection policy type of the pool to the 913 policy type indicated in the first PE. 915 B. If the pool already exists in the local namespace, but the 916 PE(s) in the pool entry is not currently a member of the 917 pool, the initiating server MUST add the PE(s) to the pool. 919 C. If the pool already exists in the local namespace AND the 920 PE(s) in the Pool entry is already a member of the pool, the 921 initiating server SHOULD replace the attributes of the 922 existing PE(s) with the new information. 924 5. When the last PEER_NAME_TABLE_RESPONSE message is received from 925 the mentor peer and unpacked into the local namespace, the 926 initialization process is completed and the initiating server 927 SHOULD start to provide ENRP services. 929 Under certain circumstances, the mentor peer itself may not be able 930 to provide a namespace download to the initiating server. For 931 example, the mentor peer is in the middle of initializing its own 932 namespace database, or it has currently too many download sessions 933 open to other servers. 935 In such a case, the mentor peer MUST reject the request by the 936 initiating server and respond with a PEER_NAME_TABLE_RESPONSE message 937 with the R flag set to '1', and with no pool entries included in the 938 response. 940 In the case where its PEER_NAME_TABLE_REQUEST is rejected by the 941 mentor peer, the initiating server SHOULD either wait for a few 942 seconds and re-send the PEER_NAME_TABLE_REQUEST to the mentor server, 943 or if there is a backup mentor peer available, select another mentor 944 peer server and send the PEER_NAME_TABLE_REQUEST to the new mentor 945 server. 947 A started namespace download session may get interrupted for some 948 reason. To cope with this, the initiating server SHOULD start a 949 timer every time it finishes sending a PEER_NAME_TABLE_REQUEST to its 950 mentor peer. If this timer expires without receiving a response from 951 the mentor peer, the initiating server SHOULD abort the current 952 download session and re-start a new namespace download with a backup 953 mentor peer, if one is available. 955 Similarly, after sending out a PEER_NAME_TABLE_RESPONSE, if the 956 mentor peer has still more data to send, it SHOULD start a session 957 timer. If this timer expires without receiving another request from 958 the initiating server, the mentor peer SHOULD abort the session, 959 cleaning out any resource and record of the session. 961 4.3 Handle PE Registration 963 To register itself with the namespace, a PE sends a REGISTRATION 964 message to its home ENRP server. The format of REGISTRATION message 965 and rules of sending it are defined in [1]. 967 In the REGISTRATION message, the PE indicates the name of the pool it 968 wishes to join in a pool handle parameter, and its complete transport 969 information and any load control information in a PE parameter. 971 The ENRP server handles the REGISTRATION message according to the 972 following rules: 974 1. If the named pool does not exist in the namespace, the ENRP 975 server MUST creates a new pool with that name in the namespace 976 and add the PE to the pool as its first PE; 978 When a new pool is created, the overall member selection policy 979 of the pool MUST be set to the policy type indicated by the first 980 PE, the overall pool transport type MUST be set to the transport 981 type indicated by the PE, and the overall pool data/control 982 channel configuration MUST be set to what is indicated in the 983 Transport Use field of the User Transport parameter by the 984 registering PE. 986 2. If the named pool already exists in the namespace, but the 987 requesting PE is not currently a member of the pool, the ENRP 988 server will add the PE as a new member to the pool; 990 However, before adding the PE to the pool, the server MUST check 991 if the policy type, transport type, and transport usage indicated 992 by the registering PE is consistent with those of the pool. If 993 different, the ENRP server MUST either attempt to override the 994 PE's value(s) or to reject the registration if overriding is not 995 possible. 997 A. Inconsistent policy - If no additional policy-related 998 information are required to perform an override of pool 999 policy (e.g., overriding Least-used with Round-robin does not 1000 require additional policy-related information), the ENRP 1001 server MUST replace the PE's policy type with the overall 1002 policy type of the pool. However, if additional policy 1003 information is required for the overriding (e.g., overriding 1004 Round-robin with Least-load will require the knowledge of the 1005 load factor of the PE), the ENRP server MUST reject the 1006 registration. 1008 B. Inconsistent transport type - The ENRP server MUST reject the 1009 registration. 1011 C. Inconsistent data/control configuration - If the overall pool 1012 configuration is "DATA ONLY", and the registering PE 1013 indicates "CONTORL plus DATA", the ENRP server SHOULD accept 1014 the registration but warn the PE that control channel cannot 1015 be used. If the pool configuration is "CONTROL plus DATA" 1016 and the PE indicates "DATA ONLY", the ENRP server MUST reject 1017 the registration. 