draft-ietf-bmwg-call-03.txt   draft-ietf-bmwg-call-04.txt 
Network Working Group J. H. Dunn Network Working Group J. H. Dunn
INTERNET-DRAFT Hewlett-Packard INTERNET-DRAFT C. E. Martin
Expires in six months C. E. Martin Expires: August, 1999 ANC, Inc.
Hewlett-Packard
October 1998
February, 1999
Terminology for Call/Cell Benchmarking Terminology for Call/Cell Benchmarking
<draft-ietf-bmwg-call-03.txt> <draft-ietf-bmwg-call-04.txt>
Status of this Memo Status of this Memo
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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 cell- benchmarking tests and the results of these tests in the context of
based and call-based switching devices. The terms defined in this cell- based and call-based switching devices. The terms defined in this
memo will be used in addition to terms defined in RFCs 1242, 1944 memo will be used in addition to terms defined in RFCs 1242, 1944 and
and 2285. This memo is a product of the Benchmarking Methodology 2285. This memo is a product of the Benchmarking Methodology Working
Working Group (BMWG) of the Internet Engineering Task Force Group (BMWG) of the Internet Engineering Task Force (IETF).
(IETF).
I. Background 1. Introduction.
1. Introduction. This document provides terminology for This document provides terminology for benchmarking cell-based and call-
benchmarking cell-based and call-based switching devices. It extends based switching devices. It extends terminology already defined for
terminology already defined for benchmarking network interconnect benchmarking network interconnect devices in RFC's 1242, 1944 and 2285.
devices in RFCs 1242, 1944 and 2285 . Although some of the Although some of the definitions in this memo may be applicable to a
definitions in this memo may be applicable to a broader group of broader group of network interconnect devices, the primary focus of the
network interconnect devices, the primary focus of the terminology in terminology in this memo is on cell-based and call-based switches.
this memo is on cell-based and call-based switches. Specifically, this Specifically, this includes Asynchronous Transfer Mode (ATM) cell relay
includes Asynchronous Transfer Mode (ATM) cell relay and signaling and signaling.
and Frame Relay (FR) signaling.
This memo contains two major sections: Background and Definitions. This memo contains two major sections: Background and Definitions.
Within the definitions section is a formal definitions subsection, Within the definitions section is a formal definitions subsection,
provided as a courtesy to the reader, and a measurement definitions provided as a courtesy to the reader, and a measurement definitions sub-
sub-section, which contains performance metrics with inherent units. section, which contains performance metrics with inherent units. The
divisions of the measurement sub-section follow the BISDN model.
The BISDN model comprises four layers and two planes. This document
addresses the interactions between these layers and how they effect the
performance of IP, TCP, etc. A schematic of the model follows:
User Plane | Control Plane
Services | | ILMI | UNI, PNNI
---------|--------------------------|-----------|---------------------
AAL |AAL1, AAL2, AAL3/4, AAL5 | AAL5 | SAAL
---------|--------------------------|-----------|---------------------
ATM | Cell Relay | OAM, RM
---------|--------------------------|---------------------------------
| Convergence |
Physical |--------------------------|---------------------------------
| Media |
---------|--------------------------|---------------------------------
This document assumes that necessary services are available and
active.
For example, IP connectivity requires SSCOP connectivity between
signaling entities. Further, it is assumed that the SUT has the
ability to configure ATM addresses (via hard coded addresses, ILMI
or PNNI neighbor discovery), has the ability to run SSCOP, and has
the ability to perform signaled call setups (via UNI or PNNI
signaling). Finally, this document presents only the terminology
associated with benchmarking IP performance over ATM; therefore,
it 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. Terminology documents and Benchmarking Methodology documents. The
The Terminology documents present the benchmarks and other related Terminology documents present the benchmarks and other related
terms. The Methodology documents define the procedures required to terms. The Methodology documents define the procedures required
collect the benchmarks cited in the corresponding Terminology to collect the benchmarks cited in the corresponding Terminology
documents. documents.
2. Existing Definitions 2. Existing Definitions
RFC 1242 "Benchmarking Terminology for Network Interconnect RFC 1242 "Benchmarking Terminology for Network Interconnect Devices"
Devices" should be consulted before attempting to make use of this should be consulted before attempting to make use of this document. RFC
document. RFC 1944 "Benchmarking Methodology for Network 1944 "Benchmarking Methodology for Network Interconnect Devices" contains
Interconnect Devices" contains discussions of a number of terms discussions of a number of terms relevant to the benchmarking of switching
relevant to the benchmarking of switching devices and should also be devices and should also be consulted. RFC 2285 "Benchmarking Terminology
consulted. RFC 2285 "Benchmarking Terminology for LAN for LAN Switching Devices" contains a number of terms pertaining to
Switching Devices" contains a number of terms pertaining to traffic traffic distributions and datagram interarrival. For the sake of clarity
distributions and datagram interarrival. For the sake of clarity and and continuity this RFC adopts the template for definitions set out in
continuity this RFC adopts the template for definitions set out in Section 2 of RFC 1242. Definitions are indexed and grouped together in
Section 2 of RFC 1242. Definitions are indexed and grouped together sections for ease of reference. The key words "MUST", "MUST NOT",
in sections for ease of reference. The key words "MUST", "MUST "REQUIRED", "SHALL, "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED",
NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "MAY", and "OPTIONAL" go in this document are to be interpreted as
"SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" described in RFC 2119.
in this document are to be interpreted as described in RFC 2119.
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 the groups. The first group is formal definitions, which are required in the
definitions of the performance metrics but are not themselves strictly definitions of the performance metrics but are not themselves strictly
metrics. These definitions are subsumed from other work done in metrics. These definitions are subsumed from other work done in other
other working groups both inside and outside the IETF. They are working groups both inside and outside the IETF. They are provided as a
provided as a courtesy to the reader. courtesy to the reader.
1. Formal Definitions Formal Definitions
1.1. Definition Format (from RFC1242) 1.1. Definition Format (from RFC1242)
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 term is Specification: The working group and document in which the term is
specified. Listed in the references. specified. Listed in the references.
1.2. ATM 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: Discussion: For ABR traffic, ACR constitutes the actual data throughput
for a particular VC. The time change of this value 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 Definition: This is the time permitted between sending RM-cells before the
before the rate is decreased to ICR (Initial Cell Rate). The time units rate is decreased to ICR (Initial Cell Rate). The time units are
are:
.01 to 10.23 seconds .01 to 10.23 seconds
with a granularity of 10 ms. with a granularity of 10 ms.
Discussion: Discussion: For ABR traffic, ADTF constitutes the time rate of the ACR.
This value effects TCP round trip time calculations, which in 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 Definition: An ABR service parameter, AIR controls the rate at which the
the cell transmission rate increases. It is signaled as AIRF, where cell transmission rate increases. It is signaled as AIRF, where
AIRF = AIR*Nrm/PCR. AIRF = AIR*Nrm/PCR.
Discussion: 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 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: Discussion: Refer to AIR.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.5. ATM Adaptation Layer (AAL): 1.2.5. ATM Adaptation Layer (AAL):
Definition: The layer in the B-ISDN reference model (see B-ISDN) Definition: The layer in the B-ISDN reference model (see B-ISDN) which
which adapts higher layer PDUs into the ATM layer. adapts higher layer PDU's into the ATM layer.
Discussion: There are 4 types of adaptation layers: Discussion: There are 4 types of adaptation layers:
- AAL1: used for circuit emulation, voice over ATM AAL 1: used for circuit emulation, voice over ATM
- AAL2: used for sub-rated voice over ATM AAL2: used for sub-rated voice over ATM
- AAL3/4: used for data over noisy ATM lines AAL3/4: used for data over noisy ATM lines
- AAL5: used for data over ATM, most widely used AAL type AAL5: used for data over ATM, most widely used AAL type
These AAL types are not measurements, but it is possible to measure These AAL types are not measurements, but it is possible to measure the
the time required for Segmentation and Reassembly (SAR). time required for Segmentation and Reassembly (SAR).
Specification: AF-UNI3.1 Specification: AF-TM3.1
1.2.6. ATM Adaptation Layer Type 5 (AAL5): 1.2.6. ATM Adaptation Layer Type 5 (AAL5):
Definition: AAL5 functions in support of variable bit rate, delay- Definition: AAL5 functions in support of variable bit rate, delay-tolerant
tolerant data traffic requiring minimal sequencing or error detection data traffic requiring minimal sequencing or error detection support.
support.
