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Summary: 0 errors (**), 0 flaws (~~), 7 warnings (==), 5 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 Operations and Management Area Working Group T. Mizrahi 2 Internet Draft Marvell 3 Intended status: Informational N. Sprecher 4 Expires: June 2014 NSN 5 E. Bellagamba 6 Ericsson 7 Y. Weingarten 9 December 16, 2013 11 An Overview of 12 Operations, Administration, and Maintenance (OAM) Tools 13 draft-ietf-opsawg-oam-overview-11.txt 15 Abstract 17 Operations, Administration, and Maintenance (OAM) is a general term 18 that refers to a toolset for fault detection and isolation, and for 19 performance measurement. Over the years various OAM tools have been 20 defined for various layers in the protocol stack. 22 This document summarizes some of the OAM tools defined in the IETF in 23 the context of IP unicast, MPLS, MPLS for the transport profile 24 (MPLS-TP), pseudowires, and TRILL. This document focuses on tools for 25 detecting and isolating failures in networks and for performance 26 monitoring. Control and management aspects of OAM are outside the 27 scope of this document. Network repair functions such as Fast Reroute 28 (FRR) and protection switching, which are often triggered by OAM 29 protocols, are also out of the scope of this document. 31 The target audience of this document includes network equipment 32 vendors, network operators and standard development organizations, 33 and can be used as an index to some of the main OAM tools defined in 34 the IETF. This document provides a brief description of each of the 35 OAM tools in the IETF. At the end of the document a list of the OAM 36 toolsets and a list of the OAM functions are presented as a summary. 38 Status of this Memo 40 This Internet-Draft is submitted to IETF in full conformance with the 41 provisions of BCP 78 and BCP 79. 43 Internet-Drafts are working documents of the Internet Engineering 44 Task Force (IETF), its areas, and its working groups. Note that 45 other groups may also distribute working documents as Internet- 46 Drafts. 48 Internet-Drafts are draft documents valid for a maximum of six months 49 and may be updated, replaced, or obsoleted by other documents at any 50 time. It is inappropriate to use Internet-Drafts as reference 51 material or to cite them other than as "work in progress." 53 The list of current Internet-Drafts can be accessed at 54 http://www.ietf.org/ietf/1id-abstracts.txt. 56 The list of Internet-Draft Shadow Directories can be accessed at 57 http://www.ietf.org/shadow.html. 59 This Internet-Draft will expire on June 16, 2014. 61 Copyright Notice 63 Copyright (c) 2013 IETF Trust and the persons identified as the 64 document authors. All rights reserved. 66 This document is subject to BCP 78 and the IETF Trust's Legal 67 Provisions Relating to IETF Documents 68 (http://trustee.ietf.org/license-info) in effect on the date of 69 publication of this document. Please review these documents 70 carefully, as they describe your rights and restrictions with respect 71 to this document. Code Components extracted from this document must 72 include Simplified BSD License text as described in Section 4.e of 73 the Trust Legal Provisions and are provided without warranty as 74 described in the Simplified BSD License. 76 Table of Contents 78 1. Introduction ................................................. 4 79 1.1. Background .............................................. 4 80 1.2. Target Audience.......................................... 5 81 1.3. OAM-related Work in the IETF ............................ 5 82 1.4. Focusing on the Data Plane .............................. 6 83 2. Terminology .................................................. 7 84 2.1. Abbreviations ........................................... 7 85 2.2. Terminology used in OAM Standards ....................... 9 86 2.2.1. General Terms ...................................... 9 87 2.2.2. Operations, Administration and Maintenance ......... 9 88 2.2.3. Functions, Tools and Protocols ..................... 9 89 2.2.4. Data Plane, Control Plane and Management Plane .... 10 90 2.2.5. The Players ....................................... 11 91 2.2.6. Proactive and On-demand Activation ................ 12 92 2.2.7. Connectivity Verification and Continuity Checks ... 12 93 2.2.8. Connection Oriented vs. Connectionless Communication13 94 2.2.9. Point-to-point vs. Point-to-multipoint Services ... 14 95 2.2.10. Failures ......................................... 14 96 3. OAM Functions ............................................... 15 97 4. OAM Tools in the IETF - a Detailed Description .............. 16 98 4.1. IP Ping ................................................ 16 99 4.2. IP Traceroute .......................................... 16 100 4.3. Bidirectional Forwarding Detection (BFD) ............... 17 101 4.3.1. Overview .......................................... 17 102 4.3.2. Terminology ....................................... 18 103 4.3.3. BFD Control ....................................... 18 104 4.3.4. BFD Echo .......................................... 18 105 4.4. MPLS OAM ............................................... 19 106 4.5. MPLS-TP OAM ............................................ 20 107 4.5.1. Overview .......................................... 20 108 4.5.2. Terminology ....................................... 20 109 4.5.3. Generic Associated Channel ........................ 22 110 4.5.4. MPLS-TP OAM Toolset ............................... 22 111 4.5.4.1. Continuity Check and Connectivity Verification 23 112 4.5.4.2. Route Tracing ................................ 23 113 4.5.4.3. Lock Instruct ................................ 23 114 4.5.4.4. Lock Reporting ............................... 24 115 4.5.4.5. Alarm Reporting .............................. 24 116 4.5.4.6. Remote Defect Indication ..................... 24 117 4.5.4.7. Client Failure Indication .................... 24 118 4.5.4.8. Performance Monitoring ....................... 24 119 4.5.4.8.1. Packet Loss Measurement (LM) ............ 25 120 4.5.4.8.2. Packet Delay Measurement (DM) ........... 25 121 4.6. Pseudowire OAM ......................................... 26 122 4.6.1. Pseudowire OAM using Virtual Circuit Connectivity 123 Verification (VCCV) ...................................... 26 124 4.6.2. Pseudowire OAM using G-ACh ........................ 27 125 4.6.3. Attachment Circuit - Pseudowire Mapping ........... 27 126 4.7. OWAMP and TWAMP......................................... 27 127 4.7.1. Overview .......................................... 27 128 4.7.2. Control and Test Protocols ........................ 28 129 4.7.3. OWAMP ............................................. 29 130 4.7.4. TWAMP ............................................. 29 131 4.8. TRILL .................................................. 29 132 5. Summary ..................................................... 30 133 5.1. Summary of OAM Tools ................................... 30 134 5.2. Summary of OAM Functions ............................... 32 135 5.3. Guidance to Network Equipment Vendors .................. 34 136 6. Security Considerations ..................................... 34 137 7. IANA Considerations ......................................... 34 138 8. Acknowledgments ............................................. 34 139 9. References .................................................. 34 140 9.1. Informative References ................................. 34 141 Appendix A. List of OAM Documents .............................. 40 142 A.1. List of IETF OAM Documents ............................. 40 143 A.2. List of Selected Non-IETF OAM Documents ................ 45 145 1. Introduction 147 OAM is a general term that refers to a toolset for detecting, 148 isolating and reporting failures and for monitoring the network 149 performance. 151 There are several different interpretations to the "OAM" acronym. 152 This document refers to Operations, Administration and Maintenance, 153 as recommended in Section 3 of [RFC6291]. 155 This document summarizes some of the OAM tools defined in the IETF in 156 the context of IP unicast, MPLS, MPLS for the transport profile 157 (MPLS-TP), pseudowires, and TRILL. 159 This document focuses on tools for detecting and isolating failures 160 and for performance monitoring. Hence, this document focuses on the 161 tools used for monitoring and measuring the data plane; control and 162 management aspects of OAM are outside the scope of this document. 163 Network repair functions such as Fast Reroute (FRR) and protection 164 switching, which are often triggered by OAM protocols, are also out 165 of the scope of this document. 167 1.1. Background 169 OAM was originally used in traditional communication technologies 170 such as E1 and T1, evolving into PDH and then later in SONET/SDH. ATM 171 was probably the first technology to include inherent OAM support 172 from day one, while in other technologies OAM was typically defined 173 in an ad hoc manner after the technology was already defined and 174 deployed. Packet-based networks were traditionally considered 175 unreliable and best-effort, but as packet-based networks evolved, 176 they have become the common transport for both data and telephony, 177 replacing traditional transport protocols. Consequently, packet-based 178 networks were expected to provide a similar "carrier grade" 179 experience, and specifically to support OAM. 181 As typical networks have a multi-layer architecture, the set of OAM 182 protocols similarly take a multi-layer structure; each layer has its 183 own OAM protocols. Moreover, OAM can be used at different levels of 184 hierarchy in the network to form a multi-layer OAM solution, as shown 185 in the example in Figure 1. 187 Figure 1 illustrates a network in which IP traffic between two 188 customer edges is transported over an MPLS provider network. MPLS OAM 189 is used at the provider-level for monitoring the connection between 190 the two provider edges, while IP OAM is used at the customer-level 191 for monitoring the end-to-end connection between the two customer 192 edges. 194 |<-------------- Customer-level OAM -------------->| 195 IP OAM (Ping, Traceroute, OWAMP, TWAMP) 197 |<- Provider-level OAM ->| 198 MPLS OAM (LSP Ping) 200 +-----+ +----+ +----+ +-----+ 201 | | | |========================| | | | 202 | |-------| | MPLS | |-------| | 203 | | IP | | | | IP | | 204 +-----+ +----+ +----+ +-----+ 205 Customer Provider Provider Customer 206 Edge Edge Edge Edge 208 Figure 1 Example: Multi-layer OAM 210 1.2. Target Audience 212 The target audience of this document includes: 214 o Standard development organizations - both IETF working groups and 215 non-IETF organizations can benefit from this document when 216 designing new OAM protocols, or when looking to reuse existing OAM 217 tools for new technologies. 219 o Network equipment vendors and network operators - can use this 220 document as an index to some of the common IETF OAM tools. 222 It should be noted that this document is not necessarily suitable for 223 beginners without any background in OAM. 225 1.3. OAM-related Work in the IETF 227 This memo provides an overview of the different sets of OAM tools 228 defined by the IETF. The set of OAM tools described in this memo are 229 applicable to IP unicast, MPLS, pseudowires, MPLS for the transport 230 profile (MPLS-TP), and TRILL. While OAM tools that are applicable to 231 other technologies exist, they are beyond the scope of this memo. 233 This document focuses on IETF documents that have been published as 234 RFCs, while other ongoing OAM-related work is outside the scope. 