1019 3. If the named pool already exists in the namespace AND the 1020 requesting PE is already a member of the pool, the ENRP server 1021 SHOULD consider this as a re-registration case. The ENRP server 1022 MUST perform the same tests on policy, transport type, transport 1023 use, as described above. If the re-registration is accepted 1024 after the test, the ENRP Server SHOULD replace the attributes of 1025 the existing PE with the information carried in the received 1026 REGISTRATION message. 1028 4. After accepting the registration, the ENRP server MUST assign 1029 itself the owner of this PE. If this is a re-registration, the 1030 ENRP server MUST take over ownership of this PE regardless of 1031 whether the PE was previously owned by this server or by another 1032 server. 1034 5. The ENRP server may reject the registration due to reasons such 1035 as invalid values, lack of resource, authentication failure, etc. 1037 In all above cases, the ENRP server MUST reply to the requesting PE 1038 with a REGISTRATION_RESPONSE message. If the registration is 1039 accepted, the ENRP server MUST set the 'R' flag in the 1040 REGISTRATION_RESPONSE to '0'. If the registration is rejected, the 1041 ENRP server MUST indicate the rejection by setting the 'R' flag in 1042 the REGISTRATION_RESPONSE to '1'. 1044 If the registration is rejected, the ENRP server SHOULD include the 1045 proper error cause(s) in the REGISTRATION_RESPONSE message. 1047 If the registration is granted but with an override of some PE's 1048 original values, in the REGISTRATION_RESPONSE message the ENRP server 1049 SHOULD include the proper error cause(s) so that the PE can be warned 1050 about the overriding and be informed about the new value(s). 1052 If the registration is granted (either a new registration or a 1053 re-registration case), the ENRP server MUST assign itself to be the 1054 home ENRP server of the PE, i.e., to "own" the PE. 1056 Implementation note: for better performance, the ENRP server may 1057 find it both efficient and convenient to internally maintain two 1058 separate PE lists or tables - one is for the PEs that are "owned" 1059 by the ENRP server and the other for all the PEs owned by its 1060 peer(s). 1062 Moreover, if the registration is granted, the ENRP server MUST take 1063 the namespace update action as described in Section 4.6 to inform its 1064 peers about the change just made. If the registration is denied, no 1065 message will be sent to its peers. 1067 4.3.1 Rules on PE Re-registration 1069 A PE may re-register itself to the namespace with a new set of 1070 attributes in order to, for example, extend its registration life, 1071 change its load factor value, etc. 1073 A PE may modify its load factor value at any time via 1074 re-registration. Based on the number of PEs in the pool and the 1075 pool's overall policy type, this operation allows the PE to 1076 dynamically control its share of inbound messages received by the 1077 pool (also see Section ???? in [1] for more on load control). 1079 Moreover, when re-registering, the PE MUST NOT change its policy 1080 type. The server MUST reject the re-registration if the PE attempt 1081 to change its policy type. In the rejection, the server SHOULD 1082 attach an error code "Pooling Policy Inconsistent". 1084 Regardless whether it is the current owner of the PE, if the 1085 re-registration is granted to the PE, the ENRP server MUST assign 1086 itself to be the new home ENRP server of the PE. 1088 Moreover, if the re-registration is granted, the ENRP server MUST 1089 take the namespace update action as described in Section 4.6 to 1090 inform its peers about the change just made. If the re-registration 1091 is denied, no message will be sent to its peers. 1093 4.4 Handle PE De-registration 1095 To remove itself from a pool, a PE sends a DEREGISTRATION message to 1096 its home ENRP server. The complete format of DEREGISTRATION message 1097 and rules of sending it are defined in [1]. 1099 In the DEREGISTRATION message the PE indicates the name of the pool 1100 it belongs to in a pool handle parameter and provides its PE 1101 identifier. 1103 Upon receiving the message, the ENRP server SHALL remove the PE from 1104 its namespace. Moreover, if the PE is the last one of the named 1105 pool, the ENRP server will remove the pool from the namespace as 1106 well. 1108 If the ENRP server fails to find any record of the PE in its 1109 namespace, it SHOULD consider the de-registration granted and 1110 completed. 1112 The ENRP server may reject the de-registration request for various 1113 reasons, such as invalid parameters, authentication failure, etc. 1115 In response, the ENRP server MUST send a DEREGISTRATION_RESPONSE 1116 message to the PE. If the de-registration is rejected, the ENRP 1117 server MUST indicate the rejection by including the proper Operation 1118 Error parameter. 