draft-ietf-bmwg-atm-term-abr-03.txt   rfc3134.txt 
Network Working Group J. H. Dunn
INTERNET-DRAFT C. E. Martin
Expires: August, 2001 ANC, Inc.
April, 2001
Terminology for ATM ABR Benchmarking
<draft-ietf-bmwg-atm-term-abr-03.txt>
Status of this Memo
This document is an Internet-Draft and is in full conformance with all
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Internet-Drafts are draft documents valid for a maximum of six months Network Working Group J. Dunn
and may be updated, replaced, or obsoleted by other documents at any Request for Comments: 3134 C. Martin
time. It is inappropriate to use Internet-Drafts as reference material Category: Informational ANC, Inc.
or to cite them other than as "work in progress." June 2001
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (1999). All Rights Reserved. Copyright (C) The Internet Society (2001). All Rights Reserved.
Abstract Abstract
This memo discusses and defines terms associated with performance This memo discusses and defines terms associated with performance
benchmarking tests and the results of these tests in the context of benchmarking tests and the results of these tests in the context of
Asynchronous Transfer Mode (ATM) based switching devices supporting ABR. Asynchronous Transfer Mode (ATM) based switching devices supporting
The terms defined in this memo will be used in addition to terms defined ABR (Available Bit Rate). The terms defined in this memo will be
in RFCs 1242, 2285, and 2544 and 2761. This memo is a product of the used in addition to terms defined in RFCs 1242, 2285, and 2544 and
Benchmarking Methodology Working Group (BMWG) of the Internet 2761. This memo is a product of the Benchmarking Methodology Working
Engineering Task Force (IETF). Group (BMWG) of the Internet Engineering Task Force (IETF).
1. Introduction. 1. Introduction
This document provides terminology for benchmarking ATM based switching This document provides terminology for benchmarking ATM based
devices supporting ABR. It extends terminology already defined for switching devices supporting ABR. It extends terminology already
benchmarking network interconnect devices in RFC's 1242, 2285, and 2544 defined for benchmarking network interconnect devices in RFC's 1242,
and 2761. Although some of the definitions in this memo may be 2285, and 2544 and 2761. Although some of the definitions in this
applicable to a broader group of network interconnect devices, the memo may be applicable to a broader group of network interconnect
primary focus of the terminology in this memo is on ATM ABR. devices, the primary focus of the terminology in this memo is on ATM
ABR.
This memo contains two major sections: Background and Definitions. The This memo contains two major sections: Background and Definitions.
background section provides the reader with an overview of the The background section provides the reader with an overview of the
technology and IETF formalisms. The definitions section is split into technology and IETF formalisms. The definitions section is split
two sub- sections. The formal definitions sub-section is provided as a into two sub-sections. The formal definitions sub-section is
courtesy to the reader. The measurement definitions sub-section provided as a courtesy to the reader. The measurement definitions
contains performance metrics with inherent units. sub-section contains performance metrics with inherent units.
This document assumes that necessary services are available and active. This document assumes that necessary services are available and
For example, IP connectivity requires SSCOP connectivity between active. For example, IP connectivity requires SSCOP connectivity
signaling entities. Further, it is assumed that the SUT has the ability between signaling entities. Further, it is assumed that the SUT has
to configure ATM addresses (via hard coded addresses, ILMI or PNNI the ability to configure ATM addresses (via hard coded addresses,
neighbor discovery), has the ability to run SSCOP, and has the ability ILMI or PNNI neighbor discovery), has the ability to run SSCOP, and
to perform signaled call setups (via UNI or PNNI signaling). Finally, has the ability to perform signaled call setups (via UNI or PNNI
this document presents only the terminology associated with benchmarking signaling). Finally, this document presents only the terminology
IP performance over ATM; therefore, it does not represent a total associated with benchmarking IP performance over ATM; therefore, it
compilation of ATM test terminology. does not represent a total compilation of ATM test terminology.
The BMWG produces two major classes of documents: Benchmarking The BMWG produces two major classes of documents: Benchmarking
Terminology documents and Benchmarking Methodology documents. The Terminology documents and Benchmarking Methodology documents. The
Terminology documents present the benchmarks and other related terms. Terminology documents present the benchmarks and other related terms.
The Methodology documents define the procedures required to collect the The Methodology documents define the procedures required to collect
benchmarks cited in the corresponding Terminology documents. the benchmarks cited in the corresponding Terminology documents.
2. Existing Definitions. 2. Existing Definitions.
RFC 1242 "Benchmarking Terminology for Network Interconnect Devices" RFC 1242, "Benchmarking Terminology for Network Interconnect
should be consulted before attempting to make use of this document. RFC Devices", should be consulted before attempting to make use of this
2544 "Benchmarking Methodology for Network Interconnect Devices" document. RFC 2544, "Benchmarking Methodology for Network
contains discussions of a number of terms relevant to the benchmarking Interconnect Devices", contains discussions of a number of terms
of switching devices and should be consulted. RFC 2285 "Benchmarking relevant to the benchmarking of switching devices and should be
Terminology for LAN Switching Devices" contains a number of terms consulted. RFC 2285, "Benchmarking Terminology for LAN Switching
pertaining to traffic distributions and datagram interarrival. RFC 2761 Devices", contains a number of terms pertaining to traffic
" Terminology for ATM Benchmarking" contains a number terms pertaining distributions and datagram interarrival. RFC 2761, "Terminology for
to traffic management [TM4.0, TM4.1]. Many of the metrics defined in ATM Benchmarking", contains a number terms pertaining to traffic
RFC 2761 (e.g. CDV, CER, CLR, CMR, and CTD) also apply to ABR management [TM4.0, TM4.1]. Many of the metrics defined in RFC 2761
performance benchmarking. These metrics will not be redefined in this (e.g., CDV, CER, CLR, CMR, and CTD) also apply to ABR performance
document. For the sake of clarity and continuity, this RFC adopts the benchmarking. These metrics will not be redefined in this document.
template for definitions set out in Section 2 of RFC 1242. For the sake of clarity and continuity, this RFC adopts the template
for definitions set out in Section 2 of RFC 1242.
