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Checking references for intended status: Informational ---------------------------------------------------------------------------- == Unused Reference: 'RFC4868' is defined on line 1058, but no explicit reference was found in the text ** Obsolete normative reference: RFC 5226 (Obsoleted by RFC 8126) Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group Murtaza S. Chiba 3 Internet-Draft Alexander Clemm 4 Intended status: Informational Steven Medley 5 Expires: April 22, 2013 Joseph Salowey 6 Sudhir Thombare 7 Eshwar Yedavalli 8 Cisco Systems 9 October 19, 2012 11 Cisco Service Level Assurance Protocol 12 draft-cisco-sla-protocol-04 14 Abstract 16 Cisco's Service Level Assurance Protocol (Cisco's SLA Protocol) is a 17 Performance Measurement protocol that has been widely deployed. The 18 protocol is used to measure service level parameters such as network 19 latency, delay variation, and packet/frame loss. This draft 20 describes the Cisco SLA Protocol UDP measurement type to enable 21 vendor interoperability. 23 Requirements Language 25 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 26 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 27 document are to be interpreted as described in RFC 2119 [RFC2119]. 29 Status of this Memo 31 This Internet-Draft is submitted in full conformance with the 32 provisions of BCP 78 and BCP 79. 34 Internet-Drafts are working documents of the Internet Engineering 35 Task Force (IETF). Note that other groups may also distribute 36 working documents as Internet-Drafts. The list of current Internet- 37 Drafts is at http://datatracker.ietf.org/drafts/current/. 39 Internet-Drafts are draft documents valid for a maximum of six months 40 and may be updated, replaced, or obsoleted by other documents at any 41 time. It is inappropriate to use Internet-Drafts as reference 42 material or to cite them other than as "work in progress." 44 This Internet-Draft will expire on April 22, 2013. 46 Copyright Notice 48 Copyright (c) 2012 IETF Trust and the persons identified as the 49 document authors. All rights reserved. 51 This document is subject to BCP 78 and the IETF Trust's Legal 52 Provisions Relating to IETF Documents 53 (http://trustee.ietf.org/license-info) in effect on the date of 54 publication of this document. Please review these documents 55 carefully, as they describe your rights and restrictions with respect 56 to this document. Code Components extracted from this document must 57 include Simplified BSD License text as described in Section 4.e of 58 the Trust Legal Provisions and are provided without warranty as 59 described in the Simplified BSD License. 61 Table of Contents 63 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 64 2. Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 65 2.1. Control Phase . . . . . . . . . . . . . . . . . . . . . . 5 66 2.1.1. Control Request . . . . . . . . . . . . . . . . . . . 6 67 2.1.1.1. Command Header . . . . . . . . . . . . . . . . . . 7 68 2.1.1.2. CSLDs . . . . . . . . . . . . . . . . . . . . . . 9 69 2.1.2. Control Response Message . . . . . . . . . . . . . . . 15 70 2.2. Measurement Phase . . . . . . . . . . . . . . . . . . . . 16 71 3. Implementation notes . . . . . . . . . . . . . . . . . . . . . 19 72 4. Extensions . . . . . . . . . . . . . . . . . . . . . . . . . . 20 73 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 74 6. Security Considerations . . . . . . . . . . . . . . . . . . . 23 75 6.1. Message Authentication . . . . . . . . . . . . . . . . . . 23 76 6.2. IPSec Considerations . . . . . . . . . . . . . . . . . . . 24 77 6.2.1. Control Traffic . . . . . . . . . . . . . . . . . . . 24 78 6.2.2. Measurement Traffic . . . . . . . . . . . . . . . . . 24 79 6.3. Replay Protection . . . . . . . . . . . . . . . . . . . . 25 80 7. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 25 81 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 26 82 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 26 83 9.1. Normative References . . . . . . . . . . . . . . . . . . . 26 84 9.2. Informative References . . . . . . . . . . . . . . . . . . 26 85 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 27 87 1. Introduction 89 Network performance measurements are becoming critical data points 90 for administrators monitoring the health of the network. As Service 91 Providers look to differentiate their offerings, performance 92 measurement is increasingly becoming an important tool to monitor 93 Service Level guarantees and, in general, to monitor the health of a 94 network. 96 Performance metrics, both one-way and two-way, can be used for pre- 97 deployment validation as well as for measuring in-band live network 98 performance characteristics. It can be used to measure service 99 levels in L2 and L3 networks as well as for applications running on 100 top of L3. Performance measurements are gathered by analyzing 101 actively generated synthetic request and response packets/frames. 102 This is in contrast to passive measurements that analyze production 103 traffic flowing through a particular network element. 105 There is a growing body of work on Performance Measurement standards 106 that enable interoperability between different vendors network 107 elements by describing common measurement protocols as well as 108 metrics. IETF has actively developed standards on the subject and 109 two such standards are One-Way Active Measurement Protocol(OWAMP) 110 [RFC4656] and Two-Way Active Measurement Protocol (TWAMP) [RFC5357]. 112 Cisco's SLA Protocol is another example of a performance measurement 113 protocol that offers a rich set of measurement message types. The 114 measurement types can be classified as those that test connectivity 115 (ping like) by providing round trip or, one-way latency measures and 116 those that provide a richer set of statistics including network 117 jitter and packet/frame loss. Each type of active measurement 118 exchanges mimic an actual protocol exchange. 