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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 DHC M. Stapp 3 Internet-Draft Cisco Systems, Inc. 4 Expires: April 14, 2008 October 12, 2007 6 DHCPv6 Bulk Leasequery 7 draft-stapp-dhc-dhcpv6-bulk-leasequery-00.txt 9 Status of this Memo 11 By submitting this Internet-Draft, each author represents that any 12 applicable patent or other IPR claims of which he or she is aware 13 have been or will be disclosed, and any of which he or she becomes 14 aware will be disclosed, in accordance with Section 6 of BCP 79. 16 Internet-Drafts are working documents of the Internet Engineering 17 Task Force (IETF), its areas, and its working groups. Note that 18 other groups may also distribute working documents as Internet- 19 Drafts. 21 Internet-Drafts are draft documents valid for a maximum of six months 22 and may be updated, replaced, or obsoleted by other documents at any 23 time. It is inappropriate to use Internet-Drafts as reference 24 material or to cite them other than as "work in progress." 26 The list of current Internet-Drafts can be accessed at 27 http://www.ietf.org/ietf/1id-abstracts.txt. 29 The list of Internet-Draft Shadow Directories can be accessed at 30 http://www.ietf.org/shadow.html. 32 This Internet-Draft will expire on April 14, 2008. 34 Copyright Notice 36 Copyright (C) The IETF Trust (2007). 38 Abstract 40 The Dynamic Host Configuration Protocol for IPv6 (DHCPv6) has been 41 extended with a Leasequery capability that allows a client to request 42 information about DHCPv6 bindings. That mechanism is limited to 43 queries for individual bindings. In some situations individual 44 binding queries may not be efficient, or even possible. This 45 document specifies extensions to the Leasequery protocol that add new 46 query types and allow for bulk DHCPv6 binding data transfer. 48 Table of Contents 50 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 51 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 52 3. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 4 53 4. Message and Option Definitions . . . . . . . . . . . . . . . . 4 54 4.1. Message Framing for TCP . . . . . . . . . . . . . . . . . 5 55 4.2. Messages . . . . . . . . . . . . . . . . . . . . . . . . . 5 56 4.2.1. LEASEQUERY-DATA . . . . . . . . . . . . . . . . . . . 5 57 4.2.2. LEASEQUERY-DONE . . . . . . . . . . . . . . . . . . . 6 58 4.3. Query Types . . . . . . . . . . . . . . . . . . . . . . . 6 59 4.3.1. QUERY_BY_RELAYID . . . . . . . . . . . . . . . . . . . 6 60 4.3.2. QUERY_BY_LINK_ADDRESS . . . . . . . . . . . . . . . . 7 61 4.3.3. QUERY_BY_REMOTE_ID . . . . . . . . . . . . . . . . . . 7 62 4.4. Options . . . . . . . . . . . . . . . . . . . . . . . . . 7 63 4.4.1. Relay-ID Option . . . . . . . . . . . . . . . . . . . 7 64 4.5. Status Codes . . . . . . . . . . . . . . . . . . . . . . . 8 65 4.6. Connection and Transmission Parameters . . . . . . . . . . 8 66 5. Requestor Behavior . . . . . . . . . . . . . . . . . . . . . . 9 67 5.1. Connecting . . . . . . . . . . . . . . . . . . . . . . . . 9 68 5.2. Forming Queries . . . . . . . . . . . . . . . . . . . . . 9 69 5.3. Processing Replies . . . . . . . . . . . . . . . . . . . . 9 70 5.4. Querying Multiple Servers . . . . . . . . . . . . . . . . 10 71 5.5. Multiple Queries to a Single Server . . . . . . . . . . . 10 72 5.6. Closing Connections . . . . . . . . . . . . . . . . . . . 10 73 6. Server Behavior . . . . . . . . . . . . . . . . . . . . . . . 11 74 6.1. Accepting Connections . . . . . . . . . . . . . . . . . . 11 75 6.2. Forming Replies . . . . . . . . . . . . . . . . . . . . . 11 76 6.3. Multiple or Parallel Queries . . . . . . . . . . . . . . . 12 77 6.4. Closing Connections . . . . . . . . . . . . . . . . . . . 13 78 7. Security Considerations . . . . . . . . . . . . . . . . . . . 13 79 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 80 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14 81 10. Modification History . . . . . . . . . . . . . . . . . . . . . 14 82 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14 83 11.1. Normative References . . . . . . . . . . . . . . . . . . . 14 84 11.2. Informative References . . . . . . . . . . . . . . . . . . 15 85 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 15 86 Intellectual Property and Copyright Statements . . . . . . . . . . 