II. Definitions II. Definitions
The definitions presented in this section have been divided into two The definitions presented in this section have been divided into two
groups. The first group is formal definitions, which are required in groups. The first group is formal definitions, which are required in
the definitions of the performance metrics but are not themselves the definitions of the performance metrics but are not themselves
strictly metrics. These definitions are subsumed from other work done strictly metrics. These definitions are subsumed from other work
in other working groups both inside and outside the IETF. They are done in other working groups both inside and outside the IETF. They
provided as a courtesy to the reader. are provided as a courtesy to the reader.
1. Formal Definitions 1. Formal Definitions
1.1. Definition Format (from RFC 1242) 1.1. Definition Format (from RFC 1242)
Term to be defined. Term to be defined.
Definition: The specific definition for the term. Definition: The specific definition for the term.
Discussion: A brief discussion of the term, its application and any Discussion: A brief discussion of the term, its application and any
restrictions on measurement procedures. restrictions on measurement procedures.
Specification: The working group and document in which the terms are Specification: The working group and document in which the terms are
specified and are listed in the references section. specified and are listed in the references section.
1.2. Related Definitions. 1.2. Related Definitions.
1.2.1. Allowed Cell Rate (ACR) 1.2.1. Allowed Cell Rate (ACR)
Definition: An ABR service parameter, ACR is the current rate Definition: An ABR service parameter, ACR is the current rate
(cells/second) at which a source is allowed to send. (cells/second) at which a source is allowed to send.
Discussion: For ABR traffic, ACR constitutes the actual data throughput Discussion: For ABR traffic, ACR constitutes the actual data
for a particular VC. The time change of this value effects TCP round trip throughput for a particular VC. The time change of this value
time calculations, which in turn effects TCP throughput. effects TCP round trip time calculations, which in turn effects TCP
throughput.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.2. ACR Decrease Time Factor (ADTF) 1.2.2. ACR Decrease Time Factor (ADTF)
Definition: This is the time permitted between sending RM-cells before the
rate is decreased to ICR (Initial Cell Rate). The time units are
.01 to 10.23 seconds
with a granularity of 10 ms. Definition: This is the time permitted between sending RM-cells
before the rate is decreased to ICR (Initial Cell Rate). The time
units are .01 to 10.23 seconds with a granularity of 10 ms.
Discussion: For ABR traffic, ADTF constitutes the time rate of the ACR. Discussion: For ABR traffic, ADTF constitutes the time rate of the
This value effects TCP round trip time calculations, which in turn effects ACR. This value effects TCP round trip time calculations, which in
TCP throughput. turn effects TCP throughput.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.3. Additive Increase Rate (AIR) 1.2.3. Additive Increase Rate (AIR)
Definition: An ABR service parameter, AIR controls the rate at which the Definition: An ABR service parameter, AIR controls the rate at which
cell transmission rate increases. It is signaled as AIRF, where the cell transmission rate increases. It is signaled as AIRF, where
AIRF = AIR*Nrm/PCR.
Discussion: For ABR traffic, AIR effects the time rate of change of the AIRF = AIR*Nrm/PCR.
ACR. This value effects TCP round trip time calculations, which in turn
effects TCP throughput.
Specification: AF-TM4.0 Discussion: For ABR traffic, AIR effects the time rate of change of
the ACR. This value effects TCP round trip time calculations, which
in turn effects TCP throughput.
Specification: AF-TM4.0
1.2.4. Additive Increase Rate Factor (AIRF) 1.2.4. Additive Increase Rate Factor (AIRF)
Definition: Refer to AIR. Definition: Refer to AIR.
Discussion: Refer to AIR. Discussion: Refer to AIR.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.5. Available Bit Rate (ABR) 1.2.5. Available Bit Rate (ABR)
Definition: ABR is an ATM layer service category for which the limiting ATM Definition: ABR is an ATM layer service category for which the
layer transfer characteristics provided by the network may change limiting ATM layer transfer characteristics provided by the network
subsequent to connection establishment. A flow control mechanism is may change subsequent to connection establishment. A flow control
specified which supports several types of feedback to control the source mechanism is specified which supports several types of feedback to
rate in response to changing ATM layer transfer characteristics. control the source rate in response to changing ATM layer transfer
characteristics.
Discussion: It is expected that an end-system that adapts its traffic in Discussion: It is expected that an end-system that adapts its traffic
accordance with the feedback will experience a low cell loss ratio and in accordance with the feedback will experience a low cell loss ratio
obtain a fair share of the available bandwidth according to a network and obtain a fair share of the available bandwidth according to a
specific allocation policy. Cell delay variation is not controlled in this network specific allocation policy. Cell delay variation is not
service, although admitted cells are not delayed unnecessarily. controlled in this service, although admitted cells are not delayed
unnecessarily.
Specification: AF-TM4.1 Specification: AF-TM4.1
1.2.6. Available Bit Rate (ABR) Compliance (Conformance) 1.2.6. Available Bit Rate (ABR) Compliance (Conformance)
Definition: ABR connection conformance refers to the behavior specified for Definition: ABR connection conformance refers to the behavior
ABR destination and switches, but allows for delays between the source and specified for ABR destination and switches, but allows for delays
the UNI [UNI3.1, UNI4.0], which may perturb the traffic flow. between the source and the UNI [UNI3.1, UNI4.0], which may perturb
the traffic flow.