Discussion: AAL5 is the adaptation layer for UNI signaling, ILMI, Discussion: AAL5 is the adaptation layer for UNI signaling, ILMI, PNNI
PNNI signaling, and for IP PDUËs. It is the most widely used AAL signaling, and for IP PDU'S. It is the most widely used AAL type to date.
type to date.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.7. Available Bit Rate (ABR): 1.2.7. Available Bit Rate (ABR):
Definition: ABR is an ATM layer service category for which the Definition: ABR is an ATM layer service category for which the limiting
limiting ATM layer transfer characteristics provided by the network ATM layer transfer characteristics provided by the network may change
may change subsequent to connection establishment. A flow control subsequent to connection establishment. A flow control mechanism is
mechanism is specified which supports several types of feedback to specified which supports several types of feedback to control the source
control the source rate in response to changing ATM layer transfer rate in response to changing ATM layer transfer characteristics.
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 in
accordance with the feedback will experience a low cell loss ratio and accordance with the feedback will experience a low cell loss ratio and
obtain a fair share of the available bandwidth according to a network obtain a fair share of the available bandwidth according to a network
specific allocation policy. Cell delay variation is not controlled in this specific allocation policy. Cell delay variation is not controlled in this
service, although admitted cells are not delayed unnecessarily. service, although admitted cells are not delayed unnecessarily.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.8. Asynchronous Transfer Mode (ATM) 1.2.8. Asynchronous Transfer Mode (ATM)
Definition: A transfer mode in which the information is organized into Definition: A transfer mode in which the information is organized into 53
53 octet PDUs called cells. It is asynchronous in the sense that the octet PDUs called cells. It is asynchronous in the sense that the
recurrence of cells containing information from an individual user is recurrence of cells containing information from an individual user is not
not necessarily periodic. necessarily periodic.
Discussion: ATM is based on the ISDN model. Discussion: ATM is based on the ISDN model.
Specification: AF-UNI3.1 Specification: AF-UM3.1
1.2.9. ATM Link: 1.2.9. ATM Link:
Definition: A virtual path link (VPL) or a virtual channel link (VCL). Definition: A virtual path link (VPL) or a virtual channel link (VCL).
Discussion: none. Discussion: none.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.10. ATM Peer-to-Peer Connection: 1.2.10. ATM Peer-to-Peer Connection:
skipping to change at line 219 skipping to change at page 6, line 15
Definition: A virtual channel connection (VCC) or a virtual path Definition: A virtual channel connection (VCC) or a virtual path
connection (VPC). connection (VPC).
Discussion: none. Discussion: none.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.11. ATM Traffic Descriptor: 1.2.11. ATM Traffic Descriptor:
Definition: A generic list of traffic parameters, which specify the Definition: A generic list of traffic parameters, which specify the
intrinsic traffic characteristics of a requested ATM connection. See intrinsic traffic characteristics of a requested ATM connection. See GCRA
GCRA. and ABR.
Discussion: Discussion: none.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.12. ATM User-User Connection: 1.2.12. ATM User-User Connection:
Definition: An association established by the ATM Layer to support Definition: An association established by the ATM Layer to support
communication between two or more ATM service users (i.e., between communication between two or more ATM service users (i.e., between two or
two or more next higher entities or between two or more ATM- more next higher entities or between two or more ATM-entities). The
entities). The communications over an ATM Layer connection may be communications over an ATM Layer connection may be either bi-directional
either bi-directional or unidirectional. The same Virtual Channel or unidirectional. The same Virtual Channel Identifier (VCI) issued for
Identifier (VCI) issued for both directions of a connection at an both directions of a connection at an interface.
interface.
Discussion: none. Discussion: none.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.13. Backward Explicit Congestion Notification (BECN): 1.2.13. Backward Explicit Congestion Notification (BECN):
Definition: A Resource Management (RM) cell type generated by the Definition: A Resource Management (RM) cell type generated by the network
network or the destination, indicating congestion or approaching or the destination, indicating congestion or approaching congestion for
congestion for traffic flowing in the direction opposite that of the traffic flowing in the direction opposite that of the BECN cell.
BECN cell.
Discussion: Discussion: none.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.14. BECN Cell (BN): 1.2.14. BECN Cell (BN):
Definition: A Resource Management (RM) cell type indicator. The Definition: A Resource Management (RM) cell type indicator. The network or
network or the destination may generate a Backwards Explicit the destination may generate a Backwards Explicit Congestion Notification
Congestion Notification (BECN) RM-cell. To do so, BN=1 is set, to (BECN) RM-cell. To do so, BN=l is set, to indicate the cell is not source-
indicate the cell is not source-generated, and DIR=1 to indicate the generated, and DIR=1 to indicate the backward flow. Source generated RM-
backward flow. Source generated RM-cells are initialized with BN=0. cells are initialized with BN=O.
Discussion: Discussion: none.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.15. Broadband ISDN (B-ISDN) Model: 1.2.15. Broadband ISDN (B-ISDN) Model:
Definition: A layered service model that specifies the mapping of Definition: A layered service model that specifies the mapping of higher
higher layer protocols onto ATM and its underlying physical layer. layer protocols onto ATM and its underlying physical layer. The model is
The model is composed of four layers: Physical, ATM, AAL and composed of four layers: Physical, ATM, AAL and Service.
Service.
Discussion: none. Discussion: none.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.16. Burst Tolerance (BT): 1.2.16. Burst Tolerance (BT):
Definition: A traffic parameter, which, along with the Sustainable Definition: A traffic parameter, which, along with the Sustainable Cell
Cell Rate (SCR), specifies the maximum number of cells which will be Rate (SCR), specifies the maximum number of cells which will be accepted
accepted at the Peak Cell Rate (PCR) on an ATM connection. at the Peak Cell Rate (PCR) on an ATM connection.
Discussion: BT applies to ATM connections supporting VBR services Discussion: BT applies to ATM connections supporting VBR services and is
and is the limit parameter of the GCRA. the limit parameter of the GCRA.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.17. Connection Admission Control (CAC): 1.2.17. Connection Admission Control (CAC):
Definition: Connection Admission Control is defined as the set of Definition: Connection Admission Control is defined as the set of actions
actions taken by the network during the call set- up phase (or during taken by the network during the call set-up phase (or during call re-
call re-negotiation phase) in order to determine whether a connection negotiation phase) in order to determine whether a connection request can
request can be accepted or should be rejected (or whether a request for be accepted or should be rejected (or whether a request for re-allocation
re-allocation can be accommodated).
can be accommodated).
Discussion: none Discussion: none
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.18. Call: 1.2.18. Call:
Definition: A call is an association between two or more users or Definition: A call is an association between two or more users or between
between a user and a network entity that is established by the use of a user and a network entity that is established by the use of network
network capabilities. This association may have zero or more capabilities. This association may have zero or more connections.
connections.
Discussion: none Discussion: none
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.19. Call-based:
1.2.19. Call-based Definition: A transport requiring call setups- see CALL definition.
Definition: An association between two or more users or between a
user and a network entity that is established by the use of network
capabilities. This association may have zero or more connections.
Discussion: none Discussion: none
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.20. Constant Bit Rate (CBR): 1.2.20. Constant Bit Rate (CBR):
Definition: An ATM service category which supports a constant or Definition: An ATM service category which supports a constant or
guaranteed rate to transport services such as video or voice as well as guaranteed rate to transport services such as video or voice as well as
circuit emulation which requires rigorous timing control and circuit emulation which requires rigorous timing control and performance
performance parameters. parameters.
Discussion: Discussion: CBR reduces problems associated with TCP performance and
throughput. **
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.21. Cell: 1.2.21. Cell:
Definition: A unit of transmission in ATM. A fixed-size frame Definition: A unit of transmission in ATM. A fixed-size frame consisting
consisting of a 5-octet header and a 48-octet payload. of a 5-octet header and a 48-octet payload.
Discussion: none. Discussion: none.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.22. Cell Header: 1.2.22. Cell Header:
Definition: ATM Layer protocol control information. Definition: ATM Layer protocol control information.
Discussion: The ATM cell header is a 5-byte header that contains the Discussion: The ATM cell header is a 5-byte header that contains the
following fields: following fields:
- Generic Flow Control (GFC): 4 bits Generic Flow Control (GFC): 4 bits
- Virtual Path Identifier (VPI): 8 bits Virtual Path Identifier (VPI): 8 bits
- Virtual Channel Identifier (VCI): 16 bits Virtual Channel Identifier (VCI): 16 bits
- Payload Type (PT): 3 bits Payload Type (PT): 3 bits
- Cell Loss Priority (CLP): 1 bit Cell Loss Priority (CLP): 1 bit
- Header Error Check (HEC): 8 bit CRC computed over the Header Error Check (HEC): 8 bit CRC computed over the previous 4 octets
previous 4 octets
Each field is discussed in the ATM Specific definition section of this Each field is discussed in this document.
document.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.23. Congestion Indicator (CI): 1.2.23. Congestion Indicator (CI):
Definition: This is a field in a RM-cell, and is used to cause the source Definition: This is a field in a RM-cell, and is used to cause the source
to decrease its ACR. The source sets CI=0 when it sends a RM-cell. to decrease its ACR. The source sets CI=O when it sends a RM-cell.
