Network Working Group                                      J. H. Dunn
INTERNET-DRAFT                                             C. E. Martin
Expires: September, 2000 February, 2001                                    ANC, Inc.

                                                           March,

                                                           July, 2000
                   Terminology for ATM ABR Benchmarking
                   <draft-ietf-bmwg-atm-term-abr-01.txt>
                   <draft-ietf-bmwg-atm-term-abr-02.txt>

Status of this Memo

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Copyright Notice

   Copyright (C) The Internet Society (1999).  All Rights Reserved.

Abstract

   This memo  discusses  and  defines  terms  associated  with  performance
   benchmarking  tests  and  the  results  of these tests in the context of
   Asynchronous Transfer Mode (ATM) based switching devices supporting ABR.
   The terms defined in this memo will be used in addition to terms defined
   in RFCs 1242, 2285, and 2544 and 2761. This memo is  a  product  of  the
   Benchmarking   Methodology   Working   Group   (BMWG)  of  the  Internet
   Engineering Task Force (IETF).

1. Introduction.

   This document provides terminology for benchmarking ATM based  switching
   devices  supporting  ABR.   It  extends  terminology already defined for
   benchmarking network interconnect devices in RFC's 1242, 2285, and  2544
   and  2761.   Although  some  of  the  definitions  in  this  memo may be
   applicable to a broader  group  of  network  interconnect  devices,  the
   primary focus of the terminology in this memo is on ATM ABR.

   This  memo contains two major sections: Background and Definitions.  The
   background  section  provides  the  reader  with  an  overview  of   the
   technology  and  IETF formalisms.  The definitions section is split into
   two sub- sections.  The formal definitions sub-section is provided as  a
   courtesy   to  the  reader.   The  measurement  definitions  sub-section
   contains performance metrics with inherent units.

   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
   Terminology  documents  and  Benchmarking  Methodology  documents.   The
   Terminology documents present the benchmarks and  other  related  terms.
   The  Methodology documents define the procedures required to collect the
   benchmarks cited in the corresponding Terminology documents.

2. Existing Definitions.

   RFC 1242 "Benchmarking Terminology  for  Network  Interconnect  Devices"
   should be consulted before attempting to make use of this document.  RFC
   2544  "Benchmarking  Methodology  for  Network   Interconnect   Devices"
   contains  discussions  of a number of terms relevant to the benchmarking
   of switching devices and should be consulted.   RFC  2285  "Benchmarking
   Terminology  for  LAN  Switching  Devices"  contains  a  number of terms
   pertaining to traffic distributions and datagram interarrival.  RFC 2761
   "  Terminology  for ATM Benchmarking" contains a number terms pertaining
   to traffic management [TM4.0, TM4.1].  Many of the  metrics  defined  in
   RFC  2761  (e.g.  CDV,  CER,  CLR,  CMR,  and  CTD)  also  apply  to ABR
   performance benchmarking.  These metrics will not be redefined  in  this
   document.   For  the sake of clarity and continuity, this RFC adopts the
   template for definitions set out in Section 2 of RFC 1242.

3. Requirements

   In this document, the words that are used to define the significance  of
   each particular requirement are capitalized. These words are:

   *  "MUST"  This  word, or the words "REQUIRED" and "SHALL" mean that the
   item is an absolute requirement of the specification.

   * "SHOULD" This word or the adjective "RECOMMENDED" means that there may
   exist valid reasons in particular circumstances to ignore this item, but
   the full implications  should  be  understood  and  the  case  carefully
   weighed before choosing a different course.

   *  "MAY"  This  word or the adjective "OPTIONAL" means that this item is
   truly optional.  One vendor may choose to include  the  item  because  a
   particular  marketplace  requires it or because it enhances the product,
   for example; another vendor may omit the same item.

   An implementation is not compliant if it fails to satisfy one or more of
   the   MUST   requirements   for   the   protocols   it  implements.   An
   implementation  that  satisfies  all  the  MUST  and  all   the   SHOULD
   requirements   for   its   protocols  is  said  to  be  "unconditionally
   compliant"; one that satisfies all the MUST requirements but not all the
   SHOULD  requirements  for  its  protocols  is  said to be "conditionally
   compliant".