Discussion: The cells on an ABR connection applies to CLP=0 cells, which Discussion: The cells on an ABR connection applies to CLP=0 cells,
are tested upon arrival. At the arrival point, each cell is identified as which are tested upon arrival. At the arrival point, each cell is
conforming or non-conforming. The minimal conformance definition for ABR identified as conforming or non-conforming. The minimal conformance
is GCRA((1/PCR),t1), where PCR is defined for CLP=0 flow. definition for ABR is GCRA((1/PCR),t1), where PCR is defined for
CLP=0 flow.
Specification: AF-TM4.1 Specification: AF-TM4.1
1.2.7. BN 1.2.7. BN
Definition: The BN bit in the RM-cell indicated wheather the RM-cell is a Definition: The BN bit in the RM-cell indicated whether the RM-cell
BECN cell or not. is a BECN cell or not.
Discussion: If BN=0, the RM cells were generated by the source. If BN=1, Discussion: If BN=0, the RM cells were generated by the source. If
the RM cells were generated by the destination or a switch. BN=1, the RM cells were generated by the destination or a switch.
Specification: AF-TM4.1 Specification: AF-TM4.1
1.2.8. CCR 1.2.8. CCR
Definition: The CCR field in the RM-cell is set by the source to its Definition: The CCR field in the RM-cell is set by the source to its
current ACR. CCR is formatted as a rate. current ACR. CCR is formatted as a rate.
Discussion: For BECN cells, CCR=0. Discussion: For BECN cells, CCR=0.
Specification: AF-TM4.1 Specification: AF-TM4.1
1.2.9. Cell Blocks (CB) 1.2.9. Cell Blocks (CB)
Definition: Cell blocks are a sequence of N cells transmitted consecutively Definition: Cell blocks are a sequence of N cells transmitted
on a given connection. consecutively on a given connection.
Discussion: A cell block will normally correspond to the number of Discussion: A cell block will normally correspond to the number of
information cells transmitted between successive OAM cells. information cells transmitted between successive OAM cells.
Specification: AF-TM4.1 Specification: AF-TM4.1
1.2.10. Congestion Indication (CI) 1.2.10. Congestion Indication (CI)
Definition: The CI bit in the RM-cell allows a network element to indicate Definition: The CI bit in the RM-cell allows a network element to
that there is congestion in the network. indicate that there is congestion in the network.
Discussion: When the source receives a backward RM-cell with CI=1, ACR is Discussion: When the source receives a backward RM-cell with CI=1,
decreased. When the destination turns around a forward RM-cell, the CI is ACR is decreased. When the destination turns around a forward RM-
set to 1 to indicate that the previously received data cell had the EFCI cell, the CI is set to 1 to indicate that the previously received
state set. data cell had the EFCI state set.
Specification: AF-TM4.1 Specification: AF-TM4.1
1.2.11. Cutoff Decrease Factor (CDF) 1.2.11. Cutoff Decrease Factor (CDF)
Definition: CDF controls the decrease in ACR (Allowed Cell Rate) associated Definition: CDF controls the decrease in ACR (Allowed Cell Rate)
with CRM (missing RM cell count). associated with CRM (missing RM cell count).
Discussion: For ABR traffic, CDF effects the time rate of change of the Discussion: For ABR traffic, CDF effects the time rate of change of
ACR. This value effects TCP round trip time calculations, which in turn the ACR. This value effects TCP round trip time calculations, which
effects TCP throughput. in turn effects TCP throughput.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.12. DIR 1.2.12. DIR
Definition: The DIR bit in the RM-cell indicates which direction of data Definition: The DIR bit in the RM-cell indicates which direction of
flow is associated with the RM-cell. DIR is changed from 0 to 1 when an data flow is associated with the RM-cell. DIR is changed from 0 to 1
RM-cell is turned around at the destination. when an RM-cell is turned around at the destination.
Discussion: A forward RM-cell is indicated by DIR=0 and is associated with Discussion: A forward RM-cell is indicated by DIR=0 and is associated
data cells flowing in the same direction. A backward RM-cell is indicated with data cells flowing in the same direction. A backward RM-cell is
by DIR=1 and is associated with data cells flowing in the opposite indicated by DIR=1 and is associated with data cells flowing in the
direction. opposite direction.
Specification: AF-TM4.1 Specification: AF-TM4.1
1.2.13. Explicit Rate (ER) 1.2.13. Explicit Rate (ER)
Definition: The ER field in the RM-cell is used to limit the source ACR to
a specific value. For each RM-cell, ER is set by the source to a requested
rate (e.g. PCR). It may be reduced by any network element in the path to a
value that the element can sustain. ER is formatted as a rate.
Discussion: None. Definition: The ER field in the RM-cell is used to limit the source
ACR to a specific value. For each RM-cell, ER is set by the source
to a requested rate (e.g., PCR). It may be reduced by any network
element in the path to a value that the element can sustain. ER is
formatted as a rate.
Specification: AF-TM4.1 Discussion: None.
Specification: AF-TM4.1
1.2.14. Feedback 1.2.14. Feedback
Definition: Information carried in the backward RM-cells provided by the Definition: Information carried in the backward RM-cells provided by
network elements and/or the destination back to the source. the network elements and/or the destination back to the source.
Discussion: Feedback may include information in the ER field, or the CI or Discussion: Feedback may include information in the ER field, or the
NI bits of each backward RM-cell. CI or NI bits of each backward RM-cell.