Setting CI=1 is typically how destinations indicate that Explicit Setting CI=1 is typically how destinations indicate that Explicit Forward
Forward Congestion Indication (EFCI) has been received on a previous Congestion Indication (EFCI) has been received on a previous data cell.
data cell.
Discussion: Discussion: none.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.24. Cell Loss Priority (CLP): 1.2.24. Cell Loss Priority (CLP):
Definition: This bit in the ATM cell header indicates two levels of Definition: This bit in the ATM cell header indicates two levels of
priority for ATM cells. CLP=0 cells are higher priority than CLP=1 priority for ATM cells. CLP=0 cells are higher priority than CLP=1 cells.
cells. CLP=1 cells may be discarded during periods of congestion to CLP=1 cells may be discarded during periods of congestion to preserve the
preserve the CLR of CLP=0 cells. CLR of CLP=0 cells.
Discussion: The CLP bit is used to determine GCRA contract Discussion: The CLP bit is used to determine GCRA contract compliance.
compliance.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.25. Connection: 1.2.25. Connection:
Definition: An ATM connection consists of concatenation of ATM Definition: An ATM connection consists of concatenation of ATM Layer links
in order to provide an end-to-end information transfer capability to
Layer links in order to provide an end-to-end information transfer access points.
capability to access points.
Discussion: none. Discussion: none.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.26. Cutoff Decrease Factor (CDF): 1.2.26. Cutoff Decrease Factor (CDF):
Definition: CDF controls the decrease in ACR (Allowed Cell Rate) Definition: CDF controls the decrease in ACR (Allowed Cell Rate)
associated with CRM. associated with CRM (missing RM cell count).
Discussion: Discussion: For ABR traffic, CDF 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 Specification: AF-TM4.0
1.2.27. Current Cell Rate (CCR): 1.2.27. Current Cell Rate (CCR):
Definition: The Current Cell Rate is an RM-cell field set by the source Definition: The Current Cell Rate is an RM-cell field set by the source to
to its current ACR when it generates a forward RM-cell. This field its current ACR when it generates a forward RM-cell. This field may be
may be used to facilitate the calculation of ER, and may not be used to facilitate the calculation of ER, and may not be changed by
changed by network elements. CCR is formatted as a rate. network elements. CCR is formatted as a rate.
Discussion: Discussion: See actual cell rate.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.28. Cyclic Redundancy Check (CRC): 1.2.28. Cyclic Redundancy Check (CRC):
Definition: A mathematical algorithm that computes a numerical value Definition: A mathematical algorithm that computes a numerical value based
based on the bits in a block of data. This number is transmitted with on the bits in a block of data. This number is transmitted with the data
the data and the receiver uses this information and the same algorithm and the receiver uses this information and the same algorithm to insure
to insure the accurate delivery of data by comparing the results of the accurate delivery of data by comparing the results of algorithm and
algorithm and the number received. If a mismatch occurs, an error in the number received. If a mismatch occurs, an error in transmission is
transmission is presumed. presumed.
Discussion: CRC is not a measurement, but it is possible to measure Discussion: CRC is not a measurement, but it is possible to measure the
the amount of time to perform a CRC on a string of bits. This amount of time to perform a CRC on a string of bits. This measurement will
measurement will not be addressed in this document. not be addressed in this document.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.29. DIR: 1.2.29. DIR:
Definition: This is a field in a RM-cell, which indicates the direction Definition: This is a field in a RM-cell, which indicates the direction of
of the RM-cell with respect to the data flow with which it is associated. the RM-cell with respect to the data flow with which it is associated.
The source sets DIR=0 and the destination sets DIR=1. The source sets DIR=O and the destination sets DIR=1.
Discussion: none Discussion: none
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.30. Explicit Forward Congestion Indication (EFCI): 1.2.30. Explicit Forward Congestion Indication (EFCI):
Definition: EFCI is an indication in the PTI field of the ATM cell Definition: EFCI is an indication in the PTI field of the ATM cell header.
header. A network element in an impending-congested state or a A network element in an impending-congested state or a congested state may
congested state may set EFCI so that this indication may be examined set EFCI so that this indication may be examined by the destination end-
by the destination end-system. For example, the end- system may use system. For example, the end-system may use this indication to implement a
this indication to implement a protocol that adaptively lowers the cell protocol that adoptively lowers the cell rate of the connection during
rate of the connection during congestion or impending congestion. A congestion or impending congestion. A network element that is not in a
network element that is not in a congestion state or an impending congestion state or an impending congestion state will not modify the
congestion state will not modify the value of this indication. value of this indication. Impending congestion is the state when network
Impending congestion is the state when network equipment is equipment is operating around its engineered capacity level.
operating around its engineered capacity level.
Discussion: Discussion: none.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.31. Explicit Rate (ER): 1.2.31. Explicit Rate (ER):
Definition: The Explicit Rate is a RM-cell field used to limit the source Definition: The Explicit Rate is a RM-cell field used to limit the source
ACR to a specific value. It is initially set by the source to a requested ACR to a specific value. It is initially set by the source to a requested
rate (such as PCR). It may be subsequently reduced by any network rate (such as PCR). It may be subsequently reduced by any network element
element in the path to a value that the element can sustain. ER is in the path to a value that the element can sustain. ER is formatted as a
formatted as a rate. rate.
Discussion: Discussion: For ABR traffic, ER effects the ACR. This value effects TCP
round trip time calculations, which in turn effects TCP throughput.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.32. End System (ES): 1.2.32. End System (ES):
Definition: A system where an ATM connection is terminated or Definition: A system where an ATM connection is terminated or initiated.
initiated. An originating end system initiates the ATM connection, and An originating end system initiates the ATM connection, and terminating
terminating end system terminates the ATM connection. OAM cells end system terminates the ATM connection. OAM cells may be generated and
may be generated and received. received.
Discussion: An ES can be the user side of a UNI signaling interface. Discussion: An ES can be the user side of a UNI signaling interface.
Specification: AF-TEST Specification: AF-TEST-0022
1.2.33. Generic Cell Rate Algorithm (GCRA): 1.2.33. Generic Cell Rate Algorithm (GCRA):
Definition: The GCRA is used to define conformance with respect to Definition: The GCRA is used to define conformance with respect to the
the traffic contract of the connection. For each cell arrival the GCRA traffic contract of the connection. For each cell arrival the GCRA
determines whether the cell conforms to the traffic contract. The UPC determines whether the cell conforms to the traffic contract. The UPC
function may implement the GCRA, or one or more equivalent function may implement the GCRA, or one or more equivalent algorithms to
algorithms to enforce conformance. The GCRA is defined with two enforce conformance. The GCRA is defined with two parameters: the
Increment (1) and the Limit (L).
parameters: the Increment (I) and the Limit (L).
Discussion: GCRA is not a measurement, but there are a number of Discussion: GCRA is not a measurement, but there are a number of
measurements that can be obtained using the GCRA and other measurements that can be obtained using the GCRA and other parameters.
parameters.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.34. Generic Flow Control (GFC): 1.2.34. Generic Flow Control (GFC):
Definition: GFC is a field in the ATM header, which can be used to Definition: GFC is a field in the ATM header, which can be used to provide
provide local functions (e.g., flow control). It has local significance local functions (e.g., flow control). It has local significance only and
only and the value encoded in the field is not carried end-to-end. the value encoded in the field is not carried end-to-end.
Discussion: none Discussion: none
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.35. Header Error Control (HEC): 1.2.35. Header Error Control (HEC):
Definition: A check character calculated using an 8 bit CRC computed Definition: A check character calculated using an 8 bit CRC computed over
over the first 4 octets of the ATM cell header. This allows for single the first 4 octets of the ATM cell header. This allows for single bit
bit error correction or multiple bit error detection. error correction or multiple bit error detection.
Discussion: none Discussion: none
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.36. Initial Cell Rate (ICR): 1.2.36. 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 at
which a source should send initially and after an idle period. which a source should send initially and after an idle period.