1120 It should be noted that de-registration does not stop the PE from 1121 sending or receiving application messages. 1123 Once the de-registration request is granted AND the PE removed from 1124 its local copy of the namespace, the ENRP server MUST take the 1125 namespace update action described in Section 4.6 to inform its peers 1126 about the change just made. Otherwise, NO message SHALL be send to 1127 its peers. 1129 4.5 Pool Handle Translation 1131 A PU uses the pool handle translation service of an ENRP server to 1132 resolve a pool handle to a list of accessible transport addresses of 1133 the member PEs of the pool. 1135 This requires the PU to send a NAME_RESOLUTION message to its home 1136 ENRP server and in the NAME_RESOLUTION message specify the pool 1137 handle to be translated in a Pool Handle parameter. Complete 1138 definition of the NAME_RESOLUTION message and the rules of sending it 1139 are defined in [1]. 1141 An ENRP server SHOULD be prepared to receive NAME_RESOLUTION requests 1142 from PUs either over an SCTP association on the well-know SCTP port, 1143 or over a TCP connection on the well-know TCP port. 1145 Upon reception of the NAME_RESOLUTION message, the ENRP server MUST 1146 first look up the pool handle in its namespace. If the pool exits, 1147 the home ENRP server MUST compose and send back a 1148 NAME_RESOLUTION_RESPONSE message to the requesting PU. 1150 In the response message, the ENRP server SHOULD list all the PEs 1151 currently registered in this pool, in a list of PE parameters. The 1152 ENRP server MUST also include a pool member selection policy 1153 parameter to indicate the overall member selection policy for the 1154 pool, if the current pool member selection policy is not round-robin 1155 (if the overall policy is round-Robin, this parameter MAY be 1156 omitted?). 1158 If the named pool does not exist in the namespace, the ENRP server 1159 MUST respond with a NAME_UNKNOWN message. 1161 The complete format of NAME_RESOLUTION_RESPONSE and NAME_UNKNOWN 1162 messages and the rules of receiving them are defined in [1]. 1164 4.6 Server Namespace Update 1166 This includes a set of update operations used by an ENRP server to 1167 inform its peers when its local namespace is modified, e.g., addition 1168 of a new PE, removal of an existing PE, change of pool or PE 1169 properties. 1171 4.6.1 Announcing Addition or Update of PE 1173 When a new PE is granted registration to the namespace or an existing 1174 PE is granted a re-registration, the home ENRP server uses this 1175 procedure to inform all its peers. 1177 This is an ENRP announcement and is sent to all the peer of the home 1178 ENRP server. See Section 4.1 on how announcements are sent. 1180 An ENRP server MUST announce this update to all its peers in a 1181 PEER_NAME_UPDATE message with the Update Action field set to ADD_PE, 1182 indicating the addition of a new PE or the modification of an 1183 existing PE. The complete new information of the PE and the pool its 1184 belongs to MUST be indicated in the message with a PE parameter and a 1185 Pool Handle parameter, respectively. 1187 The home ENRP server SHOULD fill in its server Id in the Sender 1188 Server's ID field and leave the Receiver Server's ID blank (i.e., all 1189 0's). 1191 When a peer receives this PEER_NAME_UPDATE message, it MUST take the 1192 following actions: 1194 1. If the named pool indicated by the pool handle does not exist in 1195 its local copy of the namespace, the peer MUST create the named 1196 pool in its local namespace and add the PE to the pool as the 1197 first PE. It MUST then copy in all other attributes of the PE 1198 carried in the message. 1200 When the new pool is created, the overall member selection policy 1201 of the pool MUST be set to the policy type indicated by the PE. 1203 2. If the named pool already exists in the peer's local copy of the 1204 namespace AND the PE does not exist, the peer MUST add the PE to 1205 the pool as a new PE and copy in all attributes of the PE carried 1206 in the message. 1208 3. If the named pool exists AND the PE is already a member of the 1209 pool, the peer MUST replace the attributes of the PE with the new 1210 information carried in the message. 1212 4.6.2 Announcing Removal of PE 1214 When an existing PE is granted de-registration or is removed from its 1215 namespace for some other reasons (e.g., purging an unreachable PE, 1216 see Section 4.7), the ENRP server MUST uses this procedure to inform 1217 all its peers about the change just made. 1219 This is an ENRP announcement and is sent to all the peer of the home 1220 ENRP server. See Section 4.1 on how announcements are sent. 1222 An ENRP server MUST announce the PE removal to all its peers in a 1223 PEER_NAME_UPDATE message with the Update Action field set to DEL_PE, 1224 indicating the removal of an existing PE. The complete information 1225 of the PE and the pool its belongs to MUST be indicated in the 1226 message with a PE parameter and a Pool Handle parameter, 1227 respectively. 