II. Definitions

   The definitions presented in this section have  been  divided  into  two
   groups.   The  first  group is formal definitions, which are required in
   the definitions of  the  performance  metrics  but  are  not  themselves
   strictly  metrics.   These definitions are subsumed from other work done
   in other working groups both inside and  outside  the  IETF.   They  are
   provided as a courtesy to the reader.

1. Formal Definitions

1.1. Definition Format (from RFC 1242)

Term to be defined.

Definition: The specific definition for the term.

Discussion:  A  brief  discussion  of  the  term,  its  application and any
restrictions on measurement procedures.

Specification: The working group  and  document  in  which  the  terms  are
specified and are listed in the references section.

1.2.  Related Definitions.

1.2.1.  Allowed Cell Rate (ACR)

Definition:   An   ABR   service   parameter,   ACR  is  the  current  rate
(cells/second) at which a source is allowed to send.

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

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.

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

1.2.3. Additive Increase Rate (AIR)

Definition: An ABR service parameter, AIR controls the rate  at  which  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
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)

Definition: Refer to AIR.

Discussion: Refer to AIR.

Specification: AF-TM4.0

1.2.5. Available Bit Rate (ABR)

Definition: ABR is an ATM layer service category for which the limiting ATM
layer   transfer   characteristics  provided  by  the  network  may  change
subsequent  to  connection  establishment.  A  flow  control  mechanism  is
specified  which  supports  several types of feedback to 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
accordance  with  the  feedback  will  experience a low cell loss ratio and
obtain a fair share of the  available  bandwidth  according  to  a  network
specific  allocation policy. Cell delay variation is not controlled in this
service, although admitted cells are not delayed unnecessarily.

Specification: AF-TM4.1

1.2.6. Available Bit Rate (ABR) Compliance (Conformance)

Definition: ABR connection conformance refers to the behavior specified for
ABR  destination and switches, but allows for delays 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
are  tested upon arrival.  At the arrival point, each cell is identified as
conforming or non-conforming.  The minimal conformance definition  for  ABR
is GCRA((1/PCR),t1), where PCR is defined for CLP=0 flow.

Specification: AF-TM4.1

1.2.7. BN

Definition:  The  BN bit in the RM-cell indicated wheather the RM-cell is a
BECN cell or not.

Discussion: If BN=0, the RM cells were generated by the source.   If  BN=1,
the RM cells were generated by the destination or a switch.

Specification: AF-TM4.1

1.2.8. CCR

Definition:  The  CCR  field  in  the  RM-cell  is set by the source to its
current ACR.  CCR is formatted as a rate.

Discussion: For BECN cells, CCR=0.

Specification: AF-TM4.1

1.2.9. Cell Blocks (CB)

Definition: Cell blocks are a sequence of N cells transmitted consecutively
on a given connection.

Discussion:  A  cell  block  will  normally  correspond  to  the  number of
information cells transmitted between successive OAM cells.

Specification: AF-TM4.1

1.2.10. Congestion Indication (CI)

Definition: The CI bit in the RM-cell allows a network element to  indicate
that there is congestion in the network.

Discussion:  When  the source receives a backward RM-cell with CI=1, ACR is
decreased. When the destination turns around a forward RM-cell, the  CI  is
set  to  1  to indicate that the previously received data cell had the EFCI
state set.

Specification: AF-TM4.1

1.2.11. Cutoff Decrease Factor (CDF)

Definition: CDF controls the decrease in ACR (Allowed Cell Rate) associated
with CRM (missing RM cell count).

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

1.2.12. DIR

Definition:  The  DIR  bit in the RM-cell indicates which direction of data
flow is associated with the RM-cell.  DIR is changed from 0 to  1  when  an
RM-cell is turned around at the destination.

Discussion:  A forward RM-cell is indicated by DIR=0 and is associated with
data cells flowing in the same direction.  A backward RM-cell is  indicated
by  DIR=1  and  is  associated  with  data  cells  flowing  in the opposite
direction.