236 The IETF has defined OAM protocols and tools in several different 237 contexts. We roughly categorize these efforts into a few sets of OAM- 238 related RFCs, listed in Table 1. Each set defines a logically-coupled 239 set of RFCs, although the sets are in some cases intertwined by 240 common tools and protocols. 242 The discussion in this document is ordered according to these sets. 244 +--------------+------------+ 245 | Toolset | Transport | 246 | | Technology | 247 +--------------+------------+ 248 |IP Ping | IPv4/IPv6 | 249 +--------------+------------+ 250 |IP Traceroute | IPv4/IPv6 | 251 +--------------+------------+ 252 |BFD | generic | 253 +--------------+------------+ 254 |MPLS OAM | MPLS | 255 +--------------+------------+ 256 |MPLS-TP OAM | MPLS-TP | 257 +--------------+------------+ 258 |Pseudowire OAM| Pseudowires| 259 +--------------+------------+ 260 |OWAMP and | IPv4/IPv6 | 261 |TWAMP | | 262 +--------------+------------+ 263 |TRILL OAM | TRILL | 264 +--------------+------------+ 265 Table 1 OAM Toolset Packages in the IETF Documents 267 1.4. Focusing on the Data Plane 269 OAM tools may, and quite often do, work in conjunction with a control 270 plane and/or management plane. OAM provides instrumentation tools 271 for measuring and monitoring the data plane. OAM tools often use 272 control plane functions, e.g., to initialize OAM sessions and to 273 exchange various parameters. The OAM tools communicate with the 274 management plane to raise alarms, and often OAM tools may be 275 activated by the management (as well as by the control plane), e.g. 276 to locate and localize problems. 278 The considerations of the control plane maintenance tools and the 279 functionality of the management plane are out of scope for this 280 document, which concentrates on presenting the data plane tools that 281 are used for OAM. Network repair functions such as Fast Reroute (FRR) 282 and protection switching, which are often triggered by OAM protocols, 283 are also out of the scope of this document. 285 Since OAM protocols are used for monitoring the data plane, it is 286 imperative for OAM tools to be capable of testing the actual data 287 plane in as much accuracy as possible. Thus, it is important to 288 enforce fate-sharing between OAM traffic that monitors the data plane 289 and the data plane traffic it monitors. 291 2. Terminology 293 2.1. Abbreviations 295 ACH Associated Channel Header 297 AIS Alarm Indication Signal 299 ATM Asynchronous Transfer Mode 301 BFD Bidirectional Forwarding Detection 303 CC Continuity Check 305 CV Connectivity Verification 307 DM Delay Measurement 309 ECMP Equal Cost Multiple Paths 311 FEC Forwarding Equivalence Class 313 FRR Fast Reroute 315 G-ACh Generic Associated Channel 317 GAL Generic Associated Label 319 ICMP Internet Control Message Protocol 321 L2TP Layer Two Tunneling Protocol 323 LCCE L2TP Control Connection Endpoint 324 LDP Label Distribution Protocol 326 LER Label Edge Router 328 LM Loss Measurement 330 LSP Label Switched Path 332 LSR Label Switched Router 334 ME Maintenance Entity 336 MEG Maintenance Entity Group 338 MEP MEG End Point 340 MIP MEG Intermediate Point 342 MP Maintenance Point 344 MPLS Multiprotocol Label Switching 346 MPLS-TP MPLS Transport Profile 348 MTU Maximum Transmission Unit 350 OAM Operations, Administration, and Maintenance 352 PDH Plesiochronous Digital Hierarchy 354 PE Provider Edge 356 PW Pseudowire 358 PWE3 Pseudowire Emulation Edge-to-Edge 360 RBridge Routing Bridge 362 RDI Remote Defect Indication 364 SDH Synchronous Digital Hierarchy 366 SONET Synchronous Optical Networking 368 TRILL Transparent Interconnection of Lots of Links 370 TTL Time To Live 371 VCCV Virtual Circuit Connectivity Verification 373 2.2. Terminology used in OAM Standards 375 2.2.1. General Terms 377 A wide variety of terms is used in various OAM standards. This 378 section presents a comparison of the terms used in various OAM 379 standards, without fully quoting the definition of each term. 381 An interesting overview of the term OAM and its derivatives is 382 presented in [OAM-Def]. A thesaurus of terminology for MPLS-TP terms 383 is presented in [TP-Term], and provides a good summary of some of the 384 OAM related terminology. 386 2.2.2. Operations, Administration and Maintenance 388 The following definition of OAM is quoted from [OAM-Def]: 390 The components of the "OAM" acronym (and provisioning) are defined as 391 follows: 393 o Operations - Operation activities are undertaken to keep the 394 network (and the services that the network provides) up and 395 running. It includes monitoring the network and finding problems. 396 Ideally these problems should be found before users are affected. 398 o Administration - Administration activities involve keeping track 399 of resources in the network and how they are used. It includes 400 all the bookkeeping that is necessary to track networking 401 resources and the network under control. 403 o Maintenance - Maintenance activities are focused on facilitating 404 repairs and upgrades -- for example, when equipment must be 405 replaced, when a router needs a patch for an operating system 406 image, or when a new switch is added to a network. Maintenance 407 also involves corrective and preventive measures to make the 408 managed network run more effectively, e.g., adjusting device 409 configuration and parameters. 411 2.2.3. Functions, Tools and Protocols 413 OAM Function 415 An OAM function is an instrumentation measurement type or diagnostic. 417 OAM functions are the atomic building blocks of OAM, where each 418 function defines an OAM capability. 420 Typical examples of OAM functions are presented in Section 3. 422 OAM Protocol 424 A protocol used for implementing one or more OAM functions. 426 The OWAMP-Test [OWAMP] is an example of an OAM protocol. 428 OAM Tool 430 An OAM tool is a specific means of applying one or more OAM 431 functions. 433 In some cases an OAM protocol *is* an OAM tool, e.g., OWAMP-Test. In 434 other cases an OAM tool uses a set of protocols that are not strictly 435 OAM-related; for example, Traceroute (Section 4.2.) can be 436 implemented using UDP and ICMP messages, without using an OAM 437 protocol per se. 439 2.2.4. Data Plane, Control Plane and Management Plane 441 Data Plane 443 The data plane is the set of functions used to transfer data in the 444 stratum or layer under consideration [ITU-Terms]. 446 The Data Plane is also known as the Forwarding Plane or the User 447 Plane. 449 Control Plane 451 The control plane is the set of protocols and mechanisms that enable 452 routers to efficiently learn how to forward packets towards their 453 final destination (based on [Comp]). 455 Management Plane 457 The term Management Plane, as described in [Mng], is used to describe 458 the exchange of management messages through management protocols 459 (often transported by IP and by IP transport protocols) between 460 management applications and the managed entities such as network 461 nodes. 463 Data Plane vs. Control Plane vs. Management Plane 464 The distinction between the planes is at times a bit vague. For 465 example, the definition of "Control Plane" above may imply that OAM 466 tools such as ping, BFD and others are in fact in the control plane. 468 This document focuses on tools used for monitoring the data plane. 469 While these tools could arguably be considered to be in the control 470 plane, these tools monitor the data plane, and hence it is imperative 471 to have fate-sharing between OAM traffic that monitors the data plane 472 and the data plane traffic it monitors. 474 Another potentially vague distinction is between the management plane 475 and control plane. The management plane should be seen as separate 476 from, but possibly overlapping with, the control plane (based on 477 [Mng]). 479 2.2.5. The Players 481 An OAM tool is used between two (or more) "players". Various terms 482 are used in IETF documents to refer to the players that take part in 483 OAM. Table 2 summarizes the terms used in each of the toolsets 484 discussed in this document. 486 +--------------------------+--------------------------+ 487 | Toolset | Terms | 488 +--------------------------+--------------------------+ 489 | Ping / Traceroute |-Host | 490 | ([ICMPv4], [ICMPv6], |-Node | 491 | [TCPIP-Tools]) |-Interface | 492 | |-Gateway | 493 + ------------------------ + ------------------------ + 494 | BFD [BFD] | System | 495 + ------------------------ + ------------------------ + 496 | MPLS OAM [MPLS-OAM-FW] | LSR | 497 + ------------------------ + ------------------------ + 498 | MPLS-TP OAM [TP-OAM-FW] |-End Point - MEP | 499 | |-Intermediate Point - MIP | 500 + ------------------------ + ------------------------ + 501 | Pseudowire OAM [VCCV] |-PE | 502 | |-LCCE | 503 + ------------------------ + ------------------------ + 504 | OWAMP and TWAMP |-Host | 505 | ([OWAMP], [TWAMP]) |-End system | 506 + ------------------------ + ------------------------ + 507 | TRILL OAM [TRILL-OAM] |-RBridge | 508 +--------------------------+--------------------------+ 509 Table 2 Maintenance Point Terminology 511 2.2.6. Proactive and On-demand Activation 513 The different OAM tools may be used in one of two basic types of 514 activation: 516 Proactive 518 Proactive activation - indicates that the tool is activated on a 519 continual basis, where messages are sent periodically, and errors are 520 detected when a certain number of expected messages are not received. 522 On-demand 524 On-demand activation - indicates that the tool is activated 525 "manually" to detect a specific anomaly. 527 2.2.7. Connectivity Verification and Continuity Checks 529 Two distinct classes of failure management functions are used in OAM 530 protocols, connectivity verification and continuity checks. The 531 distinction between these terms is defined in [MPLS-TP-OAM], and is 532 used similarly in this document. 534 Continuity Check 536 Continuity checks are used to verify that a destination is reachable, 537 and are typically sent proactively, though they can be invoked on- 538 demand as well. 540 Connectivity Verification 542 A connectivity verification function allows Alice to check whether 543 she is connected to Bob or not. It is noted that while the CV 544 function is performed in the data plane, the "expected path" is 545 predetermined either in the control plane or in the management plane. 546 A connectivity verification (CV) protocol typically uses a CV 547 message, followed by a CV reply that is sent back to the originator. 548 A CV function can be applied proactively or on-demand. 550 Connectivity Verification tools often perform path verification as 551 well, allowing Alice to verify that messages from Bob are received 552 through the correct path, thereby verifying not only that the two MPs 553 are connected, but also that they are connected through the expected 554 path, allowing detection of unexpected topology changes. 556 Connectivity verification and continuity checks are considered 557 complementary mechanisms, and are often used in conjunction with each 558 other. 560 2.2.8. Connection Oriented vs. Connectionless Communication 562 Connection Oriented 564 In Connection Oriented technologies an end-to-end connection is 565 established (by a control protocol or provisioned by a management 566 system) prior to the transmission of data. 568 Typically a connection identifier is used to identify the connection. 569 In connection oriented technologies it is often the case (although 570 not always) that all packets belonging to a specific connection use 571 the same route through the network. 