1229 [editor's note: only the pool handle and the PE's id are needed, it 1230 should reduce the size of the message] 1231 The sending server MUST fill in its server ID in the Sender Server's 1232 ID field and leave the Receiver Server's ID blank (i.e., set to all 1233 0's). 1235 When a peer receives this PEER_NAME_UPDATE message, it MUST first 1236 find pool and the PE in its own namespace, and then remove the PE 1237 from its local namespace. If the removed PE is the last one in the 1238 pool, the peer MUST also delete the pool from its local namespace. 1240 If the peer fails to find the PE or the pool in its namespace, it 1241 SHOULD take no further actions. 1243 4.7 Detecting and Removing Unreachable PE 1245 Whenever a PU finds a PE unreachable (e.g., via an SCTP SEND.FAILURE 1246 Notification, see section 10.2 of [7]), the PU SHOULD send an 1247 ENDPOINT_UNREACHABLE message to its home ENRP server. The message 1248 SHOULD contain the pool handle and the PE Id of the unreachable PE. 1250 Upon the reception of an ENDPOINT_UNREACHABLE message, a server MUST 1251 immediately send a point-to-point ENDPOINT_KEEP_ALIVE message to the 1252 PE in question. If this ENDPOINT_KEEP_ALIVE fails (e.g., it results 1253 in an SCTP SEND.FAILURE notification), the ENRP server MUST consider 1254 the PE as truly unreachable and MUST remove the PE from its namespace 1255 and take actions described in Section 4.6.2. 1257 If the ENDPOINT_UNREACHABLE message is transmitted successfully to 1258 the PE, the ENRP server MUST retain the PE in its namespace. 1259 Moreover, the server SHOULD keep a counter to record how many 1260 ENDPOINT_UNREACHABLE messages it has received reporting reachability 1261 problem relating to this PE. If the counter exceeds the protocol 1262 threshold MAX-BAD-PE-REPORT, the ENRP server SHOULD remove the PE 1263 from its namespace and take actions described in Section 4.6.2. 1265 Optionally, an ENRP server may also periodically send point-to-point 1266 ENDPOINT_KEEP_ALIVE messages to each of the PEs owned by the ENRP 1267 server in order to check their reachability status. If the send of 1268 ENDPOINT_KEEP_ALIVE to a PE fails, the ENRP server MUST consider the 1269 PE as unreachable and MUST remove the PE from its namespace and take 1270 actions described in Section 4.6.2. Note, if an ENRP server owns a 1271 large number of PEs, the implementation should pay attention not to 1272 flood the network with bursts of ENDPOINT_KEEP_ALIVE messages. 1273 Instead, the implementation should try to smooth out the 1274 ENDPOINT_KEEP_ALIVE message traffic over time. 1276 The complete definition and rules of sending ENDPOINT_UNREACHABLE and 1277 receiving ENDPOINT_KEEP_ALIVE messages are described in [1]. 1279 4.8 Helping PE and PU to Discover Home ENRP Server 1281 At its startup time, or whenever its current home ENRP server is not 1282 providing services, a PE or PU will attempt to find a new home 1283 server. For this reason, the PE or PU will need to maintain a list 1284 of currently available ENRP servers in its scope. 1286 To help the PE or PU maintaining this list, an ENRP server, if it is 1287 enabled for multicast, SHOULD periodically send out a SERVER_ANNOUNE 1288 message every SERVER-ANNOUNCE-CYCLE seconds to the well-known ASAP 1289 multicast channel. And in the SERVER_ANNOUNE message the ENRP server 1290 SHOULD include all the transport addresses available for ASAP 1291 communications. If the ENRP server only supports SCTP for ASAP 1292 communications, the transport information MAY be omitted in the 1293 SERVER_ANNOUNCE message. 1295 For the complete procedure of this, see Section 3.6?? in [1]. 1297 4.9 Maintaining Peer List and Monitoring Peer Status 1299 An ENRP server MUST keep an internal record on the status of each of 1300 its known peers. This record is referred to as the server's "peer 1301 list" 1303 4.9.1 Discovering New Peer 1305 If a message of any type is received from a previously unknown peer, 1306 the ENRP server MUST consider this peer a new peer in the operation 1307 scope and add it to the peer list. 1309 The ENRP server MUST send a PEER_PRESENCE message with the 1310 Reply-required flag set to '1' to the source address found in the 1311 arrived message. This will force the new peer to reply with its own 1312 PEER_PRESENCE containing its full server information (see Section 1313 3.1). 1315 [editor's note: should we ask for a peer list from the new peer? 1316 this may help mending two split networks.] 1318 4.9.2 Server Sending Heartbeat 1320 Every PEER-HEARTBEAT-CYCLE seconds, an ENRP server MUST announce its 1321 continued presence to all its peer with a PEER_PRESENCE message. In 1322 the PEER_PRESENCE message, the ENRP server MUST set the 1323 'Replay_required' flag to '0', indicating that no response is 1324 required. 1326 The arrival of this periodic PEER_PRESENCE message will cause all its 1327 peers to update their internal variable "peer.last.heard" for the 1328 sending server (see Section 4.9.3 for more details). 