Specification: AF-TM4.1

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.

Specification: AF-TM4.1

1.2.14. Feedback

Definition:  Information  carried  in the backward RM-cells provided by the
network elements and/or the destination back to the source.

Discussion: Feedback may include information in the ER field, or the CI  or
NI bits of each backward RM-cell.

Specification: AF-TM4.1

1.2.15. Ideal Transmission Time (ITT)

Definition:  The  transmission  time for ABR CLP=0 cells, if the difference
between itself and the transmission time for the previous CLP=0 cell on the
connection  is  greater than or equal to the minimum: a) the inverse of the
ACR in effect immediately after the transmission time of the first  of  the
two  cells  b)  the  inverse  of  the  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
automatically an ITT.

Specification: AF-TM4.1

1.2.16. Initial Cell Rate (ICR)

Definition:  An  ABR  service  parameter, in cells/sec, that is the rate at
which a source should send initially and after an idle period.

Discussion: none.

Specification: AF-TM4.0

1.2.17. In-Rate Cells

Definition: In-Rate ABR cells are sent with CLP=0.

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
with CLP=0.

Specification: AF-TM4.1

1.2.18. Minimum Cell Rate (MCR)

Definition: An ABR service traffic descriptor, in cells/sec,  that  is  the
rate at which the source is always allowed to send.

Discussion:  MCR  may  be  set  to  zero.  The bandwidth available from the
network may vary, but shall not become less than MCR.

Specification: AF-TM4.1

1.2.19. Mrm

Definition: An ABR service parameter that controls allocation of  bandwidth
between forward W-cells, backward RM-cells, and data cells.

Discussion: none.

Specification: AF-TM4.0

1.2.20. No Increase (NI)

Definition:  The  NI  bit  in  the RM-cell is used to prevent a source from
increasing its ACR.  NI does not require any decrease in value.

Discussion: None.

Specification: AF-TM4.0

1.2.21. Nrm

Definition: An ABR service parameter, Nrm is the maximum number of cells  a
source may send for each forward RM-cell.

Discussion: none.

Specification: AF-TM4.0

1.2.22. Out-of-Rate Cells

Definition: Out-of-Rate ABR cells are sent with CLP=1.

Discussion:  This  may  be  used to enable a rate increate for a connection
that has an ACR=0.  The source would generate out-of-rate  cells  to  probe
the network to learn when it may increase its rate.

Specification: AF-TM4.1

1.2.23. Rate Decrease Factor (RDF)

Definition: An ABR service parameter, RDF controls the decrease in 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
ACR.  This  value  effects  TCP round trip time calculations, which in turn
effects TCP throughput.

Specification: AF-TM4.0

1.2.24. Rate Increase Factor (RIF)

Definition: This controls the amount by which the  cell  transmission  rate
may  increase  upon  receipt  of  a  RM-cell.  The  additive  increase 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
ACR.  This  value  effects  TCP round trip time calculations, which in turn
effects TCP throughput.

Specification: AF-TM4.0

1.2.25.  Resource Management (RM) Cells

Definition:  RM  cells  are  used  to  convey  network  status   (available
bandwidth,  congestion  levels) and request peak cell rates for ATM blocks.
The RM cell has the following format:

Header: 5 bytes, same as the ATM cell header
Protocol ID: 3 bytes, protocol ID value is 1 for ABR service
Function specific field: 45 bytes, data required for the specific protocol
(See DIR, BN, CI, NI, ER, CCR, and MCR for field information.)
Rsvd: 6 bytes, reserved for future specification
EDC: 10 bytes, CRC-10 error detection code computed over the cell payload
      (except the CRC-10 field) and used to check for data corruption

Discussion: RM information can exist at the VP and/or VC  level.  VP  level
cells  are  identified with a VCI value of 6. VC level cells are identified
with a PT of 6.  See DIR, BN, CI, NI,  ER,  CCR,  and  MCR  for  additional
protocol field information.

Specification: AF-TM4.0

1.2.26. Severely Errored Cell Block (SECB)

Definition:  A  severely cell block outcome occurs when more than M errored

cells, lost cells, or misinserted cell outcomes are observed in a  received
cell block.

Discussion: none.

Specification: AF-TM4.1

1.2.27. Tagged Cell Rate (TCR)

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  fixed  at  10
cells/second.

Discussion: none.

Specification: AF-TM4.0

1.2.28. TDF

Definition:  An  ABR  service  parameter,  TDF controls the decrease in ACR
associated with TOF. TDF is signaled as TDFF, where TDF=TDFF/RDF 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
ACR.  This  value  effects  TCP round trip time calculations, which in turn
effects TCP throughput.

Specification: AF-TM4.0

1.2.29. TDFF

Definition: Refer to TDF. TDFF is either zero or a  power  of  two  in  the
range 1/64 to 1 in units of 1 /cells.

Discussion: Refer to TDF.

Specification: AF-TM4.0

1.2.30. Time Out Factor (TOF)

Definition:  An  ABR  service  parameter,  TOF  controls  the  maximum time
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
the range: 1/8 to 4,096.

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

1.2.31. Time Out Factor (TOFF)

Definition: Refer to TOF.

Discussion: none.

Specification: AF-TM4.0

1.2.32. Trm

Definition: An ABR service parameter that provides an upper  bound  on  the
time between forward RM-cells for an active source. It is 100 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
ACR.  This  value  effects  TCP round trip time calculations, which in turn
effects TCP throughput.

Specification: AF-TM4.0

1.2.33. Virtual Source/Virtual Destination (VSND)

Definition: An ABR connection may be divided into two  or  more  separately
controlled  ABR  segments.  Each  ABR control segment, except the first, is
sourced by a virtual source. A virtual source implements the behavior of an
ABR  source  endpoint.  Backward  RM-cells received by a virtual source are
removed from the connection.  Each ABR control segment, except the last, is
terminated  by  a  virtual  destination.  A virtual destination assumes the
behavior of an ABR destination endpoint. Forward  RM-cells  received  by  a
virtual destination are turned around and not forwarded to the next segment
of the connection.

Discussion: none.

Specification: AF-TM4.0

1.2.34. Xrm Decrease Factor (XDM)

Definition: An ABR service parameter, XDF  controls  the  decrease  in  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
ACR. This value effects TCP round trip time  calculations,  which  in  turn
effects TCP throughput.

Specification: AF-TM4.0

1.2.35. Xrm

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
range is 0-255.

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

2. Performance Metrics

2. 1. Definition Format (from RFC 1242)

Metric to be defined.

Definition: The specific definition for the metric.

Discussion:  A  brief  discussion  of  the  metric, its application and any
restrictions on measurement procedures.

Measurement units: Intrinsic units  used  to  quantify  this  metric.  This
includes  subsidiary  units;  e.g.,  microseconds  are  acceptable  if  the
intrinsic unit is seconds.

2.2. Definitions

2.2.1. ABR Rate Decrease Response Time (ARDRT)

Definition:  The  amount  of  time  required  by  the  SUT  to  adjust  its
transmission rate based on an ABR rate decrease request.

Discussion:   During the ARDRT, cells transmitted by the SUT may be dropped
by the network due to traffic policing.  These dropped cells may contain  a
portion of an IP datagram.  This may cause IP and TCP packet loss.

Measurement Units: seconds

2.2.2. ABR Rate Increase Response Time (ARIRT)

Definition:  The  amount  of  time  required  by  the  SUT  to  adjust  its
transmission rate based on an ABR rate increase request.

Discussion:  During the ARIRT, the SUT will not fully utilize the available
bandwidth.  This will negatively impact IP and TCP throughput.

Measurement Units: seconds

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
buffering and RM-cell scheduling.

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)

Definition:  The ratio of RM-cells with payload errors in a transmission in

relation to the total number of RM-cells sent in a transmission  associated
with  a  given  traffic  load,  orientation and distribution, as well as an
integration period.  Note that errors occurring in the RM-cell header  will
cause  RM-cell loss at the ATM 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.