16 88 1. Introduction 90 The DHCPv6 [1] protocol specifies a mechanism for the assignment of 91 IPv6 address and configuration information to IPv6 nodes. IPv6 92 Prefix Delegation for DHCPv6 (PD) [2] specifies a mechanism for 93 DHCPv6 delegation of IPv6 prefixes and related data. DHCPv6 servers 94 maintain authoritative information including binding information for 95 delegated IPv6 prefixes. 97 The client of a PD binding is typically a router, which then 98 advertises the delegated prefix to locally-connected hosts. The 99 delegated IPv6 prefix must be routeable in order to be useful. The 100 actual DHCPv6 PD client may not be permitted to inject routes into 101 the delegating network. In service-provider (SP) networks, for 102 example, an edge router typically acts as a DHCPv6 relay agent, and 103 this edge router often has the responsibility to maintain routes 104 within the service-provider network for clients' PD bindings. 106 A DHCPv6 relay with this responsibility requires a means to recover 107 binding information from the authoritative DHCPv6 server(s) in the 108 event of replacement or reboot, in order to restore routeability to 109 delegated prefixes. The relay may be a network device without 110 adequate local storage to maintain the necessary binding-to-route 111 data. A DHCPv6 Leasequery protocol [6] has been developed that 112 allows queries for individual bindings from the authoritative DHCPv6 113 Server(s). The individual query mechanism is only useable when the 114 target binding is known to the requestor. In the case of DHCPv6 115 Prefix Delegation, the PD binding data may need to be known before 116 any traffic arrives from the client router. The DHCPv6 relay router 117 may not be able to form individual queries in such cases. 119 This document extends the DHCPv6 Leasequery protocol to add support 120 for queries that address these requirements. At the SP edge there 121 may be many thousands of delegated prefixes per relay, so we specify 122 the use of TCP [3] for efficiency of data transfer. We specify a new 123 DHCPv6 option, the Relay Identifier option, to support efficient 124 recovery of all data associated with a specific relay agent; we also 125 add a query-type for this purpose. We add query-types by network 126 segment and by Remote-ID option value, to assist a relay that needs 127 to recover a subset of its clients' bindings. 129 2. Terminology 131 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 132 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 133 document are to be interpreted as described in [4]. 135 DHCPv6 terminology is defined in [1]. DHCPv6 Leasequery terminology 136 is defined in [6]. 138 3. Protocol Overview 140 The Bulk Leasequery mechanism is modeled on the existing individual 141 Leasequery protocol; most differences arise from the use of TCP. A 142 Bulk Leasequery client opens a TCP connection to a DHCPv6 Server, 143 using the DHCPv6 port 547. The client sends a LEASEQUERY message, 144 containing a query-type and data about bindings it is interested in. 145 The server uses the query-type and the data to identify any relevant 146 bindings. The server replies with a LEASEQUERY-REPLY message, 147 indicating the success or failure of the query. If the query was 148 successful, the server includes the first client's binding data in 149 the LEASEQUERY-REPLY message also. If more than one client's 150 bindings are being returned, the server then transmits the additional 151 client bindings in a series of LEASEQUERY-DATA messages. If the 152 server has sent at least one client's bindings, it sends a 153 LEASEQUERY-DONE message when it has finished sending its replies. 154 Each end of the TCP connection can be closed after all data has been 155 sent. 157 This specification includes a new DHCPv6 option, the Relay-ID option. 158 The option contains a DUID identifying a DHCPv6 relay agent. Relay 159 agents can include this option in Relay-Forward messages they send. 160 Servers can retain the Relay-ID and associate it with bindings made 161 on behalf of the relay's clients. A relay can then recover binding 162 information about downstream clients by using the Relay-ID in a 163 LEASEQUERY message. The Relay-ID option is defined in Section 4.4.1. 165 Bulk Leasequery supports the queries by IPv6 address and by Client 166 DUID as specified in [6], and adds the following new query types: 168 Query by Relay Identifier - This query asks a server for the 169 bindings associated with a specific relay; the relay is identified 170 by a DUID carried in a Relay-ID option. 171 Query by Link Address - This query asks a server for the bindings on 172 a particular network segment; the link is specified in the query's 173 link-address field. 