Specification: AF-TM4.1 Specification: AF-TM4.1
1.2.15. Ideal Transmission Time (ITT) 1.2.15. Ideal Transmission Time (ITT)
Definition: The transmission time for ABR CLP=0 cells, if the difference Definition: The transmission time for ABR CLP=0 cells, if the
between itself and the transmission time for the previous CLP=0 cell on the difference between itself and the transmission time for the previous
connection is greater than or equal to the minimum: a) the inverse of the CLP=0 cell on the connection is greater than or equal to the minimum:
ACR in effect immediately after the transmission time of the first of the a) the inverse of the ACR in effect immediately after the
two cells b) the inverse of the ACR in effect immediately before the transmission time of the first of the two cells b) the inverse of the
transmission time of the second of the two cells. ACR in effect immediately before the transmission time of the second
of the two cells.
Discussion: The transmission time for the first cell on the connection is Discussion: The transmission time for the first cell on the
automatically an ITT. connection is automatically an ITT.
Specification: AF-TM4.1 Specification: AF-TM4.1
1.2.16. Initial Cell Rate (ICR) 1.2.16. Initial Cell Rate (ICR)
Definition: An ABR service parameter, in cells/sec, that is the rate at Definition: An ABR service parameter, in cells/sec, that is the rate
which a source should send initially and after an idle period. at which a source should send initially and after an idle period.
Discussion: none. Discussion: none.
Specification: AF-TM4.0
Specification: AF-TM4.0
1.2.17. In-Rate Cells 1.2.17. In-Rate Cells
Definition: In-Rate ABR cells are sent with CLP=0. Definition: In-Rate ABR cells are sent with CLP=0.
Discussion: ABR RM-cells shall be sent with CLP=0 except in certain Discussion: ABR RM-cells shall be sent with CLP=0 except in certain
circumstances, See Out-of-Rate Cells. All other ABR cells shall be sent circumstances, See Out-of-Rate Cells. All other ABR cells shall be
with CLP=0. sent with CLP=0.
Specification: AF-TM4.1 Specification: AF-TM4.1
1.2.18. Minimum Cell Rate (MCR) 1.2.18. Minimum Cell Rate (MCR)
Definition: An ABR service traffic descriptor, in cells/sec, that is the Definition: An ABR service traffic descriptor, in cells/sec, that is
rate at which the source is always allowed to send. the rate at which the source is always allowed to send.
Discussion: MCR may be set to zero. The bandwidth available from the Discussion: MCR may be set to zero. The bandwidth available from the
network may vary, but shall not become less than MCR. network may vary, but shall not become less than MCR.
Specification: AF-TM4.1 Specification: AF-TM4.1
1.2.19. Mrm 1.2.19. Mrm
Definition: An ABR service parameter that controls allocation of bandwidth Definition: An ABR service parameter that controls allocation of
between forward W-cells, backward RM-cells, and data cells. bandwidth between forward W-cells, backward RM-cells, and data cells.
Discussion: none. Discussion: none.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.20. No Increase (NI) 1.2.20. No Increase (NI)
Definition: The NI bit in the RM-cell is used to prevent a source from Definition: The NI bit in the RM-cell is used to prevent a source
increasing its ACR. NI does not require any decrease in value. from increasing its ACR. NI does not require any decrease in value.
Discussion: None. Discussion: None.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.21. Nrm 1.2.21. Nrm
Definition: An ABR service parameter, Nrm is the maximum number of cells a Definition: An ABR service parameter, Nrm is the maximum number of
source may send for each forward RM-cell. cells a source may send for each forward RM-cell.
Discussion: none. Discussion: none.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.22. Out-of-Rate Cells 1.2.22. Out-of-Rate Cells
Definition: Out-of-Rate ABR cells are sent with CLP=1. Definition: Out-of-Rate ABR cells are sent with CLP=1.
Discussion: This may be used to enable a rate increate for a connection Discussion: This may be used to enable a rate increase for a
that has an ACR=0. The source would generate out-of-rate cells to probe connection that has an ACR=0. The source would generate out-of-rate
the network to learn when it may increase its rate. cells to probe the network to learn when it may increase its rate.
Specification: AF-TM4.1 Specification: AF-TM4.1
1.2.23. Rate Decrease Factor (RDF) 1.2.23. Rate Decrease Factor (RDF)
Definition: An ABR service parameter, RDF controls the decrease in the cell Definition: An ABR service parameter, RDF controls the decrease in
transmission rate. RDF is a power of 2 from 1/32,768 to 1. the cell transmission rate. RDF is a power of 2 from 1/32,768 to 1.
Discussion: For ABR traffic, RDF effects the time rate of change of the Discussion: For ABR traffic, RDF effects the time rate of change of
ACR. This value effects TCP round trip time calculations, which in turn the ACR. This value effects TCP round trip time calculations, which
effects TCP throughput. in turn effects TCP throughput.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.24. Rate Increase Factor (RIF) 1.2.24. Rate Increase Factor (RIF)
Definition: This controls the amount by which the cell transmission rate Definition: This controls the amount by which the cell transmission
may increase upon receipt of a RM-cell. The additive increase rate rate may increase upon receipt of a RM-cell. The additive increase
AIR=PCR*RIF. RIF is a power of 2, ranging from 1/32,768 to 1. rate AIR=PCR*RIF. RIF is a power of 2, ranging from 1/32,768 to 1.