1330 4.9.3 Detecting Peer Server Failure 1332 An ENRP server MUST keep an internal variable "peer.last.heard" for 1333 each of its known peers and the value of this variable MUST be 1334 updated to the current local time every time a message of any type 1335 (point-to-point or announcement) is received from the corresponding 1336 peer. 1338 If a peer has not been heard for more than MAX-TIME-LAST-HEARD 1339 seconds, the ENRP server MUST immediately send a point-to-point 1340 PEER_PRESENCE with 'Reply_request' flag set to '1' to that peer. 1342 If the send fails or the peer does not reply after 1343 MAX-TIME-NO-RESPONSE seconds, the ENRP server MUST consider the peer 1344 server dead and SHOULD initiate the takeover procedure defined in 1345 Section 4.10. 1347 4.10 Taking-over a Failed Peer Server 1349 In the following descriptions, We call the ENRP server that detects 1350 the failed peer server and initiates the take-over the "initiating 1351 server" and the failed peer server the "target server." 1353 4.10.1 Initiate Server Take-over Arbitration 1355 The initiating server SHOULD first start a take-over arbitration 1356 process by announcing a PEER_INIT_TAKEOVER message to all its peer 1357 servers. See Section 4.1 on how announcements are sent. In the 1358 message, the initiating server MUST fill in the Sender Server's ID 1359 and Target Server's ID. 1361 After announcing the PEER_INIT_TAKEOVER message, the initiating 1362 server SHOULD wait for a PEER_INIT_TAKEOVER_ACK message from _each_ 1363 of its known peers, except of the target server. [editor's note: how 1364 long should it wait?] 1366 Each of the peer servers that receives the PEER_INIT_TAKEOVER message 1367 from the initiating server SHOULD take the following actions: 1369 1. If the peer server finds that itself is the target server 1370 indicated in the PEER_INIT_TAKEOVER message, it MUST immediately 1371 announce a PEER_PRESENCE message to all its peer ENRP servers in 1372 an attempt to stop this take-over process. This indicates a 1373 false failure detection case by the initiating server. 1375 2. If the peer server finds that itself has already started its own 1376 take-over arbitration process on the same target server, it MUST 1377 perform the following arbitration: 1379 A. if the peer's server ID is smaller in value than the Sender 1380 Server's ID in the arrived PEER_INIT_TAKEOVER message, the 1381 peer server SHOULD immediately abort its own take-over 1382 attempt. Moreover, the peer SHOULD mark the target server as 1383 "not active" on its internal peer list so that its status 1384 will no longer be monitored by the peer, and reply the 1385 initiating server with a PEER_INIT_TAKEOVER_ACK message. 1387 B. Otherwise, the peer MUST ignore the PEER_INIT_TAKEOVER 1388 message and take no action. 1390 3. If the peer finds that it is neither the target server nor is in 1391 its own take-over process, the peer SHOULD: a) mark the target 1392 server as "not active" on its internal peer list so that its 1393 status will no longer be monitored by this peer, and b) reply to 1394 the initiating server with a PEER_INIT_TAKEOVER_ACK message. 1396 Once the initiating server has received PEER_INIT_TAKEOVER_ACK 1397 message from _all_ of its currently known peers (except for the 1398 target server), it SHOULD consider that it has won the arbitration 1399 and SHOULD proceed to complete the take-over, following the steps 1400 described in Section 4.10.2. 1402 However, if it receives a PEER_PRESENCE from the target server at any 1403 point in the arbitration process, the initiating server SHOULD 1404 immediately abort the take-over process and mark the status of the 1405 target server as "active". 1407 4.10.2 Take-over Target Peer Server 1409 The initiating ENRP server SHOULD first send, via an announcement, a 1410 PEER_TAKEOVER_SERVER message to inform all its active peers that the 1411 take-over is enforced. The target server's ID MUST be filled in the 1412 message. The initiating server SHOULD then remove the target server 1413 from its internal peer list. 1415 [editor's note: peers should remove the target server from their list 1416 upon receiving this message. Do we really need this message? we can 1417 consolidate this with the ownership_change msg.] 1419 Then it SHOULD examine its local copy of the namespace and claim 1420 ownership of each of the PEs originally owned by the target server, 1421 by following these steps: 1423 1. mark itself as the home ENRP server of each of the PEs originally 1424 owned by the target server; 1426 2. send a point-to-point ENDPOINT_KEEP_ALIVE message to each of the 1427 PEs. This will trigger the PE to adopt the initiating sever as 1428 its new home ENRP server; 1430 3. after claiming the ownership of all the PEs originally owned by 1431 the target server, announce the ownership changes of all the 1432 affected PEs in a PEER_OWNERSHIP_CHANGE message to all the 1433 currently known peers. Note, if the list of affected PEs is 1434 long, the sender MAY announce the ownership changes in multiple 1435 PEER_OWNERSHIP_CHANGE messages. 