573 Connectionless 575 In Connectionless technologies data is typically sent between end 576 points without prior arrangement. Packets are routed independently 577 based on their destination address, and hence different packets may 578 be routed in a different way across the network. 580 Discussion 582 The OAM tools described in this document include tools that support 583 connection oriented technologies, as well as tools for connectionless 584 technologies. 586 In connection oriented technologies OAM is used to monitor a 587 *specific* connection; OAM packets are forwarded through the same 588 route as the data traffic and receive the same treatment. In 589 connectionless technologies, OAM is used between a source and 590 destination pair without defining a specific connection. Moreover, in 591 some cases the route of OAM packets may differ from the one of the 592 data traffic. For example, the connectionless IP Ping (Section 4.1.) 593 tests the reachability from a source to a given destination, while 594 the connection oriented LSP Ping (Section 4.4.) is used for 595 monitoring a specific LSP (connection), and provides the capability 596 to monitor all the available paths used by an LSP. 598 It should be noted that in some cases connectionless protocols are 599 monitored by connection oriented OAM protocols. For example, while IP 600 is a connectionless protocol, it can monitored by BFD (Section 4.3. 601 ), which is connection oriented. 603 2.2.9. Point-to-point vs. Point-to-multipoint Services 605 Point-to-point (P2P) 607 A P2P service delivers data from a single source to a single 608 destination. 610 Point-to-multipoint (P2MP) 612 A P2MP service delivers data from a single source to a one or more 613 destinations (based on [Signal]). 615 An MP2MP service as a service that delivers data from more than one 616 source to one or more receivers (based on [Signal]). 618 Discussion 620 The OAM tools described in this document include tools for P2P 621 services, as well as tools for P2MP services. 623 The distinction between P2P services and P2MP services affects the 624 corresponding OAM tools. A P2P service is typically simpler to 625 monitor, as it consists of a single pair of end points. P2MP services 626 present several challenges. For example, in a P2MP service, the OAM 627 mechanism not only verifies that each of the destinations is 628 reachable from the source, but also verifies that the P2MP 629 distribution tree is intact and loop-free. 631 2.2.10. Failures 633 The terms Failure, Fault, and Defect are used interchangeably in the 634 standards, referring to a malfunction that can be detected by a 635 connectivity or a continuity check. In some standards, such as 636 802.1ag [IEEE802.1Q] , there is no distinction between these terms, 637 while in other standards each of these terms refers to a different 638 type of malfunction. 640 The terminology used in IETF MPLS-TP OAM is based on the ITU-T 641 terminology, which distinguishes between these three terms in 642 [ITU-T-G.806]; 644 Fault 645 The term Fault refers to an inability to perform a required action, 646 e.g., an unsuccessful attempt to deliver a packet. 648 Defect 650 The term Defect refers to an interruption in the normal operation, 651 such as a consecutive period of time where no packets are delivered 652 successfully. 654 Failure 656 The term Failure refers to the termination of the required function. 657 While a Defect typically refers to a limited period of time, a 658 failure refers to a long period of time. 660 3. OAM Functions 662 This subsection provides a brief summary of the common OAM functions 663 used in OAM-related standards. These functions are used as building 664 blocks in the OAM standards described in this document. 666 o Connectivity Verification (CV), Path Verification and Continuity 667 Checks (CC): 668 As defined in Section 2.2.7. 670 o Path Discovery / Fault Localization: 671 This function can be used to trace the route to a destination, 672 i.e., to identify the nodes along the route to the destination. 673 When more than one route is available to a specific destination, 674 this function traces one of the available routes. When a failure 675 occurs, this function also allows to detect the location of the 676 failure. 677 Note that the term route tracing (or Traceroute) that is used in 678 the context of IP and MPLS, is sometimes referred to as path 679 tracing in the context of other protocols, such as TRILL. 681 o Performance Monitoring: 682 Typically refers to: 684 o Loss Measurement (LM) - monitors the packet loss rate. 686 o Delay Measurement (DM) - monitors the delay and delay 687 variation. 689 4. OAM Tools in the IETF - a Detailed Description 691 This section presents a detailed description of the sets of OAM- 692 related tools in each of the toolsets in Table 1. 694 4.1. IP Ping 696 Ping is a common network diagnosis application for IP networks that 697 uses ICMP. According to [NetTerms], 'Ping' is an abbreviation for 698 Packet internet groper, although the term has been so commonly used 699 that it stands on its own. As defined in [NetTerms], it is a program 700 used to test reachability of destinations by sending them an ICMP 701 echo request and waiting for a reply. 703 The ICMP Echo request/reply exchange in Ping is used as a continuity 704 check function for the Internet Protocol. The originator transmits an 705 ICMP Echo request packet, and the receiver replies with an Echo 706 reply. ICMP ping is defined in two variants, [ICMPv4] is used for 707 IPv4, and [ICMPv6] is used for IPv6. 709 Ping implementations typically use ICMP messages. UDP Ping is a 710 variant that uses UDP messages instead of ICMP echo messages. 712 Ping is a single-ended continuity check, i.e., it allows the 713 *initiator* of the Echo request to test the reachability. If it is 714 desirable for both ends to test the reachability, both ends have to 715 invoke Ping independently. 717 Note that since ICMP filtering is deployed in some routers and 718 firewalls, the usefulness of Ping is sometimes limited in the wider 719 internet. This limitation is equally relevant to Traceroute. 721 4.2. IP Traceroute 723 Traceroute ([TCPIP-Tools], [NetTools]) is an application that allows 724 users to discover a path between an IP source and an IP destination. 726 The most common way to implement Traceroute [TCPIP-Tools] is 727 described as follows. Traceroute sends a sequence of UDP packets to 728 UDP port 33434 at the destination. By default, Traceroute begins by 729 sending three packets (the number of packets is configurable in most 730 Traceroute implementations), each with an IP Time-To-Live (or Hop 731 Limit in IPv6) value of one to the destination. These packets expire 732 as soon as they reach the first router in the path. Consequently, 733 that router sends three ICMP Time Exceeded Messages back to the 734 Traceroute application. Traceroute now sends another three UDP 735 packets, each with the TTL value of 2. These messages cause the 736 second router to return ICMP messages. This process continues, with 737 ever increasing values for the TTL field, until the packets actually 738 reach the destination. Because no application listens to port 33434 739 at the destination, the destination returns ICMP Destination 740 Unreachable Messages indicating an unreachable port. This event 741 indicates to the Traceroute application that it is finished. The 742 Traceroute program displays the round-trip delay associated with each 743 of the attempts. 745 While Traceroute is a tool that finds *a* path from A to B, it should 746 be noted that traffic from A to B is often forwarded through Equal 747 Cost Multiple Paths (ECMP). Paris Traceroute [Paris] is an extension 748 to Traceroute that attempts to discovers all the available paths from 749 A to B by scanning different values of header fields (such as UDP 750 ports) in the probe packets. 752 It is noted that Traceroute is an application, and not a protocol. As 753 such, it has various different implementations. One of the most 754 common ones uses UDP probe packets, as described above. Other 755 implementations exist that use other types of probe messages, such as 756 ICMP or TCP. 758 Note that IP routing may be asymmetric. While Traceroute discovers a 759 path between a source and destination, it does not reveal the reverse 760 path. 762 A few ICMP extensions ([ICMP-MP], [ICMP-Int]) have been defined in 763 the context of Traceroute. These documents define several extensions, 764 including extensions to the ICMP Destination Unreachable message, 765 that can be used by Traceroute applications. 767 4.3. Bidirectional Forwarding Detection (BFD) 769 4.3.1. Overview 771 While multiple OAM tools have been defined for various protocols in 772 the protocol stack, Bidirectional Forwarding Detection [BFD], defined 773 by the IETF BFD working group, is a generic OAM tool that can be 774 deployed over various encapsulating protocols, and in various medium 775 types. The IETF has defined variants of the protocol for IP ([BFD- 776 IP], [BFD-Multi]), for MPLS LSPs [BFD-LSP], and for pseudowires [BFD- 777 VCCV]. The usage of BFD in MPLS-TP is defined in [TP-CC-CV]. 779 BFD includes two main OAM functions, using two types of BFD packets: 780 BFD Control packets, and BFD Echo packets. 782 4.3.2. Terminology 784 BFD operates between *systems*. The BFD protocol is run between two 785 or more systems after establishing a *session*. 787 4.3.3. BFD Control 789 BFD supports a bidirectional continuity check, using BFD control 790 packets, that are exchanged within a BFD session. BFD sessions 791 operate in one of two modes: 793 o Asynchronous mode (i.e. proactive): in this mode BFD control 794 packets are sent periodically. When the receiver detects that no 795 BFD control packets have been received during a predetermined 796 period of time, a failure is detected. 798 o Demand mode: in this mode, BFD control packets are sent on-demand. 799 Upon need, a system initiates a series of BFD control packets to 800 check the continuity of the session. BFD control packets are sent 801 independently in each direction. 803 Each of the end-points (referred to as systems) of the monitored path 804 maintains its own session identification, called a Discriminator, 805 both of which are included in the BFD Control Packets that are 806 exchanged between the end-points. At the time of session 807 establishment, the Discriminators are exchanged between the two-end 808 points. In addition, the transmission (and reception) rate is 809 negotiated between the two end-points, based on information included 810 in the control packets. These transmission rates may be renegotiated 811 during the session. 813 During normal operation of the session, i.e. no failures are 814 detected, the BFD session is in the Up state. If no BFD Control 815 packets are received during a period of time called the Detection 816 Time, the session is declared to be Down. The detection time is a 817 function of the pre-configured or negotiated transmission time, and a 818 parameter called Detect Mult. Detect Mult determines the number of 819 missing BFD Control packets that cause the session to be declared as 820 Down. This parameter is included in the BFD Control packet. 822 4.3.4. BFD Echo 824 A BFD echo packet is sent to a peer system, and is looped back to the 825 originator. The echo function can be used proactively, or on-demand. 827 The BFD echo function has been defined in BFD for IPv4 and IPv6 828 ([BFD-IP]), but is not used in BFD for MPLS LSPs, PWs, or in BFD for 829 MPLS-TP. 831 4.4. MPLS OAM 833 The IETF MPLS working group has defined OAM for MPLS LSPs. The 834 requirements and framework of this effort are defined in 835 [MPLS-OAM-FW] and [MPLS-OAM], respectively. The corresponding OAM 836 tool defined, in this context, is LSP Ping [LSP-Ping]. OAM for P2MP 837 services is defined in [MPLS-P2MP]. 