idnits 2.17.1 draft-ietf-bmwg-atm-term-00.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- ** Looks like you're using RFC 2026 boilerplate. This must be updated to follow RFC 3978/3979, as updated by RFC 4748. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- ** The document seems to lack a 1id_guidelines paragraph about Internet-Drafts being working documents. ** The document is more than 15 pages and seems to lack a Table of Contents. == No 'Intended status' indicated for this document; assuming Proposed Standard == The page length should not exceed 58 lines per page, but there was 28 longer pages, the longest (page 2) being 60 lines == It seems as if not all pages are separated by form feeds - found 0 form feeds but 29 pages Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** The document seems to lack an IANA Considerations section. (See Section 2.2 of https://www.ietf.org/id-info/checklist for how to handle the case when there are no actions for IANA.) ** The document seems to lack separate sections for Informative/Normative References. All references will be assumed normative when checking for downward references. ** There are 376 instances of weird spacing in the document. Is it really formatted ragged-right, rather than justified? ** There are 542 instances of too long lines in the document, the longest one being 4 characters in excess of 72. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the RFC 3978 Section 5.4 Copyright Line does not match the current year == The "Author's Address" (or "Authors' Addresses") section title is misspelled. == Line 12 has weird spacing: '... This docum...' == Line 13 has weird spacing: '...visions of S...' == Line 14 has weird spacing: '...cuments of th...' == Line 15 has weird spacing: '...tribute worki...' == Line 19 has weird spacing: '...eted by other...' == (371 more instances...) -- The document seems to lack a disclaimer for pre-RFC5378 work, but may have content which was first submitted before 10 November 2008. If you have contacted all the original authors and they are all willing to grant the BCP78 rights to the IETF Trust, then this is fine, and you can ignore this comment. If not, you may need to add the pre-RFC5378 disclaimer. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- Couldn't find a document date in the document -- date freshness check skipped. Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Unused Reference: 'AF-TEST-0022' is defined on line 1323, but no explicit reference was found in the text -- Possible downref: Non-RFC (?) normative reference: ref. 'AF-TEST-0022' Summary: 7 errors (**), 0 flaws (~~), 12 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 Network Working Group J. H. Dunn 2 INTERNET-DRAFT C. E. Martin 3 Expires: February, 2000 ANC, Inc. 5 August, 1999 7 Terminology for ATM Benchmarking 8 10 Status of this Memo 12 This document is an Internet-Draft and is in full conformance with all 13 provisions of Section 10 of RFC2026. Internet-Drafts are working 14 documents of the Internet Engineering Task Force (IETF), its areas, and 15 its working groups. Note that other groups may also distribute working 16 documents as Internet-Drafts. 18 Internet-Drafts are draft documents valid for a maximum of six months 19 and may be updated, replaced, or obsoleted by other documents at any 20 time. It is inappropriate to use Internet-Drafts as reference material 21 or to cite them other than as "work in progress." 23 The list of current Internet-Drafts can be accessed at 24 http://www.ietf.org/ietf/1id-abstracts.txt 26 The list of Internet-Draft Shadow Directories can be accessed at 27 http://www.ietf.org/shadow.html. 29 Abstract 31 This memo discusses and defines terms associated with performance 32 benchmarking tests and the results of these tests in the context of 33 Asynchronous Transfer Mode (ATM) based switching devices. The terms 34 defined in this memo will be used in addition to terms defined in RFCs 35 1242, 2285, and 2544. This memo is a product of the Benchmarking 36 Methodology Working Group (BMWG) of the Internet Engineering Task Force 37 (IETF). 39 1. Introduction. 41 This document provides terminology for benchmarking ATM based switching 42 devices. It extends terminology already defined for benchmarking 43 network interconnect devices in RFCs 1242, 2285, and 2544. Although 44 some of the definitions in this memo may be applicable to a broader 45 group of network interconnect devices, the primary focus of the 46 terminology in this memo is on ATM cell relay and signaling. 48 This memo contains two major sections: Background and Definitions. 49 Within the definitions section is a formal definitions subsection, 50 provided as a courtesy to the reader, and a measurement definitions sub- 51 section, that contains performance metrics with inherent units. The 52 divisions of the measurement sub-section follow the BISDN model. 54 The BISDN model comprises four layers and two planes. This document 55 addresses the interactions between these layers and how they effect IP 56 and TCP throughput. A schematic of the B-ISDN model follows: 58 ---------|--------------------------|------------------------------------ 59 | User Plane | Control Plane 60 ---------|--------------------------|------------------------------------ 61 Services | IP | ILMI | UNI, PNNI 62 ---------|--------------------------|-----------|------------------------ 63 AAL | AAL1, AAL2, AAL3/4, AAL5 | AAL5 | SAAL 64 ---------|--------------------------|-----------|------------------------ 65 ATM | Cell Relay | OAM, RM 66 ---------|--------------------------|------------------------------------ 67 | Convergence | 68 Physical |--------------------------|------------------------------------ 69 | Media | 70 ---------|--------------------------|------------------------------------ 72 This document assumes that necessary services are available and active. 73 For example, IP connectivity requires SSCOP connectivity between 74 signaling entities. Further, it is assumed that the SUT has the ability 75 to configure ATM addresses (via hard coded addresses, ILMI or PNNI 76 neighbor discovery), has the ability to run SSCOP, and has the ability 77 to perform signaled call setups (via UNI or PNNI signaling). This 78 document covers only CBR, VBR and UBR traffic types. ABR will be 79 handled in a separate document. Finally, this document presents only 80 the terminology associated with benchmarking IP performance over ATM; 81 therefore, it does not represent a total compilation of ATM test 82 terminology. 84 The BMWG produces two major classes of documents: Benchmarking 85 Terminology documents and Benchmarking Methodology documents. The 86 Terminology documents present the benchmarks and other related terms. 87 The Methodology documents define the procedures required to collect the 88 benchmarks cited in the corresponding Terminology documents. 90 2. Existing Definitions 92 RFC 1242 "Benchmarking Terminology for Network Interconnect Devices" 93 should be consulted before attempting to make use of this document. RFC 94 2544 "Benchmarking Methodology for Network Interconnect Devices" 95 contains discussions of a number of terms relevant to the benchmarking 96 of switching devices and should be consulted. RFC 2285 "Benchmarking 97 Terminology for LAN Switching Devices" contains a number of terms 98 pertaining to traffic distributions and datagram interarrival. For the 99 sake of clarity and continuity, this RFC adopts the template for 100 definitions set out in Section 2 of RFC 1242. Definitions are indexed 101 and grouped together in sections for ease of reference. The key words 102 "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD 103 NOT", "RECOMMENDED", "MAY", and "OPTIONAL" go in this document are to be 104 interpreted as described in RFC 2119. 