1437 When a peer receives the PEER_OWNERSHIP_CHANGE message from the 1438 initiating server, it SHOULD find each of the reported PEs in its 1439 local copy of the namespace and update the PE's home ENRP server to 1440 be the sender of the message (i.e., the initiating server). 1442 4.11 Namespace Data Auditing and Re-synchronization 1444 Message losses or certain temporary breaks in network connectivity 1445 may result in data inconsistency in the local namespace copy of some 1446 of the ENRP servers in an operation scope. Therefore, each ENRP 1447 server in the operation scope SHOULD periodically verify that its 1448 local copy of namespace data is still in sync with that of its peers. 1450 This section defines the auditing and re-synchronization procedures 1451 for an ENRP server to maintain its namespace data consistency. 1453 4.11.1 Auditing Procedures 1455 The auditing of namespace consistency is based on the following 1456 procedures: 1458 1. An ENRP server SHOULD keep a separate PE checksum (a 32-bit 1459 integer internal variable) for each of its known peers and for 1460 itself. For an ENRP server with 'k' known peers, we denote these 1461 internal variables as "pe.checksum.pr0", "pe.checksum.pr1", ..., 1462 "pe.checksum.prk", where "pe.checksum.pr0" is the server's own PE 1463 checksum. The definition and detailed algorithm for calculating 1464 these PE checksum variables are given in Section 4.11.2. 1466 2. Each time an ENRP server sends out a PEER_PRESENCE, it SHOULD 1467 include in the message its current PE checksum (i.e., 1468 "pe.checksum.pr0"). 1470 3. When an ENRP server (server A) receives a PE checksum (carried in 1471 an arrived PEER_PRESENCE) from a peer ENRP server (server B), 1472 server A SHOULD compare the PE checksum found in the 1473 PEER_PRESENCE with its own internal PE checksum of server B 1474 (i.e., "pe.checksum.prB"). 1476 4. If the two values match, server A will consider that there is no 1477 namespace inconsistency between itself and server B and should 1478 take no further actions. 1480 5. If the two values do NOT match, server A SHOULD consider that 1481 there is a namespace inconsistency between itself and server B 1482 and a re-synchronization process SHOULD be carried out 1483 immediately with server B (see Section 4.11.3). 1485 4.11.2 PE Checksum Calculation Algorithm 1487 When an ENRP server (server A) calculate an internal PE checksum for 1488 a peer (server B), it MUST use the following algorithm. 1490 Let us assume that in server A's internal namespace there are 1491 currently 'M' PEs that are owned by server B. Each of the 'M' PEs 1492 will then contribute to the checksum calculation with the following 1493 byte block: 1495 0 1 2 3 1496 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 1497 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1498 : Pool handle string of the pool the PE belongs (padded with : 1499 : zeros to next 32-bit word boundary if needed) : 1500 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1501 | PE Id (4 octets) | 1502 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1504 Note, these are not TLVs. This byte block gives each PE a unique 1505 byte pattern in the scope. The 32-bit PE checksum for server B 1506 "pe.checksum.prB" is then calculated over the byte blocks contributed 1507 by the 'M' PEs one by one. 1509 Server A MUST calculate its own PE checksum (i.e., "pe.checksum.pr0") 1510 in the same fashion, using the byte blocks of all the PEs owned by 1511 itself. 1513 Note, whenever an ENRP finds that its internal namespace has changed 1514 (e.g., due to PE registration/deregistration, receiving peer updates, 1515 removing failed PEs, downloading namespace pieces from a peer, etc.), 1516 it MUST immediately update all its internal PE checksums that are 1517 affected by the change. 1519 Implementation Note: when the internal namespace changes (e.g., a new 1520 PE added or an existing PE removed), an implementation needs not to 1521 re-calculate the affected PE checksum; it should instead simply 1522 update the checksum by adding or subtracting the byte block of the 1523 corresponding PE from the previous checksum value. 1525 4.11.3 Re-synchronization Procedures 1527 Once an ENRP server determines that there is inconsistency between 1528 its local namespace data and a peer's namespace data with regarding 1529 to the PEs owned by that peer, it SHOULD perform the following steps 1530 to re-synchronize the data: 1532 1. The ENRP server SHOULD first "mark" every PE it knows about that 1533 is owned by the peer in its local namespace database; 1535 2. The ENRP server SHOULD then send a PEER_NAME_TABLE_REQUEST 1536 message with W flag set to '1' to the peer to request a complete 1537 list of PEs owned by the peer; 1539 3. Upon reception of the PEER_NAME_TABLE_REQUEST message with W flag 1540 set to '1', the peer server SHOULD immediately respond with a 1541 PEER_NAME_TABLE_RESPONSE message listing all PEs currently owned 1542 by the peer. 1544 4. Upon reception of the PEER_NAME_TABLE_RESPONSE message, the ENRP 1545 server SHOULD transfer the PE entries carried in the message into 1546 its local namespace database. If an PE entry being transferred 1547 already exists in its local database, the ENRP server MUST 1548 replace the entry with the copy found in the message and remove 1549 the "mark" from the entry. 