120 Cisco's SLA Protocol UDP measurement message exchanges, as covered in 121 this document to enable interoperability, simulates a UDP application 122 and can be used to simulate either Voice or Video traffic that is 123 encoded in RTP frames within UDP envelopes. The UDP measurement type 124 message exchanges carry information that provide the ability to 125 derive a robust set of statistics. 127 2. Protocol 129 The Cisco Service Level Assurance Protocol consists of two distinct 130 phases, the Control phase and the Measurement phase. Each phase is 131 comprised of exchange of information between a network element acting 132 as the Sender and another element designated as the Responder. 134 The Control Phase is the first phase of message exchanges and forms 135 the base protocol. This phase establishes the identity of the Sender 136 and provides information for the Measurement Phase. A single message 137 pair of Control Request and Control Response marks this phase. The 138 Sender initiates a Control Request message that is acknowledged by 139 the Responder with a Control Response message. The Control Request 140 may be sent multiple times if a Control Response has not been 141 received; the number of times the message is retried is configurable 142 on the Sender element. 144 The Measurement Phase forms the second phase and is comprised of a 145 sequence of Request/Response messages. These messages may be 146 exchanged as often as required. Each Measurement Request message is 147 acknowledged by the Responder with a Measurement Response Message. 149 The number and frequency with which messages are sent SHOULD be 150 controlled by configuration on the Sender element, along with the 151 waiting time for a Control Response. 153 The following sequence diagram depicts the message exchanges: 155 +-+-+-+-+-+-+-+ Control Request +-+-+-+-+-+-+-+ 156 | | | | 157 | Sender | | Responder | 158 | | | | 159 | | | | 160 +-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+ 161 | | 162 | Control Request | 163 | -------------------------------------------->| 164 | | 165 | Control Response | 166 |<---------------------------------------------| 167 | | 168 | | 169 | Measurement Request(1) | 170 | -------------------------------------------->| 171 | | 172 | Measurement Response(1) | 173 |<---------------------------------------------| 174 | | 175 . . 176 . . 177 . . 178 . . 179 . Measurement Request(n) . 180 | -------------------------------------------->| 181 | | 182 | Measurement Response(n) | 183 |<---------------------------------------------| 184 | | 186 2.1. Control Phase 188 The Control Phase begins with the Sender sending a Control Request 189 message to the Responder. The Control Request message is sent to UDP 190 port 1167 on the Responder requesting a measurement phase UDP port be 191 opened and, in addition, indicates the requested amount of time that 192 the port needs to be opened for. The Responder replies by sending a 193 Control Response with appropriate Status indicating Success when the 194 sender identity is verified (if used) and the requested UDP port was 195 successfully opened. In all other cases a non-zero Status is 196 returned. 198 The sequence of exchanges is as indicated in the diagram. 200 +-+-+-+-+-+-+-+ Control Request +-+-+-+-+-+-+-+ 201 | |------------------------------->| | 202 | Sender | | Responder | 203 | | Control Response | | 204 | |<-------------------------------| | 205 +-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+ 207 2.1.1. Control Request 209 The Control Request message consists of a Command Header followed by 210 one or more Command, Status, Length and Data sections (henceforth 211 known as CSLD). At the minimum, there SHOULD be at the least two 212 CSLD sections, one of which is the authentication CSLD section and 213 the other carries information for the Measurement Phase simulation 214 type. 216 0 1 2 3 217 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 1 218 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 219 | | 220 + + 221 | | 222 + + 223 | Command Header | 224 + + 225 | | 226 + + 227 | | 228 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 229 | Command | Status | 230 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 231 | Command Length | 232 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 233 | | 234 . . 235 . Data . 236 . . 237 | | 238 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 239 | Command | Status | 240 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 241 | Command Length | 242 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 243 | | 244 . . 245 . Data . 246 . . 247 | | 248 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 250 2.1.1.1. Command Header 252 The Command Header is the first section of the Control Request 253 message and is depicted below: 255 0 1 2 3 256 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 1 257 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 258 | Version = 2 | Reserved | Status | 259 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 260 | Sequence Number | 261 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 262 | Total Length | 263 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 264 | Send Timestamp | 265 + + 266 | | 267 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 269 The Command Header fields hold the following meaning: 271 +-----------+-----------+-------------------------------------------+ 272 | Field | Size | Usage | 273 | | (bits) | | 274 +-----------+-----------+-------------------------------------------+ 275 | Version | 8 | Current version supported and is to be | 276 | | | set to 2. | 277 | --------- | --------- | -------------------------- | 278 | Reserved | 8 | Reserved field, MUST be set to 0 | 279 | --------- | --------- | -------------------------- | 