Discussion:  The measurement is taken over a time interval and is desirable
to be measured on an in-service circuit. RM-CER 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-CER will
adversely effect TCP throughput and cause SAR timeout.

Measurement Units: dimensionless.

2.2.5. RM-Cell Loss Ratio (RM-CLR)

Definition: The ratio of lost RM-cells in a transmission in relation to the
total RM-cells sent in a transmission associated with a given traffic load,
orientation and distribution, as well as an integration period.

          RM-CLR = Lost RM-Cells / Total RM-Cells Transmitted.

Discussion:  The  objective  is  to minimize RM-CLR.  It is expressed as 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
condition  of  the  network.   This  in  turn  effects  TCP round trip time
calculations.  Large values of RM-CLR will adversely effect TCP  throughput
and cause SAR timeout.

Measurement Units: dimensionless.

2.2.6. RM-Cell Misinsertion Ratio (RM-CMR)

Definition:  The  ratio  of  RM-cells received at an endpoint that were not
originally transmitted by the source end in relation to the total number of
RM-cells  properly  transmitted  associated  with  a  given  traffic  load,
orientation and distribution, as well as an integration period.

          RM-CMR = Misinserted RM-Cells / Total RM-Cells Transmitted.

Discussion: The measurement is taken over a time interval and is  desirable
to be measured on an in-service circuit.

RM-CMR  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-CMR will adversely effect TCP throughput
and cause SAR timeout.

Measurement Units: dimensionless.

2.2.7. RM-CRC Error Ratio

Definition: The ratio of RM-cells received at an endpoint which contain  an
invalid   CRC  in  relation  to  the  total  number  of  RM-cells  properly
transmitted  associated  with  a  given  traffic  load,   orientation   and
distribution, as well as an integration period.

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
condition of the network.   This  in  turn  effects  TCP  round  trip  time
calculations.   Large values of RM-CRC will adversely effect TCP throughput
and cause SAR timeout.

Measurement Units: dimensionless

2.2.8. RM-Cell Transfer Delay (RM-CTD)

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-
cell entry event at a measurement point 2 (e.g., the destination UNI) for a
particular connection.

Discussion:  The  RM-cell  transfer delay between two measurement points is
the sum of the total inter-ATM node transmission delay and  the  total  ATM
node  processing  delay. This number is a constant and should not adversely
effect performance.

Measurement units: seconds

2.2.9. Severely Errored Cell Block Ratio (SECBR)

Definition: The ratio of severely errored cell blocks in a transmission  in
relation  to the total cell blocks sent in a transmission associated with a
given traffic load, orientation and distribution, as well as an integration
period.

      SECBR = Severely Errored Cell Blocks/Total Transmitted Cell Blocks

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.

Measurement Units: dimensionless.

3. Security Considerations.

   As this document is  solely  for  providing  terminology  and  describes
   neither  a  protocol  nor  an  implementation,  there  are  no  security
   considerations associated with this document.

4. Notices

Internet Engineering Task Force

   The IETF takes no position  regarding  the  validity  or  scope  of  any
   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
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5. Disclaimer

   Copyright (C) The Internet Society (1999). All Rights Reserved.

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6. References

    [AF-TM4.0] ATM Forum, Traffic Management Specification Version 4.0, af-
   tm-0056.00, April 1996.

   [AF-TM4.1] ATM Forum, Traffic Management Specification Version 4.1,  af-
   tm- 0121.000, March 1999.

   [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.

7. Editors Addresses
   Jeffrey Dunn
   Advanced Network Consultants, Inc.
   4214 Crest Place, Ellicott City, MD 21043 USA
   Phone: +1 (410) 750-1700, E-mail: Jeffrey.Dunn@worldnet.att.net

   Cynthia Martin
   Advanced Network Consultants, Inc.
   4214 Crest Place, Ellicott City, MD 21043 USA
   Phone: +1 (410) 750-1700, E-mail: Cynthia.E.Martin@worldnet.att.net