1551 5. After transferring all the PE entries from the received 1552 PEER_NAME_TABLE_RESPONSE message into its local database, the 1553 ENRP server SHOULD check whether there are still PE entries that 1554 remain "marked" in its local namespace. If so, the ENRP server 1555 SHOULD silently remove those "marked" entries. 1557 Note, similar to what is described in Section 4.2.3, the peer may 1558 reject the PEER_NAME_TABLE_REQUEST or use more than one 1559 PEER_NAME_TABLE_RESPONSE message to respond. 1561 4.12 Handling Unrecognized Message or Unrecognized Parameter 1563 When an ENRP server receives an ENRP message with an unknown message 1564 type or a message of known type that contains an unknown parameter, 1565 it SHOULD handle the unknown message or the unknown parameter 1566 according to the unrecognized message and parameter handling rules 1567 defined in Sections 3 and 4 in [10]. 1569 According to the rules, if an error report to the message sender is 1570 needed, the ENRP server that discovered the error SHOULD send back an 1571 ENRP_ERROR message with proper error cause code. 1573 5. Variables and Thresholds 1575 5.1 Variables 1577 peer.last.heard - the local time that a peer server was last heard 1578 (via receiving either a multicast or point-to-point message from 1579 the peer). 1581 pe.checksum.pr - the internal 32-bit PE checksum that an ENRP server 1582 keeps for a peer. A separate PE checksum is kept for each of its 1583 known peers as well as for itself. 1585 5.2 Thresholds 1587 MAX-NUMBER-SERVER-HUNT - the maximal number of attempts a sender will 1588 make to contact an ENRP server (Default=3 times). 1590 TIMEOUT-SERVER-HUNT - pre-set threshold for how long a sender will 1591 wait for a response from an ENRP server (Default=5 seconds). 1593 PEER-HEARTBEAT-CYCLE - the period for an ENRP server to announce a 1594 heartbeat message to all its known peers. (Default=30 secs.) 1596 SERVER-ANNOUNCE-CYCLE - the period for an ENRP server to announce a 1597 SERVER_ANNOUNCE message to all PEs and PUs. (Default=5 secs.) 1599 MAX-TIME-LAST-HEARD - pre-set threshold for how long an ENRP server 1600 will wait before considering a silent peer server potentially 1601 dead. (Default=61 secs.) 1603 MAX-TIME-NO-RESPONSE - pre-set threshold for how long a message 1604 sender will wait for a response after sending out a message. 1605 (Default=5 secs.) 1607 MAX-BAD-PE-REPORT - the maximal number of unreachability reports on a 1608 PE that an ENRP server will allow before purging this PE from the 1609 namespace. (Default=3) 1611 6. Security Considerations 1613 Threats Introduced by Rserpool and Requirements for Security in 1614 Response to Threats [11] describes the threats to the Rserpool 1615 architecture in detail and lists the security requirements in 1616 response to each threat. From the threats described in this 1617 document, the security services required for the Rserpool protocol 1618 are enumerated below. 1620 Threat 1) PE registration/deregistration flooding or spoofing 1621 ----------- 1622 Security mechanism in response: ENRP server authenticates the PE 1624 Threat 2) PE registers with a malicious ENRP server 1625 ----------- 1626 Security mechanism in response: PE authenticates the ENRP server 1628 Threat 1 and 2 taken together results in mutual authentication of the 1629 ENRP server and the PE. 1631 Threat 3) Malicious ENRP server joins the ENRP server pool 1632 ----------- 1633 Security mechanism in response: ENRP servers mutually authenticate 1635 Threat 4) A PU communicates with a malicious ENRP server for name 1636 resolution 1637 ----------- 1638 Security mechanism in response: The PU authenticates the ENRP server 1640 Threat 5) Replay attack 1641 ----------- 1642 Security mechanism in response: Security protocol which has 1643 protection from replay attacks 1645 Threat 6) Corrupted data which causes a PU to have misinformation 1646 concerning a pool handle resolution 1647 ----------- 1648 Security mechanism in response: Security protocol which supports 1649 integrity protection 1651 Threat 7) Eavesdropper snooping on namespace information 1652 ----------- 1653 Security mechanism in response: Security protocol which supports data 1654 confidentiality 1656 Threat 8) Flood of Endpoint_Unreachable messages from the PU to ENRP 1657 server 1658 ----------- 1659 Security mechanism in response: ASAP must control the number of 1660 endpoint unreachable messages transmitted from the PU to the ENRP 1661 server. 1663 Threat 9) Flood of Endpoint_KeepAlive messages to the PE from the 1664 ENRP server 1665 ----------- 1666 Security mechanism in response: ENRP server must control the number 1667 of Endpoint_KeepAlive messages to the PE 1669 To summarize the threats 1-7 require security mechanisms which 1670 support authentication, integrity, data confidentiality, protection 1671 from replay attacks. 