174 Query by Remote ID - This query asks a server for the bindings 175 associated with a Relay Agent Remote-ID option [5] value. 177 4. Message and Option Definitions 178 4.1. Message Framing for TCP 180 The use of TCP for the Bulk Leasequery protocol permits one or more 181 DHCPv6 messages to be sent at a time. The receiver needs to be able 182 to determine how large each message is. Two octets containing the 183 message size in network byte-order are prepended to each DHCPv6 184 message sent on a Bulk Leasequery TCP connection. The two message- 185 size octets 'frame' each DHCPv6 message. 187 DHCPv6 message framed for TCP: 189 0 1 2 3 190 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 1 191 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 192 | message-size | msg-type | trans-id | 193 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 194 | transaction-id (cont'd) | | 195 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 196 | . 197 . options . 198 . (variable) . 199 | | 200 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 202 message-size the number of octets in the message that 203 follows, as a 16-bit integer in network 204 byte-order. 206 All other fields are as specified in DHCPv6 [1]. 208 4.2. Messages 210 The LEASEQUERY and LEASEQUERY-REPLY messages are defined in [6]. In 211 a Bulk Leasequery exchange, a single LEASEQUERY-REPLY message is used 212 to indicate the success or failure of a query, and to carry data that 213 do not change in the context of a single query and answer, such as 214 the Server-ID and Client-ID options. If a query is successful, only 215 a single LEASEQUERY-REPLY message MUST appear. If the server is 216 returning binding data, the LEASEQUERY-REPLY also contains the first 217 client's binding data in an OPTION_CLIENT_DATA option. 219 4.2.1. LEASEQUERY-DATA 221 The LEASEQUERY-DATA message (message type TBD) carries data about a 222 single DHCPv6 client's leases and/or PD bindings on a single link. 224 The purpose of the message is to reduce redundant data when there are 225 multiple bindings to be sent. The LEASEQUERY-DATA message MUST be 226 preceded by a LEASEQUERY-REPLY message. The LEASEQUERY-REPLY conveys 227 the query's status, carries the Leasequery's Client-ID and Server-ID 228 options, and carries the first client's binding data if the query was 229 successful. 231 LEASEQUERY-DATA MUST ONLY be sent in response to a successful 232 LEASEQUERY, and only if more than one client's data is to be sent. 233 The LEASEQUERY-DATA message's transaction-id field MUST match the 234 transaction-id of the LEASEQUERY request message. The Server-ID, 235 Client-ID, and OPTION_STATUS_CODE options SHOULD NOT be included: 236 that data should be constant for any one Bulk Leasequery reply, and 237 should have been conveyed in the LEASEQUERY-REPLY message. 239 4.2.2. LEASEQUERY-DONE 241 The LEASEQUERY-DONE message (message type TBD) indicates the end of a 242 group of related Leasequery replies. The LEASEQUERY-DONE message's 243 transaction-id field MUST match the transaction-id of the LEASEQUERY 244 request message. The presence of the message itself signals the end 245 of a stream of reply messages. A single LEASEQUERY-DONE MUST BE sent 246 after all replies to a successful Bulk Leasequery request that 247 returned at least one binding. 249 A server may encounter an error condition after it has sent the 250 initial LEASEQUERY-REPLY. In that case, it SHOULD attempt to send a 251 LEASEQUERY-DONE with an OPTION_STATUS_CODE option indicating the 252 error condition to the requestor. Other DHCPv6 options SHOULD NOT be 253 included in the LEASEQUERY-DONE message. 255 4.3. Query Types 257 The OPTION_LQ_QUERY option is defined in [6]. We introduce three new 258 query-types: QUERY_BY_RELAYID, QUERY_BY_LINK_ADDRESS, and 259 QUERY_BY_REMOTE_ID. These queries are designed to assist relay 260 agents in recovering binding data in circumstances where some or all 261 of the relay's binding data has been lost. 263 4.3.1. QUERY_BY_RELAYID 265 This query asks the server to return bindings associated with the 266 specified relay DUID. 268 QUERY_BY_RELAYID (3) - The query-options MUST contain an 269 OPTION_RELAYID option. If the link-address field is 0::0, the 270 query asks for all bindings associated with the specified relay 271 DUID. If the link-address is specified, the query asks for 272 bindings on that link. 274 4.3.2. QUERY_BY_LINK_ADDRESS 276 The QUERY_BY_LINK_ADDRESS asks the server to return bindings on a 277 network segment identified by an link-address value from a relay's 278 Relay-Forward message. 