Discussion: none Discussion: none
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.37. Integrated Local Management Interface 1.2.37. Integrated Local Management Interface
Definition: A management protocol which uses SNMP carried on Definition: A management protocol which uses SNMPv1 carried on AAL5 to
AAL5 to provide ATM network devices with status and configuration provide ATM network devices with status and configuration information
information concerning VPCs, VCCs, registered ATM addresses and concerning VPC's, VCC's, registered ATM addresses and the capabilities of
the capabilities of ATM interfaces. ATM interfaces.
Discussion: ILMI is a conditionally required portion of UNI3.1; Discussion: ILMI is a conditionally required portion of UNI3.1; however,
however, ILMI 4.0 has been issued as a separate specification. This ILMI 4.0 has been issued as a separate specification. This document will
document will refer to ILMI 4.0. refer to ILMI 4.0.
Specification: ILMI4.0 Specification: AF-ILMI4.0
1.2.38. Intermediate System (IS): 1.2.38. Intermediate System (IS):
Definition: A system that provides forwarding functions or relaying Definition: A system that provides forwarding functions or relaying
functions or both for a specific ATM connection. OAM cells may be functions or both for a specific ATM connection. OAM cells may be
generated and received. generated and received.
Discussion: An IS can be either the user or network side of a UNI Discussion: An IS can be either the user or network side of a UNI
signaling interface, or the network side of a PNNI signaling interface. signaling interface, or the network side of a PNNI signaling interface.
Specification: AF-TEST Specification: AF-TEST-0022
1.2.39. Leaky Bucket (LB): 1.2.39. Leaky Bucket (LB):
Definition: Leaky Bucket is the term used as an analogous description Definition: Leaky Bucket is the term used as an analogous description of
of the algorithm used for conformance checking of cell flows from a the algorithm used for conformance checking of cell flows from a user or
user or network. See GCRA, UPC and NPC. The "leaking hole in the network. See GCRA and UPC. The "leaking hole in the bucket" applies to
bucket" applies to the sustained rate at which cells can be the sustained rate at which cells can be accommodated, while the "bucket
accommodated, while the "bucket depth" applies to the tolerance to depth" applies to the tolerance to cell bursting over a given time period.
cell bursting over a given time period.
Discussion: There are two types of LB algorithms- single and dual. Discussion: There are two types of LB algorithms- single and dual. Single
Single LB defines a PCR, dual LB defines a PCR and SCR. LB defines a PCR; dual LB defines a PCR and SCR.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.40. Maximum Cell Rate (MCR): 1.2-40. Maximum Cell Rate (MCR):
Definition: This is the maximum capacity usable by connections Definition: This is the maximum capacity usable by connections belonging
belonging to the specified service category. to the specified service category.
Discussion: none Discussion: none
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.41. Maximum Burst Size (MBS): 1.2.41. Maximum Burst Size (MBS):
Definition: In the signaling message, the Burst Tolerance (BT) is Definition: In the signaling message, the Burst Tolerance (BT) is conveyed
conveyed through the MBS that is coded as a number of cells. The BT through the MBS that is coded as a number of cells. The BT together with
together with the SCR and the GCRA determine the MBS that may be the SCR and the GCRA determine the MBS that may be transmitted at the peak
transmitted at the peak rate and still is in conformance with the GCRA. rate and still is in conformance with the GCRA.
Discussion: none Discussion: none
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.42. Minimum Cell Rate (MCR): 1.2.42. 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 the
rate at which the source is always allowed to send. rate at which the source is always allowed to send.
Discussion: none Discussion: none
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.43. Missing RM-Cell Count (CRM): 1.2.43. Missing RM-Cell Count (CRM):
Definition: CRM limits the number of forward RM-cells that may be Definition: CRM limits the number of forward RM-cells that may be sent in
sent in the absence of received backward RM-cells. the absence of received backward RM-cells.
Discussion: Discussion: none.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.44. Mrm: 1.2.44. Mrm:
Definition: An ABR service parameter that controls allocation of Definition: An ABR service parameter that controls allocation of bandwidth
bandwidth between forward RM-cells, backward RM-cells, and data between forward W-cells, backward RM-cells, and data cells.
cells.
Discussion: none Discussion: none
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.45. Nrm: 1.2.45. Nrm:
Definition: An ABR service parameter, Nrm is the maximum number Definition: An ABR service parameter, Nrm is the maximum number of cells a
of cells a source may send for each forward RM-cell. source may send for each forward RM-cell.
Discussion: none. Discussion: none.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.46. Operations Administration and Maintenance (OAM): 1.2.46. Operations, Administration, and Maintenance (OAM):
Definition: A group of network management functions that provide Definition: A group of network management functions that provide network
network fault indication, performance information, and data and fault indication, performance information, and data and diagnosis
diagnosis functions. functions.
Discussion: There are four types of ATM OAM flows: segment or Discussion: There are four types of ATM OAM flows: segment or end-to-end
end-to-end VP termination management (i.e. F4 segment, F4 E2E) and VP termination management (i.e. F4 segment, F4 E2E) and segment or end-to-
segment or end-to-end VC termination management (i.e. F5 segment, end VC termination management (i.e. F5 segment, F5 E2E). These OAM cells
F5 E2E). These OAM cells can be used to identify fault management, can be used to identify fault management, connection verification, and
connection verification, and loopback measurements. loopback measurements.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.47. Protocol Data Unit (PDU): 1.2.47. Protocol Data Unit (PDU):
Definition: A PDU is a message of a given protocol comprising Definition: A PDU is a message of a given protocol comprising payload and
payload and protocol-specific control information, typically contained protocol-specific control information, typically contained in a header.
in a header. PDUs pass over the protocol interfaces that exist between PDU's pass over the protocol interfaces that exist between the layers of
the layers of protocols (per OSI model). protocols (per OSI model).
Discussion: In ATM networks, a PDU can refer to an ATM cell, Discussion: In ATM networks, a PDU can refer to an ATM cell, multiple ATM
multiple ATM cells, an AAL segment, an IP datagram and others. cells, an AAL segment, an IP datagram and others.
Specification: Specification: -
1.2.48. Private Network-Network Interface (PNNI): 1.2.48. Private Network-Network Interface (PNNI):
Definition: A routing information protocol that enables extremely Definition: A routing information protocol that enables extremely,
scalable, full function, dynamic multi-vendor ATM switches to be scalable, full function, dynamic multi-vendor ATM switches to be
integrated in the same network. integrated in the same network.
Discussion: PNNI consists of signaling and routing between ATM Discussion: PNNI consists of signaling and routing between ATM network
network devices. PNNI signaling is based on UNI 4.0 signaling devices. PNNI signaling is based on UNI 4.0 signaling between two network
between two network side interfaces, while PNNI routing provides a side interfaces, while PNNI routing provides a mechanism to route ATM
mechanism to route ATM cells between two separate, autonomous cells between two separate, autonomous ATM networks.
ATM networks.
Specification: AF-PNNI1.0 Specification: AF-PNNI1.0
1.2.49. Payload Type Indicator (PTI): 1.2.49. Payload Type Indicator (PTI):
Definition: Payload Type Indicator is the Payload Type field value Definition: Payload Type Indicator is the Payload Type field value
distinguishing the various management cells and user cells. Example: distinguishing the various management cells and user cells.
Resource Management cell has PTI=110, end-to-end OAM F5 Flow Example:
cell has PTI=101. Resource Management cell is indicated as PTI=110,
end-to-end OAM F5 Flow cell is indicated as PTI=101.
Discussion: none. Discussion: none.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.50. Peak Cell Rate (PCR): 1.2-50. Peak Cell Rate (PCR):
Definition: A traffic parameter, which specifies the upper bound on Definition: A traffic parameter, which specifies the upper bound on the
the rate at which ATM cells can be submitted to an ATM connection. rate at which ATM cells can be submitted to an ATM connection. This
This parameter is used by the GCRA. parameter is used by the GCRA.
Discussion: Discussion: none.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.51. Permanent Virtual Circuit (PVC): 1.2.51. Permanent Virtual Circuit (PVC):
Definition: This is a link with static route defined in advance, usually Definition: This is a link with static route(s) defined in advance,
usually by manual setup.
by manual setup.
Discussion: PVCËs are widely deployed in WAN ATM networks€ Discussion: none.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.52. Permanent Virtual Channel Connection (PVCC): 1.2.52. Permanent Virtual Channel Connection (PVCC):
Definition: A Virtual Channel Connection (VCC) is an ATM Definition: A Virtual Channel Connection (VCC) is an ATM connection where
connection where switching is performed on the VPI/VCI fields of switching is performed on the VPI/VCI fields of each cell. A permanent VCC
each cell. A Permanent VCC is one that is provisioned through some is one that is provisioned through some network management function and
network management function and left up indefinitely. left up indefinitely.