106 II. Definitions 108 The definitions presented in this section have been divided into two 109 groups. The first group is formal definitions, which are required in 110 the definitions of the performance metrics but are not themselves 111 strictly metrics. These definitions are subsumed from other work done 112 in other working groups both inside and outside the IETF. They are 113 provided as a courtesy to the reader. 115 1. Formal Definitions 117 1.1. Definition Format (from RFC 1242) 119 Term to be defined. 121 Definition: The specific definition for the term. 123 Discussion: A brief discussion of the term, its application and any 124 restrictions on measurement procedures. These discussions pertain solely 125 to the impact of a particular ATM parameter on IP or TCP; therefore, 126 definitions which contain no configurable components or whose components 127 will have the discussion: None. 129 Specification: The working group and document in which the terms are 130 specified and are listed in the references section. 132 1.2. Related Definitions. 134 1.2.1. ATM Adaptation Layer (AAL) 136 Definition: The layer in the B-ISDN reference model (see B-ISDN) which 137 adapts higher layer PDUs into the ATM layer. 139 Discussion: There are four types of adaptation layers: AAL 1: used for 140 circuit emulation, voice over ATM AAL2: used for sub-rated voice over ATM 141 AAL3/4: used for data over noisy ATM lines AAL5: used for data over ATM, 142 most widely used AAL type 143 These AAL types are not measurements, but it is possible to measure the 144 time required for Segmentation and Reassembly (SAR). 146 Specification: I.363 148 1.2.2. ATM Adaptation Layer Type 5 (AAL5) 150 Definition: AAL5 adapts multi-cell higher layer PDUs into ATM with minimal 151 error checking and no error detection. The AAL5 CPCS (Common Paer 152 Convergence Sub-layer) PDU is defined as follows: 154 |---------------------------|---------------------------|----------------| 155 | Higher Layer PDU | Padding (If needed) | Trailer | 156 |---------------------------|---------------------------|----------------| 158 Where the padding is used to ensure that the trailer occupies the final 8 159 octets of the last cell. 161 The trailer is defined as follows: 163 |--------------|--------------|--------------|--------------| 164 | CPCS-UU | CPI | Length | CRC-32 | 165 |--------------|--------------|--------------|--------------| 167 where: 169 CPCS-UU is the 1 octet Common Part Convergence Sub-layer User to User 170 Indication and may be used to communicate between two AAL5 entities. 172 CPI is the 1 octet Common Part Indicator and must be set to 0. 174 Length is the 2 octet length of the higher layer PDU. 176 CRC-32 is a 32 bit (4 octet) cyclic redundancy check over the entire PDU. 178 Discussion: AAL5 is the adaptation layer for UNI signaling, ILMI, PNNI 179 signaling, and for IP PDUs. It is the most widely used AAL type to date. 180 AAL5 requires two distinct processes. The first is the encapsulation, on 181 the transmit side, and de-encapsulation, on the receive side, of the higher 182 layer PDU into the AAL5 CPCS PDU which requires the computation of the 183 length and the CRC-32. The time required for this process depends on 184 whether the CRC-32 computation is done on the interface (on-board) or in 185 machine central memory (in core). On-board computation should produce only 186 a small, constant delay; however, in core computation will produce variable 187 delay, which will negatively effect TCP RTT computations. The second 188 process is segmentation and re-assembly (SAR) which is defined below (see 189 SAR) 190 Specification: I.363.5 192 1.2.3. Asynchronous Transfer Mode (ATM) 194 Definition: A transfer mode in which the information is organized into 53 195 octet PDUs called cells. It is asynchronous in the sense that the 196 recurrence of cells containing information from an individual user is not 197 necessarily periodic. 199 Discussion: ATM is based on the ISDN model; however, unlike ISDN, ATM uses 200 fixed length (53 octet) cells. Because of the fixed length of ATM PDUs, 201 higher layer PDUs must be adapted into ATM using one of the four ATM 202 adaptation layers (see AAL). 204 Specification: AF-UNI3.1 206 1.2.4. ATM Link 208 Definition: A virtual path link (VPL) or a virtual channel link (VCL). 210 Discussion: none. 212 Specification: AF-UNI3.1 214 1.2.5. ATM Peer-to-Peer Connection 216 Definition: A virtual channel connection (VCC) or a virtual path connection 217 (VPC). 219 Discussion: none. 221 Specification: AF-UNI3.1 223 1.2.6. ATM Traffic Descriptor 225 Definition: A generic list of traffic parameters, which specify the 226 intrinsic traffic characteristics of a requested ATM connection (see GCRA), 227 which must include PCR and QoS and may include BT, SCR and best effort 228 (UBR) indicator. 230 Discussion: The effects of each traffic parameter will be discussed 231 individually. 233 Specification: AF-UNI3.1 235 1.2.7. ATM User-User Connection 237 Definition: An association established by the ATM Layer to support 238 communication between two or more ATM service users (i.e., between two or 239 more next higher entities or between two or more ATM-entities). The 240 communications over an ATM Layer connection may be either bi-directional or 241 unidirectional. The same Virtual Channel Identifier (VCI) is issued for 242 both directions of a connection at an interface. 244 Discussion: Because ATM is connection oriented, certain features of IP 245 (i.e. those which require multicast) are not available. 247 Specification: AF-UNI3.1 249 1.2.8. Broadband ISDN (B-ISDN) Model 251 Definition: A layered service model that specifies the mapping of higher 252 layer protocols onto ATM and its underlying physical layer. The model is 253 composed of four layers: Physical, ATM, AAL and Service. 255 Discussion: See discussion above. 257 Specification: I.321 259 1.2.9. Burst Tolerance (BT) 261 Definition: A traffic parameter, which, along with the Sustainable Cell 262 Rate (SCR), specifies the maximum number of cells which will be accepted at 263 the Peak Cell Rate (PCR) on an ATM connection. 265 Discussion: BT applies to ATM connections supporting VBR services and is 266 the limit parameter of the GCRA. BT will effect TCP and IP PDU loss in 267 that cells presented to an interface which violate the BT may be dropped, 268 which will cause AAL5 PDU corruption. BT will also effect TCP RTT 269 calculation. BT=(MBS-1)*(1/SCR 1/PCR) (see MBS, PCR, SCR). 271 Specification: AF-TM4.0 273 1.2.10. Call 275 Definition: A call is an association between two or more users or between a 276 user and a network entity that is established by the use of network 277 capabilities. This association may have zero or more connections. 279 Discussion: none. 281 Specification: AF-UNI3.1 283 1.2.11. Cell 285 Definition: A unit of transmission in ATM. A fixed-size frame consisting of 286 a 5-octet header and a 48-octet payload. 