rfc3287.txt

RFC 的详细文档！

    | | Data Src  | | Protocol  | | Net. Host | | App Matrix |  |
    | |   Stats   | |  Stats    | |   Stats   | |    Stats   |  |
    | |           | |           | |           | |            |  |
    | +-----------+ +-----------+ +-----------+ +------------+  |
    |                     |             |             |         |
    |                     V             V             V         |
    |               +-----------+ +-----------+ +------------+  |
    |               |           | |           | |            |  |
    |               | Protocol  | | Net. Host | | App Matrix |  |
    |               |   TopN    | |   TopN    | |    TopN    |  |
    |               |           | |           | |            |  |
    |               +-----------+ +-----------+ +------------+  |
    |                                                           |
    |                     Data Collection                       |
    |                                                           |
    +-----------------------------------------------------------+







Bierman                     Standards Track                     [Page 6]

RFC 3287                       DSMON MIB                      July 2002


   The DSMON MIB can divided into three functional components:

   -  DSMON Capabilities
      Describes which DSMON object groups are supported by the agent on
      at least one data source.

   -  Counter Aggregation Control
      Controls how individual DIFFSERV codepoint counters are aggregated
      in DSMON data collections.

   -  Data Collection
      Controls how individual statistical collections are maintained by
      the agent and reported to management applications.  The individual
      boxes within the Data Collection box represent the DSMON data
      collections (described in section 3.2):

         -  Data Source Statistics
         -  Protocol Statistics
         -  Protocol Statistics TopN Reporting
         -  Network Protocol Host Statistics
         -  Network Protocol Host Statistics TopN Reporting
         -  Application Protocol Matrix Statistics
         -  Application Protocol Matrix Statistics TopN Reporting

3.1.  DSCP Counter Aggregation

   A mechanism to configure the agent to internally aggregate counters
   is provided, based on DSCP values.  This is desirable for several
   reasons:

   -  agent data reduction
      An agent implementation can potentially reduce the number of
      counters maintained for a given DSMON collection.

   -  agent data collection limitations
      Some implementation strategies might provide for a limited number
      of high-speed (e.g., hardware-based) counters for either single or
      aggregated codepoints.

   -  application data retrieval reduction
      Applications that would otherwise aggregate counters for
      individual codepoints can move that function to the agent in order
      to reduce the polling overhead on the application, the network,
      and the agent device.

   -  some unused codepoints at this time
      Various DSCP values may be expected to remain unused on a given
      network, and may be aggregated for counting purposes.



Bierman                     Standards Track                     [Page 7]

RFC 3287                       DSMON MIB                      July 2002


   -  some DSCP values are mapped to the same packet treatment
      A network administrator may align the counter aggregation
      configuration of the monitoring device with the DS configuration,
      and aggregate statistics for DSCP values which are expected to
      receive the same treatment by the forwarding devices.

3.1.1.  Counter Aggregation Configuration

   The configuration of DSCP counter to counter aggregation group
   mappings is managed in a global manner, so that these settings can be
   shared across several DSMON collections and/or data sources.  One
   complete set of DSCP counter mappings is called a counter aggregation
   profile.  The DSMON control tables are very similar to existing
   RMON-2 control tables, except they contain an extra parameter to
   identify the counter aggregation profile the agent should use for the
   collection.

   The appropriate granularity for counter aggregation profile
   assignment may be the data source, but in order to reduce MIB
   complexity (by avoiding an extra layer of tables), an instance of the
   counter aggregation profile parameter exists for each collection.  An
   agent MAY choose to restrict configurations such that all DSMON data
   collections for the same data source must use the same counter
   aggregation profile.

   The DSMON MIB supports the configuration of an arbitrary number of
   counter aggregation profiles.  There is a top-level counter
   aggregation control table, which contains one entry for each counter
   aggregation profile.  A subordinate counter aggregation profile table
   provides information about each DSCP counter to counter aggregation
   group mapping in each profile.  An auxiliary counter aggregation
   group table also provides descriptive information about each counter
   aggregation group in each profile.  Refer to section 3.2.1 for
   details on these MIB objects.

3.2.  MIB Group Overview

   The DSMON MIB contains six groups of MIB objects:

   -  dsmonAggregateControl group
      Controls the configuration of counter aggregation groups for the
      purpose of reducing the total number of counters maintained by the
      agent.

   -  dsmonStatsObjects group
      Report per counter aggregation group distribution statistics for a
      particular RMON dataSource.




Bierman                     Standards Track                     [Page 8]

RFC 3287                       DSMON MIB                      July 2002


   -  dsmonPdistObjects group
      Report per counter aggregation group distribution statistics for
      each application protocol detected on a particular RMON
      dataSource.

   -  dsmonHostObjects group
      Report host address distribution statistics for each counter
      aggregation group, detected on a particular RMON dataSource.

   -  dsmonCapsObjects group
      Report the static DSMON MIB functional capabilities of the agent
      implementation.

   -  dsmonMatrixObjects group
      Report host address pair distribution statistics for each counter
      aggregation group, detected on a particular RMON dataSource.

3.2.1.  DSCP Counter Aggregation Control Group

   This group contains 4 scalar objects and three tables, and is used by
   a management station to configure counter aggregation profiles.

   The dsmonMaxAggGroups scalar is a read-only integer which indicates
   the maximum number of counter aggregation groups that the agent will
   allow to be configured into a single aggregation profile.  This value
   SHOULD be equal to 64 (the number of codepoints), but an agent MAY
   limit the number of counter aggregation groups because of resource
   limitations (e.g., small number of hardware-based counters).  At
   least one counter aggregation profile containing at least two counter
   aggregation groups SHOULD be supported by the agent.  (Note that
   classifying all DSCP counters into the same statistical 'bucket' may
   yield a redundant data collection, which can be achieved more easily
   with an HC-RMON or RMON-2 collection instead.)