Discussion: none. Discussion: none.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.53. Permanent Virtual Path Connection: (PVPC): 1.2.53. Permanent Virtual Path Connection: (PVPC):
Definition: A Virtual Path Connection (VPC) is an ATM connection Definition: A Virtual Path Connection (VPC) is an ATM connection where
where switching is performed on the VPI field only of each cell. A switching is performed on the VPI field only of each cell. A permanent VPC
Permanent VPC is one that is provisioned through some network is one that is provisioned through some network management function and
management function and left up indefinitely. left up indefinitely.
Discussion: none. Discussion: none.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.54. Rate Decrease Factor (RDF): 1.2.54. Rate Decrease Factor (RDF):
Definition: An ABR service parameter, RDF controls the decrease in Definition: An ABR service parameter, RDF controls the decrease in the
the cell transmission rate. RDF is a power of 2 from 1/32,768 to 1. cell transmission rate. RDF is a power of 2 from 1/32,768 to 1.
Discussion: Discussion: For ABR traffic, RDF 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 Specification: AF-TM4.0
1.2.55. Rate Increase Factor (RIF): 1.2.55. Rate Increase Factor (RIF):
Definition: This controls the amount by which the cell transmission Definition: This controls the amount by which the cell transmission rate
rate may increase upon receipt of a RM-cell. The additive increase may increase upon receipt of a RM-cell. The additive increase rate
rate AIR=PCR*RIF. RIF is a power of 2, ranging from 1/32768 to 1. AIR=PCR*RIF. RIF is a power of 2, ranging from 1/32,768 to 1.
Discussion: Discussion: For ABR traffic, RIF 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 Specification: AF-TM4.0
1.2.56. Resource Management (RM): 1.2.56. Resource Management (RM):
Definition: Resource Management is the management of critical Definition: Resource Management is the management of critical resources in
resources in an ATM network. Two critical resources are buffer space an ATM network. Two critical resources are buffer space and trunk
and trunk bandwidth. Provisioning may be used to allocate network bandwidth. Provisioning may be used to allocate network resources in order
resources in order to separate traffic flows according to service to separate traffic flows according to service characteristics. VPC's play
characteristics. VPCs play a key role in resource management. By a key role in resource management. By reserving capacity on VPCs, the
reserving capacity on VPCs, the processing required to establish processing required to establish individual VCC's is reduced. Refer to RM-
individual VCCs is reduced. Refer to RM-cell. cell.
Discussion: Discussion: none.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.57. Resource Management Cell (RM-Cell): 1.2.57. Resource Management Cell (RM-Cell):
Definition: Information about the state of the network like bandwidth Definition: Information about the state of the network like bandwidth
availability, state of congestion, and impending congestion, is availability, state of congestion, and impending congestion, is conveyed
conveyed to the source through special control cells called Resource to the source through special control cells called Resource Management
Management Cells (RM-cells). Cells (RM-cells).
Discussion: Discussion: none.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.58. Segmentation and Reassembly (SAR): 1.2-58. Segmentation and Reassembly (SAR):
Definition: The process used by the AAL in the B-ISDN reference Definition: The process used by the AAL in the B-ISDN reference model (see
model (see B-ISDN) which fragments higher layer PDUs into ATM B-ISDN) which fragments higher layer PDU's into ATM cells.
cells.
Discussion: SAR is not a measurement, but the speed in which SAR Discussion: SAR is not a measurement, but the speed in which SAR can be
can be completed on a bit stream can be measured. This measurement completed on a bit stream can be measured. This measurement will not be
will not be discussed in this document. discussed in this document.
Specification: Specification: AF-UNI3.1
1.2.59. Sustainable Cell Rate (SCR): 1.2.59. Sustainable Cell Rate (SCR):
Definition: The SCR is an upper bound on the conforming average rate Definition: The SCR is an upper bound on the conforming average rate of an
of an ATM connection over time scales which are long relative to ATM connection over time scales which are long relative to those for which
those for which the PCR is defined. Enforcement of this bound by the the PCR is defined. Enforcement of this bound by the UPC could allow the
UPC could allow the network to allocate sufficient resources, but less network to allocate sufficient resources, but less than those based on the
than those based on the PCR, and still ensure that the performance PCR, and still ensure that the performance objectives (e.g., for Cell Loss
objectives (e.g., for Cell Loss Ratio) can be achieved. Ratio) can be achieved.
Discussion: Discussion: none.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.60. Switched Virtual Circuit (SVC): 1.2.60. Switched Virtual Circuit (SVC):
Definition: A connection established via signaling. The user defines Definition: A connection established via signaling. The user defines the
the endpoints when the call is initiated. endpoints when the call is initiated.
Discussion: SVCËs are established using either UNI signaling or PNNI Discussion: SVC's are established using either UNI signaling or PNNI
signaling. The signaling mechanism follows a specific state signaling. The signaling state machine implements several timers, which
machine€ can effect the time required for call establishment. This will, in turn,
effect TCP round trip time calculation, effecting TCP throughput.
Specification: AF-UNI3.1 Specification: AF-UNI3.1, AF-UNI4.0, AF-PNNI1.0
1.2.61. Switched Virtual Channel Connection (SVCC): 1.2.61. Switched Virtual Channel Connection (SVCC):
Definition: A Switched VCC is one that is established and taken down Definition: A Switched VCC is one that is established and taken down
dynamically through control signaling. A Virtual Channel Connection dynamically through control signaling. A Virtual Channel Connection (VCC)
(VCC) is an ATM connection where switching is performed on the is an ATM connection where switching is performed on the VPI/VCI fields of
VPI/VCI fields of each cell. each cell.
Discussion: none. Discussion: none.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.62. Switched Virtual Path Connection (SVPC): 1.2.62. Switched Virtual Path Connection (SVPC):
Definition: A Switched Virtual Path Connection is one that is Definition: A Switched Virtual Path Connection is one that is established
established and taken down dynamically through control signaling. A and taken down dynamically through control signaling. A Virtual Path
Virtual Path Connection (VPC) is an ATM connection where Connection (VPC) is an ATM connection where switching is performed on the
switching is performed on the VPI field only of each cell. VPI field only of each cell.
Discussion: none. Discussion: none.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.63. Switched Connection: 1.2.63. Switched Connection:
Definition: A connection established via signaling. Definition: A connection established via signaling.
Discussion: none. Discussion: none.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.64. Tagged Cell Rate (TCR): 1.2.64. Tagged Cell Rate (TCR):
Definition: An ABR service parameter, TCR limits the rate at which a Definition: An ABR service parameter, TCR limits the rate at which a
source may send out-of-rate forward RM-cells. TCR is a constant source may send out-of-rate forward RM-cells. TCR is a constant fixed at
fixed at 10 cells/second. 10 cells/second.
Discussion: Discussion: none.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.65. Traffic Contract 1.2.65. Traffic Contract
Definition: A specification of the negotiated traffic characteristics of Definition: A specification of the negotiated traffic characteristics of
an ATM connection. an ATM connection.
Discussion: Discussion: none.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.66. Transmission Convergence (TC): 1.2.66. Transmission Convergence (TC):
Definition: A sub-layer of the physical layer of the B-ISDN model Definition: A sub-layer of the physical layer of the B-ISDN model
transforms the flow of cells into a steady flow of bits and bytes for transforms the flow of cells into a steady flow of bits and bytes for
transmission over the physical medium. On transmit, the TC sublayer transmission over the physical medium. On transmit the TC sublayer maps
maps the cells to the frame format, generates the Header Error Check the cells to the frame format, generates the Header Error Check (HEC), and
(HEC), and sends idle cells when the ATM layer has none to send. On sends idle cells when the ATM layer has none to send. On reception, the TC
reception, the TC sublayer delineates individual cells in the received sublayer delineates individual cells in the received bit stream, and uses
bit stream, and uses the HEC to detect and correct received errors. the HEC to detect and correct received errors.
Discussion: TC is not a measurement, but the speed in which TC can Discussion: TC is not a measurement, but the speed in which TC can occur
occur on a bit stream can be measured. This measurement will not be on a bit stream can be measured. This measurement will not be discussed in
discussed in this document. this document.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.67. TDF: 1.2.67. TDF:
Definition: An ABR service parameter, TDF controls the decrease in Definition: An ABR service parameter, TDF controls the decrease in ACR
ACR associated with TOF. TDF is signaled as TDFF, where TDF = associated with TOF. TDF is signaled as TDFF, where TDF=TDFF/RDF times the
TDFF/RDF times the smallest power of 2 greater or equal to PCR. smallest power of 2 greater or equal to PCR. TDF is in units of 1/seconds.
TDF is in units of 1/seconds.
Discussion: Discussion: For ABR traffic, TDF 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 Specification: AF-TM4.0
1.2.68. TDFF. 1.2.68. TDFF.
Definition: Refer to TDF. TDFF is either zero or a power of two in Definition: Refer to TDF. TDFF is either zero or a power of two in the
the range 1/64 to 1 in units of 1/cells. range 1/64 to 1 in units of 1 /cells.
Discussion: Discussion: Refer to TDF.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.69. Traffic Management (TM): 1.2.69. Traffic Management (TM):
Definition: Traffic Management is the aspect of the traffic control Definition: Traffic Management is the aspect of the traffic control and
congestion control procedures for ATM. ATM layer traffic control refers to
and congestion control procedures for ATM. ATM layer traffic the set of actions taken by the network to avoid congestion conditions.
control refers to the set of actions taken by the network to avoid ATM layer congestion control refers to the set of actions taken by the
congestion conditions. ATM layer congestion control refers to the set network to minimize the intensity, spread and duration of congestion. The
of actions taken by the network to minimize the intensity, spread and following functions form a framework for managing and controlling traffic
duration of congestion. The following functions form a framework for and congestion in ATM networks and may be used in appropriate
managing and controlling traffic and congestion in ATM networks and combinations.
may be used in appropriate combinations. Connection Admission Control
o Connection Admission Control Feedback Control
o Feedback Control Usage Parameter Control
o Usage Parameter Control Priority Control
o Priority Control Traffic Shaping
o Traffic Shaping Network Resource Management
o Network Resource Management Frame Discard
o Frame Discard ABR Flow Control
o ABR Flow Control
Discussion: Discussion: none.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.70. Time Out Factor (TOF): 1.2.70. Time Out Factor (TOF):
Definition: An ABR service parameter, TOF controls the maximum Definition: An ABR service parameter, TOF controls the maximum time
time permitted between sending forward RM-cells before a rate permitted between sending forward RM-cells before a rate decrease is
decrease is required. It is signaled as TOFF where TOF=TOFF+1. required. It is signaled as TOFF where TOF=TOFF+1. TOFF is a power of 2
TOFF is a power of 2 in the range: 1/8 to 4,096. in the range: 1/8 to 4,096.
Discussion: Discussion: For ABR traffic, TOF 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 Specification: AF-TM4.0
1.2.71. Time Out Factor (TOFF): 1.2.71. Time Out Factor (TOFF):
Definition: Refer to TOF. Definition: Refer to TOF.
Discussion: none Discussion: none
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.72. Trm. 1.2.72. Trm.
Definition: An ABR service parameter that provides an upper bound Definition: An ABR service parameter that provides an upper bound on the
on the time between forward RM-cells for an active source. It is 100 time between forward RM-cells for an active source. It is 100 times a
times a power of two with a range of 100*2-7 to 100*20 power of two with a range of 100*2-7 to 100*20
Discussion: Discussion: For ABR traffic, Trm 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 Specification: AF-TM4.0
1.2.73. Traffic Shaping (TS): 1.2.73. Traffic Shaping (TS):
Definition: Traffic Shaping is a mechanism that alters the traffic Definition: Traffic Shaping is a mechanism that alters the traffic
characteristics of a stream of cells on a connection to achieve better characteristics of a stream of cells on a connection to achieve better
network efficiency, while meeting the QoS objectives, or to ensure network efficiency, while meeting the QoS objectives, or to ensure
conformance at a subsequent interface. Traffic shaping must maintain conformance at a subsequent interface. Traffic shaping must maintain cell
cell sequence integrity on a connection. Shaping modifies traffic sequence integrity on a connection. Shaping modifies traffic
characteristics of a cell flow with the consequence of increasing the characteristics of a cell flow with the consequence of increasing the mean
mean Cell Transfer Delay. Cell Transfer Delay.
Discussion: Discussion: TS should improve TCP throughput by reducing round trip time
variations.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.74. Unspecified Bit Rate (UBR): 1.2.74. Unspecified Bit Rate (UBR):
Definition: UBR is an ATM service category, which does not specify Definition: UBR is an ATM service category, which does not specify traffic
traffic related service guarantees. Specifically, UBR does not include related service guarantees. Specifically, UBR does not include the notion
the notion of a per-connection negotiated bandwidth. No numerical of a per-connection-negotiated bandwidth. No commitments are made with
commitments are made with respect to the cell loss ratio experienced respect to the cell loss ratio experienced by a UBR connection, or as to
by a UBR connection, or as to the cell transfer delay experienced by the cell transfer delay experienced by cells on the connection.
cells on the connection.
Discussion: UBR is used with € traffic type€ Discussion: RFC 2331 specifies UBR service class for IP over ATM. UBR
service models the best effort service type specified in RFC 791;
however, UBR has specific drawbacks with respect to TCP service. Since
UBR makes no guarantee with respect to cell loss, cell delay variation or
cell mis-insertion, TCP round trip time estimates may not be accurate.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.75. User-Network Interface (UNI): 1.2.75. User-Network Interface (UNI):
Definition: An interface point between ATM end users and a private Definition: An interface point between ATM end users and a private ATM
ATM switch, or between a private ATM switch and the public carrier switch, or between a private ATM switch and the public carrier ATM
ATM network; defined by physical and protocol specifications per network; defined by physical and protocol specifications per ATM Forum UNI
ATM Forum UNI documents. The standard adopted by the ATM documents. The standard adopted by the ATM Forum to define connections
Forum to define connections between users or end stations and a local between users or end stations and a local switch.
switch.
Discussion: Discussion: none.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.76. Usage Parameter Control (UPC): 1.2.76. Usage Parameter Control (UPC):
Definition: Usage Parameter Control is defined as the set of actions Definition: Usage Parameter Control is defined as the set of actions taken
taken by the network to monitor and control traffic, in terms of traffic by the network to monitor and control traffic, in terms of traffic offered
offered and validity of the ATM connection, at the end-system access. and validity of the ATM connection, at the end-system access. Its main
Its main purpose is to protect network resources from malicious as well purpose is to protect network resources from malicious as well as
as unintentional misbehavior, which can affect the QoS of other unintentional misbehavior, which can affect the QoS of other already
already established connections, by detecting violations of negotiated established connections, by detecting violations of negotiated parameters
parameters and taking appropriate actions. and taking appropriate actions.
Discussion: Discussion: none.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.77. Variable Bit Rate (VBR): 1.2.77. Variable Bit Rate (VBR):
Definition: An ATM Forum defined service category which supports Definition: An ATM Forum defined service category which supports variable
variable bit rate data traffic with average and peak traffic parameters. bit rate data traffic with average and peak traffic parameters.
Discussion: Discussion: VBR may potentially adversely effect TCP throughput due to
large round trip time variations.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.78. VC: 1.2.78. VC:
Definition: A communications channel that provides for the sequential Definition: A communications channel that provides for the sequential
unidirectional transport of ATM cells. unidirectional transport of ATM cells.
Discussion: Discussion: none.
Specification: AF-UNI3.1 Specification: AF-TM3.1
1.2.79. Virtual Channel Connection (VCC): 1.2.79. Virtual Channel Connection (VCC):
Definition: A concatenation of VCIs that extends between the points Definition: A concatenation of VCI's that extends between the points where
where the ATM service users access the ATM layer. The points at the ATM service users access the ATM layer. The points at which the ATM
which the ATM cell payload is passed to, or received from, the users cell payload is passed to, or received from, the users of the ATM Layer
of the ATM Layer (i.e., a higher layer or ATM-entity) for processing (i.e., a higher layer or ATM-entity) for processing signify the endpoints
signify the endpoints of a VCC. VCCs are unidirectional. of a VCC. VCC's are unidirectional.
Discussion: Discussion: none.
Specification: AF-UNI3.1 Specification: AF-TM3.1
1.2.80. Virtual Channel Identifier (VCI): 1.2.80. Virtual Channel Identifier (VCI):
Definition: A unique numerical tag as defined by a 16 bit field in the Definition: A unique numerical tag as defined by a 16 bit field in the ATM
ATM cell header that identifies a virtual channel, over which the cell is cell header that identifies a virtual channel, over which the cell is to
to travel. travel.
Discussion: Discussion: none.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.81. Virtual Path (VP): 1.2.81. Virtual Path (VP):
Definition: A unidirectional logical association or bundle of VCs. Definition: A unidirectional logical association or bundle of VCs.
Discussion: Discussion: none.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.82. Virtual Path Connection (VPC): 1.2.82. Virtual Path Connection (VPC):
Definition: A concatenation of VPIs between Virtual Path Terminators Definition: A concatenation of VPIs between Virtual Path Terminators
(VPTs). VPCs are unidirectional (VPT's). VPC's are unidirectional
Discussion: Discussion: none.
Specification: AF-UNI3.1 Specification: AF-TM3.1
1.2.83. Virtual Path Identifier (VPI): 1.2.83. Virtual Path Identifier (VPI):
Definition: An eight-bit field in the ATM cell header that indicates the Definition: An eight-bit field in the ATM cell header that indicates the
virtual path over which the cell should be routed. virtual path over which the cell should be routed.
Discussion: Discussion: none.
Specification: AF-UNI3.1 Specification: AF-UNI3.1
1.2.84. Virtual Source/Virtual Destination (VS/VD): 1.2.84. Virtual Source/Virtual Destination (VSND):
Definition: An ABR connection may be divided into two or more Definition: An ABR connection may be divided into two or more separately
separately controlled ABR segments. Each ABR control segment, controlled ABR segments. Each ABR control segment, except the first, is
except the first, is sourced by a virtual source. A virtual source sourced by a virtual source. A virtual source implements the behavior of
implements the behavior of an ABR source endpoint. Backward RM- an ABR source endpoint. Backward RM-cells received by a virtual source are
cells received by a virtual source are removed from the connection. removed from the connection. Each ABR control segment, except the last,
Each ABR control segment, except the last, is terminated by a virtual is terminated by a virtual destination. A virtual destination assumes the
destination. A virtual destination assumes the behavior of an ABR behavior of an ABR destination endpoint. Forward RM-cells received by a
destination endpoint. Forward RM-cells received by a virtual virtual destination are turned around and not forwarded to the next
destination are turned around and not forwarded to the next segment of segment of the connection.
the connection.
Discussion: Discussion: none.
Specification: AF-TM4.0 Specification: AF-TM4.0
1.2.85. Xrm Decrease Factor (XDM): 1.2.85. Xrm Decrease Factor (XDM):
Definition: An ABR service parameter, XDF controls the decrease in Definition: An ABR service parameter, XDF controls the decrease in ACR
ACR associated with Xrm. It is a power of two in range: [0, 1]. associated with Xrm. It is a power of two in range: [0, 1].
Discussion: Discussion: For ABR traffic, XDM 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 Specification: AF-TM4.0
1.2.86. Xrm: 1.2.86. Xrm:
Definition: An ABR service parameter, Xrm limits the number of Definition: An ABR service parameter, Xrm limits the number of forward RM-
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 RM-cells. The range is 0-255.
Discussion: Discussion: For ABR traffic, Xrm 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 Specification: AF-TM4.0
1.3. Frame Relay Related Definitions 2. Performance Metrics
1.3.1. Backward Explicit Congestion Notification (BECN):
Definition: BECN is a bit in the frame relay header. The bit is set by a
congested network node in any frame that is traveling in the reverse
direction of the congestion.
Discussion:
Specification: FRF
1.3.2. Committed Information Rate (CIR):
Definition: CIR is the transport speed the frame relay network will
maintain between service locations when data is presented.
Discussion:
Specification: FRF
1.3.3. Discard Eligible:
Definition: This is a 1-bit field in a frame relay header that provides a
two level priority indicator, used to bias discard frames in the event of
congestion toward lower priority frames. Similar to the CLP bit in
ATM.
Discussion:
Specification: FRF 2. 1. Definition Format (from RFC 1242)
1.3.4. Forward Explicit Congestion Notification (FECN): Metric to be defined.
Definition: FECN is a bit in the frame relay header. The bit is set by a Definition: The specific definition for the metric.
congested network node in any frame that is traveling in the same
direction of the congestion.
Discussion: Discussion: A brief discussion of the metric, its application and any
restrictions on measurement procedures.
Specification: FRF Measurement units: Intrinsic units used to quantify this metric. This
includes subsidiary units; e.g., microseconds are acceptable if the
intrinsic unit is seconds.
1.3.5. Frame: 2.2. Definitions
Definition: A logical grouping of information sent as a link-layer unit 2.2.1. Physical Layer- SONET
over a transmission medium.
Discussion: 2.2.1.1. Pointer Movements
Specification: FRF Definition: Pointer Movements is the number of changes in a SONET pointer
due to clock synchronization slips.
1.3.6. Frame Relay: Discussion: SONET Pointer Movements can cause loss of information in the
SONET payload envelop (SPE) which contains IP datagrams, either in the
form of cells or as PPP delimited PDUs.
Definition: A high-performance interface for packet-switching Measurement Units: Per second.
networks; considered more efficient that X.25. Frame relay
technology can handle "bursty" communications that have rapidly
changing bandwidth requirements.
Discussion: 2.2.1.2. Transport Overhead Error Count
Specification: FRF Definition: SONET Transport Overhead Error Count is the number of SONET
transport overhead errors detected.
2. Performance Metrics Discussion: SONET Transport Overhead Errors SONET Transport Overhead
Errors cause SONET frames to be lost. These frames may contain IP
datagrams, either in the form of cells or as PPP delimited PDUs.
2.1. Definition Format (from RFC1242) Measurement Units: Positive integer
Metric to be defined. 2.2.1.3. Path Overhead Error Count
Definition: The specific definition for the metric. Definition: SONET Path Overhead Error Count is the number of SONET path
overhead errors detected.
Discussion: A brief discussion of the metric, its application and any Discussion: SONET Path Overhead Errors cause SONET frames to be lost.
restrictions on measurement procedures. These frames may contain IP datagrams, either in the form of cells or as
PPP delimited PDUs.
Measurement units: Intrinsic units used to quantify this metric. This Measurement Units: Positive integer
includes subsidiary units, e.g. microseconds are acceptable if the
intrinsic unit is seconds.
2.2 Definitions 2.2.2. ATM Layer
2.2.1. Cell Delay Variation (CDV): 2.2.2.1. Cell Delay Variation (CDV):
Definition: The variation in cell transfer delay associated with a given Definition: The variation in cell transfer delay associated with a given
traffic load, orientation and distribution, as well as an integration traffic load, orientation and distribution, as well as an integration
period. CDV = max(CTD) - min(CTD) where max and min indicate period. CDV = max (CTD) - min (CTD) where max and min indicate the maximum
the maximum and minimum over the integration period, respectively. and minimum over the integration period, respectively.
Discussion: CDV is a component of cell transfer delay, induced by Discussion:
buffering and cell scheduling. Peak-to-peak CDV is a QoS delay CDV is a component of cell transfer delay, induced by buffering and cell
parameter associated with CBR and VBR services. The peak-to-peak scheduling. Peak-to-peak CDV is a QoS delay parameter associated with CBR
CDV is the ((1-a) quantile of the CTD) minus the fixed CTD that and VBR services. The peak-to-peak CDV is the ((1-a) quantile of the CTD)
minus the fixed CTD that could be experienced by any delivered cell on a
connection during the entire connection holding time. The parameter "a" is
the probability of a cell arriving late.
could be experienced by any delivered cell on a connection during the CDV effects TCP round trip time calculations. Large values of CDV will
entire connection holding time. The parameter "a" is the probability of adversely effect TCP throughput.
a cell arriving late.
Measurement Units: seconds Measurement Units: seconds
2.2.2. Cell Delay Variation Tolerance (CDVT): 2.2.2.2. Cell Delay Variation Tolerance (CDVT):
Definition: ATM layer functions may alter the traffic characteristics of Definition: ATM layer functions may alter the traffic characteristics of
ATM connections by introducing Cell Delay Variation. When cells ATM connections by introducing Cell Delay Variation. When cells from two
from two or more ATM connections are multiplexed, cells of a given or more ATM connections are multiplexed, cells of a given ATM connection
ATM connection may be delayed while cells of another ATM may be delayed while cells of another ATM connection are being inserted at
connection are being inserted at the output of the multiplexer. the output of the multiplexer. Similarly, some cells may be delayed while
Similarly, some cells may be delayed while physical layer overhead or physical layer overhead or OAM cells are inserted. Consequently, some
OAM cells are inserted. Consequently, some randomness may affect randomness may affect the inter-arrival time between consecutive cells of
the inter-arrival time between consecutive cells of a connection as a connection as monitored at the UNI. The upper bound on the "clumping"
monitored at the UNI. The upper bound on the "clumping" measure is measure is the CDVT.
the CDVT.
Discussion: Discussion:
CDVT effects TCP round trip time calculations. Large values of CDVT will
adversely effect TCP throughput.
Measurement units: seconds Measurement units: seconds
2.2.3. Cell Error Ratio (CER): 2.2.2.3. Cell Error Ratio (CER):
Definition: The ratio of errored cells in a transmission in relation to Definition: The ratio of errored cells in a transmission in relation to
the total cells sent in a transmission associated with a given traffic the total cells sent in a transmission associated with a given traffic
load, orientation and distribution, as well as an integration period. load, orientation and distribution, as well as an integration period.
CER = Errored Cells / Total Cells Transmitted. CER = Errored Cells / Total Cells Transmitted.
Discussion: The measurement is taken over a time interval and is Discussion: The measurement is taken over a time interval and is desirable
desirable to be measured on an in-service circuit. to be measured on an in-service circuit.
CER causes ATM cells to be lost. These cells may contain AAL5 segments of
IP datagrams.
Measurement Units: dimensionless. Measurement Units: dimensionless.
2.2.4. Cell Loss Ratio (CLR): 2.2.2.4. Cell Loss Ratio (CLR):
Definition: The ratio of lost cells in a transmission in relation to the Definition: The ratio of lost cells in a transmission in relation to the
total cells sent in a transmission associated with a given traffic load, total cells sent in a transmission associated with a given traffic load,
orientation and distribution, as well as an integration period. CLR = orientation and distribution, as well as an integration period. CLR
Lost Cells / Total Cells Transmitted. Lost Cells / Total Cells Transmitted.
Discussion: CLR is a negotiated QoS parameter and acceptable values Discussion:
are network specific. The objective is to minimize CLR provided the CLR is a negotiated QoS parameter and acceptable values are network
end-system adapts the traffic to the changing ATM layer transfer specific. The objective is to minimize CLR provided the end-system adapts
characteristics. The CLR parameter is the value of CLR that the the traffic to the changing ATM layer transfer characteristics. The CLR
network agrees to offer as an objective over the lifetime of the parameter is the value of CLR that the network agrees to offer as an
connection. It is expressed as an order of magnitude, having a range of objective over the lifetime of the connection. It is expressed as an order
10-1 to 10-15 and unspecified. of magnitude, having a range of 10-1 to 10-15 and unspecified.
CLR measures the number of ATM cells lost. These cells may contain AAL5
segments of IP datagrams.
Measurement Units: dimensionless. Measurement Units: dimensionless.
2.2.5. Cell Misinsertion Rate (CMR): 2.2.2.5. Cell Misinsertion Rate (CMR):
Definition: The ratio of cells received at an endpoint that were not Definition: The ratio of cells received at an endpoint that were not
originally transmitted by the source end in relation to the total number originally transmitted by the source end in relation to the total number
of cells properly transmitted associated with a given traffic load, of cells properly transmitted associated with a given traffic load,
orientation and distribution, as well as an integration period. CMR = orientation and distribution, as well as an integration period. CMR=Mis-
Mis-inserted Cells / Total Cells Transmitted. inserted Cells / Total Cells Transmitted.
Discussion: none Discussion:
CMR causes ATM streams to be corrupted. These streams may contain AAL5
segments of IP datagrams.
Measurement Units: dimensionless. Measurement Units: dimensionless.
2.2.6. Cell Rate Margin (CRM): 2.2.2.6. Cell Rate Margin (CRM):
Definition: This is a measure of the difference between the effective Definition: This is a measure of the difference between the effective
bandwidth allocation and the allocation for sustainable rate in cells per bandwidth allocation and the allocation for sustainable rate in cells per
second. second.
Discussion: Discussion: none.
Measurement units: Cells per second Measurement units: Cells per second
2.2.7. CRC Error Ratio: 2.2.2.7. CRC Error Ratio:
Definition: The ratio of PDUs received at an endpoint that which Definition: The ratio of PDUs received at an endpoint that which contain
contain an invalid CRC in relation to the total number of cells properly an invalid CRC in relation to the total number of cells properly
transmitted associated with a given traffic load, orientation and transmitted associated with a given traffic load, orientation and
distribution, as well as an integration period. distribution, as well as an integration period.
Discussion Discussion:
CRC errors cause ATM cells to be lost. These cells may contain AAL5
segments of IP datagrams.
Measurement Units: dimensionless Measurement Units: dimensionless
2.2.8. Cell Transfer Delay (CTD): 2.2.2.8. Cell Transfer Delay (CTD):
Definition: The elapsed time between a cell exit event at the Definition: The elapsed time between a cell exit event at the measurement
measurement point 1 (e.g., at the source UNI) and the corresponding point 1 (e.g., at the source UNI) and the corresponding cell entry event
cell entry event at a measurement point 2 (e.g., the destination UNI) at a measurement point 2 (e.g., the destination UNI) for a particular
for a particular connection. connection.
Discussion: The cell transfer delay between two measurement points is Discussion:
the sum of the total inter-ATM node transmission delay and the total The cell transfer delay between two measurement points is the sum of the
ATM node processing delay. total inter-ATM node transmission delay and the total ATM node processing
delay.
Measurement units: seconds Measurement units: seconds
2.2.3. ATM Adaptation Layer (AAL) Type 5 (AAL5)
2.2.3.1. AAL5 Reassembly Errors
Definition: AAL5 Reassembly Errors constitute any error which causes the
AAL5 PDU to be corrupted.
Discussion:
AAL5 Reassembly errors cause AAL5 PDUs to be lost. These PDUs may
contain IP datagrams.
Measurement Units: Positive Integer
2.2.3.2. AAL5 Reassembly Time
Definition: AAL5 Reassembly Time constitutes the time between the arrival
of the final cell in the AAL5 PDU and the AAL5 PDU being made available to
the service layer.
Discussion:
AAL5 Reassembly time directly effects TCP round trip time calculations.
Measurement Units: seconds
2.2.3.3. AAL5 CRC Error Ratio:
Definition: The ratio of PDUs received at an endpoint that which contain
an invalid CRC in relation to the total number of cells properly
transmitted associated with a given traffic load, orientation and
distribution, as well as an integration period.
Discussion:
AAL5 CRC errors causes AAL5 PDUs to be dropped. These PDUs may contain
IP datagrams.
Measurement Units: dimensionless
3. Security Considerations. 3. Security Considerations.
As this document is solely for the purpose of providing terminology As this document is solely for the purpose of providing terminology and
and describes neither a protocol nor an implementation, there are no describes neither a protocol nor an implementation, there are no security
security considerations associated with this document. considerations associated with this document.
4. References 4. References
[ILMI4.0] ATM Forum Integrated Local Management Interface [AF-ILMI4.0] ATM Forum Integrated Local Management Interface Version 4.0,
Version 4.0, af-ilmi-0065.000, September 1996. af-ilmi-0065.000, September 1996.
[AF-TEST] Introduction to ATM Forum Test Specifications, af-test- [AF-TEST-0022] Introduction to ATM Forum Test Specifications, af-test-
0022.00, December 1994. 0022.00, December 1994.
[AF-TM4.0] ATM Forum, Traffic Management Specification Version
4.0, af-tm-0056.00, April 1996. [AF-TM4.0] ATM Forum, Traffic Management Specification Version 4.0, af-tm-
[AF-UNI3.1] ATM Forum, User Network Interface Specification 0056.00, April 1996.
Version 3.1, September 1994. [AF-UNI3.1] ATM Forum, User Network Interface Specification Version 3.1,
September 1994.
[AF-UNI4.0] ATM Forum, User Network Interface Specification Version 4.0,
July 1996.
5. Editor's Addresses 5. Editor's Addresses
Jeffrey Dunn Jeffrey Dunn
Hewlett-Packard 3701 Koppers St. Baltimore, MD 21227 USA Advanced Network Consultants, Inc.
Phone: +1 (410) 362-7612 E-mail: jeff_dunn@hp.com 11241-B Skilift Court, Columbia, MD 21044 USA
Phone: +1 (410) 730-6300, E-mail: Jeffrey.Dunn@worldnet.att.net
Cynthia Martin Cynthia Martin
Hewlett-Packard 3701 Koppers St. Baltimore, MD 21227 USA Advanced Network Consultants, Inc.
Phone +1 (410) 362-7631 E-mail: cynthia_martin@hp.com 11241-B Skilift Court, Columbia, MD 21044 USA
Phone: +1 (410) 730-6300, E-mail: Cynthia.E.Martin@worldnet.att.net
 End of changes. 

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