288 Discussion: none. 290 Specification: AF-UNI3.1 292 1.2.12. Call-based 294 Definition: A transport requiring call setups- see CALL definition. 296 Discussion: none. 298 Specification: AF-UNI3.1 300 1.2.13. Cell Delay Variation Tolerance (CDVT) 302 Definition: ATM layer functions may alter the traffic characteristics of 303 ATM connections by introducing Cell Delay Variation. When cells from two or 304 more ATM connections are multiplexed, cells of a given ATM connection may 305 be delayed while cells of another ATM connection are being inserted at the 306 output of the multiplexer. Similarly, some cells may be delayed while 307 physical layer overhead or OAM cells are inserted. Consequently, some 308 randomness may affect the inter-arrival time between consecutive cells of a 309 connection as monitored at the UNI. The upper bound on the "clumping" 310 measure is the CDVT. 312 Discussion: CDVT effects TCP round trip time calculations. Large values 313 of CDVT will adversely effect TCP throughput and cause SAR timeout. See 314 discussion under SAR. 316 Specification: AF-TM4.0 318 1.2.14. Cell Header 320 Definition: ATM Layer protocol control information. 322 Discussion: The ATM cell header is a 5-byte header that contains the 323 following fields: Generic Flow Control (GFC) 4 bits Virtual Path Identifier 324 (VPI) 8 bits Virtual Channel Identifier (VCI) 16 bits Payload Type (PT) 3 325 bits Cell Loss Priority (CLP) 1 bit Header Error Check (HEC) 8 bit CRC 326 computed over the previous four octets 328 Each field is discussed in this document. 330 Specification: AF-UNI3.1 332 1.2.15. Cell Loss Priority (CLP) 333 Definition: This bit in the ATM cell header indicates two levels of 334 priority for ATM cells. CLP=0 cells are higher priority than CLP=1 cells. 335 CLP=1 cells may be discarded during periods of congestion to preserve the 336 CLR of CLP=0 cells. 338 Discussion: The CLP bit is used to determine GCRA contract compliance. 339 Specifically, two traffic contracts may apply to a single connection: 340 CLP=0, meaning only cells with CLP=0, and CLP=0+1, meaning cells with CLP=0 341 or CLP=1. 343 Specification: AF-UNI3.1 345 1.2.16. Connection 347 Definition: An ATM connection consists of concatenation of ATM Layer links 348 in order to provide an end-to-end information transfer capability to access 349 points. 351 Discussion: none. 353 Specification: AF-UNI3.1 355 1.2.17. Connection Admission Control (CAC) 357 Definition: Connection Admission Control is defined as the set of actions 358 taken by the network during the call set-up phase (or during call re- 359 negotiation phase) in order to determine whether a connection request can 360 be accepted or should be rejected (or whether a request for re-allocation 361 can be accommodated). 363 Discussion: CAC is based on the ATM traffic descriptor (see ATM traffic 364 descriptor) associated with the call as well as the presented and existing 365 load. It may also be based on administrative policies such as calling 366 party number required or access limitations. The effect on performance of 367 these policies is beyond the scope of this document and will be handled in 368 the BMWG document: Benchmarking Terminology for Firewall Performance. 370 Specification: AF-UNI3.1 372 1.2.18. Constant Bit Rate (CBR) 374 Definition: An ATM service category which supports a constant and 375 guaranteed rate to transport services such as video or voice as well as 376 circuit emulation which requires rigorous timing control and performance 377 parameters. CBR requires the specification of PCR and QoS (see PCR and 378 QoS). 380 Discussion: Because CBR provides minimal cell delay variation (see CDV), it 381 should improve TCP throughput by stabilizing the RTT calculation. Further, 382 as CBR generally provides a high priority service, meaning that cells with 383 a CBR traffic contract usually take priority over other cells during 384 congestion, TCP segment and IP packet loss should be minimized. The cost 385 associated with using CBR is the loss of statistical multiplexing. Since 386 CBR guarantees both throughput and CDV control, the connections must be 387 subscribed at PCR. This is extremely wasteful as most protocols, e.g., 388 TCP, only utilize full bandwidth on one half of a bi- directional 389 connection. 391 Specification: AF-UNI3.1 393 1.2.19. Cyclic Redundancy Check (CRC) 395 Definition: A mathematical algorithm that computes a numerical value based 396 on the bits in a block of data. This number is transmitted with the data, 397 the receiver uses this information and the same algorithm to insure the 398 accurate delivery of data by comparing the results of algorithm, and the 399 number received. If a mismatch occurs, an error in transmission is 400 presumed. 402 Discussion: CRC is not a measurement, but it is possible to measure the 403 amount of time to perform a CRC on a string of bits. This measurement will 404 not be addressed in this document. See discussion under AAL5. 406 Specification: AF-UNI3.1 408 1.2.20. End System (ES) 410 Definition: A system where an ATM connection is terminated or initiated. 411 An originating end system initiates the ATM connection, and terminating end 412 system terminates the ATM connection. OAM cells may be generated and 413 received. 415 Discussion: An ES can be the user side of a UNI signaling interface. 417 Specification: AF-TEST-0022 419 1.2.21. Explicit Forward Congestion Indication (EFCI) 421 Definition: EFCI is an indication in the PTI field of the ATM cell header. 422 A network element in an impending-congested state or a congested state may 423 set EFCI so that this indication may be examined by the destination end- 424 system. For example, the end-system may use this indication to implement a 425 protocol that adaptively lowers the cell rate of the connection during 426 congestion or impending congestion. A network element that is not in a 427 congestion state or an impending congestion state will not modify the value 428 of this indication. Impending congestion is the state when network 429 equipment is operating around its engineered capacity level. 431 Discussion: EFCI may be used to prevent congestion by alerting a positive 432 acknowledgement protocol and causing action to be taken. In the case of 433 TCP, when EFCI cells are received the driver software could alert the TCP 434 software of impending congestion. The TCP receiver would then acknowledge 435 the current segment and set the window size to some very small number. 437 Specification: AF-TM4.0 439 1.2.22. Generic Cell Rate Algorithm (GCRA) 441 Definition: The GCRA is used to define conformance with respect to the 442 traffic contract of the connection. For each cell arrival, the GCRA 443 determines whether the cell conforms to the traffic contract. The UPC 444 function may implement the GCRA, or one or more equivalent algorithms to 445 enforce conformance. The GCRA is defined with two parameters: the Increment 446 (I) and the Limit (L). 448 Discussion: The GCRA increment and limit parameters are mapped to CBR and 449 VBR in the following fashion. For CBR, I=1/PCR and L=CDVT (CDV tolerance). 450 For VBR, there are two GCRA algorithms running (dual leaky bucket). The 451 first functions in the same fashion as CBR, I=1/PCR and L=CDVT. The 452 second, which polices cells which are in conformance with the first GCRA 453 uses I=1/SCR and L=BT (see BT, CDV, MBS, PCR and SCR). 