Discussion: For ABR traffic, RIF effects the time rate of change of the Discussion: For ABR traffic, RIF effects the time rate of change of
ACR. This value effects TCP round trip time calculations, which in turn the ACR. This value effects TCP round trip time calculations, which
effects TCP throughput. in turn effects TCP throughput.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.25. Resource Management (RM) Cells 1.2.25. Resource Management (RM) Cells
Definition: RM cells are used to convey network status (available Definition: RM cells are used to convey network status (available
bandwidth, congestion levels) and request peak cell rates for ATM blocks. bandwidth, congestion levels) and request peak cell rates for ATM
The RM cell has the following format: blocks. The RM cell has the following format:
Header: 5 bytes, same as the ATM cell header Header: 5 bytes, same as the ATM cell header Protocol ID: 3 bytes,
Protocol ID: 3 bytes, protocol ID value is 1 for ABR service protocol ID value is 1 for ABR service Function specific field: 45
Function specific field: 45 bytes, data required for the specific protocol bytes, data required for the specific protocol (See DIR, BN, CI, NI,
(See DIR, BN, CI, NI, ER, CCR, and MCR for field information.) ER, CCR, and MCR for field information.) Rsvd: 6 bytes, reserved for
Rsvd: 6 bytes, reserved for future specification future specification EDC: 10 bytes, CRC-10 error detection code
EDC: 10 bytes, CRC-10 error detection code computed over the cell payload computed over the cell payload .ti6 (except the CRC-10 field) and
(except the CRC-10 field) and used to check for data corruption used to check for data corruption
Discussion: RM information can exist at the VP and/or VC level. VP level Discussion: RM information can exist at the VP and/or VC level. VP
cells are identified with a VCI value of 6. VC level cells are identified level cells are identified with a VCI value of 6. VC level cells are
with a PT of 6. See DIR, BN, CI, NI, ER, CCR, and MCR for additional identified with a PT of 6. See DIR, BN, CI, NI, ER, CCR, and MCR for
protocol field information. additional protocol field information.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.26. Severely Errored Cell Block (SECB) 1.2.26. Severely Errored Cell Block (SECB)
Definition: A severely cell block outcome occurs when more than M errored Definition: A severely cell block outcome occurs when more than M
cells, lost cells, or misinserted cell outcomes are observed in a received errored cells, lost cells, or misinserted cell outcomes are observed
cell block. in a received cell block.
Discussion: none. Discussion: none.
Specification: AF-TM4.1 Specification: AF-TM4.1
1.2.27. Tagged Cell Rate (TCR) 1.2.27. Tagged Cell Rate (TCR)
Definition: An ABR service parameter, TCR limits the rate at which a source Definition: An ABR service parameter, TCR limits the rate at which a
may send out-of-rate forward RM-cells. TCR is a constant fixed at 10 source may send out-of-rate forward RM-cells. TCR is a constant
cells/second. fixed at 10 cells/second.
Discussion: none. Discussion: none.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.28. TDF 1.2.28. TDF
Definition: An ABR service parameter, TDF controls the decrease in ACR Definition: An ABR service parameter, TDF controls the decrease in
associated with TOF. TDF is signaled as TDFF, where TDF=TDFF/RDF times the ACR associated with TOF. TDF is signaled as TDFF, where TDF=TDFF/RDF
smallest power of 2 greater or equal to PCR. TDF is in units of 1/seconds. times the smallest power of 2 greater or equal to PCR. TDF is in
units of 1/seconds.
Discussion: For ABR traffic, TDF effects the time rate of change of the Discussion: For ABR traffic, TDF effects the time rate of change of
ACR. This value effects TCP round trip time calculations, which in turn the ACR. This value effects TCP round trip time calculations, which
effects TCP throughput. in turn effects TCP throughput.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.29. TDFF 1.2.29. TDFF
Definition: Refer to TDF. TDFF is either zero or a power of two in the Definition: Refer to TDF. TDFF is either zero or a power of two in
range 1/64 to 1 in units of 1 /cells. the range 1/64 to 1 in units of 1 /cells.
Discussion: Refer to TDF. Discussion: Refer to TDF.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.30. Time Out Factor (TOF) 1.2.30. Time Out Factor (TOF)
Definition: An ABR service parameter, TOF controls the maximum time Definition: An ABR service parameter, TOF controls the maximum time
permitted between sending forward RM-cells before a rate decrease is permitted between sending forward RM-cells before a rate decrease is
required. It is signaled as TOFF where TOF=TOFF+1. TOFF is a power of 2 in required. It is signaled as TOFF where TOF=TOFF+1. TOFF is a power
the range: 1/8 to 4,096. of 2 in the range: 1/8 to 4,096.
Discussion: For ABR traffic, TOF effects the time rate of change of the Discussion: For ABR traffic, TOF effects the time rate of change of
ACR. This value effects TCP round trip time calculations, which in turn the ACR. This value effects TCP round trip time calculations, which
effects TCP throughput. in turn effects TCP throughput.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.31. Time Out Factor (TOFF) 1.2.31. Time Out Factor (TOFF)
Definition: Refer to TOF. Definition: Refer to TOF.
Discussion: none. Discussion: none.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.32. Trm 1.2.32. Trm
Definition: An ABR service parameter that provides an upper bound on the Definition: An ABR service parameter that provides an upper bound on
time between forward RM-cells for an active source. It is 100 times a power the time between forward RM-cells for an active source. It is 100
of two with a range of 100*2-7 to 100*20 times a power of two with a range of 100*2-7 to 100*20
Discussion: For ABR traffic, Trm effects the time rate of change of the Discussion: For ABR traffic, Trm effects the time rate of change of
ACR. This value effects TCP round trip time calculations, which in turn the ACR. This value effects TCP round trip time calculations, which
effects TCP throughput. in turn effects TCP throughput.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.33. Virtual Source/Virtual Destination (VSND) 1.2.33. Virtual Source/Virtual Destination (VSND)
Definition: An ABR connection may be divided into two or more separately Definition: An ABR connection may be divided into two or more
controlled ABR segments. Each ABR control segment, except the first, is separately controlled ABR segments. Each ABR control segment, except
sourced by a virtual source. A virtual source implements the behavior of an the first, is sourced by a virtual source. A virtual source
ABR source endpoint. Backward RM-cells received by a virtual source are implements the behavior of an ABR source endpoint. Backward RM-cells
removed from the connection. Each ABR control segment, except the last, is received by a virtual source are removed from the connection. Each
terminated by a virtual destination. A virtual destination assumes the ABR control segment, except the last, is terminated by a virtual
behavior of an ABR destination endpoint. Forward RM-cells received by a destination. A virtual destination assumes the behavior of an ABR
virtual destination are turned around and not forwarded to the next segment destination endpoint. Forward RM-cells received by a virtual
of the connection. destination are turned around and not forwarded to the next segment
of the connection.
