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Background: Know: etherHistory, control and data tables , INTEGER, interval, buckets, OID, Recognize:

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RMON2 UsrHistoryEdit

BackgroundEdit

RMON2 usrHistory is based on some basic understanding of The Remote Network MONitoring (RMON) and Ethernet statistics. Remote monitoring supports RMON and RMON2 protocols, in support of the 6 group (statistics, history, alarms, events, UsrHistory, ProbeConfig). It supports the network management of platform (NETVIEW, OPENVIEW, CA). Meanwhile, it supports the management and remote control of command line mode, WEB mode, Telnet mode.The relevant wikia pages is illustated and can be useful to understand the slide:

RMON2 usrHistory

RMON: Remote Network Monitoring

OID: Object Identifier

It is pre-defined in collecting data of history in RMON1, but it allows users to define in RMON2. RMON2 generalises usrHistory, allowing recording of history of any INTEGER-derived objectAll the INTERGER-derived object such as Integer32, Counter, Gauge, TimeTicks. usrHistoryObjectVariable is used to illustrate which object it is and we can learn it by one example .[2] The usrHistory group combines mechanisms seen in the alarm and history groups. It periodically samples user-specified variables and logs that data, based on user-defined parameters.The “usrHistory” has three tables which give the information about the methods of defining history data (refer to slide Ethernet protocol statistics). And there are two control tables and one data table.[1]

For the first table: it is “usrHistoryControlTable ”. The table demonstrates the details of sampling of the function, such as the number of sampling object, sampling interval, sampling interval length and the network of buckets. Subordinate to this are one or more instances of usrHistoryObjectTable that specifies the variables to be sampled. And one line in the table defines the a table of second table.[1]

Figure 1. Structure of usrHistoryControlTable

UsrHistoryControlTable

For the second table: it is “usrHistoryObjectTable ”. It is a control table, which illustrates the sampling variable and sampling type. Subordinate to each instance in the usrHistoryObjectTable are one or more instances of usrHistoryTable that record the specified data. The number of the lines equals the numbers of the sampling objects in the table of the first table. Moreover, it controls which objects and how to sample. There are two kinds of values: absolute value and delta value. For the absolute value, it is a direct value. While for the delta value, it is the value after subtraction.[1]

Figure 2. Structure of usrHistoryObjectTable

UsrHistoryObjectTbl

The object details of usrHistoryObjectTable: The object identifier of the particular variable to be sampled. Only variables that resolve to an ASN.1 primitive type of Integer32 (Integer32, Counter, Gauge, or TimeTicks) may be sampled.Because SNMP access control is articulated entirely in terms of the contents of MIB views, no access control mechanism exists that can restrict the value of this object to identify only those objects that exist in a particular MIB view.

Because there is thus no acceptable means of restricting the read access that could be obtained through the user history mechanism, the probe must only grant write access to this object in those views that have read access to all objects on the probe.During a set operation, if the supplied variable name is not available in the selected MIB view, a badValue error must be returned.This object may not be modified if the associated usrHistoryControlStatus object is equal to active(1).[2]

For the third table: it is “usrHistoryTable ”, which is the table of data. Each row in the usrHistoryTable represents the value of a single MIB object instance during a specific sampling interval. It is controlled by one line of the table of the second table, which records values and states of every sampling variables and sampling intervals.[1]

Figure 3. Structure of usrHistoryTable

UsrHistoryTable

See Also


  1. Corresponding TELE9752 lecture slide
  2. SNMP packets in Tim's packet zoo
  3. Sharing RMON tables
  4. Control and data tables
  5. Ethernet protocol statistics

ReferencesEdit

  1. Pages for usrHistory group in IBM website
  2. SNMP Object Navigator
  3. Section 9.1.1 of D. Mauro and K. Schmidt: Essential SNMP, O'Reilly
  4. W. Stallings: SNMP, SNMPv2, SNMPv3 and RMON 1 and 2 (over 100 pages on RMON)
  5. Clemm: Network Management Fundamentals, Cisco Press, 2006
  6. Comer: Automated Network Management Systems: Current and Future Capabilities, Pearson, 2007





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