455 Specification: AF-TM4.0 457 1.2.23. Generic Flow Control (GFC) 459 Definition: GFC is a field in the ATM header, which can be used to provide 460 local functions (e.g., flow control). It has local significance only and 461 the value encoded in the field is not carried end-to-end. 463 Discussion: none. 465 Specification: AF-UNI3.1 467 1.2.24. Guaranteed Frame Rate (GFR) 469 Definition: The GFR service provides the user with a Minimum Cell Rate 470 (MCR) guarantee under the assumption of a given maximum frame size (MFS) 471 and a given Maximum Burst Size (MBS). The MFS and MBS are both expressed 472 in units of cells. GFR only applies to virtual channel connections (VCCs). 474 Discussion: GFR is intended for users who are either not able to specify 475 the range of traffic parameters needed to request most ATM services, or are 476 not equipped to comply with the (source) behavior rules required by 477 existing ATM services. Specifically, GFR provides the user with the 478 following minimum service guarantee: When the network is congested, all 479 frames whose length is less than MFS and presented to the ATM interface in 480 bursts less than MBS and at a rate less than PCR will be handled with 481 minimum frame loss. When the network is not congested, the user can burst 482 at higher rates. 484 The effect of GFR on performance is somewhat problematic as the policing 485 algorithm associated with GFR depends on the network load; however, under 486 congested condition and assuming a user who is following the GFR service 487 agreement, it should improve performance. 489 Specification: AF-TM4.1 491 1.2.25. Header Error Control (HEC) 493 Definition: A check character calculated using an 8 bit CRC computed over 494 the first 4 octets of the ATM cell header. This allows for single bit error 495 correction or multiple bit error detection. 497 Discussion: none. 499 Specification: AF-UNI3.1 501 1.2.26. Integrated Local Management Interface 503 Definition: A management protocol which uses SNMPv1 carried on AAL5 to 504 provide ATM network devices with status and configuration information 505 concerning VPCs, VCCs, registered ATM addresses and the capabilities of ATM 506 interfaces. 508 Discussion: ILMI is a conditionally required portion of UNI3.1; however, 509 ILMI 4.0 has been issued as a separate specification. This document will 510 refer to ILMI 4.0. 512 Specification: AF-ILMI4.0 514 1.2.27. Intermediate System (IS) 516 Definition: A system that provides forwarding functions or relaying 517 functions or both for a specific ATM connection. OAM cells may be generated 518 and received. 520 Discussion: An IS can be either the user or network side of a UNI signaling 521 interface, or the network side of a PNNI signaling interface. 523 Specification: AF-TEST-0022 524 1.2.28. Leaky Bucket (LB) 526 Definition: Leaky Bucket is the term used as an analogous description of 527 the algorithm used for conformance checking of cell flows from a user or 528 network. See GCRA and UPC. The "leaking hole in the bucket" applies to the 529 sustained rate at which cells can be accommodated, while the "bucket depth" 530 applies to the tolerance to cell bursting over a given time period. 532 Discussion: There are two types of LB algorithms- single and dual. Single 533 LB is used in CBR; dual LB is used in VBR (see CBR and VBR). 535 Specification: AF-TM4.0 537 1.2.29. Maximum Burst Size (MBS) 539 Definition: In the signaling message, the Burst Tolerance (BT) is conveyed 540 through the MBS that is coded as a number of cells. The BT together with 541 the SCR and the PCR determine the MBS that may be transmitted at the peak 542 rate and still is in conformance with the GCRA. 544 Discussion: See the discussion under BT. 546 Specification: AF-TM4.0 548 1.2.30. Maximum Frame Size (MFS) 550 Definition: The MFS is the maximum length of a frame, expressed in units of 551 cells, which in interface implementing GFR will accept during congested 552 conditions (see GFR). 554 Discussion: During congestion, frames whose size is in excess of the MFS 555 may be dropped or tagged. Assuming that the user is adhering to the MFS 556 limit, this behavior should improve performance by improving congestion. 558 Specification: AF-TM4.1 560 1.2.31. Operations, Administration, and Maintenance (OAM) 562 Definition: A group of network management functions that provide network 563 fault indication, performance information, and data and diagnosis 564 functions. 566 Discussion: There are four types of ATM OAM flows: segment or end-to-end VP 567 termination management (i.e. F4 segment, F4 E2E) and segment or end-to- end 568 VC termination management (i.e. F5 segment, F5 E2E). These OAM cells can be 569 used to identify fault management, connection verification, and loop back 570 measurements. 572 Specification: AF-UNI3.1 574 1.2.32. Payload Type Indicator (PTI) 576 Definition: Payload Type Indicator is the Payload Type field value 577 distinguishing the various management cells and user cells as well as 578 conveying explicit forward congestion indication (see EFCI). Example: 579 Resource Management cell is indicated as PTI=110, End-to-end OAM F5 Flow 580 cell is indicated as PTI=101. 582 Discussion: none. 584 Specification: AF-UNI3.1 586 1.2.33. Peak Cell Rate (PCR) 588 Definition: A traffic parameter, which specifies the upper bound on the 589 rate at which ATM cells can be submitted to an ATM connection. This 590 parameter is used by the GCRA. 592 Discussion: PCR directly limits the maximum data rate on an ATM connection. 593 If a user violates the PCR, cells may be dropped resulting in Cell Loss. 594 This in turn will negatively impact AAL5 PDUs, which may be carrying IP 595 datagrams. See the discussion under SAR. 597 Specification: AF-TM4.0 599 1.2.34. Permanent Virtual Circuit (PVC) 601 Definition: This is a link with static route(s) defined in advance, usually 602 by manual setup. 604 Discussion: none. 606 Specification: AF-UNI3.1 608 1.2.35. Permanent Virtual Channel Connection (PVCC) 610 Definition: A Virtual Channel Connection (VCC) is an ATM connection where 611 switching is performed on the VPI/VCI fields of each cell. A permanent VCC 612 is one that is provisioned through some network management function and 613 left up indefinitely. 615 Discussion: none. 617 Specification: AF-UNI3.1 619 1.2.36. Permanent Virtual Path Connection: (PVPC) 620 Definition: A Virtual Path Connection (VPC) is an ATM connection where 621 switching is performed on the VPI field only of each cell. A permanent VPC 622 is one that is provisioned through some network management function and 623 left up indefinitely. 625 Discussion: none. 627 Specification: AF-UNI3.1 629 1.2.37. Private Network-Network Interface (PNNI) 631 Definition: A routing information protocol that enables extremely, 632 scalable, full function, dynamic multi-vendor ATM switches to be integrated 633 in the same network. 635 Discussion: PNNI consists of signaling and routing between ATM network 636 devices. PNNI signaling is based on UNI 4.0 signaling between two network 637 side interfaces, while PNNI routing provides a mechanism to route ATM cells 638 between two separate, autonomous ATM networks. 640 Specification: AF-PNNI1.0 642 1.2.38. Protocol Data Unit (PDU) 644 Definition: A PDU is a message of a given protocol comprising payload and 645 protocol-specific control information, typically contained in a header. 