839 LSP Ping is modeled after the Ping/Traceroute paradigm and thus it 840 may be used in one of two modes: 842 o "Ping" mode: In this mode LSP Ping is used for end-to-end 843 connectivity verification between two LERs. 845 o "Traceroute" mode: This mode is used for hop-by-hop fault 846 isolation. 848 LSP Ping extends the basic ICMP Ping operation (of data-plane 849 connectivity verification) with functionality to verify data-plane 850 vs. control-plane consistency for a Forwarding Equivalence Class 851 (FEC) and also Maximum Transmission Unit (MTU) problems. 853 The Traceroute functionality may be used to isolate and localize the 854 MPLS faults, using the Time-to-live (TTL) indicator to incrementally 855 identify the sub-path of the LSP that is successfully traversed 856 before the faulty link or node. 858 The challenge in MPLS networks is that the traffic of a given LSP may 859 be load balanced across Equal Cost Multiple paths (ECMP). LSP Ping 860 monitors all the available paths of an LSP by monitoring its 861 different Forwarding Equivalence Classes (FEC). Conversely, MPLS-TP 862 does not use ECMP, and thus does not require OAM over multiple paths. 864 Another challenge is that an MPLS LSP does not necessarily have a 865 return path, and thus responding to an LSP Ping message is not 866 necessarily as trivial as in IP Ping, where the responder just swaps 867 the source and destination IP addresses. Note that this challenge is 868 not applicable to MPLS-TP, where a return path is always available. 870 It should be noted that LSP Ping supports unique identification of 871 the LSP within an addressing domain. The identification is checked 872 using the full FEC identification. LSP Ping is easily extensible to 873 include additional information needed to support new functionality, 874 by use of Type-Length-Value (TLV) constructs. The usage of TLVs is 875 typically not easy to perform in hardware, and is thus typically 876 handled by the control plane. 878 LSP Ping supports both asynchronous, as well as, on-demand 879 activation. 881 4.5. MPLS-TP OAM 883 4.5.1. Overview 885 The MPLS working group has defined the OAM toolset that fulfills the 886 requirements for MPLS-TP OAM. The full set of requirements for MPLS- 887 TP OAM are defined in [MPLS-TP-OAM], and include both general 888 requirements for the behavior of the OAM tools and a set of 889 operations that should be supported by the OAM toolset. The set of 890 mechanisms required are further elaborated in [TP-OAM-FW], which 891 describes the general architecture of the OAM system as well as 892 giving overviews of the functionality of the OAM toolset. 894 Some of the basic requirements for the OAM toolset for MPLS-TP are: 896 o MPLS-TP OAM must be able to support both an IP based and non-IP 897 based environment. If the network is IP based, i.e. IP routing and 898 forwarding are available, then the MPLS-TP OAM toolset should rely 899 on the IP routing and forwarding capabilities. On the other hand, 900 in environments where IP functionality is not available, the OAM 901 tools must still be able to operate without dependence on IP 902 forwarding and routing. 904 o OAM packets and the user traffic are required to be congruent 905 (i.e. OAM packets are transmitted in-band) and there is a need to 906 differentiate OAM packets from data plane ones. Inherent in this 907 requirement is the principle that MPLS-TP OAM be independent of 908 any existing control-plane, although it should not preclude use of 909 the control-plane functionality. 910 OAM packets are identified by the Generic Associated Label (GAL), 911 which is a reserved MPLS label value (13). 913 4.5.2. Terminology 915 Maintenance Entity (ME) 917 The MPLS-TP OAM tools are designed to monitor and manage a 918 Maintenance Entity (ME). An ME, as defined in [TP-OAM-FW], defines a 919 relationship between two points of a transport path to which 920 maintenance and monitoring operations apply. 922 The term Maintenance Entity (ME) is used in ITU-T Recommendations 923 (e.g. [ITU-T-Y1731]), as well as in the MPLS-TP terminology 924 ([TP-OAM-FW]). 926 Maintenance Entity Group (MEG) 928 The collection of one or more MEs that belongs to the same transport 929 path and that are maintained and monitored as a group are known as a 930 Maintenance Entity Group (based on [TP-OAM-FW]). 932 Maintenance Point (MP) 934 A Maintenance Point (MP) is a functional entity that is defined at a 935 node in the network, and can initiate and/or react to OAM messages. 936 This document focuses on the data-plane functionality of MPs, while 937 MPs interact with the control plane and with the management plane as 938 well. 940 The term MP is used in IEEE 802.1ag, and was similarly adopted in 941 MPLS-TP ([TP-OAM-FW]). 943 Maintenance End Point (MEP) 945 A Maintenance End Point (MEP) is one of the end points of an ME, and 946 can initiate OAM messages and respond to them (based on [TP-OAM-FW]). 948 Maintenance Intermediate Point (MIP) 950 In between MEPs, there are zero or more intermediate points, called 951 Maintenance Entity Group Intermediate Points (based on [TP-OAM-FW]). 953 A Maintenance Intermediate Point (MIP) is an intermediate point that 954 does not generally initiate OAM frames (one exception to this is the 955 use of AIS notifications), but is able to respond to OAM frames that 956 are destined to it. A MIP in MPLS-TP identifies OAM packets destined 957 to it by the value of the TTL field in the OAM packet. The term 958 Maintenance Point is a general term for MEPs and MIPs. 960 Up and Down MEPs 962 The IEEE 802.1ag [IEEE802.1Q] defines a distinction between Up MEPs 963 and Down MEPs. A MEP is a bridge interface that is monitored by an 964 OAM protocol either in the direction facing the network, or in the 965 direction facing the bridge. A Down MEP is a MEP that receives OAM 966 packets from, and transmits them to the direction of the network. An 967 Up MEP receives OAM packets from, and transmits them to the direction 968 of the bridging entity. MPLS-TP ([TP-OAM-FW]) uses a similar 969 distinction on the placement of the MEP - either at the ingress, 970 egress, or forwarding function of the node (Down / Up MEPs). This 971 placement is important for localization of a failure. 973 The distinction between Up and Down MEPs was defined in [TP-OAM-FW], 974 but has not been used in other MPLS-TP RFCs, as of the writing of 975 this document. 977 4.5.3. Generic Associated Channel 979 In order to address the requirement for in-band transmission of MPLS- 980 TP OAM traffic, MPLS-TP uses a Generic Associated Channel (G-ACh), 981 defined in [G-ACh] for LSP-based OAM traffic. This mechanism is based 982 on the same concepts as the PWE3 ACH and VCCV mechanisms. However, 983 to address the needs of LSPs as differentiated from PW, the following 984 concepts were defined for [G-ACh]: 986 o An Associated Channel Header (ACH), that uses a format similar to 987 the PW Control Word, is a 4-byte header that is prepended to OAM 988 packets. 990 o A Generic Associated Label (GAL). The GAL is a reserved MPLS label 991 value (13) that indicates that the packet is an ACH packet and the 992 payload follows immediately after the label stack. 994 It should be noted that while the G-ACh was defined as part of the 995 MPLS-TP definition effort, the G-ACh is a generic tool that can be 996 used in MPLS in general, and not only in MPLS-TP. 998 4.5.4. MPLS-TP OAM Toolset 1000 To address the functionality that is required of the OAM toolset, the 1001 MPLS WG conducted an analysis of the existing IETF and ITU-T OAM 1002 tools and their ability to fulfill the required functionality. The 1003 conclusions of this analysis are documented in [OAM-Analys]. The MPLS 1004 working group currently plans to use a mixture of OAM tools that are 1005 based on various existing standards, and adapt them to the 1006 requirements of [MPLS-TP-OAM]. Some of the main building blocks of 1007 this solution are based on: 1009 o Bidirectional Forwarding Detection ([BFD], [BFD-LSP]) for 1010 proactive continuity check and connectivity verification. 1012 o LSP Ping as defined in [LSP-Ping] for on-demand connectivity 1013 verification. 1015 o New protocol packets, using G-ACH, to address different 1016 functionality. 1018 o Performance measurement protocols that are based on the 1019 functionality that is described in [ITU-T-Y1731]. 1021 The following sub-sections describe the OAM tools defined for MPLS-TP 1022 as described in [TP-OAM-FW]. 1024 4.5.4.1. Continuity Check and Connectivity Verification 1026 Continuity Check and Connectivity Verification are presented in 1027 Section 2.2.7. of this document. As presented there, these tools may 1028 be used either proactively or on-demand. When using these tools 1029 proactively, they are generally used in tandem. 1031 For MPLS-TP there are two distinct tools, the proactive tool is 1032 defined in [TP-CC-CV] while the on-demand tool is defined in 1033 [OnDemand-CV]. In on-demand mode, this function should support 1034 monitoring between the MEPs and, in addition, between a MEP and MIP. 1035 [TP-OAM-FW] highlights, when performing Connectivity Verification, 1036 the need for the CC-V messages to include unique identification of 1037 the MEG that is being monitored and the MEP that originated the 1038 message. 1040 The proactive tool [TP-CC-CV] is based on extensions to BFD (see 1041 Section 4.3.) with the additional limitation that the transmission 1042 and receiving rates are based on configuration by the operator. The 1043 on-demand tool [OnDemand-CV] is an adaptation of LSP Ping (see 1044 Section 4.4.) for the required behavior of MPLS-TP. 1046 4.5.4.2. Route Tracing 1048 [MPLS-TP-OAM] defines that there is a need for functionality that 1049 would allow a path end-point to identify the intermediate and end- 1050 points of the path. This function would be used in on-demand mode. 1051 Normally, this path will be used for bidirectional PW, LSP, and 1052 sections, however, unidirectional paths may be supported only if a 1053 return path exists. The tool for this is based on the LSP Ping (see 1054 Section 4.4.) functionality and is described in [OnDemand-CV]. 1056 4.5.4.3. Lock Instruct 1058 The Lock Instruct function [Lock-Loop] is used to notify a transport 1059 path end-point of an administrative need to disable the transport 1060 path. This functionality will generally be used in conjunction with 1061 some intrusive OAM function, e.g. Performance measurement, Diagnostic 1062 testing, to minimize the side-effect on user data traffic. 1064 4.5.4.4. Lock Reporting 1066 Lock Reporting is a function used by an end-point of a path to report 1067 to its far-end end-point that a lock condition has been affected on 1068 the path. 1070 4.5.4.5. Alarm Reporting 1072 Alarm Reporting [TP-Fault] provides the means to suppress alarms 1073 following detection of defect conditions at the server sub-layer. 1074 Alarm reporting is used by an intermediate point of a path, that 1075 becomes aware of a fault on the path, to report to the end-points of 1076 the path. [TP-OAM-FW] states that this may occur as a result of a 1077 defect condition discovered at a server sub-layer. This generates an 1078 Alarm Indication Signal (AIS) that continues until the fault is 1079 cleared. The consequent action of this function is detailed in 1080 [TP-OAM-FW]. 1082 4.5.4.6. Remote Defect Indication 1084 Remote Defect Indication (RDI) is used proactively by a path end- 1085 point to report to its peer end-point that a defect is detected on a 1086 bidirectional connection between them. [MPLS-TP-OAM] points out that 1087 this function may be applied to a unidirectional LSP only if there a 1088 return path exists. [TP-OAM-FW] points out that this function is 1089 associated with the proactive CC-V function. 1091 4.5.4.7. Client Failure Indication 1093 Client Failure Indication (CFI) is defined in [MPLS-TP-OAM] to allow 1094 the propagation information from one edge of the network to the 1095 other. The information concerns a defect to a client, in the case 1096 that the client does not support alarm notification. 1098 4.5.4.8. Performance Monitoring 1100 The definition of MPLS performance monitoring was motivated by the 1101 MPLS-TP requirements [MPLS-TP-OAM], but was defined generically for 1102 MPLS in [MPLS-LM-DM]. An additional document [TP-LM-DM] defines a 1103 performance monitoring profile for MPLS-TP. 1105 4.5.4.8.1. Packet Loss Measurement (LM) 1107 Packet Loss Measurement is a function used to verify the quality of 1108 the service. Packet loss, as defined in [IPPM-1LM] and [MPLS-TP-OAM], 1109 indicates the ratio of the number of user packets lost to the total 1110 number of user packets sent during a defined time interval. 1112 There are two possible ways of determining this measurement: 1114 o Using OAM packets, it is possible to compute the statistics based 1115 on a series of OAM packets. This, however, has the disadvantage of 1116 being artificial, and may not be representative since part of the 1117 packet loss may be dependent upon packet sizes and upon the 1118 implementation of the MEPs that take part in the protocol. 1120 o Sending delimiting messages for the start and end of a measurement 1121 period during which the source and sink of the path count the 1122 packets transmitted and received. After the end delimiter, the 1123 ratio would be calculated by the path OAM entity. 1125 4.5.4.8.2. Packet Delay Measurement (DM) 1127 Packet Delay Measurement is a function that is used to measure one- 1128 way or two-way delay of a packet transmission between a pair of the 1129 end-points of a path (PW, LSP, or Section). Where: 1131 o One-way packet delay, as defined in [IPPM-1DM], is the time 1132 elapsed from the start of transmission of the first bit of the 1133 packet by a source node until the reception of the last bit of 1134 that packet by the destination node. Note that one-way delay 1135 measurement requires the clocks of the two end-points to be 1136 synchronized. 1138 o Two-way packet delay, as defined in [IPPM-2DM], is the time 1139 elapsed from the start of transmission of the first bit of the 1140 packet by a source node until the reception of the last bit of the 1141 loop-backed packet by the same source node, when the loopback is 1142 performed at the packet's destination node. Note that due to 1143 possible path asymmetry, the one-way packet delay from one end- 1144 point to another is not necessarily equal to half of the two-way 1145 packet delay. 1146 As opposed to one-way delay measurement, two-way delay measurement 1147 does not require the two end-points to be synchronized. 1149 For each of these two metrics, the DM function allows the MEP to 1150 measure the delay, as well as the delay variation. Delay measurement 1151 is performed by exchanging timestamped OAM packets between the 1152 participating MEPs. 1154 4.6. Pseudowire OAM 1156 4.6.1. Pseudowire OAM using Virtual Circuit Connectivity Verification 1157 (VCCV) 1159 VCCV, as defined in [VCCV], provides a means for end-to-end fault 1160 detection and diagnostics tools to be extended for PWs (regardless of 1161 the underlying tunneling technology). The VCCV switching function 1162 provides a control channel associated with each PW. [VCCV] defines 1163 three Control Channel (CC) types, i.e., three possible methods for 1164 transmitting and identifying OAM messages: 1166 o CC Type 1: In-band VCCV, as described in [VCCV], is also referred 1167 to as "PWE3 Control Word with 0001b as first nibble". It uses the 1168 PW Associated Channel Header [PW-ACH]. 1170 o CC Type 2: Out-of-band VCCV [VCCV], is also referred to as "MPLS 1171 Router Alert Label". In this case the control channel is created 1172 by using the MPLS router alert label [RFC3032] immediately above 1173 the PW label. 1175 o CC Type 3: TTL expiry VCCV [VCCV], is also referred to as "MPLS PW 1176 Label with TTL == 1", i.e., the control channel is identified when 1177 the value of the TTL field in the PW label is set to 1. 1179 VCCV currently supports the following OAM tools: ICMP Ping, LSP Ping, 1180 and BFD. ICMP and LSP Ping are IP encapsulated before being sent over 1181 the PW ACH. BFD for VCCV [BFD-VCCV] supports two modes of 1182 encapsulation - either IP/UDP encapsulated (with IP/UDP header) or 1183 PW-ACH encapsulated (with no IP/UDP header) and provides support to 1184 signal the AC status. The use of the VCCV control channel provides 1185 the context, based on the MPLS-PW label, required to bind and 1186 bootstrap the BFD session to a particular pseudo wire (FEC), 1187 eliminating the need to exchange Discriminator values. 1189 VCCV consists of two components: (1) signaled component to 1190 communicate VCCV capabilities as part of VC label, and (2) switching 1191 component to cause the PW payload to be treated as a control packet. 1193 VCCV is not directly dependent upon the presence of a control plane. 1194 The VCCV capability negotiation may be performed as part of the PW 1195 signaling when LDP is used. In case of manual configuration of the 1196 PW, it is the responsibility of the operator to set consistent 1197 options at both ends. The manual option was created specifically to 1198 handle MPLS-TP use cases where no control plane was a requirement. 1199 However, new use cases such as pure mobile backhaul find this 1200 functionality useful too. 1202 The PWE3 working group has conducted an implementation survey of VCCV 1203 [VCCV-SURVEY], which analyzes which VCCV mechanisms are used in 1204 practice. 1206 4.6.2. Pseudowire OAM using G-ACh 1208 As mentioned above, VCCV enables OAM for PWs by using a control 1209 channel for OAM packets. When PWs are used in MPLS-TP networks, 1210 rather than the control channels defined in VCCV, the G-ACh can be 1211 used as an alternative control channel. The usage of the G-ACh for 1212 PWs is defined in [PW-G-ACh]. 1214 4.6.3. Attachment Circuit - Pseudowire Mapping 1216 The PWE3 working group has defined a mapping and notification of 1217 defect states between a pseudowire (PW) and the Attachment Circuits 1218 (ACs) of the end-to-end emulated service. This mapping is of key 1219 importance to the end-to-end functionality. Specifically, the mapping 1220 is provided by [PW-MAP], by [L2TP-EC] for L2TPv3 pseudowires, and 1221 Section 5.3 of [ATM-L2] for ATM. 1223 4.7. OWAMP and TWAMP 1225 4.7.1. Overview 1227 The IPPM working group in the IETF defines common criteria and 1228 metrics for measuring performance of IP traffic ([IPPM-FW]). Some of 1229 the key RFCs published by this working group have defined metrics for 1230 measuring connectivity [IPPM-Con], delay ([IPPM-1DM], [IPPM-2DM]), 1231 and packet loss [IPPM-1LM]. It should be noted that the work of the 1232 IETF in the context of performance metrics is not limited to IP 1233 networks; [PM-CONS] presents general guidelines for considering new 1234 performance metrics. 1236 The IPPM working group has defined not only metrics for performance 1237 measurement, but also protocols that define how the measurement is 1238 carried out. The One-way Active Measurement Protocol [OWAMP] and the 1239 Two-Way Active Measurement Protocol [TWAMP] define a method and 1240 protocol for measuring performance metrics in IP networks. 1242 OWAMP [OWAMP] enables measurement of one-way characteristics of IP 1243 networks, such as one-way packet loss and one-way delay. For its 1244 proper operation OWAMP requires accurate time of day setting at its 1245 end points. 1247 TWAMP [TWAMP] is a similar protocol that enables measurement of both 1248 one-way and two-way (round trip) characteristics. 1250 OWAMP and TWAMP are both comprised of two separate protocols: 1252 o OWAMP-Control/TWAMP-Control: used to initiate, start, and stop 1253 test sessions and to fetch their results. Continuity Check and 1254 Connectivity Verification are tested and confirmed by establishing 1255 the OWAMP/TWAMP Control Protocol TCP connection. 1257 o OWAMP-Test/TWAMP-Test: used to exchange test packets between two 1258 measurement nodes. Enables the loss and delay measurement 1259 functions, as well as detection of other anomalies, such as packet 1260 duplication and packet reordering. 1262 It should be noted that while [OWAMP] and [TWAMP] define tools for 1263 performance measurement, they do not define the accuracy of these 1264 tools. The accuracy depends on scale, implementation and network 1265 configurations. 1267 Alternative protocols for performance monitoring are defined, for 1268 example, in MPLS-TP OAM ([MPLS-LM-DM], [TP-LM-DM]), and in Ethernet 1269 OAM [ITU-T-Y1731]. 1271 4.7.2. Control and Test Protocols 1273 OWAMP and TWAMP control protocols run over TCP, while the test 1274 protocols run over UDP. The purpose of the control protocols is to 1275 initiate, start, and stop test sessions, and for OWAMP to fetch 1276 results. The test protocols introduce test packets (which contain 1277 sequence numbers and timestamps) along the IP path under test 1278 according to a schedule, and record statistics of packet arrival. 1279 Multiple sessions may be simultaneously defined, each with a session 1280 identifier, and defining the number of packets to be sent, the amount 1281 of padding to be added (and thus the packet size), the start time, 1282 and the send schedule (which can be either a constant time between 1283 test packets or exponentially distributed pseudo-random). Statistics 1284 recorded conform to the relevant IPPM RFCs. 1286 OWAMP and TWAMP test traffic is designed with security in mind. Test 1287 packets are hard to detect because they are simply UDP streams 1288 between negotiated port numbers, with potentially nothing static in 1289 the packets. OWAMP and TWAMP also include optional authentication 1290 and encryption for both control and test packets. 1292 4.7.3. OWAMP 1294 OWAMP defines the following logical roles: Session-Sender, Session- 1295 Receiver, Server, Control-Client, and Fetch-Client. The Session- 1296 Sender originates test traffic that is received by the Session- 1297 Receiver. The Server configures and manages the session, as well as 1298 returning the results. The Control-Client initiates requests for 1299 test sessions, triggers their start, and may trigger their 1300 termination. The Fetch-Client requests the results of a completed 1301 session. Multiple roles may be combined in a single host - for 1302 example, one host may play the roles of Control-Client, Fetch-Client, 1303 and Session-Sender, and a second playing the roles of Server and 1304 Session-Receiver. 1306 In a typical OWAMP session the Control-Client establishes a TCP 1307 connection to port 861 of the Server, which responds with a server 1308 greeting message indicating supported security/integrity modes. The 1309 Control-Client responds with the chosen communications mode and the 1310 Server accepts the modes. The Control-Client then requests and fully 1311 describes a test session to which the Server responds with its 1312 acceptance and supporting information. More than one test session 1313 may be requested with additional messages. The Control-Client then 1314 starts a test session and the Server acknowledges. The Session- 1315 Sender then sends test packets with pseudorandom padding to the 1316 Session-Receiver until the session is complete or until the Control- 1317 client stops the session. Once finished, the Fetch-Client sends a 1318 fetch request to the server, which responds with an acknowledgement 1319 and immediately thereafter the result data. 1321 4.7.4. TWAMP 1323 TWAMP defines the following logical roles: session-sender, session- 1324 reflector, server, and control-client. These are similar to the 1325 OWAMP roles, except that the Session-Reflector does not collect any 1326 packet information, and there is no need for a Fetch-Client. 1328 In a typical TWAMP session the Control-Client establishes a TCP 1329 connection to port 862 of the Server, and mode is negotiated as in 1330 OWAMP. The Control-Client then requests sessions and starts them. 1331 The Session-Sender sends test packets with pseudorandom padding to 1332 the Session-Reflector which returns them with insertion of 1333 timestamps. 1335 4.8. TRILL 1337 The requirements of OAM in TRILL are defined in [TRILL-OAM]. The 1338 challenge in TRILL OAM, much like in MPLS networks, is that traffic 1339 between RBridges RB1 and RB2 may be forwarded through more than one 1340 path. Thus, an OAM protocol between RBridges RB1 and RB2 must be able 1341 to monitor all the available paths between the two RBridge. 1343 During the writing of this document the detailed definition of the 1344 TRILL OAM tools are still work in progress. This subsection presents 1345 the main requirements of TRILL OAM. 1347 The main requirements defined in [TRILL-OAM] are: 1349 o Continuity Checking (CC) - the TRILL OAM protocol must support a 1350 function for CC between any two RBridges RB1 and RB2. 1352 o Connectivity Verification (CV) - connectivity between two RBridges 1353 RB1 and RB2 can be verified on a per-flow basis. 1355 o Path Tracing - allows an RBridge to trace all the available paths 1356 to a peer RBridge. 1358 o Performance monitoring - allows an RBridge to monitor the packet 1359 loss and packet delay to a peer RBridge. 1361 5. Summary 1363 This section summarizes the OAM tools and functions presented in this 1364 document. This summary is an index to some of the main OAM tools 1365 defined in the IETF. This compact index that can be useful to all 1366 readers from network operators to standard development organizations. 1367 The summary includes a short subsection that presents some guidance 1368 to network equipment vendors. 1370 5.1. Summary of OAM Tools 1372 This subsection provides a short summary of each of the OAM toolsets 1373 described in this document. 1375 A detailed list of the RFCs related to each toolset is given in 1376 Appendix A.1. 1378 +-----------+------------------------------------------+------------+ 1379 | Toolset | Description | Transport | 1380 | | | Technology | 1381 +-----------+------------------------------------------+------------+ 1382 |IP Ping | Ping ([IntHost], [NetTerms]) is a simple | IPv4/IPv6 | 1383 | | application for testing reachability that| | 1384 | | uses ICMP Echo messages ([ICMPv4], | | 1385 | | [ICMPv6]). | | 1386 +-----------+------------------------------------------+------------+ 1387 |IP | Traceroute ([TCPIP-Tools], [NetTools]) is| IPv4/IPv6 | 1388 |Traceroute | an application that allows users to trace| | 1389 | | the path between an IP source and an IP | | 1390 | | destination, i.e., to identify the nodes | | 1391 | | along the path. If more than one path | | 1392 | | exists between the source and destination| | 1393 | | Traceroute traces *a* path. The most | | 1394 | | common implementation of Traceroute | | 1395 | | uses UDP probe messages, although there | | 1396 | | are other implementations that use | | 1397 | | different probes, such as ICMP or TCP. | | 1398 +-----------+------------------------------------------+------------+ 1399 |BFD | Bidirectional Forwarding Detection (BFD) | generic | 1400 | | is defined in [BFD] as a framework for a | | 1401 | | lightweight generic OAM tool. The | | 1402 | | intention is to define a base tool | | 1403 | | that can be used with various | | 1404 | | encapsulation types, network | | 1405 | | environments, and in various medium | | 1406 | | types. | | 1407 +-----------+------------------------------------------+------------+ 1408 |MPLS OAM | MPLS LSP Ping, as defined in [MPLS-OAM], | MPLS | 1409 | | [MPLS-OAM-FW] and [LSP-Ping], is an OAM | | 1410 | | tool for point-to-point and | | 1411 | | point-to-multipoint MLPS LSPs. | | 1412 | | It includes two main functions: Ping and | | 1413 | | Traceroute. | | 1414 | | It is noted that while this category | | 1415 | | focuses on LSP Ping, other OAM tools | | 1416 | | can be used in MPLS networks, e.g., BFD. | | 1417 +-----------+------------------------------------------+------------+ 1418 |MPLS-TP OAM| MPLS-TP OAM is defined in a set of RFCs. | MPLS-TP | 1419 | | The OAM requirements for MPLS Transport | | 1420 | | Profile (MPLS-TP) are defined in | | 1421 | | [MPLS-TP-OAM]. Each of the tools in the | | 1422 | | OAM toolset is defined in its own RFC, as| | 1423 | | specified in Section A.1. | | 1424 +-----------+------------------------------------------+------------+ 1425 |Pseudowire | The PWE3 OAM architecture defines control| Pseudowire | 1426 |OAM | channels that support the use of existing| | 1427 | | IETF OAM tools to be used for a pseudo- | | 1428 | | wire (PW). The control channels that are| | 1429 | | defined in [VCCV] and [PW-G-ACh] may be | | 1430 | | used in conjunction with ICMP Ping, LSP | | 1431 | | Ping, and BFD to perform CC and CV | | 1432 | | functionality. In addition the channels | | 1433 | | support use of any of the MPLS-TP based | | 1434 | | OAM tools for completing their respective| | 1435 | | OAM functionality for a PW. | | 1436 +-----------+------------------------------------------+------------+ 1437 |OWAMP and | The One Way Active Measurement Protocol | IPv4/IPv6 | 1438 |TWAMP | (OWAMP) and the Two Way Active Measure- | | 1439 | | ment Protocols (TWAMP) are two protocols | | 1440 | | defined in the IP Performance Metrics | | 1441 | | (IPPM) working group in the IETF. These | | 1442 | | protocols allow various performance | | 1443 | | metrics to be measured, such as packet | | 1444 | | loss, delay and delay variation, | | 1445 | | duplication and reordering. | | 1446 +-----------+------------------------------------------+------------+ 1447 |TRILL OAM | The requirements of OAM in TRILL are | TRILL | 1448 | | defined in [TRILL-OAM]. These | | 1449 | | requirements include continuity checking,| | 1450 | | connectivity verification, path tracing | | 1451 | | and performance monitoring. During the | | 1452 | | writing of this document the detailed | | 1453 | | definition of the TRILL OAM tools | | 1454 | | is work in progress. | | 1455 +-----------+------------------------------------------+------------+ 1456 Table 3 Summary of OAM-related IETF Tools 1458 5.2. Summary of OAM Functions 1460 Table 4 summarizes the OAM functions that are supported in each of 1461 the toolsets that were analyzed in this section. The columns of this 1462 tables are the typical OAM functions described in Section 1.3. 1464 +-----------+-------+--------+--------+-------+----------+ 1465 | |Continu|Connecti|Path |Perform|Other | 1466 | |ity |vity |Discover|ance |Function | 1467 | |Check |Verifica|y |Monitor|s | 1468 | Toolset | |tion | |ing | | 1469 +-----------+-------+--------+--------+-------+----------+ 1470 |IP Ping |Echo | | | | | 1471 + --------- + ----- + ------ + ------ + ----- + -------- + 1472 |IP | | |Tracerou| | | 1473 |Traceroute | | |te | | | 1474 + --------- + ----- + ------ + ------ + ----- + -------- + 1475 |BFD |BFD |BFD | | |RDI usi- | 1476 | |Control|Control | | |ng BFD | 1477 | |/ Echo | | | |Control | 1478 + --------- + ----- + ------ + ------ + ----- + -------- + 1479 |MPLS OAM | |"Ping" |"Tracero| | | 1480 |(LSP Ping) | |mode |ute" | | | 1481 | | | |mode | | | 1482 + --------- + ----- + ------ + ------ + ----- + -------- + 1483 |MPLS-TP |CC |CV/pro- |Route |-LM |-Diagnos- | 1484 |OAM | |active |Tracing |-DM | tic Test | 1485 | | |or on- | | |-Lock | 1486 | | |demand | | |-Alarm | 1487 | | | | | |Reporting | 1488 | | | | | |-Client | 1489 | | | | | |Failure | 1490 | | | | | |Indication| 1491 | | | | | |-RDI | 1492 + --------- + ----- + ------ + ------ + ----- + -------- + 1493 |Pseudowire |BFD |-BFD |LSP-Ping| | | 1494 |OAM | |-ICMP | | | | 1495 | | | Ping | | | | 1496 | | |-LSP- | | | | 1497 | | | Ping | | | | 1498 + --------- + ----- + ------ + ------ + ----- + -------- + 1499 |OWAMP and | - control | |-Delay | | 1500 |TWAMP | protocol | | measur| | 1501 | | | | ement | | 1502 | | | |-Packet| | 1503 | | | | loss | | 1504 | | | | measur| | 1505 | | | | ement | | 1506 + --------- + ----- + ------ + ------ + ----- + -------- + 1507 |TRILL OAM |CC |CV |Path |-Delay | | 1508 | | | |tracing | measur| | 1509 | | | | | ement | | 1510 | | | | |-Packet| | 1511 | | | | | loss | | 1512 | | | | | measur| | 1513 | | | | | ement | | 1514 +-----------+-------+--------+--------+-------+----------+ 1515 Table 4 Summary of the OAM Functionality in IETF OAM Tools 1517 5.3. Guidance to Network Equipment Vendors 1519 As mentioned in Section 1.4. , it is imperative for OAM tools to be 1520 capable of testing the actual data plane in as much accuracy as 1521 possible. Thus, it is important to enforce fate-sharing between OAM 1522 traffic that monitors the data plane and the data plane traffic it 1523 monitors. 1525 6. Security Considerations 1527 This memo presents an overview of existing OAM tools, and proposes 1528 no new OAM tools. Therefore, this document introduces no security 1529 considerations. However, the OAM tools reviewed in this document can 1530 and do present security issues. The reader is encouraged to review 1531 the Security Considerations section of each document referenced by 1532 this memo. 1534 7. IANA Considerations 1536 There are no new IANA considerations implied by this document. 1538 8. Acknowledgments 1540 The authors gratefully acknowledge Sasha Vainshtein, Carlos 1541 Pignataro, David Harrington, Dan Romascanu, Ron Bonica and other 1542 members of the OPSAWG mailing list for their helpful comments. 1544 This document was prepared using 2-Word-v2.0.template.dot. 1546 9. References 1548 9.1. Informative References 1550 [ATM-L2] Singh, S., Townsley, M., and C. Pignataro, 1551 "Asynchronous Transfer Mode (ATM) over Layer 2 1552 Tunneling Protocol Version 3 (L2TPv3)", RFC 4454, May 1553 2006. 1555 [BFD] Katz, D., Ward, D., "Bidirectional Forwarding Detection 1556 (BFD)", RFC 5880, June 2010. 1558 [BFD-Gen] Katz, D., Ward, D., "Generic Application of 1559 Bidirectional Forwarding Detection (BFD)", RFC 5882, 1560 June 2010. 1562 [BFD-IP] Katz, D., Ward, D., "Bidirectional Forwarding Detection 1563 (BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881, June 1564 2010. 1566 [BFD-LSP] Aggarwal, R., Kompella, K., Nadeau, T., and Swallow, 1567 G., "Bidirectional Forwarding Detection (BFD) for MPLS 1568 Label Switched Paths (LSPs)", RFC 5884, June 2010. 1570 [BFD-Multi] Katz, D., Ward, D., "Bidirectional Forwarding Detection 1571 (BFD) for Multihop Paths", RFC 5883, June 2010. 1573 [BFD-VCCV] Nadeau, T., Pignataro, C., "Bidirectional Forwarding 1574 Detection (BFD) for the Pseudowire Virtual Circuit 1575 Connectivity Verification (VCCV)", RFC 5885, June 1576 2010. 1578 [Comp] Bonaventure, O., "Computer Networking: Principles, 1579 Protocols and Practice", 2008. 1581 [Cont] Dugal, D., Pignataro, C., Dunn, R., "Protecting the 1582 Router Control Plane", RFC 6192, March 2011. 