280 QUERY_BY_LINK_ADDRESS (4) - The query's link-address contains an 281 address a relay may have used in the link-address of a Relay- 282 Forward message. The Server attempts to locate bindings on the 283 same network segment as the link-address. 285 4.3.3. QUERY_BY_REMOTE_ID 287 The QUERY_BY_REMOTE_ID asks the server to return bindings associated 288 with a Remote-ID option value from a relay's Relay-Forward message. 289 The query-options MUST include a Relay-ID option. 291 In order to support this query, a server needs to record the most- 292 recent Remote-ID option value seen in a Relay-Forward message along 293 with its other binding data. 295 QUERY_BY_REMOTE_ID (5) - The query-options MUST include a Relay 296 Agent Remote-ID option. If the Server has recorded Remote-ID 297 values with its bindings, it uses the option's value to identify 298 bindings to return. 300 4.4. Options 302 4.4.1. Relay-ID Option 304 The Relay-ID option carries a DUID. A relay agent MAY include the 305 option in Relay-Forward messages it sends. Obviously, it will not be 306 possible for a server to respond to QUERY_BY_RELAYID queries unless 307 the relay agent has included this option. A relay SHOULD be able to 308 generate a DUID for this purpose, and capture the result in stable 309 storage. A relay SHOULD also allow the DUID value to be 310 configurable: doing so allows an administrator to replace a relay 311 agent while retaining the association between the relay and existing 312 DHCPv6 bindings. 314 A DHCPv6 Server MAY associate Relay-ID options from Relay-Forward 315 messages it processes with PD and/or lease bindings that result. 317 Doing so allows it to respond to QUERY_BY_RELAYID Leasequeries. 319 The format of the Relay-ID option is shown below: 321 0 1 2 3 322 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 1 323 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 324 | OPTION_RELAYID | option-len | 325 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 326 . . 327 . DUID . 328 . (variable length) . 329 . . 330 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 332 option-code OPTION_RELAYID (TBD). 334 option-len Length of DUID in octets. 336 DUID The DUID for the relay agent. 338 4.5. Status Codes 340 TODO: are any new status codes needed - to indicate a connection or 341 resource problem e.g.? 343 4.6. Connection and Transmission Parameters 345 DHCPv6 Servers that support Bulk Leasequery SHOULD listen for 346 incoming TCP connections on the DHCPv6 server port 547. 347 Implementations MAY offer to make the incoming port configurable, but 348 port 547 MUST be the default. Client implementations SHOULD make TCP 349 connections to port 547, and MAY offer to make the destination server 350 port configurable. 352 This section presents a table of values used to control Bulk 353 Leasequery behavior, including recommended defaults. Implementations 354 MAY make these values configurable. 356 Parameter Default Description 357 ------------------------------------------ 358 BULK_LQ_CONN_TIMEOUT 30 secs Bulk Leasequery connection timeout 359 BULK_LQ_DATA_TIMEOUT 30 secs Bulk Leasequery data timeout 360 BULK_LQ_MAX_RETRY 60 secs Max Bulk Leasequery retry timeout value 361 BULK_LQ_MAX_CONNS 10 Max Bulk Leasequery TCP connections 363 5. Requestor Behavior 365 5.1. Connecting 367 A Requestor attempts to establish a TCP connection to a DHCPv6 Server 368 in order to initiate a Leasequery exchange. The Requestor SHOULD be 369 prepared to abandon the connection attempt after 370 BULK_LQ_CONN_TIMEOUT. If the attempt fails, the Requestor MAY retry. 371 Retries MUST use an exponential backoff timer, increasing the 372 interval between attempts up to BULK_LQ_MAX_RETRY. 374 5.2. Forming Queries 376 After a connection is established, the Requestor constructs a 377 Leasequery message, as specified in [6]. The query may have any of 378 the defined query-types, and includes the options and data required 379 by the query-type chosen. The Requestor sends the message size then 380 sends the actual DHCPv6 message, as described in Section 4.1. 382 If the TCP connection becomes blocked while the Requestor is sending 383 its query, the Requestor SHOULD be prepared to terminate the 384 connection after BULK_LQ_DATA_TIMEOUT. We make this recommendation 385 to allow Requestors to control the period of time they are willing to 386 wait before abandoning a connection, independent of notifications 387 from the TCP implementations they may be using. 