1673 For Rserpool we need to authenticate the following: 1675 PU <---- ENRP Server (PU authenticates the ENRP server) 1676 PE <----> ENRP Server (mutual authentication) 1677 ENRP server <-----> ENRP Server (mutual authentication) 1679 We do not define any new security mechanisms specifically for 1680 responding to threats 1-7. Rather we use existing IETF security 1681 protocols to provide the security services required. TLS supports 1682 all these requirements and MUST be implemented. The 1683 TLS_RSA_WITH_AES_128_CBC_SHA ciphersuite MUST be supported at a 1684 minimum by implementers of TLS for Rserpool. For purposes of 1685 backwards compatibility, ENRP SHOULD support 1686 TLS_RSA_WITH_3DES_EDE_CBC_SHA. Implementers MAY also support any 1687 other ciphersuite. 1689 Threat 8 requires the ASAP protocol to limit the number of 1690 Endpoint_Unreachable messages (see Section 3.5??? in [1]) to the ENRP 1691 server. 1693 Threat 9 requires the ENRP protocol to limit the number of 1694 Endpoint_KeepAlive messages to the PE (see Section x.y???). 1696 6.1 Implementing Security Mechanisms 1698 ENRP servers, PEs, PUs MUST implement TLS. ENRP servers and PEs must 1699 support mutual authentication. ENRP servers must support mutual 1700 authentication among themselves. PUs MUST authenticate ENRP servers. 1702 ENRP servers and PEs SHOULD possess a site certificate whose subject 1703 corresponds to their canonical hostname. PUs MAY have certificates 1704 of their own for mutual authentication with TLS, but no provisions 1705 are set forth in this document for their use. All Rserpool elements 1706 that support TLS MUST have a mechanism for validating certificates 1707 received during TLS negotiation; this entails possession of one or 1708 more root certificates issued by certificate authorities (preferably 1709 well-known distributors of site certificates comparable to those that 1710 issue root certificates for web browsers). 1712 Implementations MUST support TLS with SCTP as described in RFC3436 1713 [8] or TLS over TCP as described in RFC2246 [6]. When using TLS/SCTP 1714 we must ensure that RSerPool does not use any features of SCTP that 1715 are not available to an TLS/SCTP user. This is not a difficult 1716 technical problem, but simply a requirement. When describing an API 1717 of the RSerPool lower layer we have also to take into account the 1718 differences between TLS and SCTP. 1720 7. Acknowledgements 1722 The authors wish to thank John Loughney, Lyndon Ong, and many others 1723 for their invaluable comments. 1725 8. References 1727 8.1 Normative References 1729 [1] Stewart, R., Xie, Q., Stillman, M. and M. Tuexen, "Aggregate 1730 Server Access Protocol (ASAP)", draft-ietf-rserpool-asap-09 1731 (work in progress), June 2004. 1733 [2] Tuexen, M., Xie, Q., Stewart, R., Shore, M., Ong, L., Loughney, 1734 J. and M. Stillman, "Requirements for Reliable Server Pooling", 1735 RFC 3237, January 2002. 1737 [3] Tuexen, M., Xie, Q., Stewart, R., Shore, M. and J. Loughney, 1738 "Architecture for Reliable Server Pooling", 1739 draft-ietf-rserpool-arch-07 (work in progress), October 2003. 1741 [4] Bradner, S., "The Internet Standards Process -- Revision 3", 1742 BCP 9, RFC 2026, October 1996. 1744 [5] Bradner, S., "Key words for use in RFCs to Indicate Requirement 1745 Levels", BCP 14, RFC 2119, March 1997. 1747 [6] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0", RFC 1748 2246, January 1999. 1750 [7] Stewart, R., Xie, Q., Morneault, K., Sharp, C., Schwarzbauer, 1751 H., Taylor, T., Rytina, I., Kalla, M., Zhang, L. and V. Paxson, 1752 "Stream Control Transmission Protocol", RFC 2960, October 2000. 1754 [8] Jungmaier, A., Rescorla, E. and M. Tuexen, "TLS over SCTP", RFC 1755 3436, December 2002. 1757 [9] Bellovin, S., Ioannidis, J., Keromytis, A. and R. Stewart, "On 1758 the Use of Stream Control Transmission Protocol (SCTP) with 1759 IPsec", RFC 3554, July 2003. 1761 [10] Stewart, R., Xie, Q., Stillman, M. and M. Tuexen, "Aggregate 1762 Server Access Protocol (ASAP) and Endpoint Name Resolution 1763 (ENRP) common parameters document", 1764 draft-ietf-rserpool-common-param-06 (work in progress), June 1765 2004. 1767 [11] Stillman, M., "Threats Introduced by Rserpool and Requirements 1768 for Security in Response to Threats", 1769 draft-ietf-rserpool-threats-02 (work in progress), Sept 2003. 1771 8.2 Informative References 1773 [12] Eastlake, D., Crocker, S. and J. Schiller, "Randomness 1774 Recommendations for Security", RFC 1750, December 1994. 1776 Authors' Addresses 1778 Qiaobing Xie 1779 Motorola, Inc. 1780 1501 W. Shure Drive, 2-F9 1781 Arlington Heights, IL 60004 1782 US 1784 Phone: +1-847-632-3028 1785 EMail: qxie1@email.mot.com 1787 Randall R. Stewart 1788 Cisco 1789 24 Burning Bush Trail 1790 Crystal Lake, IL 60012 1791 US 1793 Phone: +1-815-477-2127 1794 EMail: rrs@cisco.com 1796 Maureen Stillman 1797 Nokia 1798 127 W. 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