280 | Status | 16 | Indicates success or failure for the | 281 | | | entire message; not used for request and | 282 | | | MUST be set to 0 | 283 | --------- | --------- | -------------------------- | 284 | Sequence | 32 | Used to map requests to responses. This | 285 | Number | | is a monotonically increasing number. | 286 | | | Implementations MAY reset the sequence | 287 | | | number to 0 after a reboot, and SHOULD | 288 | | | wrap around after all bits have been | 289 | | | exceeded. | 290 | --------- | --------- | -------------------------- | 291 | Total | 32 | Carries the total length of the control | 292 | Length | | message in number of octets | 293 | --------- | --------- | -------------------------- | 294 | Send | 64 | This field is set to the time the command | 295 | Timestamp | | was submitted for transmission and is | 296 | | | updated for a response. This field MAY | 297 | | | be used when security is of concern in | 298 | | | order to prevent replay attacks. SHOULD | 299 | | | be updated for a response. When not | 300 | | | being used it MUST be set to all 0's. | 301 | | | The format is as given in RFC5905 | 302 +-----------+-----------+-------------------------------------------+ 303 The sequence number field MUST include a new number for each new 304 request and is monotonically increasing. When the Control Request is 305 to be retried, the sequence number MUST remain unchanged. 307 2.1.1.2. CSLDs 309 The two CSLDs to be included, in order, along with the Command Header 310 are: 312 o The Authentication CSLD 314 o A Measurement Type CSLD 316 In this revision of the protocol, only a single Measurement Type CSLD 317 has been defined, the UDP Measurement Type CSLD. For future 318 extensions it is possible to add additional Measurement Type CSLDs. 319 For more details please see the section on Extensions. 321 2.1.1.2.1. Authentication CSLD 323 The Authentication CSLD provides the message authentication and 324 verifies the requester knows the shared-secret. The following is the 325 format for the Authentication CSLD 326 0 1 2 3 327 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 1 328 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 329 | Command = 1 | Status | 330 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 331 | Command Length | 332 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 333 | Mode | Reserved | Key Id | 334 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 335 | | 336 + + 337 | | 338 + Random Number + 339 | | 340 + + 341 | | 342 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 343 | | 344 + + 345 | | 346 + + 347 | | 348 . . 349 . . 350 . Message Authentication Digest . 351 . . 352 . . 353 | | 354 + + 355 | | 356 + + 357 | | 358 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 360 The fields for the Authentication CSLD have the following meaning 361 +----------------+-----------+--------------------------------------+ 362 | Field | Size | Description | 363 | | (bits) | | 364 +----------------+-----------+--------------------------------------+ 365 | Command | 16 | Indicates the CSLD is of type | 366 | | | Authentication | 367 | --------- | --------- | -------------------------- | 368 | Status | 16 | Not used for a request and MUST be | 369 | | | set to 0 | 370 | --------- | --------- | -------------------------- | 371 | Command Length | 16 | Indicates the length of the CSLD in | 372 | | | octets. | 373 | --------- | --------- | -------------------------- | 374 | Mode | 8 | Indicates the type of authentication | 375 | | | being used and is set as follows: 0 | 376 | | | - No Authentication, 1 - SHA256 | 377 | | | Authentication, 2 - HMAC-SHA-256 | 378 | --------- | --------- | -------------------------- | 379 | Reserved | 8 | This field is reserved for future | 380 | | | extensions and MUST be set to 0 | 381 | --------- | --------- | -------------------------- | 382 | Key ID | 16 | Indicates the index number of the | 383 | | | shared-secret to be used for | 384 | | | authenticating the Control Request | 385 | | | Message | 386 | --------- | --------- | -------------------------- | 387 | Random Number | 128 | This field is to be unique over the | 388 | | | shared secret life and is used to | 389 | | | make it difficult to predict the | 390 | | | shared secret via multiple packet | 391 | | | captures. The value is reflected in | 392 | | | a response message. This field MAY | 393 | | | be used when security is of concern | 394 | | | and is useful to prevent dictionary | 395 | | | attacks. When not being used it | 396 | | | should be set to all 0's | 397 | --------- | --------- | -------------------------- | 398 | Message | 256 | Contains the message authentication | 399 | Authentication | | digest and is computed over the | 400 | Digest | | entire control packet including this | 401 | | | field set to all 0s | 402 +----------------+-----------+--------------------------------------+ 404 2.1.1.2.2. UDP Measurement CSLD 406 The UDP Measurement CSLD indicates the Measurement Type to be used 407 during the Measurement Phase and specifies the addresses and UDP port 408 to be opened as well as the duration the port has to be kept open for 409 the measurement phase. The format of the CSLD is as follows: 411 0 1 2 3 412 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 1 413 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 414 | Command = 2 | Status | 415 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 416 | Command length | 417 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 418 | Address Type | Role | Reserved | 419 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 420 | Session Identifier | 421 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 422 | | 423 + + 424 | Control Source Address | 425 + + 426 | | 427 + + 428 | | 429 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 430 | | 431 + + 432 | | 433 + + 434 | Control Destination Address | 435 + + 436 | | 437 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 438 | | 439 + + 440 | | 441 + + 442 | Measurement Source Address | 443 + + 444 | | 445 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 446 | | 447 + + 448 | | 449 + + 450 | Measurement Destination Address | 451 + + 452 | | 453 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 454 | Control Source Port | Reserved | 455 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 456 | Measurement Source Port | Measurement Destination Port | 457 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 458 | Duration | 459 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 461 Note: Duration is specified in seconds. 