Discussion: none. Discussion: none.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.34. Xrm Decrease Factor (XDM) 1.2.34. Xrm Decrease Factor (XDM)
Definition: An ABR service parameter, XDF controls the decrease in ACR Definition: An ABR service parameter, XDF controls the decrease in
associated with Xrm. It is a power of two in range: [0, 1]. ACR associated with Xrm. It is a power of two in range: [0, 1].
Discussion: For ABR traffic, XDM effects the time rate of change of the Discussion: For ABR traffic, XDM effects the time rate of change of
ACR. This value effects TCP round trip time calculations, which in turn the ACR. This value effects TCP round trip time calculations, which
effects TCP throughput. in turn effects TCP throughput.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.35. Xrm 1.2.35. Xrm
Definition: An ABR service parameter, Xrm limits the number of forward RM- Definition: An ABR service parameter, Xrm limits the number of
cells which may be sent in the absence of received backward PM-cells. The forward RM-cells which may be sent in the absence of received
range is 0-255. backward PM-cells. The range is 0-255.
Discussion: For ABR traffic, Xrm effects the time rate of change of the Discussion: For ABR traffic, Xrm effects the time rate of change of
ACR. This value effects TCP round trip time calculations, which in turn the ACR. This value effects TCP round trip time calculations, which
effects TCP throughput. in turn effects TCP throughput.
Specification: AF-TM4.0 Specification: AF-TM4.0
2. Performance Metrics 2. Performance Metrics
2. 1. Definition Format (from RFC 1242) 2.1. Definition Format (from RFC 1242)
Metric to be defined. Metric to be defined.
Definition: The specific definition for the metric. Definition: The specific definition for the metric.
Discussion: A brief discussion of the metric, its application and any Discussion: A brief discussion of the metric, its application and any
restrictions on measurement procedures. restrictions on measurement procedures.
Measurement units: Intrinsic units used to quantify this metric. This Measurement units: Intrinsic units used to quantify this metric.
includes subsidiary units; e.g., microseconds are acceptable if the This includes subsidiary units; e.g., microseconds are acceptable if
intrinsic unit is seconds. the intrinsic unit is seconds.
2.2. Definitions 2.2. Definitions
2.2.1. ABR Rate Decrease Response Time (ARDRT) 2.2.1. ABR Rate Decrease Response Time (ARDRT)
Definition: The amount of time required by the SUT to adjust its Definition: The amount of time required by the SUT to adjust its
transmission rate based on an ABR rate decrease request. transmission rate based on an ABR rate decrease request.
Discussion: During the ARDRT, cells transmitted by the SUT may be dropped Discussion: During the ARDRT, cells transmitted by the SUT may be
by the network due to traffic policing. These dropped cells may contain a dropped by the network due to traffic policing. These dropped cells
portion of an IP datagram. This may cause IP and TCP packet loss. may contain a portion of an IP datagram. This may cause IP and TCP
packet loss.
Measurement Units: seconds Measurement Units: seconds
2.2.2. ABR Rate Increase Response Time (ARIRT) 2.2.2. ABR Rate Increase Response Time (ARIRT)
Definition: The amount of time required by the SUT to adjust its Definition: The amount of time required by the SUT to adjust its
transmission rate based on an ABR rate increase request. transmission rate based on an ABR rate increase request.
Discussion: During the ARIRT, the SUT will not fully utilize the available Discussion: During the ARIRT, the SUT will not fully utilize the
bandwidth. This will negatively impact IP and TCP throughput. available bandwidth. This will negatively impact IP and TCP
throughput.
Measurement Units: seconds Measurement Units: seconds
2.2.3. RM-Cell Delay Variation (RM-CDV) 2.2.3. RM-Cell Delay Variation (RM-CDV)
Definition: The variation in RM-cell transfer delay (RM-CTD) of RM-cells
associated with a given traffic load, orientation and distribution, as well
as an integration period. RM-CDV = max (RM-CTD) - min (RM-CTD) where max
and min indicate the maximum and minimum over the integration period,
respectively.
Discussion: RM-CDV is a component of RM-cell transfer delay, induced by Definition: The variation in RM-cell transfer delay (RM-CTD) of RM-
buffering and RM-cell scheduling. cells associated with a given traffic load, orientation and
distribution, as well as an integration period. RM-CDV = max (RM-
CTD) - min (RM-CTD) where max and min indicate the maximum and
minimum over the integration period, respectively.
RM-CDV effects the time required to notify the source of a change in the Discussion: RM-CDV is a component of RM-cell transfer delay, induced
condition of the network. This in turn effects TCP round trip time by buffering and RM-cell scheduling.
calculations. Large values of RM-CDV will adversely effect TCP throughput
and cause SAR timeout.
Measurement Units: seconds RM-CDV effects the time required to notify the source of a change in
the condition of the network. This in turn effects TCP round trip
time calculations. Large values of RM-CDV will adversely effect TCP
throughput and cause SAR timeout.