389 5.3. Processing Replies 391 The Requestor attempts to read a LEASEQUERY-REPLY message from the 392 TCP connection. If the stream of replies becomes blocked, the 393 Requestor SHOULD be prepared to terminate the connection after 394 BULK_LQ_DATA_TIMEOUT, and MAY begin retry processing if configured to 395 do so. 397 The Requestor examines the LEASEQUERY-REPLY message, and determines 398 how to proceed. Message validation rules are specified in DHCPv6 399 Leasequery [6]. If the reply contains an error status code (carried 400 in an OPTION_STATUS_CODE option), the Requestor follows the 401 recommendations in [6]. A successful reply that does not include an 402 OPTION_CLIENT_DATA option indicates that the target server had no 403 bindings matching the query. 405 The Leasequery protocol uses the OPTION_CLIENT_LINK option as an 406 indicator that multiple bindings were present in response to a single 407 query. For Bulk Leasequery, the OPTION_CLIENT_LINK option is not 408 used, and MUST NOT be present in replies. 410 A successful LEASEQUERY-REPLY that is returning binding data includes 411 an OPTION_CLIENT_DATA option and possibly additional options. If 412 there are additional bindings to be returned, they will be carried in 413 LEASEQUERY-DATA messages. Each LEASEQUERY-DATA message contains an 414 OPTION_CLIENT_DATA option, and possibly other options. A LEASEQUERY- 415 DATA message that does not contain an OPTION_CLIENT_DATA MUST BE 416 discarded. 418 A single bulk query can result in a large number of replies. For 419 example, a single relay agent might be responsible for routes for 420 thousands of clients' delegated prefixes. The Requestor MUST be 421 prepared to receive more than one LEASEQUERY-DATA with transaction- 422 ids matching a single LEASEQUERY message. 424 The LEASEQUERY-DONE message ends a successful Bulk Leasequery session 425 that returned at least one binding. A LEASEQUERY-REPLY without any 426 bindings MUST NOT be followed by a LEASEQUERY-DONE message for the 427 same transaction-id. After receiving LEASEQUERY-DONE from a server, 428 the Requestor MAY close the TCP connection to that server. If the 429 transaction-id in the LEASEQUERY-DONE does not match an outstanding 430 LEASEQUERY message, the client MUST close the TCP connection. 432 5.4. Querying Multiple Servers 434 A Bulk Leasequery client MAY be configured to attempt to connect to 435 and query from multiple DHCPv6 servers in parallel. The DHCPv6 436 Leasequery specification [6] includes a discussion about reconciling 437 binding data received from multiple DHCPv6 servers. 439 5.5. Multiple Queries to a Single Server 441 Bulk Leasequery clients may need to make multiple queries in order to 442 recover binding information. A Requestor MAY use a single connection 443 to issue multiple queries, each with a unique transaction id. 444 Requestors should be aware that servers are not required to process 445 queries in parallel, and that servers are likely to limit the rate at 446 which they process queries from any one Requestor. 448 5.6. Closing Connections 450 The Requestor MAY close its end of the TCP connection after sending a 451 LEASEQUERY message to the server. The Requestor MAY choose to retain 452 the connection if it intends to issue additional queries. Note that 453 this client behavior does not guarantee that the connection will be 454 available for additional queries: the server might decide to close 455 the connection based on its own configuration. 457 6. Server Behavior 459 6.1. Accepting Connections 461 Servers that implement DHCPv6 Bulk Leasequery listen for incoming TCP 462 connections. Port numbers are discussed in Section 4.6. Servers 463 MUST be able to limit the number of currently accepted and active 464 connections. The value BULK_LQ_MAX_CONNS MUST be the default; 465 implementations MAY permit the value to be configurable. 467 Servers MAY restrict Bulk Leasequery connections and LEASEQUERY 468 messages to certain clients. Connections not from permitted clients 469 SHOULD BE closed immediately, to avoid server connection resource 470 exhaustion. Servers MAY restrict some clients to certain query 471 types. Servers MAY reply to queries that are not permitted with the 472 NotAllowed status code [6], or MAY close the connection. 474 If the TCP connection becomes blocked while the Server is accepting a 475 connection or reading a query, it SHOULD be prepared to terminate the 476 connection after BULK_LQ_DATA_TIMEOUT. We make this recommendation 477 to allow Servers to control the period of time they are willing to 478 wait before abandoning an inactive connection, independent of the TCP 479 implementations they may be using. 