463 The fields in the UDP Measurement CSLD have the following meaning: 465 +-------------+-----------+-----------------------------------------+ 466 | Field | Size | Definition | 467 | | (bits) | | 468 +-------------+-----------+-----------------------------------------+ 469 | Command | 16 | Indicates that the CSLD is to simulate | 470 | | | UDP traffic measurements. | 471 | --------- | --------- | -------------------------- | 472 | Status | 16 | Not used for a request and MUST be set | 473 | | | to 0 | 474 | --------- | --------- | -------------------------- | 475 | Command | 32 | Indicates the length of the CSLD in | 476 | Length | | octets. | 477 | --------- | --------- | -------------------------- | 478 | Address | 8 | Indicates the address type and is set | 479 | Type | | to one of the values in the Cisco | 480 | | | Service Level Performance Measurement | 481 | | | Protocol - Address Family Registry. (1 | 482 | | | - IPv4 addresses, 2 - IPv6 addresses) | 483 | --------- | --------- | -------------------------- | 484 | Role | 8 | Indicates the role of the endpoint | 485 | | | receiving the control message and is | 486 | | | set as follows: 1 - Responder | 487 | --------- | --------- | -------------------------- | 488 | Reserved | 16 | Reserved and MUST be set to 0 | 489 | --------- | --------- | -------------------------- | 490 | Session | 32 | Carries a session identifier that is a | 491 | Identifier | | locally significant unique value to the | 492 | | | originator of the message. MUST be 0 | 493 | | | when not specified. | 494 | --------- | --------- | -------------------------- | 495 | Control | 128 | Set to the address from which the | 496 | Source | | Sender initiates control messages. For | 497 | Address | | IPv4 addresses only the first 32 bits | 498 | | | are filled and the remaining bits MUST | 499 | | | be set to 0 | 500 | --------- | --------- | -------------------------- | 501 | Control | 128 | Set to the address on the Responder | 502 | Destination | | where the control message will be sent. | 503 | Address | | For IPv4 addresses only the first 32 | 504 | | | bits are filled and the remaining bits | 505 | | | MUST be set to 0 | 506 | --------- | --------- | -------------------------- | 507 | Measurement | 128 | Set to the address of the Sender from | 508 | Source | | where the measurement packets will | 509 | Address | | originate. For IPv4 addresses only the | 510 | | | first 32 bits are filled and the | 511 | | | remaining bits MUST be set to 0 | 512 | --------- | --------- | -------------------------- | 513 | Measurement | 128 | Set to the address on the Responder | 514 | Destination | | towards which the measurement packets | 515 | Address | | will be sent and is a way to identify | 516 | | | an ingress interface on the Responder. | 517 | | | For IPv4 addresses only the first 32 | 518 | | | bits are filled and the remaining bits | 519 | | | MUST be set to 0 | 520 | --------- | --------- | -------------------------- | 521 | Control | 16 | Indicates the port on the Sender from | 522 | Source Port | | which Control message is sent. If | 523 | | | unset the value should be derived from | 524 | | | the incoming packet. | 525 | --------- | --------- | -------------------------- | 526 | Reserved | 16 | Reserved Field, MUST be set to 0. | 527 | --------- | --------- | -------------------------- | 528 | Measurement | 16 | Indicates the UDP Port on the Sender | 529 | Source Port | | from which the measurement packets will | 530 | | | be sent | 531 | --------- | --------- | -------------------------- | 532 | Measurement | 16 | Indicates the UDP Port on the Responder | 533 | Destination | | towards which the measurement packets | 534 | Port | | will be sent | 535 | --------- | --------- | -------------------------- | 536 | Duration | 32 | This is the duration in seconds the | 537 | | | port needs to be kept open for | 538 | | | accepting measurement phase messages. | 539 | | | Measurement messages received after the | 540 | | | duration MUST be ignored | 541 +-------------+-----------+-----------------------------------------+ 543 Note: The source addresses are only indicative of identity of the 544 originator and cannot be used as destination address for responses in 545 a NAT environment. 547 2.1.2. Control Response Message 549 In response to the Control Request Message the network element 550 designated the Responder sends back a Control Response Message that 551 reflects the Command Header with an updated Status field and includes 552 the two CSLD sections that also carry updated Status fields. Hence, 553 the format is identical to the Control Request message as described 554 above. 