rfc2761.txt

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

RFC 2761            Terminology for ATM Benchmarking       February 2000


   2. Multiple cells in the AAL5 PDU contain payload errors. In this
   case, there is not a one-to-one correspondence between cell payload
   errors and the number of corrupted AAL5 PDUs.

   Measurement Units: dimensionless.

2.2.2.3. Cell Loss Ratio (CLR)

   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, orientation and distribution, as well as an integration
   period.

        CLR = Lost Cells / Total Cells Transmitted.

   Discussion: CLR is a negotiated QoS parameter and acceptable values
   are network specific. The objective is to minimize CLR provided the
   end-system adapts the traffic to the changing ATM layer transfer
   characteristics. The CLR parameter is the value of CLR that the
   network agrees to offer as an objective over the lifetime of the
   connection. It is expressed as an order of magnitude, having a range
   of 10^-1 to 10^-15 and unspecified.

   CLR indicates the number of ATM cells lost in relation to the total
   number of cells sent. CLR is closely related to the number of
   corrupted AAL5 PDUs; however, there is not a direct numerical
   correlation between the number of cells lost and the number of
   corrupted AAL5 PDUs.  See the discussion under SAR.

   Measurement Units: dimensionless.

2.2.2.4. Cell Misinsertion Ratio (CMR)

   Definition: The ratio of cells received at an endpoint that were not
   originally transmitted by the source end 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.

        CMR = Misinserted Cells / Total Cells Transmitted.

   Discussion: The measurement is taken over a time interval and is
   desirable to be measured on an in-service circuit.  CMR is closely
   related to the number of corrupted AAL5 PDUs; however, there is not a
   direct numerical correlation between the number of mis-inserted cells
   and the number of corrupted AAL5 PDUs.  There are two cases described
   below.





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RFC 2761            Terminology for ATM Benchmarking       February 2000


   1.  Only one cell is mis-inserted into an AAL5 PDU.  In this case,
   there is a one-to-one correspondence between cell mis-insertion and
   the number of corrupted AAL5 PDUs.

   2.  Multiple cells are mis-inserted into an AAL5. In this case, there
   is not a one-to-one correspondence between cell mis-insertion and the
   number of corrupted AAL5 PDUs.

   Measurement Units: dimensionless.

2.2.2.5. Cell Rate Margin (CRM)

   Definition: This is a measure of the difference between the effective
   bandwidth allocation and the allocation for sustainable rate in cells
   per second.

   Discussion: This measures the amount of provisioned bandwidth which
   is not utilized.  This lack of utilization may be caused by
   encapsulation overhead, e.g., AAL5 trailer and padding, or by the
   protocol itself, e.g., TCP usually transmits in only one direction.

   Measurement units: Cells per second

2.2.2.6. 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: CRC errors cause ATM cells to be lost.  Although this
   will appear as cell loss at the ATM layer, this measurement can be
   made in-service using a test probe which measures CRC errors at the
   TC layer.

   Measurement Units: dimensionless

2.2.2.7. Cell Transfer Delay (CTD)

   Definition: The elapsed time between a cell exit event at the
   measurement point 1 (e.g., at the source UNI) and the corresponding
   cell entry event at a measurement point 2 (e.g., the destination UNI)
   for a particular connection.








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   Discussion: The 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.  While this number is a constant and
   should not adversely effect performance, it is a component in RTT.

   Measurement units: seconds

2.2.3. ATM Adaptation Layer (AAL) Type 5 (AAL5)

2.2.3.1. AAL5 Re-assembly Errors

   Definition: AAL5 Re-assembly Errors constitute any error, which
   causes the AAL5 PDU to be corrupted.

   Discussion: AAL5 Re-assembly 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 PDUs payload
   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 cause AAL5 re-assembly errors.  See
   discussion under AAL5 re-assembly errors.

   Measurement Units: dimensionless










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RFC 2761            Terminology for ATM Benchmarking       February 2000


2.2.4. ATM Service: Signaling

2.2.4.1. CAC Denial Time

   Definition: The amount of time required for CAC to determine that a
   call must be rejected.

   Discussion: In the case where Call Proceeding is implemented, this
   number will be less than 4 seconds. Otherwise, it will be less than
   10 seconds.  Large values of this measurement will adversely effect
   performance on systems where an alternate, non-NBMA, service is
   available.

   Measurement Units: seconds

2.2.4.2. Connection Establishment Time

   Definition: The amount of time between the first Setup message from
   the calling party and the Connect message to the calling party.