Measurement Units: seconds
2.2.4. RM-Cell Error Ratio (RM-CER) 2.2.4. RM-Cell Error Ratio (RM-CER)
Definition: The ratio of RM-cells with payload errors in a transmission in Definition: The ratio of RM-cells with payload errors in a
relation to the total number of RM-cells sent in a transmission associated transmission in relation to the total number of RM-cells sent in a
with a given traffic load, orientation and distribution, as well as an transmission associated with a given traffic load, orientation and
integration period. Note that errors occurring in the RM-cell header will distribution, as well as an integration period. Note that errors
cause RM-cell loss at the ATM layer. Note further that multiple errors in occurring in the RM-cell header will cause RM-cell loss at the ATM
a payload will only be counted as one cell payload error. layer. Note further that multiple errors in a payload will only be
counted as one cell payload error.
RM-CER = RM-Cells with payload errors / Total RM-Cells Transmitted. RM-CER = RM-Cells with payload errors / Total RM-Cells Transmitted.
Discussion: The measurement is taken over a time interval and is desirable Discussion: The measurement is taken over a time interval and is
to be measured on an in-service circuit. RM-CER effects the time required desirable to be measured on an in-service circuit. RM-CER effects the
to notify the source of a change in the condition of the network. This in time required to notify the source of a change in the condition of
turn effects TCP round trip time calculations. Large values of RM-CER will the network. This in turn effects TCP round trip time calculations.
adversely effect TCP throughput and cause SAR timeout. Large values of RM-CER will adversely effect TCP throughput and cause
SAR timeout.
Measurement Units: dimensionless. Measurement Units: dimensionless.
2.2.5. RM-Cell Loss Ratio (RM-CLR) 2.2.5. RM-Cell Loss Ratio (RM-CLR)
Definition: The ratio of lost RM-cells in a transmission in relation to the Definition: The ratio of lost RM-cells in a transmission in relation
total RM-cells sent in a transmission associated with a given traffic load, to the total RM-cells sent in a transmission associated with a given
orientation and distribution, as well as an integration period. traffic load, orientation and distribution, as well as an integration
period.
RM-CLR = Lost RM-Cells / Total RM-Cells Transmitted. RM-CLR = Lost RM-Cells / Total RM-Cells Transmitted.
Discussion: The objective is to minimize RM-CLR. It is expressed as an Discussion: The objective is to minimize RM-CLR. It is expressed as
order of magnitude, having a range of 10^-1 to 10^-15 and unspecified. an order of magnitude, having a range of 10^-1 to 10^-15 and
unspecified.
RM-CLR effects the time required to notify the source of a change in the RM-CLR effects the time required to notify the source of a change in
condition of the network. This in turn effects TCP round trip time the condition of the network. This in turn effects TCP round trip
calculations. Large values of RM-CLR will adversely effect TCP throughput time calculations. Large values of RM-CLR will adversely effect TCP
and cause SAR timeout. throughput and cause SAR timeout.
Measurement Units: dimensionless. Measurement Units: dimensionless.
2.2.6. RM-Cell Misinsertion Ratio (RM-CMR) 2.2.6. RM-Cell Misinsertion Ratio (RM-CMR)
Definition: The ratio of RM-cells received at an endpoint that were not Definition: The ratio of RM-cells received at an endpoint that were
originally transmitted by the source end in relation to the total number of not originally transmitted by the source end in relation to the total
RM-cells properly transmitted associated with a given traffic load, number of RM-cells properly transmitted associated with a given
orientation and distribution, as well as an integration period. traffic load, orientation and distribution, as well as an integration
period.
RM-CMR = Misinserted RM-Cells / Total RM-Cells Transmitted. RM-CMR = Misinserted RM-Cells / Total RM-Cells Transmitted.
Discussion: The measurement is taken over a time interval and is desirable Discussion: The measurement is taken over a time interval and is
to be measured on an in-service circuit. desirable to be measured on an in-service circuit.
RM-CMR effects the time required to notify the source of a change in the RM-CMR effects the time required to notify the source of a change in
condition of the network. This in turn effects TCP round trip time the condition of the network. This in turn effects TCP round trip
calculations. Large values of RM-CMR will adversely effect TCP throughput time calculations. Large values of RM-CMR will adversely effect TCP
and cause SAR timeout. throughput and cause SAR timeout.
Measurement Units: dimensionless. Measurement Units: dimensionless.
2.2.7. RM-CRC Error Ratio 2.2.7. RM-CRC Error Ratio
Definition: The ratio of RM-cells received at an endpoint which contain an Definition: The ratio of RM-cells received at an endpoint which
invalid CRC in relation to the total number of RM-cells properly contain an invalid CRC in relation to the total number of RM-cells
transmitted associated with a given traffic load, orientation and properly transmitted associated with a given traffic load,
distribution, as well as an integration period. orientation and distribution, as well as an integration period.
Discussion: RM-CRC errors cause ATM RM-cells to be lost. Discussion: RM-CRC errors cause ATM RM-cells to be lost.
RM-CRC effects the time required to notify the source of a change in the RM-CRC effects the time required to notify the source of a change in
condition of the network. This in turn effects TCP round trip time the condition of the network. This in turn effects TCP round trip
calculations. Large values of RM-CRC will adversely effect TCP throughput time calculations. Large values of RM-CRC will adversely effect TCP
and cause SAR timeout. throughput and cause SAR timeout.