556 Following table shows the supported values of the Status fields: 558 +-----------+-------------------------------------------------------+ 559 | Status | Description | 560 | Value | | 561 +-----------+-------------------------------------------------------+ 562 | 0 | Success | 563 | --------- | -------------------------- | 564 | 1 | Fail - catch all | 565 | --------- | -------------------------- | 566 | 2 | Authentication Failure | 567 | --------- | -------------------------- | 568 | 3 | Format error - sent when any CSLD type is not | 569 | | recognized or any part of a CSLD has a value that is | 570 | | not recognized | 571 | --------- | -------------------------- | 572 | 4 | Port in use - the UDP/TCP port is already being used | 573 | | by some other application and cannot be reserved | 574 | --------- | -------------------------- | 575 | 5+ | Future extension and experimental values, please | 576 | | refer to Status Types Registry in the IANA | 577 | | Considerations section | 578 +-----------+-------------------------------------------------------+ 580 The Command Header Status indicates Success only if all the CSLD 581 sections have Status as Success. It is non-zero otherwise. Future 582 extensions MAY extend these values as appropriate. 584 The Control Response message, besides the update of the Status 585 fields, SHOULD also update the Sent Timestamp (if used) in the 586 Command Header and the Message Authentication Digest in the 587 Authentication CSLD. The Message Authentication Digest is computed 588 in the same way as the Control Request message. The Random Number 589 field MUST be reflected without modification. The Session Identifier 590 MAY be updated to reflect a locally significant unique value, MUST be 591 0 if not specified. 593 2.2. Measurement Phase 595 Upon receiving the Control Response message with the Status set to 596 Success, the second phase of the protocol, the Measurement Phase, is 597 initiated. In all other cases when the Status is not success no 598 measurement traffic is initiated. In the Measurement Phase the 599 Sender sends a stream of measurement messages. The measurement 600 message stream consists of packets/frames that are spaced a 601 configured number of milliseconds apart. 603 +-+-+-+-+-+-+-+ Measurement Request(n) +-+-+-+-+-+-+-+ 604 | |------------------------------->| | 605 | Sender | | Responder | 606 | | Measurement Response(n) | | 607 | |<-------------------------------| | 608 +-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+ 610 The format of the Measurement messages as defined by this document 611 for UDP Measurements is as shown below and is the same for the 612 exchange in both directions, that is the format is the same when sent 613 from the Sender to the Responder and when sent back from the 614 Responder to the Sender with the only difference being the update of 615 those fields that are designated with the Responder prefix, all other 616 fields MUST remain unchanged. 618 0 1 2 3 619 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 1 620 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 621 | Measurement Type = 3 | Reserved | 622 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 623 | Sender Send Time | 624 + + 625 | | 626 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 627 | Responder Receive Time | 628 + + 629 | | 630 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 631 | Responder Send Time | 632 + + 633 | | 634 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 635 | Sender Receive Time | 636 + + 637 | | 638 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 639 | Sender Clock Offset | 640 + + 641 | | 642 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 643 | Responder Clock Offset | 644 + + 645 | | 646 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 647 | Sender Sequence No. | 648 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 649 | Responder Sequence No. | 650 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 651 | | 652 . . 653 . Data . 654 . . 655 | | 656 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 658 The fields for the UDP Measurement Request have the following 659 meaning: 661 +-------------+-----------+-----------------------------------------+ 662 | Field | Size | Description | 663 | | (bits) | | 664 +-------------+-----------+-----------------------------------------+ 665 | Measurement | 16 | Carries the type of measurement being | 666 | Type | | performed; 1 - Reserved, 2 - Reserved, | 667 | | | 3 - UDP | 668 | --------- | --------- | -------------------------- | 669 | Reserved | 16 | Reserved field and MUST be set to 0 | 670 | --------- | --------- | -------------------------- | 671 | Sender Send | 64 | Carries the timestamp when the | 672 | Time | | measurement message was submitted for | 673 | | | transmission by Sender | 674 | --------- | --------- | -------------------------- | 675 | Responder | 64 | Carries the timestamp when the | 676 | Receive | | measurement message was received by | 677 | Time | | Responder | 678 | --------- | --------- | -------------------------- | 679 | Responder | 64 | Carries the timestamp when the | 680 | Send Time | | measurement message was submitted for | 681 | | | transmission by the Responder. It MUST | 682 | | | be 0 in the Sender to Responder | 683 | | | direction | 684 | --------- | --------- | -------------------------- | 685 | Sender | 64 | Carries the timestamp when the Sender | 686 | Receive | | received the measurement message. It | 687 | Time | | MUST be 0 in both directions on the | 688 | | | wire and is filled on the Sender side | 689 | | | as soon as the measurement message is | 690 | | | received | 691 | --------- | --------- | -------------------------- | 692 | Sender | 64 | Gives an estimate of the Sender clock | 693 | Clock | | skew measured in second and fractional | 694 | Offset | | seconds | 695 | --------- | --------- | -------------------------- | 696 | Responder | 64 | Gives an estimate of the Responder | 697 | Clock | | clock skew measured in seconds and | 698 | Offset | | fractional seconds | 699 | --------- | --------- | -------------------------- | 700 | Sender | 32 | The sequence number of the measurement | 701 | Sequence | | message on the Sender side. This field | 702 | Number | | is monotonically increasing and MAY | 703 | | | wraparound | 704 | --------- | --------- | -------------------------- | 705 | Responder | 32 | The