   The dsmonAggControlLocked scalar is used as a top level switch,
   controlling most write access to the dsmonAggControlTable,
   dsmonAggProfileTable, and dsmonAggGroupTable.  (The
   dsmonAggControlOwner object is the only exception.)  All active DSMON
   collection data is deleted, and collection suspended, while this
   object is equal to 'false', since the meaning of one or more counter
   aggregation control tables may change when it is set back to 'true'.

   The dsmonAggControlChanges counter and dsmonAggControlLastChangeTime
   timestamp can be used by a management station to detect that the
   codepoint to counter aggregation group mappings may have changed
   between polls.





Bierman                     Standards Track                     [Page 9]

RFC 3287                       DSMON MIB                      July 2002


   The dsmonAggControlTable is a read-create table which contains one
   entry for each counter aggregation profile configured on the agent.
   Each entry is identified by a dsmonAggControlIndex value, which is
   also used as the major index into the dsmonAggProfileTable and
   dsmonAggGroupTable.  The DSMON control tables with DataSource objects
   select a counter aggregation profile by referencing this index value.

   The dsmonAggProfileTable is a read-write table which contains 64 rows
   for each associated entry in the dsmonAggControlTable, which MUST be
   indexed from 0 to 63.  The agent creates this set of 64 instances
   when the associated dsmonAggControlEntry is activated, and deletes
   them when that dsmonAggControlEntry is deactivated.  Each of the 64
   rows represents a conceptual DSCP counter, identified by the same
   dsmonAggProfileDSCP value, and contains the DSCP counter to counter
   aggregation group mapping for that DSCP counter, in the indicated
   profile.  The agent SHOULD use the value zero as the initial counter
   aggregation group assignment for each entry in this table.

   The dsmonAggGroupTable contains an administratively assigned
   descriptive label for each configured counter aggregation group.
   This table is not required to be fully configured in order for data
   collection to occur, since collections are identified by the agent
   with integer indices.  It is provided to allow the agent to store a
   descriptive string for each configured counter aggregation group.
   There is no attempt made to convey any real semantics for each
   counter aggregation group.  A management station MAY choose not to
   configure entries in this table.

3.2.2.  DS Statistics Group

   This group contains two tables, the dsmonStatsControlTable and the
   dsmonStatsTable, and supports counter aggregation group distribution
   statistics for half and full-duplex, low and high speed interfaces.
   Packet and octets distributions are maintained in the dsmonStatsTable
   for each active control row in the dsmonStatsControlTable.

   This group provides the lowest statistics granularity in the DSMON
   MIB.  It is expected that a management application will analyze
   certain DS deployment or performance problems by first examining the
   counter aggregation group distribution for an entire data source with
   this group.

3.2.3.  DS Protocol Distribution Group

   This group contains two tables for statistics collection,
   (dsmonPdistCtlTable and dsmonPdistStatsTable), and two tables for a
   'Top N' reporting function for the collected statistics
   (dsmonPdistTopNCtlTable and dsmonPdistTopNTable).



Bierman                     Standards Track                    [Page 10]

RFC 3287                       DSMON MIB                      July 2002


   The dsmonPdistCtlTable and dsmonPdistStatsTable tables provide
   counter aggregation group distribution statistics for each selected
   protocol encapsulation in packets monitored on a particular
   dataSource.  Packet and octets distributions (per counter aggregation
   group per protocol) are maintained in the dsmonPdistStatsTable for
   each active control row in the dsmonPdistCtlTable.

   Due to the potentially large number of entries, the DS Protocol
   Distribution is different from the RMON-2 protocol distribution group
   in several ways:

   -  maximum desired entries parameter added to the control table

   -  inserts and deletes counters added to the control table

   -  support for LRU garbage collection in the dsmonPdistStatsTable

   -  TimeFilter index added to the dsmonPdistStatsTable

   -  the selection of protocols is not configurable.  Rather than
      select individual protocols to monitor, (e.g., via a
      'supportedOn/Off' extension to the protocolDirTable [RFC 2021]), a
      simplified configuration mechanism is provided.  Since DSCP usage
      statistics are most interesting at the application layer, the
      dsmonPdistStatsTable is 'hardwired' to select only application
      layer (i.e., 'terminal') protocols for statistical analysis.

   The TopN feature requires two additional tables: the
   dsmonPdistTopNCtlTable and the dsmonPdistTopNTable, and supports
   periodic usage reporting for the statistics maintained in the
   dsmonPdistStatsTable.  This feature allows for simple periodic
   retrieval of the most used application/counter aggregation group
   combinations.

3.2.4.  DS Host Distribution Group

   This group contains two tables for statistics collection,
   (dsmonHostCtlTable and dsmonHostTable), and two tables for a 'Top N'
   reporting function for the collected statistics
   (dsmonHostTopNCtlTable and dsmonHostTopNTable).

   The dsmonHostCtlTable and dsmonHostTables provide host distribution
   statistics for each counter aggregation group detected in packets
   monitored on a particular dataSource.  The DSMON Host collection is
   similar to the RMON-2 network layer host collection (nlHostTable).
   There is no DSMON application host table defined at this time.





Bierman                     Standards Track                    [Page 11]

RFC 3287                       DSMON MIB                      July 2002


   It is expected that a management application will analyze certain DS
   deployment or performance problems by first determining the high
   priority DSCP values to examine (beyond the scope of this document)
   and then examining the dsmonHostTable or dsmonHostTopNTable
   statistics to determine which hosts are using the selected counter
   aggregation groups.