1584 [Dup] Uijterwaal, H., "A One-Way Packet Duplication Metric", 1585 RFC 5560, May 2009. 1587 [G-ACh] Bocci, M., Vigoureux, M., Bryant, S., "MPLS Generic 1588 Associated Channel", RFC 5586, June 2009. 1590 [ICMP-Ext] Bonica, R., Gan, D., Tappan, D., Pignataro, C., "ICMP 1591 Extensions for Multiprotocol Label Switching", RFC 1592 4950, August 2007. 1594 [ICMP-Int] Atlas, A., Bonica, R., Pignataro, C., Shen, N., Rivers, 1595 JR., "Extending ICMP for Interface and Next-Hop 1596 Identification", RFC 5837, April 2010. 1598 [ICMP-MP] Bonica, R., Gan, D., Tappan, D., Pignataro, C., 1599 "Extended ICMP to Support Multi-Part Messages", RFC 1600 4884, April 2007. 1602 [ICMPv4] Postel, J., "Internet Control Message Protocol", STD 5, 1603 RFC 792, September 1981. 1605 [ICMPv6] Conta, A., Deering, S., and M. Gupta, "Internet Control 1606 Message Protocol (ICMPv6) for the Internet Protocol 1607 Version 6 (IPv6) Specification", RFC 4443, March 2006. 1609 [IEEE802.1Q] IEEE 802.1Q, "IEEE Standard for Local and metropolitan 1610 area networks - Media Access Control (MAC) Bridges and 1611 Virtual Bridged Local Area Networks", October 2012. 1613 [IEEE802.3ah] IEEE 802.3, "IEEE Standard for Information technology - 1614 Local and metropolitan area networks - Carrier sense 1615 multiple access with collision detection (CSMA/CD) 1616 access method and physical layer specifications", 1617 clause 57, December 2008. 1619 [IntHost] Braden, R., "Requirements for Internet Hosts -- 1620 Communication Layers", RFC 1122, October 1989. 1622 [IPPM-1DM] Almes, G., Kalidindi, S., Zekauskas, M., "A One-way 1623 Delay Metric for IPPM", RFC 2679, September 1999. 1625 [IPPM-1LM] Almes, G., Kalidindi, S., Zekauskas, M., "A One-way 1626 Packet Loss Metric for IPPM", RFC 2680, September 1627 1999. 1629 [IPPM-2DM] Almes, G., Kalidindi, S., Zekauskas, M., "A Round-trip 1630 Delay Metric for IPPM", RFC 2681, September 1999. 1632 [IPPM-Con] Mahdavi, J., Paxson, V., "IPPM Metrics for Measuring 1633 Connectivity", RFC 2678, September 1999. 1635 [IPPM-FW] Paxson, V., Almes, G., Mahdavi, J., and Mathis, M., 1636 "Framework for IP Performance Metrics", RFC 2330, May 1637 1998. 1639 [ITU-G8113.1] ITU-T Recommendation G.8113.1/Y.1372.1, "Operations, 1640 Administration and Maintenance mechanism for MPLS-TP 1641 in Packet Transport Network (PTN)", November 2012. 1643 [ITU-G8113.2] ITU-T Recommendation G.8113.2/Y.1372.2, "Operations, 1644 administration and maintenance mechanisms for MPLS-TP 1645 networks using the tools defined for MPLS", November 1646 2012. 1648 [ITU-T-CT] Betts, M., "Allocation of a Generic Associated Channel 1649 Type for ITU-T MPLS Transport Profile Operation, 1650 Maintenance, and Administration (MPLS-TP OAM)", RFC 1651 6671, November 2012. 1653 [ITU-T-G.806] ITU-T Recommendation G.806, "Characteristics of 1654 transport equipment - Description methodology and 1655 generic functionality", January 2009. 1657 [ITU-T-Y1711] ITU-T Recommendation Y.1711, "Operation & Maintenance 1658 mechanism for MPLS networks", February 2004. 1660 [ITU-T-Y1731] ITU-T Recommendation G.8013/Y.1731, "OAM Functions and 1661 Mechanisms for Ethernet-based Networks", July 2011. 1663 [ITU-Terms] ITU-R/ITU-T Terms and Definitions, online, 2013. 1665 [L2TP-EC] McGill, N. and C. Pignataro, "Layer 2 Tunneling 1666 Protocol Version 3 (L2TPv3) Extended Circuit Status 1667 Values", RFC 5641, August 2009. 1669 [Lock-Loop] Boutros, S., Sivabalan, S., Aggarwal, R., Vigoureux, 1670 M., Dai, X., "MPLS Transport Profile Lock Instruct and 1671 Loopback Functions", RFC 6435, November 2011. 1673 [LSP-Ping] Kompella, K., Swallow, G., "Detecting Multi-Protocol 1674 Label Switched (MPLS) Data Plane Failures", RFC 4379, 1675 February 2006. 1677 [Mng] Farrel, A., "Inclusion of Manageability Sections in 1678 Path Computation Element (PCE) Working Group Drafts", 1679 RFC 6123, February 2011. 1681 [MPLS-LM-DM] Frost, D., Bryant, S., "Packet Loss and Delay 1682 Measurement for MPLS Networks", RFC 6374, September 1683 2011. 1685 [MPLS-OAM] Nadeau, T., Morrow, M., Swallow, G., Allan, D., 1686 Matsushima, S., "Operations and Management (OAM) 1687 Requirements for Multi-Protocol Label Switched (MPLS) 1688 Networks", RFC 4377, February 2006. 1690 [MPLS-OAM-FW] Allan, D., Nadeau, T., "A Framework for Multi-Protocol 1691 Label Switching (MPLS) Operations and Management 1692 (OAM)", RFC 4378, February 2006. 1694 [MPLS-P2MP] Yasukawa, S., Farrel, A., King, D., Nadeau, T., 1695 "Operations and Management (OAM) Requirements for 1696 Point-to-Multipoint MPLS Networks", RFC 4687, 1697 September 2006. 1699 [MPLS-TP-OAM] Vigoureux, M., Ward, D., Betts, M., "Requirements for 1700 OAM in MPLS Transport Networks", RFC 5860, May 2010. 1702 [NetTerms] Jacobsen, O., Lynch, D., "A Glossary of Networking 1703 Terms", RFC 1208, March 1991. 1705 [NetTools] Enger, R., Reynolds, J., "FYI on a Network Management 1706 Tool Catalog: Tools for Monitoring and Debugging 1707 TCP/IP Internets and Interconnected Devices", RFC 1708 1470, June 1993. 1710 [OAM-Analys] Sprecher, N., Fang, L., "An Overview of the OAM Tool 1711 Set for MPLS based Transport Networks", RFC 6669, 1712 July 2012. 1714 [OAM-Def] Andersson, L., Van Helvoort, H., Bonica, R., Romascanu, 1715 D., Mansfield, S., "Guidelines for the use of the OAM 1716 acronym in the IETF ", RFC 6291, June 2011. 1718 [OAM-Label] Ohta, H., "Assignment of the 'OAM Alert Label' for 1719 Multiprotocol Label Switching Architecture (MPLS) 1720 Operation and Maintenance (OAM) Functions", RFC 3429, 1721 November 2002. 1723 [OnDemand-CV] Gray, E., Bahadur, N., Boutros, S., Aggarwal, R. "MPLS 1724 On-Demand Connectivity Verification and Route 1725 Tracing", RFC 6426, November 2011. 1727 [OWAMP] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and 1728 Zekauskas, M., "A One-way Active Measurement Protocol 1729 (OWAMP)", RFC 4656, September 2006. 1731 [PARIS] Brice Augustin, Timur Friedman and Renata Teixeira, 1732 "Measuring Load-balanced Paths in the Internet", IMC, 1733 2007. 1735 [PM-CONS] Clark, A. and B. Claise, "Guidelines for Considering 1736 New Performance Metric Development", BCP 170, RFC 1737 6390, October 2011. 1739 [PW-ACH] Bryant, S., Swallow, G., Martini, L., McPherson, D., 1740 "Pseudowire Emulation Edge-to-Edge (PWE3) Control Word 1741 for Use over an MPLS PSN", RFC 4385, February 2006. 1743 [PW-G-ACh] Li, H., Martini, L., He, J., Huang, F., "Using the 1744 Generic Associated Channel Label for Pseudowire in the 1745 MPLS Transport Profile (MPLS-TP)", RFC 6423, November 1746 2011. 1748 [PW-MAP] Aissaoui, M., Busschbach, P., Martini, L., Morrow, M., 1749 Nadeau, T., and Y(J). Stein, "Pseudowire (PW) 1750 Operations, Administration, and Maintenance (OAM) 1751 Message Mapping", RFC 6310, July 2011. 1753 [PW-Map] M. Aissaoui, P. Busschbach, L. Martini, M. Morrow, T. 1754 Nadeau, "Pseudowire (PW) Operations, Administration, 1755 and Maintenance (OAM) Message Mapping", RFC 6310, July 1756 2011. 1758 [Reorder] Morton, A., Ciavattone, L., Ramachandran, G., Shalunov, 1759 S., and J. Perser, "Packet Reordering Metrics", RFC 1760 4737, November 2006. 1762 [Signal] Yasukawa, S., "Signaling Requirements for Point-to- 1763 Multipoint Traffic-Engineered MPLS Label Switched 1764 Paths (LSPs)", RFC 4461, April 2006. 1766 [TCPIP-Tools] Kessler, G., Shepard, S., "A Primer On Internet and 1767 TCP/IP Tools and Utilities", RFC 2151, June 1997. 1769 [TP-CC-CV] Allan, D., Swallow, G., Drake, J., "Proactive 1770 Connectivity Verification, Continuity Check and Remote 1771 Defect indication for MPLS Transport Profile", RFC 1772 6428, November 2011. 1774 [TP-Fault] Swallow, G., Fulignoli, A., Vigoureux, M., Boutros, S., 1775 "MPLS Fault Management Operations, Administration, and 1776 Maintenance (OAM)", RFC 6427, November 2011. 1778 [TP-LM-DM] Frost, D., Bryant, S., "A Packet Loss and Delay 1779 Measurement Profile for MPLS-Based Transport 1780 Networks", RFC 6375, September 2011. 1782 [TP-OAM-FW] Busi, I., Allan, D., "Operations, Administration and 1783 Maintenance Framework for MPLS-based Transport 1784 Networks ", RFC 6371, September 2011. 1786 [TP-Term] Van Helvoort, H., Andersson, L., Sprecher, N., "A 1787 Thesaurus for the Terminology used in Multiprotocol 1788 Label Switching Transport Profile (MPLS-TP) 1789 drafts/RFCs and ITU-T's Transport Network 1790 Recommendations", work-in-progress, draft-ietf-mpls- 1791 tp-rosetta-stone, July 2012. 1793 [TRILL-OAM] Senevirathne, T., Bond, D., Aldrin, S., Li, Y., Watve, 1794 R., "Requirements for Operations, Administration, and 1795 Maintenance (OAM) in Transparent Interconnection of 1796 Lots of Links (TRILL)", RFC 6905, March 2013. 1798 [TWAMP] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and 1799 Babiarz, J., "A Two-Way Active Measurement Protocol 1800 (TWAMP)", RFC 5357, October 2008. 1802 [VCCV] Nadeau, T., Pignataro, C., "Pseudowire Virtual Circuit 1803 Connectivity Verification (VCCV): A Control Channel 1804 for Pseudowires", RFC 5085, December 2007. 1806 [VCCV-SURVEY] Del Regno, N., Malis, A., "The Pseudowire (PW) & 1807 Virtual Circuit Connectivity Verification (VCCV) 1808 Implementation Survey Results", work-in-progress, 1809 draft-ietf-pwe3-vccv-impl-survey-results, August 2013. 1811 Appendix A. List of OAM Documents 1813 A.1. List of IETF OAM Documents 1815 Table 5 summarizes the OAM related RFCs published by the IETF. 1817 It is important to note that the table lists various RFCs that are 1818 different by nature. For example, some of these documents define OAM 1819 tools or OAM protocols (or both), while others define protocols that 1820 are not strictly OAM-related, but are used by OAM tools. The table 1821 also includes RFCs that define the requirements or the framework of 1822 OAM in a specific context (e.g., MPLS-TP). 1824 The RFCs in the table are categorized in a few sets as defined in 1825 Section 1.3. 1827 +-----------+--------------------------------------+----------+ 1828 | Toolset | Title | RFC | 1829 +-----------+--------------------------------------+----------+ 1830 |IP Ping | Requirements for Internet Hosts -- | RFC 1122 | 1831 | | Communication Layers [IntHost] | | 1832 | +--------------------------------------+----------+ 1833 | | A Glossary of Networking Terms | RFC 1208 | 1834 | | [NetTerms] | | 1835 | +--------------------------------------+----------+ 1836 | | Internet Control Message Protocol | RFC 792 | 1837 | | [ICMPv4] | | 1838 | +--------------------------------------+----------+ 1839 | | Internet Control Message Protocol | RFC 4443 | 1840 | | (ICMPv6) for the Internet Protocol | | 1841 | | Version 6 (IPv6) Specification | | 1842 | | [ICMPv6] | | 1843 +-----------+--------------------------------------+----------+ 1844 |IP | A Primer On Internet and TCP/IP | RFC 2151 | 1845 |Traceroute | Tools and Utilities [TCPIP-Tools] | | 1846 | +--------------------------------------+----------+ 1847 | | FYI on a Network Management Tool | RFC 1470 | 1848 | | Catalog: Tools for Monitoring and | | 1849 | | Debugging TCP/IP Internets and | | 1850 | | Interconnected Devices [NetTools] | | 1851 | +--------------------------------------+----------+ 1852 | | Internet Control Message Protocol | RFC 792 | 1853 | | [ICMPv4] | | 1854 | +--------------------------------------+----------+ 1855 | | Internet Control Message Protocol | RFC 4443 | 1856 | | (ICMPv6) for the Internet Protocol | | 1857 | | Version 6 (IPv6) Specification | | 1858 | | [ICMPv6] | | 1859 | +--------------------------------------+----------+ 1860 | | Extended ICMP to Support Multi-Part | RFC 4884 | 1861 | | Messages [ICMP-MP] | | 1862 | +--------------------------------------+----------+ 1863 | | Extending ICMP for Interface and | RFC 5837 | 1864 | | Next-Hop Identification [ICMP-Int] | | 1865 +-----------+--------------------------------------+----------+ 1866 |BFD | Bidirectional Forwarding Detection | RFC 5880 | 1867 | | [BFD] | | 1868 | +--------------------------------------+----------+ 1869 | | Bidirectional Forwarding Detection | RFC 5881 | 1870 | | (BFD) for IPv4 and IPv6 (Single Hop) | | 1871 | | [BFD-IP] | | 1872 | +--------------------------------------+----------+ 1873 | | Generic Application of Bidirectional | RFC 5882 | 1874 | | Forwarding Detection [BFD-Gen] | | 1875 | +--------------------------------------+----------+ 1876 | | Bidirectional Forwarding Detection | RFC 5883 | 1877 | | (BFD) for Multihop Paths [BFD-Multi] | | 1878 | +--------------------------------------+----------+ 1879 | | Bidirectional Forwarding Detection | RFC 5884 | 1880 | | for MPLS Label Switched Paths (LSPs) | | 1881 | | [BFD-LSP] | | 1882 | +--------------------------------------+----------+ 1883 | | Bidirectional Forwarding Detection | RFC 5885 | 1884 | | for the Pseudowire Virtual Circuit | | 1885 | | Connectivity Verification (VCCV) | | 1886 | | [BFD-VCCV] | | 1887 +-----------+--------------------------------------+----------+ 1888 |MPLS OAM | Operations and Management (OAM) | RFC 4377 | 1889 | | Requirements for Multi-Protocol Label| | 1890 | | Switched (MPLS) Networks [MPLS-OAM] | | 1891 | +--------------------------------------+----------+ 1892 | | A Framework for Multi-Protocol | RFC 4378 | 1893 | | Label Switching (MPLS) Operations | | 1894 | | and Management (OAM) [MPLS-OAM-FW] | | 1895 | +--------------------------------------+----------+ 1896 | | Detecting Multi-Protocol Label | RFC 4379 | 1897 | | Switched (MPLS) Data Plane Failures | | 1898 | | [LSP-Ping] | | 1899 | +--------------------------------------+----------+ 1900 | | Operations and Management (OAM) | RFC 4687 | 1901 | | Requirements for Point-to-Multipoint | | 1902 | | MPLS Networks [MPLS-P2MP] | | 1903 | +--------------------------------------+----------+ 1904 | | ICMP Extensions for Multiprotocol | RFC 4950 | 1905 | | Label Switching [ICMP-Ext] | | 1906 +-----------+--------------------------------------+----------+ 1907 |MPLS-TP | Requirements for OAM in MPLS-TP | RFC 5860 | 1908 |OAM | [MPLS-TP-OAM] | | 1909 | +--------------------------------------+----------+ 1910 | | MPLS Generic Associated Channel | RFC 5586 | 1911 | | [G-ACh] | | 1912 | +--------------------------------------+----------+ 1913 | | MPLS-TP OAM Framework | RFC 6371 | 1914 | | [TP-OAM-FW] | | 1915 | +--------------------------------------+----------+ 1916 | | Proactive Connectivity Verification, | RFC 6428 | 1917 | | Continuity Check, and Remote Defect | | 1918 | | Indication for the MPLS Transport | | 1919 | | Profile [TP-CC-CV] | | 1920 | +--------------------------------------+----------+ 1921 | | MPLS On-Demand Connectivity | RFC 6426 | 1922 | | Verification and Route Tracing | | 1923 | | [OnDemand-CV] | | 1924 | +--------------------------------------+----------+ 1925 | | MPLS Fault Management Operations, | RFC 6427 | 1926 | | Administration, and Maintenance (OAM)| | 1927 | | [TP-Fault] | | 1928 | +--------------------------------------+----------+ 1929 | | MPLS Transport Profile Lock Instruct | RFC 6435 | 1930 | | and Loopback Functions [Lock-Loop] | | 1931 | +--------------------------------------+----------+ 1932 | | Packet Loss and Delay Measurement for| RFC 6374 | 1933 | | MPLS Networks [MPLS-LM-DM] | | 1934 | +--------------------------------------+----------+ 1935 | | A Packet Loss and Delay Measurement | RFC 6375 | 1936 | | Profile for MPLS-Based Transport | | 1937 | | Networks [TP-LM-DM] | | 1938 +-----------+--------------------------------------+----------+ 1939 |Pseudowire | Pseudowire Virtual Circuit | RFC 5085 | 1940 |OAM | Connectivity Verification (VCCV): | | 1941 | | A Control Channel for Pseudowires | | 1942 | | [VCCV] | | 1943 | +--------------------------------------+----------+ 1944 | | Bidirectional Forwarding Detection | RFC 5885 | 1945 | | for the Pseudowire Virtual Circuit | | 1946 | | Connectivity Verification (VCCV) | | 1947 | | [BFD-VCCV] | | 1948 | +--------------------------------------+----------+ 1949 | | Using the Generic Associated Channel | RFC 6423 | 1950 | | Label for Pseudowire in the MPLS | | 1951 | | Transport Profile (MPLS-TP) | | 1952 | | [PW-G-ACh] | | 1953 | +--------------------------------------+----------+ 1954 | | Pseudowire (PW) Operations, | RFC 6310 | 1955 | | Administration, and Maintenance (OAM)| | 1956 | | Message Mapping [PW-Map] | | 1957 +-----------+--------------------------------------+----------+ 1958 |OWAMP and | A One-way Active Measurement Protocol| RFC 4656 | 1959 |TWAMP | [OWAMP] | | 1960 | +--------------------------------------+----------+ 1961 | | A Two-Way Active Measurement Protocol| RFC 5357 | 1962 | | [TWAMP] | | 1963 | +--------------------------------------+----------+ 1964 | | Framework for IP Performance Metrics | RFC 2330 | 1965 | | [IPPM-FW] | | 1966 | +--------------------------------------+----------+ 1967 | | IPPM Metrics for Measuring | RFC 2678 | 1968 | | Connectivity [IPPM-Con] | | 1969 | +--------------------------------------+----------+ 1970 | | A One-way Delay Metric for IPPM | RFC 2679 | 1971 | | [IPPM-1DM] | | 1972 | +--------------------------------------+----------+ 1973 | | A One-way Packet Loss Metric for IPPM| RFC 2680 | 1974 | | [IPPM-1LM] | | 1975 | +--------------------------------------+----------+ 1976 | | A Round-trip Delay Metric for IPPM | RFC 2681 | 1977 | | [IPPM-2DM] | | 1978 | +--------------------------------------+----------+ 1979 | | Packet Reordering Metrics | RFC 4737 | 1980 | | [Reorder] | | 1981 | +--------------------------------------+----------+ 1982 | | A One-Way Packet Duplication Metric | RFC 5560 | 1983 | | [Dup] | | 1984 +-----------+--------------------------------------+----------+ 1985 |TRILL OAM | Requirements for Operations, | RFC 6905 | 1986 | | Administration, and Maintenance (OAM)| | 1987 | | in Transparent Interconnection of | | 1988 | | Lots of Links (TRILL) | | 1989 +-----------+--------------------------------------+----------+ 1990 Table 5 Summary of IETF OAM Related RFCs 1992 A.2. List of Selected Non-IETF OAM Documents 1994 In addition to the OAM tools defined by the IETF, the IEEE and ITU-T 1995 have also defined various OAM tools that focus on Ethernet, and 1996 various other transport network environments. These various tools, 1997 defined by the three standard organizations, are often tightly 1998 coupled, and have had a mutual effect on each other. The ITU-T and 1999 IETF have both defined OAM tools for MPLS LSPs, [ITU-T-Y1711] and 2000 [LSP-Ping]. The following OAM standards by the IEEE and ITU-T are to 2001 some extent linked to IETF OAM tools listed above and are mentioned 2002 here only as reference material: 2004 o OAM tools for Layer 2 have been defined by the ITU-T in 2005 [ITU-T-Y1731], and by the IEEE in 802.1ag [IEEE802.1Q] . The IEEE 2006 802.3 standard defines OAM for one-hop Ethernet links 2007 [IEEE802.3ah]. 2009 o The ITU-T has defined OAM for MPLS LSPs in [ITU-T-Y1711], and 2010 MPLS-TP OAM in [ITU-G8113.1] and [ITU-G8113.2]. 2012 It should be noted that these non-IETF documents deal in many cases 2013 with OAM functions below the IP layer (Layer 2, Layer 2.5) and in 2014 some cases operators use a multi-layered OAM approach, which is a 2015 function of the way their networks are designed. 2017 Table 6 summarizes some of the main OAM standards published by non- 2018 IETF standard organizations. This document focuses on IETF OAM 2019 standards, but these non-IETF standards are referenced in this 2020 document where relevant. 2022 +-----------+--------------------------------------+---------------+ 2023 | | Title |Standard/Draft | 2024 +-----------+--------------------------------------+---------------+ 2025 |ITU-T | Operation & Maintenance mechanism | ITU-T Y.1711 | 2026 |MPLS OAM | for MPLS networks [ITU-T-Y1711] | | 2027 | +--------------------------------------+---------------+ 2028 | | Assignment of the 'OAM Alert Label' | RFC 3429 | 2029 | | for Multiprotocol Label Switching | | 2030 | | Architecture (MPLS) Operation and | | 2031 | | Maintenance (OAM) Functions | | 2032 | | [OAM-Label] | | 2033 | | | | 2034 | | Note: although this is an IETF | | 2035 | | document, it is listed as one of the| | 2036 | | non-IETF OAM standards, since it | | 2037 | | was defined as a complementary part | | 2038 | | of ITU-T Y.1711. | | 2039 +-----------+--------------------------------------+---------------+ 2040 |ITU-T | Operations, administration and |ITU-T G.8113.2 | 2041 |MPLS-TP OAM| Maintenance mechanisms for MPLS-TP | | 2042 | | networks using the tools defined for | | 2043 | | MPLS [ITU-G8113.2] | | 2044 | | | | 2045 | | Note: this document describes the | | 2046 | | OAM toolset defined by the IETF for | | 2047 | | MPLS-TP, whereas ITU-T G.8113.1 | | 2048 | | describes the OAM toolset defined | | 2049 | | by the ITU-T. | | 2050 | +--------------------------------------+---------------+ 2051 | | Operations, Administration and |ITU-T G.8113.1 | 2052 | | Maintenance mechanism for MPLS-TP in | | 2053 | | Packet Transport Network (PTN) | | 2054 | +--------------------------------------+---------------+ 2055 | | Allocation of a Generic Associated | RFC 6671 | 2056 | | Channel Type for ITU-T MPLS Transport| | 2057 | | Profile Operation, Maintenance, and | | 2058 | | Administration (MPLS-TP OAM) | | 2059 | | [ITU-T-CT] | | 2060 | | | | 2061 | | Note: although this is an IETF | | 2062 | | document, it is listed as one of the| | 2063 | | non-IETF OAM standards, since it | | 2064 | | was defined as a complementary part | | 2065 | | of ITU-T G.8113.1. | | 2066 +-----------+--------------------------------------+---------------+ 2067 |ITU-T | OAM Functions and Mechanisms for | ITU-T Y.1731 | 2068 |Ethernet | Ethernet-based Networks | | 2069 |OAM | [ITU-T-Y1731] | | 2070 +-----------+--------------------------------------+---------------+ 2071 |IEEE | Connectivity Fault Management | IEEE 802.1ag | 2072 |CFM | [IEEE802.1Q] | | 2073 | | | | 2074 | | Note: CFM was originally published | | 2075 | | as IEEE 802.1ag, but is now | | 2076 | | incorporated in the 802.1Q standard.| | 2077 +-----------+--------------------------------------+---------------+ 2078 |IEEE | Management of Data Driven and Data | IEEE 802.1ag | 2079 |DDCFM | Dependent Connectivity Faults | | 2080 | | [IEEE802.1Q] | | 2081 | | | | 2082 | | Note: DDCFM was originally published| | 2083 | | as IEEE 802.1Qaw, but is now | | 2084 | | incorporated in the 802.1Q standard.| | 2085 +-----------+--------------------------------------+---------------+ 2086 |IEEE | Media Access Control Parameters, | IEEE 802.3ah | 2087 |802.3 | Physical Layers, and Management | | 2088 |link level | Parameters for Subscriber Access | | 2089 |OAM | Networks [IEEE802.3ah] | | 2090 | | | | 2091 | | Note: link level OAM was originally | | 2092 | | defined in IEEE 802.3ah, and is now | | 2093 | | incorporated in the 802.3 standard. | | 2094 +-----------+--------------------------------------+---------------+ 2095 Table 6 Non-IETF OAM Standards Mentioned in this Document 2097 Authors' Addresses 2099 Tal Mizrahi 2100 Marvell 2101 6 Hamada St. 2102 Yokneam, 20692 2103 Israel 2105 Email: talmi@marvell.com 2107 Nurit Sprecher 2108 NSN 2109 3 Hanagar St. Neve Ne'eman B 2110 Hod Hasharon, 45241 2111 Israel 2113 Email: nurit.sprecher@nsn.com 2115 Elisa Bellagamba 2116 Ericsson 2117 6 Farogatan St. 2119 Stockholm, 164 40 2120 Sweden 2122 Phone: +46 761440785 2123 Email: elisa.bellagamba@ericsson.com 2125 Yaacov Weingarten 2126 34 Hagefen St. 2127 Karnei Shomron, 4485500 2128 Israel 2130 Email: wyaacov@gmail.com