sequence number of the measurement | 706 | Sequence | | message on the Responder side. This | 707 | Number | | field is monotonically increasing and | 708 | | | MAY wraparound | 709 | --------- | --------- | -------------------------- | 710 | Data | 32 bit | This field is used to pad up to the | 711 | | aligned | configured request data size. The | 712 | | | minimum size for this field SHOULD be | 713 | | | 64 octets. | 714 +-------------+-----------+-----------------------------------------+ 716 Note: All timestamps have the default format as described in RFC 5905 717 [RFC5905] and is as follows: the first 32 bits represent the unsigned 718 integer number of seconds elapsed since 0h on 1 January 1900; the 719 next 32 bits represent the fractional part of a second thereof. The 720 timestamp definition is also similar to RFC 4656 [RFC4656] 722 In addition, the timestamp format used can be as described for the 723 low-order 64 bits of the IEEE 1588-2008 (1588v2) Precision Time 724 Protocol timestamp format [IEEE1588]. This truncated format consists 725 of a 32-bit seconds field followed by a 32-bit nanoseconds field, and 726 is the same as the IEEE 1588v1 timestamp format. This timestamp 727 definition is similar to the default timestamp as specified in RFC 728 6374 [RFC6374] 730 Implementations MUST use only one of the two formats. The chosen 731 format is negotiated out-of-band between the endpoints or defaults to 732 the format as defined in RFC 5905. [RFC5905] 734 3. Implementation notes 736 Responder implementations SHOULD support simultaneous measurements 737 destined to a single port either from the same or a different Sender. 738 For different measurement instances that originate from the same 739 sender, there MUST be a clear method for the Responder to distinguish 740 the traffic, for example per a unique 5-tuple of protocol, source 741 address, source port, destination address and destination port. 743 A Control Request that is received for the same measurement request 744 as identified by the 5-tuples, for instance, SHOULD result in the 745 resetting of the duration timer as well as the Responder Sequence 746 Number. 748 A Control Phase followed by the Measurement Phase can be repeated in 749 order to have a continuous measurement over the entire time a device 750 is alive. 752 The Random Number field in the Measurement packets is to be set to a 753 random value in environments where security is a concern and is used 754 to prevent dictionary attacks. It MUST always be included, when not 755 used it MUST be set to all 0s. 757 The Authentication CSLD MUST always be included. When the mode field 758 is set to 0, the Random Number field and the Message Authentication 759 Digest MUST both be set to all 0s. For the SHA256 authenticator mode 760 the shared secret is prepended to the Control Message and the 761 authentication algorithm is then run over the complete data including 762 the shared secret. The SHA256 mode is included for ease of 763 implementation and it is recommended to use the HMAC variant to 764 afford better security. 766 If the UDP port indicated in the UDP Measurement CSLD is busy, the 767 Responder MAY suggest an alternative port, the Status of the UDP 768 Measurement CSLD MUST be set to Success in that case. The Sender MAY 769 set a value of 0 in the field, in which case the Responder MAY choose 770 to open a port and send that back along with the Status of Success. 771 It should be noted that this behavior has security ramifications and 772 the port needs to be chosen very carefully by the Responder. 774 The measurement stream typically consists of packets/frames with a 775 periodic inter-packet distribution. The Sender need not wait for a 776 Measurement Response packet to arrive before sending another 777 Measurement Request packet, and in many cases it will not be possible 778 in order to maintain the desired inter-packet distribution. 780 The default format for all timestamps is as specified in RFC 5905. 781 [RFC5905] 783 All messages and all fields within a message are assumed to be in 784 network order. In addition, all data fields are unsigned unless 785 mentioned otherwise. 787 4. Extensions 789 This section describes how the protocol can be extended to allow for 790 additional functionality, such as new types of measurements. 792 In order to allow for new types of measurements, additional 793 Measurement Type CSLDs can be defined to be carried within the 794 Control Request and Control Response messages in place of the UDP 795 Measurement CSLD defined in this document . The meaning and precise 796 format of such CSLD needs to be defined in a separate specification. 797 Such a specification will also need to describe the appropriate 798 formats for the messages in the Measurement Phase. 800 In addition, the protocol can be extended by adding support for new 801 values to registries defined in this document. 803 5. IANA Considerations 805 The following registries are needed for the extensibility of the 806 protocol and the terms 'Private Use' and 'Experimental Use' found in 807 the registries in this section have the same meaning as described in 808 RFC 5226 [RFC5226]. 810 Furthermore, for the following registries, the ranges designated 811 "Available for future extensions" will be governed by the policy 'RFC 812 Required' as described in RFC 5226 [RFC5226]. 814 Cisco Service Level Assurance Protocol - Version Number Registry 816 +-----------+---------------------------------+ 817 | Version | Description | 818 +-----------+---------------------------------+ 819 | 0 | Reserved | 820 | 1 | Reserved | 821 | 2 | Version 2 | 822 | 3 - 200 | Available for future extensions | 823 | 201 - 225 | Private Use | 824 | 226 - 255 | Experimental Use | 825 +-----------+---------------------------------+ 827 The version number should be changed only when the structure of the 828 Command Messages is different from the basic Command Header and CSLD 829 structure described in this document. 