481 6.2. Forming Replies 483 The DHCPv6 Leasequery [6] specification describes the initial 484 construction of LEASEQUERY-REPLY messages and the processing of 485 QUERY_BY_ADDRESS and QUERY_BY_CLIENTID. Use of the LEASEQUERY-REPLY 486 and LEASEQUERY-DATA messages to carry multiple bindings are described 487 in Section 4.2. Message transmission and framing for TCP is 488 described in Section 4.1. If the connection becomes blocked while 489 the server is attempting to send reply messages, the server SHOULD be 490 prepared to terminate the TCP connection after BULK_LQ_DATA_TIMEOUT. 492 If the server encounters an error during initial query processing, 493 before any reply has been sent, it SHOULD send a LEASEQUERY-REPLY 494 containing an error code in an OPTION_STATUS_CODE option. This 495 signals to the requestor that no data will be returned. If the 496 server encounters an error while processing a query that has already 497 resulted in one or more reply messages, the server SHOULD send a 498 LEASEQUERY-DONE message with an error status. The server SHOULD 499 close its end of the connection as an indication that it was not able 500 to complete query processing. 502 If the server does not find any bindings satisfying a query, it 503 SHOULD send a LEASEQUERY-REPLY without an OPTION_STATUS_CODE option 504 and without any OPTION_CLIENT_DATA option. Otherwise, the server 505 sends each binding's data in a reply message. The first reply 506 message is a LEASEQUERY-REPLY. The binding data is carried in an 507 OPTION_CLIENT_DATA option, as specified in [6] and extended below. 508 The server returns subsequent bindings in LEASEQUERY-DATA messages, 509 which can avoid redundant data (such as the requestor's Client-ID). 511 For QUERY_BY_RELAYID, the Server locates each binding associated with 512 the query's Relay-ID option value. In order to give a meaningful 513 reply to a QUERY_BY_RELAYID, the Server has to be able to maintain 514 this association in its DHCPv6 binding data. If the query's link- 515 address is not set to 0::0, the server only returns bindings on links 516 that could contain that address. If the link-address is not 0::0 and 517 the server cannot find any matching links, the server SHOULD return 518 the NotConfigured status in a LEASEQUERY-REPLY. 520 For QUERY_BY_LINK_ADDRESS, the Server locates each binding associated 521 with the link identified by the query's link-address value. 523 For QUERY_BY_REMOTE_ID, the Server locates each binding associated 524 with the query's Relay Remote-ID option value. In order to be able 525 to give meaningful replies to this query, the Server has to be able 526 to maintain this association in its binding database. If the query 527 message's link-address is not set to 0::0, the server only returns 528 bindings on links that could contain that address. If the link- 529 address is not 0::0 and the server cannot find any matching links, 530 the server SHOULD return the NotConfigured status in a LEASEQUERY- 531 REPLY. 533 The server sends the LEASEQUERY-DONE message as specified in 534 Section 4.2. 536 6.3. Multiple or Parallel Queries 538 As discussed in Section 5.5, Requestors may want to leverage an 539 existing connection if they need to make multiple queries. Servers 540 MAY support reading and processing multiple queries from a single 541 connection. A server MUST NOT read more query messages from a 542 connection than it is prepared to process simultaneously. 544 This MAY be a feature that is administratively controlled. Servers 545 that are able to process queries in parallel SHOULD offer 546 configuration that limits the number of simultaneous queries 547 permitted from any one Requestor, in order to control resource use if 548 there are multiple Requestors seeking service. 550 6.4. Closing Connections 552 The server MAY close its end of the TCP connection after sending its 553 last message (a LEASEQUERY-REPLY or a LEASEQUERY-DONE) in response to 554 a query. Alternatively, the server MAY retain the connection and 555 wait for additional queries from the client. The server SHOULD be 556 prepared to limit the number of connections it maintains, and SHOULD 557 be prepared to close idle connections to enforce the limit. 559 The server MUST close its end of the TCP connection if it finds that 560 it has to abort an in-process request, or if it encounters an error 561 sending data on the connection. If the server detects that the 562 client end has been closed, the server MUST close its end of the 563 connection after it has finished processing any outstanding requests 564 from the client. 566 7. Security Considerations 568 The "Security Considerations" section of [1] details the general 569 threats to DHCPv6. The DHCPv6 Leasequery specification [6] describes 570 recommendations for the Leasequery protocol, especially with regard 571 to relayed LEASEQUERY messages, mitigation of packet-flooding DOS 572 attacks, restriction to trusted clients, and use of IPsec [7]. 574 The use of TCP introduces some additional concerns. Attacks that 575 attempt to exhaust the DHCPv6 server's available TCP connection 576 resources, such as SYN flooding attacks, can compromise the ability 577 of legitimate clients to receive service. Malicious clients who 578 succeed in establishing connections, but who then send invalid 579 queries, partial queries, or no queries at all also can exhaust a 580 server's pool of available connections. We recommend that servers 581 offer configuration to limit the sources of incoming connections, 582 that they limit the number of accepted connections and the number of 583 in-process queries from any one connection, and that they limit the 584 period of time during which an idle connection will be left open. 586 8. IANA Considerations 588 IANA is requested to assign a new DHCPv6 Option Code in the registry 589 maintained in http://www.iana.org/assignments/dhcpv6-parameters: 591 OPTION_RELAYID 593 IANA is requested to assign values for the following new DHCPv6 594 Message types in the registry maintained in 595 http://www.iana.org/assignments/dhcpv6-parameters: 597 LEASEQUERY-DONE 598 LEASEQUERY-DATA 600 IANA is requested to assign the following new values in the registry 601 of query-types for the DHCPv6 OPTION_LQ_QUERY option: 603 QUERY_BY_RELAYID 3 604 QUERY_BY_LINK_ADDRESS 4 605 QUERY_BY_REMOTE_ID 5 607 9. Acknowledgements 609 Many of the ideas in this document were proposed by Kim Kinnear, 610 Richard Johnson, Hemant Singh, Ole Troan, and Bernie Volz. 612 10. Modification History 614 11. References 616 11.1. Normative References 618 [1] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. 619 Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", 620 RFC 3315, July 2003. 622 [2] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic Host 623 Configuration Protocol (DHCP) version 6", RFC 3633, 624 December 2003. 626 [3] Duke, M., Braden, R., Eddy, W., and E. Blanton, "A Roadmap for 627 Transmission Control Protocol (TCP) Specification Documents", 628 RFC 4614, September 2006. 630 [4] Bradner, S., "Key words for use in RFCs to Indicate Requirement 631 Levels", BCP 14, RFC 2119, March 1997. 633 [5] Volz, B., "Dynamic Host Configuration Protocol for IPv6 (DHCPv6) 634 Relay Agent Remote-ID Option", RFC 4649, August 2006. 636 [6] Brzozowski, J., Kinnear, K., Volz, B., and S. Zeng, "DHCPv6 637 Leasequery", RFC 5007, September 2007. 639 11.2. Informative References 641 [7] Kent, S. and R. Atkinson, "Security Architecture for the 642 Internet Protocol", RFC 2401, November 1998. 644 Author's Address 646 Mark Stapp 647 Cisco Systems, Inc. 648 1414 Massachusetts Ave. 649 Boxborough, MA 01719 650 USA 652 Phone: +1 978 936 0000 653 Email: mjs@cisco.com 655 Full Copyright Statement 657 Copyright (C) The IETF Trust (2007). 659 This document is subject to the rights, licenses and restrictions 660 contained in BCP 78, and except as set forth therein, the authors 661 retain all their rights. 663 This document and the information contained herein are provided on an 664 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 665 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 666 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 667 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 668 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 669 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 671 Intellectual Property 673 The IETF takes no position regarding the validity or scope of any 674 Intellectual Property Rights or other rights that might be claimed to 675 pertain to the implementation or use of the technology described in 676 this document or the extent to which any license under such rights 677 might or might not be available; nor does it represent that it has 678 made any independent effort to identify any such rights. 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