646 PDUs pass over the protocol interfaces that exist between the layers of 647 protocols (per OSI model). 649 Discussion: In ATM networks, a PDU can refer to an ATM cell, multiple ATM 650 cells, an AAL segment, an IP datagram and others. 652 Specification: Common Usage 654 1.2.39. Segmentation and Reassembly (SAR) 656 Definition: The process used by the AAL in the B-ISDN reference model (see 657 B-ISDN) which fragments higher layer PDUs into ATM cells. 659 Discussion: SAR is not a measurement, but the speed in which SAR can be 660 completed on a bit stream can be measured. Although this measurement is not 661 included in this document, it should be noted that the manner in which SAR 662 is performed will greatly effect performance. SAR can be performed either 663 on the interface card (on board) or in machine central memory (in core). 664 On-board computation should produce only a small, constant delay; however, 665 in core computation will produce variable delay, which will negatively 666 effect TCP RTT computations. This situation is further complicated by the 667 location of the CRC-32 calculation. Given an in core CRC-32 calculation, 668 bus contention may cause on board SAR to be slower than in core SAR. 669 Clearly, on board CRC-32 calculation and SAR will produce the most 670 favorable performance results. 672 SAR performance will also be effected by ATM layer impairments. Cell error 673 (CE), cell loss(CL), cell mis-insertion (CM) and cell delay variation (CDV) 674 will all negatively effect SAR. CE will cause an AAL5 PDU to fail the 675 CRC-32 check and be discarded, thus discarding the packet which the PDU 676 contained. CL and CM will both cause an AAL5 PDU to fail the length check 677 and be discarded. CL can have other effects depending on whether the cell 678 which was lost is the final cell (PTI=1) of the AAL5 PDU. The following 679 discussion enumerates the possibilities. 681 1. PTI=0 cell is lost. In this case, re-assembly registers a length 682 discrepancy and discards the PDU. 684 2. PTI=1 cell is lost. 686 2. A. The AAL5 re-assembly timer expires before the first cell, PTI=0, of 687 the next AAL5 PDU arrives. The AAL5 PDU with the missing PTI=1 cell is 688 discarded due to re-assembly timeout and one packet is lost. 690 2. B. The first cell of the next AAL5 PDU arrives before the re-assembly 691 timer expires. The AAL5 with the missing PTI=1 cell is prepended to the 692 next AAL5 PDU in the SAR engine. This yields two possibilities: 694 2. B. i. The AAL5 re-assembly timer expires before the last cell, PTI=1, of 695 the next AAL5 PDU arrives. The AAL5 PDU with the missing PTI=1 cell and 696 the next AAL5 PDU are discarded due to re-assembly timeout and two packets 697 are lost. 699 2. B. ii. The last cell of the next AAL5 PDU arrives before the re-assembly 700 timer expires. In this case, AAL5 registers a length discrepancy and 701 discards the PDU; therefore, the AAL5 PDU with the missing PTI=1 cell and 702 the next AAL5 PDU are discarded due to their concatenation and two packets 703 are lost. 705 2. C. Coupled with re-assembly, there exists some mechanism for identifying 706 the start of a higher layer PDU, e.g., IP, and the cells associated with 707 the first incomplete AAL5 PDU are discarded, resulting in the loss of one 708 packet. 710 Specification: AF-UNI3.1 712 1.2.40. Sustainable Cell Rate (SCR) 714 Definition: The SCR is an upper bound on the conforming average rate of an 715 ATM connection over time scales which are long relative to those for which 716 the PCR is defined. Enforcement of this bound by the UPC could allow the 717 network to allocate sufficient resources, but less than those based on the 718 PCR, and still ensure that the performance objectives (e.g., for Cell Loss 719 Ratio) can be achieved. 721 Discussion: SCR limits the average data rate on an ATM connection. If a 722 user violates the SCR, cells may be dropped resulting in Cell Loss. This 723 in turn will negatively impact AAL5 PDUs, which may be carrying IP 724 datagrams. See the discussion under SAR. 726 Specification: AF-TM4.0 728 1.2.41. Switched Connection 730 Definition: A connection established via signaling. 732 Discussion: none. 734 Specification: AF-UNI3.1 736 1.2.42. Switched Virtual Channel Connection (SVCC) 738 Definition: A Switched VCC is one that is established and taken down 739 dynamically through control signaling. A Virtual Channel Connection (VCC) 740 is an ATM connection where switching is performed on the VPI/VCI fields of 741 each cell. 743 Discussion: none. 745 Specification: AF-UNI3.1 747 1.2.43. Switched Virtual Circuit (SVC) 749 Definition: A connection established via signaling. The user defines the 750 endpoints when the call is initiated. 752 Discussion: SVCs are established using either UNI signaling or PNNI 753 signaling. The signaling state machine implements several timers, which 754 can effect the time required for call establishment. This will effect TCP 755 round trip time calculation, effecting TCP throughput. Specifically, there 756 are two possibilities. In the case where Call Proceeding is not 757 implemented, there is only one timer, T310, with a value of 10 seconds. In 758 the case where Call Proceeding is implemented, there are two timers, T303 759 and T310, with the values 4 and 10 seconds, respectively. In either case, 760 if a timer, either T303 or T310, expires after a Setup message is send, the 761 calling party has the option of re-transmitting the Setup. In the T303 762 case, this yields a maximum setup time of 18 seconds and, In the T310 763 case, a maximum setup time of 20 seconds. Thus, the initial TCP RTT 764 calculation will be on he order of 20 seconds. 766 Specification: AF-UNI3.1, AF-UNI4.0, AF-PNNI1.0 768 1.2.44. Switched Virtual Path Connection (SVPC) 770 Definition: A Switched Virtual Path Connection is one that is established 771 and taken down dynamically through control signaling. A Virtual Path 772 Connection (VPC) is an ATM connection where switching is performed on the 773 VPI field only of each cell. 775 Discussion: none. 777 Specification: AF-UNI3.1 779 1.2.45. Traffic Contract 781 Definition: A specification of the negotiated traffic characteristics of an 782 ATM connection. 784 Discussion: See discussions under BT, CAC, CDV, GCRA, PCR and SCR. 786 Specification: AF-TM4.0 788 1.2.46. Traffic Management (TM) 790 Definition: Traffic Management is the aspect of the traffic control and 791 congestion control procedures for ATM. ATM layer traffic control refers to 792 the set of actions taken by the network to avoid congestion conditions. 793 ATM layer congestion control refers to the set of actions taken by the 794 network to minimize the intensity, spread and duration of congestion. The 795 following functions form a framework for managing and controlling traffic 796 and congestion in ATM networks and may be used in appropriate combinations. 797 Connection Admission Control 798 Feedback Control 799 Usage Parameter Control 800 Priority Control 801 Traffic Shaping 802 Network Resource Management 803 Frame Discard 804 ABR Flow Control 806 Discussion: See CAC and traffic shaping. 808 Specification: AF-TM4.0 810 1.2.47. Traffic Shaping (TS) 811 Definition: Traffic Shaping is a mechanism that alters the traffic 812 characteristics of a stream of cells on a connection to achieve better 813 network efficiency, while meeting the QoS objectives, or to ensure 814 conformance at a subsequent interface. Traffic shaping must maintain cell 815 sequence integrity on a connection. Shaping modifies traffic 816 characteristics of a cell flow with the consequence of increasing the mean 817 Cell Transfer Delay. 