831 Cisco Service Level Assurance Protocol - CSLD Command Registry 833 +---------------+---------------------------------+ 834 | CSLD Type | Description | 835 +---------------+---------------------------------+ 836 | 0 | Reserved | 837 | 1 | Authentication CSLD | 838 | 2 | UDP Measurements | 839 | 3 - 52 | Reserved | 840 | 53 - 10239 | Available for future extensions | 841 | 10240 - 20479 | Private Use | 842 | 20480 - 65535 | Experimental Use | 843 +---------------+---------------------------------+ 845 It is envisioned that future documents will provide their own 846 measurement type number along with the format of the Data portion. 848 Cisco Service Level Assurance Protocol - Authenticator Modes Registry 849 +-----------+---------------------------------+ 850 | Mode | Description | 851 +-----------+---------------------------------+ 852 | 0 | No Authentication | 853 | 1 | SHA256 | 854 | 2 | HMAC-SHA-256 | 855 | 3 - 200 | Available for future extensions | 856 | 201 - 225 | Private Use | 857 | 226 - 255 | Experimental Use | 858 +-----------+---------------------------------+ 860 Cisco Service Level Assurance Protocol - Roles Registry 862 +-----------+---------------------------------+ 863 | Role | Description | 864 +-----------+---------------------------------+ 865 | 0 | Reserved | 866 | 1 | Sender | 867 | 2 | Responder | 868 | 3 - 200 | Available for future extensions | 869 | 201 - 225 | Private Use | 870 | 226 - 255 | Experimental Use | 871 +-----------+---------------------------------+ 873 Cisco Service Level Assurance Protocol - Measurement Type Registry 875 +------------------+---------------------------------+ 876 | Measurement Type | Description | 877 +------------------+---------------------------------+ 878 | 0 | Reserved | 879 | 1 | Reserved | 880 | 2 | Reserved | 881 | 3 | UDP | 882 | 4 - 52 | Reserved | 883 | 53-10239 | Available for future extensions | 884 | 10240 - 20479 | Private Use | 885 | 20480 - 65535 | Experimental Use | 886 +------------------+---------------------------------+ 888 The following registry is also needed for the extensibility of the 889 protocol, however, the range designated "Available for future 890 extensions" will be governed by the policy 'First Come First Served' 891 as described in RFC 5226 [RFC5226] 893 Cisco Service Level Assurance Protocol - Status Types Registry 894 +-----------+-------------------------------------------------------+ 895 | Status | Description | 896 +-----------+-------------------------------------------------------+ 897 | 0 | Success | 898 | --------- | -------------------------- | 899 | 1 | Fail - catch all | 900 | --------- | -------------------------- | 901 | 2 | Authentication failure | 902 | --------- | -------------------------- | 903 | 3 | Format error - sent when any CSLD type is not | 904 | | recognized or any part of a CSLD has a value that is | 905 | | not recognized | 906 | --------- | -------------------------- | 907 | 4 | Port in use - the UDP/TCP port is already being used | 908 | | by some other application and cannot be reserved | 909 | --------- | -------------------------- | 910 | 5 - 40959 | Available for future extensions | 911 | --------- | -------------------------- | 912 | 40960 - | Experimental Use | 913 | 65535 | | 914 +-----------+-------------------------------------------------------+ 916 Finally, the following registry is also needed for the extensibility 917 of the protocol, however, the range designated "Available for future 918 extensions" will be governed by the policy 'Specification Required' 919 as described in RFC 5226 [RFC5226] 921 Cisco Service Level Assurance Protocol - Address Family Registry 923 +--------------+---------------------------------+ 924 | Address Type | Description | 925 +--------------+---------------------------------+ 926 | 0 | Reserved | 927 | 1 | IPv4 | 928 | 2 | IPv6 | 929 | 3 - 200 | Available for future extensions | 930 | 201 - 225 | Private Use | 931 | 226 - 255 | Experimental Use | 932 +--------------+---------------------------------+ 934 6. Security Considerations 936 6.1. Message Authentication 938 When the mode for the Authentication CSLD is set to 1, the Message 939 Authentication Digest is generated using the SHA 256 algorithm and is 940 to be calculated over the entire packet including the Message 941 Authentication Digest field which MUST be set to all 0s. 943 When the mode for the Authentication CSLD is set to 2, the Message 944 Authentication Digest is generated using the HMAC-SHA-256 as 945 described in RFC 4868 [RFC4868]algorithm and is to be calculated over 946 the entire packet including the Message Authentication Digest field 947 which MUST be set to all 0s 949 When the mode field is set to 0, the Random Number field and the 950 Message Authentication Digest MUST both be set to all 0s. 952 6.2. IPSec Considerations 954 It is RECOMMENDED that IPSec be employed to afford better security. 955 IPSec provides enhanced privacy as well as an automated key 956 distribution mechanism. The following recommendations are similar to 957 RFC3579, Section 2 [RFC3579] 959 6.2.1. Control Traffic 961 For Senders implementing this specification, the IPSec policy would 962 be "Initiate IPSec, from me to any, destination port UDP 1167". This 963 causes the Sender to initiate IPSec when sending Control traffic to 964 any Responder. If some Responders contacted by the Sender do not 965 support IPSec, then a more granular policy will be required, such as 966 "Initiate IPSec, from me to IPSec-Capable-Responder, destination port 967 UDP 1167". 969 For Responders implementing this specification, the IPSec policy 970 would be "Require IPSec, from any to me, destination port UDP 1167". 971 This causes the Responder to require use of IPSec. If some Sender 972 does not support IPSec, then a more granular policy will be required: 973 "Require IPSec, from IPSec-Capable-Sender to me". 