Measurement Units: dimensionless Measurement Units: dimensionless
2.2.8. RM-Cell Transfer Delay (RM-CTD) 2.2.8. RM-Cell Transfer Delay (RM-CTD)
Definition: The elapsed time between a RM-cell exit event at the Definition: The elapsed time between a RM-cell exit event at the
measurement point 1 (e.g., at the source UNI) and the corresponding RM- measurement point 1 (e.g., at the source UNI) and the corresponding
cell entry event at a measurement point 2 (e.g., the destination UNI) for a RM-cell entry event at a measurement point 2 (e.g., the destination
particular connection. UNI) for a particular connection.
Discussion: The RM-cell transfer delay between two measurement points is Discussion: The RM-cell transfer delay between two measurement points
the sum of the total inter-ATM node transmission delay and the total ATM is the sum of the total inter-ATM node transmission delay and the
node processing delay. This number is a constant and should not adversely total ATM node processing delay. This number is a constant and
effect performance. should not adversely effect performance.
Measurement units: seconds Measurement units: seconds
2.2.9. Severely Errored Cell Block Ratio (SECBR) 2.2.9. Severely Errored Cell Block Ratio (SECBR)
Definition: The ratio of severely errored cell blocks in a transmission in Definition: The ratio of severely errored cell blocks in a
relation to the total cell blocks sent in a transmission associated with a transmission in relation to the total cell blocks sent in a
given traffic load, orientation and distribution, as well as an integration transmission associated with a given traffic load, orientation and
period. distribution, as well as an integration period.
SECBR = Severely Errored Cell Blocks/Total Transmitted Cell Blocks SECBR = Severely Errored Cell Blocks/Total Transmitted Cell Blocks
Discussion: SECBR may cause the SUT to drop cells that may contain a Discussion: SECBR may cause the SUT to drop cells that may contain a
portion of an IP datagram. This may cause IP and TCP packet loss. portion of an IP datagram. This may cause IP and TCP packet loss.
Measurement Units: dimensionless. Measurement Units: dimensionless.
3. Security Considerations. 3. Security Considerations
As this document is solely for providing terminology and describes As this document is solely for providing terminology and describes
neither a protocol nor an implementation, there are no security neither a protocol nor an implementation, there are no security
considerations associated with this document. considerations associated with this document.
4. Notices 4. References
Internet Engineering Task Force [AF-TM4.0] ATM Forum, Traffic Management Specification Version 4.0,
The IETF takes no position regarding the validity or scope of any af-tm-0056.00, April 1996.
intellectual property or other rights that might be claimed to pertain
to the implementation or use of the technology described in this
document or the extent to which any license under such rights might or
might not be available; neither does it represent that it has made any
effort to identify any such rights. Information on the IETFs procedures
with respect to rights in standards-track and standards-related
documentation can be found in BCP-11. Copies of claims of rights made
available for publication and any assurances of licenses to be made
available, or the result of an attempt made to obtain a general license
or permission for the use of such proprietary rights by implementors or
users of this specification can be obtained from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any [AF-TM4.1] ATM Forum, Traffic Management Specification Version 4.1,
copyrights, patents or patent applications, or other proprietary rights, af-tm-0121.000, March 1999.
which may cover technology that may be required to practice this
standard. Please address the information to the IETF Executive
Director.
5. Disclaimer [AF-UNI3.1] ATM Forum, User Network Interface Specification Version
3.1, September 1994.
Copyright (C) The Internet Society (1999). All Rights Reserved. [AF-UNI4.0] ATM Forum, User Network Interface Specification Version
4.0, July 1996.
This document and translations of it may be copied and furnished to 5. Editors' Addresses
others, and derivative works that comment on or otherwise explain it or
assist in its implementation may be prepared, copied, published and
distributed, in whole or in part, without restriction of any kind,
provided that the above copyright notice and this paragraph are included
on all such copies and derivative works. However, this document itself
may not be modified in any way, such as by removing the copyright notice
or references to the Internet Society or other Internet organizations,
except as needed for the purpose of developing Internet standards in
which case the procedures for copyrights defined in the Internet
Standards process must be followed, or as required to translate it into
languages other than English.
The limited permissions granted above are perpetual and will not be Jeffrey Dunn
revoked by the Internet Society or its successors or assigns. This Advanced Network Consultants, Inc.
document and the information contained herein is provided on an "AS IS" 4214 Crest Place
basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE Ellicott City, MD 21043 USA
DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE
ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A
PARTICULAR PURPOSE.
6. References Phone: +1 (410) 750-1700
EMail: Jeffrey.Dunn@worldnet.att.net
[AF-TM4.0] ATM Forum, Traffic Management Specification Version 4.0, af- Cynthia Martin
tm-0056.00, April 1996. Advanced Network Consultants, Inc.
4214 Crest Place
Ellicott City, MD 21043 USA
[AF-TM4.1] ATM Forum, Traffic Management Specification Version 4.1, af- Phone: +1 (410) 750-1700
tm- 0121.000, March 1999. EMail: Cynthia.E.Martin@worldnet.att.net
[AF-UNI3.1] ATM Forum, User Network Interface Specification Version 3.1, Full Copyright Statement
September 1994.
[AF-UNI4.0] ATM Forum, User Network Interface Specification Version 4.0, Copyright (C) The Internet Society (2001). All Rights Reserved.
July 1996.
7. Editors Addresses This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
Jeffrey Dunn The limited permissions granted above are perpetual and will not be
Advanced Network Consultants, Inc. revoked by the Internet Society or its successors or assigns.
4214 Crest Place, Ellicott City, MD 21043 USA
Phone: +1 (410) 750-1700, E-mail: Jeffrey.Dunn@worldnet.att.net
Cynthia Martin This document and the information contained herein is provided on an
Advanced Network Consultants, Inc. "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
4214 Crest Place, Ellicott City, MD 21043 USA TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
Phone: +1 (410) 750-1700, E-mail: Cynthia.E.Martin@worldnet.att.net BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
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