819 Discussion: TS should improve TCP throughput by reducing RTT variations. 820 As a result, TCP RTT calculations should be more stable. 822 Specification: AF-UNI3.1 824 1.2.48. Transmission Convergence (TC) 826 Definition: A sub-layer of the physical layer of the B-ISDN model 827 transforms the flow of cells into a steady flow of bits and bytes for 828 transmission over the physical medium. On transmit the TC sublayer maps the 829 cells to the frame format, generates the Header Error Check (HEC), and 830 sends idle cells when the ATM layer has none. to send. On reception, the TC 831 sublayer delineates individual cells in the received bit stream, and uses 832 the HEC to detect and correct received errors. 834 Discussion: TC is not a measurement, but the speed in which TC can occur on 835 a bit stream can be measured. This measurement will not be discussed in 836 this document; however, its value should be constant and small with respect 837 to cell inter-arrival at the maximum data rate. 839 Specification: AF-UNI3.1 841 1.2.49. Unspecified Bit Rate (UBR) 843 Definition: UBR is an ATM service category, which does not specify traffic 844 related service guarantees. Specifically, UBR does not include the notion 845 of a per-connection-negotiated bandwidth. No commitments are made with 846 respect to the cell loss ratio experienced by a UBR connection, or as to 847 the cell transfer delay experienced by cells on the connection. 849 Discussion: RFC 2331 specifies UBR service class for IP over ATM. UBR 850 service models the "best effort" service type specified in RFC 791; 851 however, UBR has specific drawbacks with respect to TCP service. Since UBR 852 makes no guarantee with respect to cell loss (CL), cell delay variation 853 (CDV) or cell mis-insertion(CM), TCP RTT estimates will be highly variable. 854 Further, all negatively impact AAL5 re-assembly, which in turn may cause 855 packet loss. See discussions under CDV and SAR. 857 Specification: AF-TM4.0 858 1.2.50. Usage Parameter Control (UPC) 860 Definition: Usage Parameter Control is defined as the set of actions taken 861 by the network to monitor and control traffic, in terms of traffic offered 862 and validity of the ATM connection, at the end-system access. Its main 863 purpose is to protect network resources from malicious as well as 864 unintentional misbehavior, which can affect the QoS of established 865 connections, by detecting violations of negotiated parameters and taking 866 appropriate actions. 868 Discussion: See discussions under BT, CAC, CDV, GCRA, PCR and SCR. 870 Specification: AF-TM4.0 872 1.2.51. User-Network Interface (UNI) 874 Definition: An interface point between ATM end users and a private ATM 875 switch, or between a private ATM switch and the public carrier ATM network; 876 defined by physical and protocol specifications per ATM Forum UNI 877 documents. The standard adopted by the ATM Forum to define connections 878 between users or end stations and a local switch. 880 Discussion: none. 882 Specification: AF-UNI3.1 884 1.2.52. Variable Bit Rate (VBR) 886 Definition: An ATM Forum defined service category which supports variable 887 bit rate data traffic with average and peak traffic parameters. 889 Discussion: VBR may potentially adversely effect TCP throughput due to 890 large RTT variations. This in turn will cause the TCP RTT estimates to be 891 unstable. 893 Specification: AF-TM4.0 895 1.2.53. Virtual Channel (VC) Definition: A communications channel that 896 provides for the sequential unidirectional transport of ATM cells. 898 Discussion: none. 900 Specification: AF-TM3.1 902 1.2.54. Virtual Channel Connection (VCC) 904 Definition: A concatenation of VCIs that extends between the points where 905 the ATM service users access the ATM layer. The points at which the ATM 906 cell payload is passed to, or received from, the users of the ATM Layer 907 (i.e., a higher layer or ATM-entity) for processing signify the endpoints 908 of a VCC. VCCs are unidirectional. 910 Discussion: none. 912 Specification: AF-TM3.1 914 1.2.55. Virtual Channel Identifier (VCI) 916 Definition: A unique numerical tag as defined by a 16 bit field in the ATM 917 cell header that identifies a virtual channel, over which the cell is to 918 travel. 920 Discussion: none. 922 Specification: AF-UNI3.1 924 1.2.56. Virtual Path (VP) 926 Definition: A unidirectional logical association or bundle of VCs. 928 Discussion: none. 930 Specification: AF-UNI3.1 932 1.2.57. Virtual Path Connection (VPC) 934 Definition: A concatenation of VPIs between Virtual Path Terminators 935 (VPTs). VPCs are unidirectional 937 Discussion: none. 939 Specification: AF-TM3.1 941 1.2.58. Virtual Path Identifier (VPI) 943 Definition: An eight-bit field in the ATM cell header that indicates the 944 virtual path over which the cell should be routed. 946 Discussion: none. 948 Specification: AF-UNI3.1 950 2. Performance Metrics 952 2.1. Definition Format (from RFC 1242) 953 Metric to be defined. 955 Definition: The specific definition for the metric. 957 Discussion: A brief discussion of the metric, its application and any 958 restrictions on measurement procedures. 960 Measurement units: Intrinsic units used to quantify this metric. This 961 includes subsidiary units; e.g., microseconds are acceptable if the 962 intrinsic unit is seconds. 964 2.2. Definitions 966 2.2.1. Physical Layer- SONET 968 2.2.1.1. Pointer Movements 970 Definition: Pointer Movements is the number of changes in a SONET pointer 971 due to clock synchronization slips. 973 Discussion: SONET Pointer Movements can cause loss of information in the 974 SONET payload envelop (SPE) which contains IP datagrams, either in the form 975 of ATM cells or as PPP delimited PDUs. 977 Measurement Units: Per second. 979 2.2.1.2. Transport Overhead Error Count 981 Definition: SONET Transport Overhead Error Count is the number of SONET 982 transport overhead errors detected. 984 Discussion: SONET Transport Overhead Errors SONET Transport Overhead Errors 985 cause SONET frames to be lost. These frames may contain IP datagrams; 986 either in the form of cells or as PPP delimited PDUs. 988 Measurement Units: Positive integer 990 2.2.1.3. Path Overhead Error Count 992 Definition: SONET Path Overhead Error Count is the number of SONET path 993 overhead errors detected. 995 Discussion: SONET Path Overhead Errors cause SONET frames to be lost. 996 These frames may contain IP datagrams; either in the form of cells or as 997 PPP delimited PDUs. 999 Measurement Units: Positive integer 1000 2.2.2. ATM Layer 1002 2.2.2.1. Cell Delay Variation (CDV) 1004 Definition: The variation in cell transfer delay (CTD) associated with a 1005 given traffic load, orientation and distribution, as well as an integration 1006 period. CDV = max (CTD) - min (CTD) where max and min indicate the maximum 1007 and minimum over the integration period, respectively. 