975 6.2.2. Measurement Traffic 977 As the Control Phase occurs before the Measurement Phase, it should 978 be possible to build an IPSec Security Association once a successful 979 Control Response is received. 981 For Senders implementing this specification, the IPSec policy would 982 be "Initiate IPSec, from me to negotiated address, destination is 983 negotiated port". This causes the Sender to initiate IPSec when 984 sending Measurement traffic to the Responder. If some Responders 985 contacted by the Sender do not support IPSec, then a more granular 986 policy will be required, such as "Initiate IPSec, from me to IPSec- 987 Capable-Responder, destination is negotiated port". 989 For Responders implementing this specification, the IPSec policy 990 would be "Require IPSec, from negotiated address to me, destination 991 is negotiated port". This causes the Responder to require use of 992 IPSec. If some Sender does not support IPSec, then a more granular 993 policy will be required: "Require IPSec, from IPSec-Capable-Sender to 994 me, destination is negotiated port". 996 6.3. Replay Protection 998 For the Control Messages the originator of the message MAY choose to 999 include a current value in the Sent Timestamp field indicating the 1000 time the message was submitted for transmission, it MUST be set to 0 1001 otherwise. The receiver of the message MAY choose to validate if the 1002 timestamp is within an acceptable range. The Measurement Traffic 1003 described in this document contains a timestamp to indicate the sent 1004 time and hence no new field is required. 1006 7. Terminology 1008 +-------------+-----------------------------------------------------+ 1009 | Term | Description | 1010 +-------------+-----------------------------------------------------+ 1011 | Control | A phase during which Control Request and Control | 1012 | Phase | Response is exchanged. | 1013 | --------- | -------------------------- | 1014 | L2 | OSI Data Link Layer | 1015 | --------- | -------------------------- | 1016 | L3 | OSI Network Layer | 1017 | --------- | -------------------------- | 1018 | Measurement | Active measurement phase that is marked by a | 1019 | Phase | sequence of Measurement Request and Measurement | 1020 | | Response exchanges. | 1021 | --------- | -------------------------- | 1022 | Metric | A particular characteristic of the network data | 1023 | | traffic, for example latency, jitter, packet/frame | 1024 | | loss | 1025 | --------- | -------------------------- | 1026 | Responder | A network element that responds to a message | 1027 | --------- | -------------------------- | 1028 | RTP | Real-time Transport Protocol | 1029 | --------- | -------------------------- | 1030 | Sender | A network element that is the initiator of a | 1031 | | message exchange | 1032 | --------- | -------------------------- | 1033 | Service | This is the level of service that is agreed upon | 1034 | Level | between the Provider and the Customer | 1035 | --------- | -------------------------- | 1036 | UDP | User Datagram Protocol | 1037 +-------------+-----------------------------------------------------+ 1039 8. Acknowledgements 1041 The authors wish to acknowledge the contributions of several key 1042 people who contributed to the current form of the document. Hanlin 1043 Fang, David Wang, Anantha Ramaiah, Max Pritikin, and Malini 1044 Vijayamohan. 1046 9. References 1048 9.1. Normative References 1050 [IEEE1588] 1051 IEEE, "1588-2008 Standard for a Precision Clock 1052 Synchronization Protocol for Networked Measurement and 1053 Control Systems", March 2008. 1055 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1056 Requirement Levels", BCP 14, RFC 2119, March 1997. 1058 [RFC4868] Kelly, S. and S. Frankel, "Using HMAC-SHA-256, HMAC-SHA- 1059 384, and HMAC-SHA-512 with IPsec", RFC 4868, May 2007. 1061 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 1062 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 1063 May 2008. 1065 [RFC5905] Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network 1066 Time Protocol Version 4: Protocol and Algorithms 1067 Specification", RFC 5905, June 2010. 1069 9.2. Informative References 1071 [RFC3579] Aboba, B. and P. Calhoun, "RADIUS (Remote Authentication 1072 Dial In User Service) Support For Extensible 1073 Authentication Protocol (EAP)", RFC 3579, September 2003. 1075 [RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. 1076 Zekauskas, "A One-way Active Measurement Protocol 1077 (OWAMP)", RFC 4656, September 2006. 1079 [RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J. 1080 Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)", 1081 RFC 5357, October 2008. 1083 [RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay 1084 Measurement for MPLS Networks", RFC 6374, September 2011. 1086 Authors' Addresses 1088 Murtaza S. Chiba 1089 Cisco Systems 1090 170 West Tasman Drive 1091 San Jose, 95134 1092 USA 1094 Phone: 1-408-526-4000 1095 Fax: 1096 Email: mchiba@cisco.com 1097 URI: 1099 Alexander Clemm 1100 Cisco Systems 1101 170 West Tasman Drive 1102 San Jose, 95134 1103 USA 1105 Phone: 1-408-526-4000 1106 Fax: 1107 Email: alex@cisco.com 1108 URI: 1110 Steven Medley 1111 Cisco Systems 1112 170 West Tasman Drive 1113 San Jose, 95134 1114 USA 1116 Phone: 1-408-526-4000 1117 Fax: 1118 Email: stmedley@cisco.com 1119 URI: 1121 Joseph Salowey 1122 Cisco Systems 1123 170 West Tasman Drive 1124 San Jose, 95134 1125 USA 1127 Phone: 1-408-526-4000 1128 Fax: 1129 Email: jsalowey@cisco.com 1130 URI: 1132 Sudhir Thombare 1133 Cisco Systems 1134 170 West Tasman Drive 1135 San Jose, 95134 1136 USA 1138 Phone: 1-408-526-4000 1139 Fax: 1140 Email: thombare@cisco.com 1141 URI: 1143 Eshwar Yedavalli 1144 Cisco Systems 1145 170 West Tasman Drive 1146 San Jose, 95134 1147 USA 1149 Phone: 1-408-526-4000 1150 Fax: 1151 Email: eshwar@cisco.com 1152 URI: