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Network Working Group B. StockmanRequest for Comments: 1404 NORDUnet/SUNET January 1993 A Model for Common Operational StatisticsStatus of the Memo This memo provides information for the Internet community. It does not specify an Internet standard. Distribution of this memo is unlimited.Abstract This memo describes a model for operational statistics in the Internet. It gives recommendations for metrics, measurements, polling periods, storage formats and presentation formats.Acknowledgements The author would like to thank the members of the Operational Statistics Working Group of the IETF whose efforts made this memo possible.Table of Contents 1. Introduction ............................................. 2 2. The Model ................................................ 5 2.1 Metrics and Polling Periods .............................. 5 2.2 Format for Storing Collected Data ........................ 6 2.3 Reports .................................................. 6 2.4 Security Issues .......................................... 6 3. Categorization of Metrics ................................ 7 3.1 Overview ................................................. 7 3.2 Categorization of Metrics Based on Measurement Areas ..... 7 3.2.1 Utilization Metrics ...................................... 7 3.2.2 Performance Metrics ...................................... 7 3.2.3 Availability Metrics ..................................... 7 3.2.4 Stability Metrics ........................................ 8 3.3 Categorization Based on Availability of Metrics .......... 8 3.3.1 Per Interface Variables Already in Standard MIB .......... 8 3.3.2 Per Interface Variables in Private Enterprise MIB ........ 9 3.3.3 Per interface Variables Needing High Resolution Polling .. 9 3.3.4 Per Interface Variables not in any MIB ................... 9 3.3.5 Per Node Variables ....................................... 9 3.3.6 Metrics not being Retrievable with SNMP ................. 10 3.4 Recommended Metrics ..................................... 10Stockman [Page 1] RFC 1404 Operational Statistics January 1993 3.4.1 Chosen Metrics .......................................... 10 4. Polling Frequencies ..................................... 11 4.1 Variables Needing High Resolution Polling ............... 11 4.2 Variables not Needing High Resolution Polling ........... 11 5. Pre-Processing of Raw Statistical Data .................. 12 5.1 Optimizing and Concentrating Data to Resources .......... 12 5.2 Aggregation of Data ..................................... 12 6. Storing of Statistical Data ............................. 13 6.1 The Storage Format ...................................... 13 6.1.1 The Label Section ....................................... 14 6.1.2 The Device Section ...................................... 14 6.1.3 The Data Section ........................................ 16 6.2 Storage Requirement Estimations ......................... 17 7. Report Formats .......................................... 18 7.1 Report Types and Contents ............................... 18 7.2 Contents of the Reports ................................. 18 7.2.1 Offered Load by Link .................................... 18 7.2.2 Offered Load by Customer ................................ 18 7.2.3 Resource Utilization Reporting .......................... 19 7.2.3.1 Utilization as Maximum Peak Behavior .................... 19 7.2.3.2 Utilization as Frequency Distribution of Peaks .......... 19 8. Considerations for Future Development ................... 20 8.1 A Client/Server Based Statistical Exchange System ....... 20 8.2 Inclusion of Variables not in the Internet Standard MIB . 20 8.3 Detailed Resource Utilization Statistics ................ 20 Appendix A Some formulas for statistical aggregation ........... 21 Appendix B An example .......................................... 24 Security Considerations ......................................... 27 Author's Address ................................................ 271. Introduction Today it is not uncommon for many network administrations to collect and archive network management metrics that indicate network utilization, growth, and outages. The primary goal is to facilitate near-term problem isolation and longer-term network planning within the organization. There is also the larger goal of cooperative problem isolation and network planning between network administrations. This larger goal is likely to become increasingly important as the Internet continues to grow. There exist a variety of network management tools for the collection and presentation of network management metrics. However, different kinds of measurement and presentation techniques makes it difficult to compare data between networks. Plus, there is not common agreement on what metrics should be regularly collected or how they should be displayed.Stockman [Page 2] RFC 1404 Operational Statistics January 1993 There needs to be an agreed-upon model for 1) A minimal set of common network management metrics to satisfy the goals stated above. 2) Tools for collecting these metrics. 3) A common storage format to facilitate the usage of these data by common presentation tools. 4) Common presentation formats. Under this Operational Statistics model, collection tools will collect and store data in a given format to be retrieved later by presentation tools displaying the data in a predefined way. (See figure below.)Stockman [Page 3] RFC 1404 Operational Statistics January 1993 The Operational Statistics Model (Collection of common metrics, by commonly available tools, stored in a common format, displayed in common formats by commonly available presentation tools.) !-----------------------! ! Network ! !---+---------------+---! / \ / \ / \ --------+------ ----+--------- ! New ! ! Old ! ! Collection ! ! Collection ! ! Tool ! ! Tool ! !