1009 Discussion: CDV is a component of cell transfer delay, induced by 1010 buffering and cell scheduling. Peak-to-peak CDV is a QoS delay parameter 1011 associated with CBR and VBR services. The peak-to-peak CDV is the ((1-a) 1012 quantile of the CTD) minus the fixed CTD that could be experienced by any 1013 delivered cell on a connection during the entire connection holding time. 1014 The parameter "a" is the probability of a cell arriving late. 1016 CDV effects TCP round trip time calculations. Large values of CDV will 1017 adversely effect TCP throughput and cause SAR timeout. See discussion 1018 under SAR. 1020 Measurement Units: seconds 1022 2.2.2.2. Cell Error Ratio (CER) 1024 Definition: The ratio of cells with payload errors in a transmission in 1025 relation to the total number of cells sent in a transmission associated 1026 with a given traffic load, orientation and distribution, as well as an 1027 integration period. Note that errors occurring in the cell header will 1028 cause cell loss at the ATM layer. Note further that multiple errors in a 1029 payload will only be counted as one cell payload error. 1031 CER = Cells with payload errors / Total Cells Transmitted. 1033 Discussion: The measurement is taken over a time interval and is desirable 1034 to be measured on an in-service circuit. CER is closely related to the 1035 number of corrupted AAL5 PDUs; however, there is not a direct numerical 1036 correlation between the number of errored cells and the number of corrupted 1037 AAL5 PDUs. There are two cases described below. 1039 1. Only one cell in an AAL5 PDU contains payload errors. In this case, 1040 there is a one-to-one correspondence between cell payload errors and the 1041 number of corrupted AAL5 PDUs. 1043 2. Multiple cells in the AAL5 PDU contain payload errors. In this case, 1044 there is not a one-to-one correspondence between cell payload errors and 1045 the number of corrupted AAL5 PDUs. 1047 Measurement Units: dimensionless. 1049 2.2.2.3. Cell Loss Ratio (CLR) 1051 Definition: The ratio of lost cells in a transmission in relation to the 1052 total cells sent in a transmission associated with a given traffic load, 1053 orientation and distribution, as well as an integration period. 1055 CLR = Lost Cells / Total Cells Transmitted. 1057 Discussion: CLR is a negotiated QoS parameter and acceptable values are 1058 network specific. The objective is to minimize CLR provided the end-system 1059 adapts the traffic to the changing ATM layer transfer characteristics. The 1060 CLR parameter is the value of CLR that the network agrees to offer as an 1061 objective over the lifetime of the connection. It is expressed as an order 1062 of magnitude, having a range of 10^-1 to 10^-15 and unspecified. 1064 CLR indicates the number of ATM cells lost in relation to the total number 1065 of cells sent. CLR is closely related to the number of corrupted AAL5 PDUs; 1066 however, there is not a direct numerical correlation between the number of 1067 cells lost and the number of corrupted AAL5 PDUs. See the discussion under 1068 SAR. 1070 Measurement Units: dimensionless. 1072 2.2.2.4. Cell Misinsertion Ratio (CMR) 1074 Definition: The ratio of cells received at an endpoint that were not 1075 originally transmitted by the source end in relation to the total number of 1076 cells properly transmitted associated with a given traffic load, 1077 orientation and distribution, as well as an integration period. 1079 CMR = Misinserted Cells / Total Cells Transmitted. 1081 Discussion: The measurement is taken over a time interval and is desirable 1082 to be measured on an in-service circuit. CMR is closely related to the 1083 number of corrupted AAL5 PDUs; however, there is not a direct numerical 1084 correlation between the number of mis-inserted cells and the number of 1085 corrupted AAL5 PDUs. There are two cases described below. 1087 1. Only one cell is mis-inserted into an AAL5 PDU. In this case, there is 1088 a one-to-one correspondence between cell mis-insertion and the number of 1089 corrupted AAL5 PDUs. 1091 2. Multiple cells are mis-inserted into an AAL5. In this case, there is 1092 not a one-to-one correspondence between cell mis-insertion and the number 1093 of corrupted AAL5 PDUs. 1095 Measurement Units: dimensionless. 1097 2.2.2.5. Cell Rate Margin (CRM) 1099 Definition: This is a measure of the difference between the effective 1100 bandwidth allocation and the allocation for sustainable rate in cells per 1101 second. 1103 Discussion: This measures the amount of provisioned bandwidth which is not 1104 utilized. This lack of utilization may be caused by encapsulation 1105 overhead, e.g., AAL5 trailer and padding, or by the protocol itself, e.g., 1106 TCP usually transmits in only one direction. 1108 Measurement units: Cells per second 1110 2.2.2.6. CRC Error Ratio 1112 Definition: The ratio of PDUs received at an endpoint that which contain an 1113 invalid CRC in relation to the total number of cells properly transmitted 1114 associated with a given traffic load, orientation and distribution, as well 1115 as an integration period. 1117 Discussion: CRC errors cause ATM cells to be lost. Although this will 1118 appear as cell loss at the ATM layer, this measurement can be made in- 1119 service using a test probe which measures CRC errors at the TC layer. 1121 Measurement Units: dimensionless 1123 2.2.2.7. Cell Transfer Delay (CTD) 1125 Definition: The elapsed time between a cell exit event at the measurement 1126 point 1 (e.g., at the source UNI) and the corresponding cell entry event at 1127 a measurement point 2 (e.g., the destination UNI) for a particular 1128 connection. 1130 Discussion: The cell transfer delay between two measurement points is the 1131 sum of the total inter-ATM node transmission delay and the total ATM node 1132 processing delay. While this number is a constant and should not adversely 1133 effect performance, it is a component in RTT. 1135 Measurement units: seconds 1137 2.2.3. ATM Adaptation Layer (AAL) Type 5 (AAL5) 1139 2.2.3.1. AAL5 Re-assembly Errors 1141 Definition: AAL5 Re-assembly Errors constitute any error, which causes the 1142 AAL5 PDU to be corrupted. 1144 Discussion: AAL5 Re-assembly errors cause AAL5 PDUs to be lost. These PDUs 1145 may contain IP datagrams. 1147 Measurement Units: Positive Integer 1149 2.2.3.2. AAL5 Reassembly Time 1151 Definition: AAL5 Reassembly Time constitutes the time between the arrival 1152 of the final cell in the AAL5 PDU and the AAL5 PDUs payload being made 1153 available to the service layer. 1155 Discussion: AAL5 Reassembly time directly effects TCP round trip time 1156 calculations. 1158 Measurement Units: seconds 1160 2.2.3.3. AAL5 CRC Error Ratio 1162 Definition: The ratio of PDUs received at an endpoint that which contain an 1163 invalid CRC in relation to the total number of cells properly transmitted 1164 associated with a given traffic load, orientation and distribution, as well 1165 as an integration period. 1167 Discussion: AAL5 CRC errors cause AAL5 re-assembly errors. See discussion 1168 under AAL5 re-assembly errors. 1170 Measurement Units: dimensionless 1172 2.2.4. ATM Service: Signaling 1174 2.2.4.1. CAC Denial Time 1176 Definition: The amount of time required for CAC to determine that a call 1177 must be rejected. 1179 Discussion: In the case where Call Proceeding is implemented, this number 1180 will be less than 4 seconds. Otherwise, it will be less than 10 seconds. 1181 Large values of this measurement will adversely effect performance on 1182 systems where an alternate, non-NBMA, service is available. 