   Discussion:  See discussion under SVC.

   Measurement Units: seconds

2.2.4.3. Connection Teardown Time

   Definition: The amount of between the Release message being sent and
   the Release Complete message being received.

   Discussion: Large values of this measurement will adversely effect
   performance in systems where the total number of open calls or VCs is
   limited.  Specifically, a new VC cannot be instantiated with the same
   VPI/VCI before the old one is released.

   Measurement Units: seconds

2.2.4.4. Crankback Time

   Definition: The amount of time between the issuance of the first
   release or release complete message by the switch where the current
   Designated Transit List (DTL) is blocked and the receipt of the SETUP
   with the updated DTLs by the target switch.

   Discussion: This measurement does not take into account the amount of
   time associated with either the successful portion of the call setup
   transit or the time required for the calling party to receive .bp a
   response from the called party.  As a result, the call may still fail
   to complete if the call setup timer on the calling party expires.



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RFC 2761            Terminology for ATM Benchmarking       February 2000


   See discussion under SVC.

   Measurement Units: seconds

2.2.4.5. Route Update Response Time

   Definition: The amount of time between the receipt of a PNNI Topology
   State Element (PTSE), which is the PNNI routing PDU, containing a
   topology different from the current topology and the point at which
   the switch begins to generate DTLs reflecting the routing change.

   Discussion: This measurement provides a lower bound on the amount of
   time during which SETUP messages will be forwarded along a sub-
   optimal or blocked path.

   Measurement Units: seconds

2.2.5. ATM Service: ILMI

2.2.5.1. MIB Alignment Time

   Definition: The amount of time between the issuance of the final cold
   start message and the final get response associated with the exchange
   of static MIB information.

   Discussion: This measurement reflects the amount of time required by
   the switch and end system to exchange all information required to
   characterize and align the capabilities of both systems.  It does not
   include address registration.  It should also be noted that this
   measurement will depend on the number of MIB elements implemented by
   both systems.

   Measurement Units: seconds

2.2.5.2. Address Registration Time

   Definition: The amount of time between the initial set request issued
   by the switch and the final get response issued by the switch.

   Discussion: This measurement assumes that the switch has checked the
   network prefix status object and the end system has checked the ATM
   address status object.  In the case where the end system checks the
   ATM address status object only after the switch has issued a set
   request of the network prefix status object, this measurement will
   not reflect the actual time required to complete the address
   registration.

   Measurement Units: seconds



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RFC 2761            Terminology for ATM Benchmarking       February 2000


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

   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 effort to identify any such rights.  Information on the
   IETFs procedures with respect to rights in standards-track and
   standards-related documentation can be found in BCP-11.  Copies of
   claims of rights made available for publication and any assurances of
   licenses to be made available, or the result of an attempt made to
   obtain a general license or permission for the use of such
   proprietary rights by implementors or users of this specification can
   be obtained from the IETF Secretariat.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights which may cover technology that may be required to practice
   this standard.  Please address the information to the IETF Executive
   Director.

5. References

   [AF-ILMI4.0]   ATM Forum Integrated Local Management Interface
                  Version 4.0, af-ilmi-0065.000, September 1996.

   [AF-TEST-0022] Introduction to ATM Forum Test Specifications, af-
                  test-0022.00, December 1994.

   [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 (final ballot), btd-tm-01.02, July 1998.

   [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.




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RFC 2761            Terminology for ATM Benchmarking       February 2000


   [I.321]        ITU-T, B-ISDN protocol reference model and its
                  application, April 1991.

   [I.363]        ITU-T, B-ISDN ATM Adaptation Layer Specification
                  series, 1996-1997.

   [I.363.5]      ITU-T, B-ISDN ATM Adaptation Layer Specification: Type
                  5 AAL, August 1996.

6. Editors' Addresses

   Jeffrey Dunn
   Advanced Network Consultants, Inc.
   4214 Crest Place
   Ellicott City, MD 21043 USA

   Phone: [phone]
   EMail: [e-mail]


   Cynthia Martin
   Advanced Network Consultants, Inc.
   11241-B Skilift Court
   Columbia, MD 21044 USA

   Phone: [phone]
   EMail: [e-mail]
























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RFC 2761            Terminology for ATM Benchmarking       February 2000


7.  Full Copyright Statement

   Copyright (C) The Internet Society (2000).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.



















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