---------+---! !------+-----! \ ! \ !-------+--------! \ ! Post-Processor ! \ !--+-------------! \ / \ / \ / !--+-------+---! ! Common ! ! Statistics ! ! Database ! !-+--------+---! / \ / \ / \ / !-+-------------! / ! Pre-Processor ! / !-------+-------! !-----------+--! ! ! New ! !-------+-------! ! Presentation ! ! Old ! ! Tool ! ! Presentation ! !---------+----! ! Tool ! \ !--+------------! \ / \ / !-+---------------+-! ! Graphical Output ! ! (e.g., to paper ! ! or X-window) ! !-------------------!Stockman [Page 4] RFC 1404 Operational Statistics January 1993 This memo gives an overview of this model for common operational statistics. The model defines the gathering, storing and presentation of network operational statistics and classifies the types of information that should be available at each network operation center conforming to this model. The model defines a minimal set of metrics, how these metrics should gathered and stored. Finally the model gives recommendations on the content and the layout of statistical reports making it possible to easily compare networks statistics between NOCs. The primary purpose of this model is to define ways and methods on how NOCs could most effectively share their operational statistics. One intention with this model is to specify a baseline capability that NOCs conforming to the this model may support with a minimal development effort and a minimal ongoing effort.2. The Model The model defines three areas of interest on which all underlying concepts are based. 1. The definition of a minimal set of metrics to be gathered 2. The definition of a format for storing collected statistical data. 3. The definition of methods and formats for generating reports. The model indicates that old tools used today could be retrofitted into the new paradigm. This could be done by providing conversion- filters between the old and the new environment tools. In this sense this model intends to advocate the development of public domain software for use by participating NOCs. One basic idea with the model is that statistical data stored at one place could be retrieved and displayed at some other place.2.1 Metrics and Polling Periods The intention here is to define a minimal set of metrics that easily could be gathered using standard SNMP based network management tools. These metrics should hence be available as variables in the Internet Standard MIB. If the Internet Standard MIB is changed also this minimal set of metrics could be reconsidered as there are many metrics viewed asStockman [Page 5] RFC 1404 Operational Statistics January 1993 important but currently not being defined in the standard MIB. For some metrics being highly desirable to collect there are currently no way to get them into the Internet Standard MIB as these metrics probably are not possible to retrieve using SNMP. Tools and methods in gathering such metrics should be explicitly defined if such metrics are to be considered. This is, however, outside of the scope of this memo.2.2 Format for Storing Collected Data A format for storing data is defined. The intention is to minimize redundant information by using a single header structure where all information relevant to a certain set of statistical data is stored. This header section will give information on when and where the corresponding statistical data where collected.2.3 Reports Some basic classes of reports are suggested with regards to different views of network behavior. For this reason reports on totals of octets and packets over some period in time are regarded as essential to give an overall view of the traffic flows in a network. Differentiation between application and protocols to give ideas on which type of traffic is dominant is regarded as needed. Finally reports on resource utilization are recommended.. Depending on the intention with a report the timeperiod over which it spans may vary. For capacity planning there may be a need for longer term reports while in engineering and operation there may be sufficient with reports on weekly or daily basis.2.4 Security Issues There are legal, ethical and political concerns of data sharing. People are concerned about showing data that may make one of the networks look bad. For this reason there is a need to insure integrity, conformity and confidentiality of the shared data. To be useful, the same data must be collected from all of the involved sites and it must be collected at the same interval. To prevent vendors from getting an unfair performance information, certain data must not be made available.Stockman [Page 6] RFC 1404 Operational Statistics January 19933. Categorization of Metrics3.1 Overview This section gives a classification of metrics with regard to scope and easiness of retrieve. A recommendation of a minimal set of metrics is given. The section also gives some hints on metrics to be considered for future inclusion when available in the network management environment. Finally some thoughts on storage requirements are presented.3.2 Categorization of Metrics Based on Measurement Areas The metrics used in evaluating network traffic could be classified into (at least) four major categories: - Utilization metrics - Performance metrics - Availability metrics - Stability metrics3.2.1. Utilization Metrics These category describes different aspects of the total traffic being forwarded through the network. Possible metrics are: - Total input and output packets and octets. - Various peak metrics. - Per protocol and per application metrics.3.2.2 Performance Metrics These metrics describes the quality of service such as delays and congestion situations. Possible metrics are: - RTT metrics on different protocol layers. - Number of collisions on a bus network⌨️ 快捷键说明
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