1184 Measurement Units: seconds 1186 2.2.4.2. Connection Establishment Time 1188 Definition: The amount of time between the first Setup message from the 1189 calling party and the Connect message to the calling party. 1191 Discussion: See discussion under SVC. 1193 Measurement Units: seconds 1195 2.2.4.3. Connection Teardown Time 1197 Definition: The amount of between the Release message being sent and the 1198 Release Complete message being received. 1200 Discussion: Large values of this measurement will adversely effect 1201 performance in systems where the total number of open calls or VCs is 1202 limited. Specifically, a new VC cannot be instantiated with the same 1203 VPI/VCI before the old one is released. 1205 Measurement Units: seconds 1207 2.2.4.4. Crankback Time 1209 Definition: The amount of time between the issuance of the first release 1210 or release complete message by the switch where the current Designated 1211 Transit List (DTL) is blocked and the receipt of the SETUP with the updated 1212 DTLs by the target switch. 1214 Discussion: This measurement does not take into account the amount of time 1215 associated with either the successful portion of the call setup transit or 1216 the time required for the calling party to receive a response from the 1217 called party. As a result, the call may still fail to complete if the call 1218 setup timer on the calling party expires. See discussion under SVC. 1220 Measurement Units: seconds 1222 2.2.4.5. Route Update Response Time 1224 Definition: The amount of time between the receipt of a PNNI Topology 1225 State Element (PTSE), which is the PNNI routing PDU, containing a topology 1226 different from the current topology and the point at which the switch 1227 begins to generate DTLs reflecting the routing change. 1229 Discussion: This measurement provides a lower bound on the amount of time 1230 during which SETUP messages will be forwarded along a sub-optimal or 1231 blocked path. 1233 Measurement Units: seconds 1235 2.2.5. ATM Service: ILMI 1237 2.2.5.1. MIB Alignment Time 1239 Definition: The amount of time between the issuance of the final cold 1240 start message and the final get response associated with the exchange of 1241 static MIB information. 1243 Discussion: This measurement reflects the amount of time required by the 1244 switch and end system to exchange all information required to characterize 1245 and align the capabilities of both systems. It does not include address 1246 registration. It should also be noted that this measurement will depend on 1247 the number of MIB elements implemented by both systems. 1249 Measurement Units: seconds 1251 2.2.5.2. Address Registration Time 1253 Definition: The amount of time between the initial set request issued by 1254 the switch and the final get response issued by the switch. 1256 Discussion: This measurement assumes that the switch has checked the 1257 network prefix status object and the end system has checked the ATM address 1258 status object. In the case where the end system checks the ATM address 1259 status object only after the switch has issued a set request of the network 1260 prefix status object, this measurement will not reflect the actual time 1261 required to complete the address registration. 1263 Measurement Units: seconds 1265 3. Security Considerations. 1267 As this document is solely for providing terminology and describes 1268 neither a protocol nor an implementation, there are no security 1269 considerations associated with this document. 1271 4. Notices 1273 The IETF takes no position regarding the validity or scope of any 1274 intellectual property or other rights that might be claimed to pertain 1275 to the implementation or use of the technology described in this 1276 document or the extent to which any license under such rights might or 1277 might not be available; neither does it represent that it has made any 1278 effort to identify any such rights. Information on the IETFs procedures 1279 with respect to rights in standards-track and standards-related 1280 documentation can be found in BCP-11. Copies of claims of rights made 1281 available for publication and any assurances of licenses to be made 1282 available, or the result of an attempt made to obtain a general license 1283 or permission for the use of such proprietary rights by implementors or 1284 users of this specification can be obtained from the IETF Secretariat. 1286 The IETF invites any interested party to bring to its attention any 1287 copyrights, patents or patent applications, or other proprietary rights 1288 which may cover technology that may be required to practice this 1289 standard. Please address the information to the IETF Executive 1290 Director. 1292 5. Disclaimer 1294 Copyright (C) The Internet Society (1999). All Rights Reserved. 1296 This document and translations of it may be copied and furnished to 1297 others, and derivative works that comment on or otherwise explain it or 1298 assist in its implementation may be prepared, copied, published and 1299 distributed, in whole or in part, without restriction of any kind, 1300 provided that the above copyright notice and this paragraph are included 1301 on all such copies and derivative works. However, this document itself 1302 may not be modified in any way, such as by removing the copyright notice 1303 or references to the Internet Society or other Internet organizations, 1304 except as needed for the purpose of developing Internet standards in 1305 which case the procedures for copyrights defined in the Internet 1306 Standards process must be followed, or as required to translate it into 1307 languages other than English. 1309 The limited permissions granted above are perpetual and will not be 1310 revoked by the Internet Society or its successors or assigns. This 1311 document and the information contained herein is provided on an "AS IS" 1312 basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE 1313 DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED 1314 TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE 1315 ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A 1316 PARTICULAR PURPOSE. 1318 6. References 1320 [AF-ILMI4.0] ATM Forum Integrated Local Management Interface Version 1321 4.0, af-ilmi-0065.000, September 1996. 1323 [AF-TEST-0022] Introduction to ATM Forum Test Specifications, af-test- 1324 0022.00, December 1994. 1326 [AF-TM4.0] ATM Forum, Traffic Management Specification Version 4.0, af- 1327 tm- 0056.00, April 1996. 1329 [AF-TM4.1] ATM Forum, Traffic Management Specification Version 4.1 1330 (final ballot), btd-tm-01.02, July 1998. 1332 [AF-UNI3.1] ATM Forum, User Network Interface Specification Version 3.1, 1333 September 1994. 1335 [AF-UNI4.0] ATM Forum, User Network Interface Specification Version 4.0, 1336 July 1996. 1338 [I.321] ITU-T, B-ISDN protocol reference model and its application, 1339 April 1991. 1341 [I.363] ITU-T, B-ISDN ATM Adaptation Layer Specification series, 1996- 1342 1997. 1344 [I.363.5] ITU-T, B-ISDN ATM Adaptation Layer Specification: Type 5 AAL, 1345 August 1996. 1347 7. Editors Addresses 1349 Jeffrey Dunn 1350 Advanced Network Consultants, Inc. 1351 11241-B Skilift Court, Columbia, MD 21044 USA 1352 Phone: +1 (410) 730-6300, E-mail: Jeffrey.Dunn@worldnet.att.net 1354 Cynthia Martin 1355 Advanced Network Consultants, Inc. 1356 11241-B Skilift Court, Columbia, MD 21044 USA 1357 Phone: +1 (410) 730-6300, E-mail: Cynthia.E.Martin@worldnet.att.net