rfc2819.txt

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   an ethernet network and stores them for later retrieval.  This group
   consists of the etherHistoryTable.






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RFC 2819             Remote Network Monitoring MIB              May 2000


2.3.4.  The Alarm Group

   The alarm group periodically takes statistical samples from variables
   in the probe and compares them to previously configured thresholds.
   If the monitored variable crosses a threshold, an event is generated.

   A hysteresis mechanism is implemented to limit the generation of
   alarms.  This group consists of the alarmTable and requires the
   implementation of the event group.

2.3.5.  The Host Group

   The host group contains statistics associated with each host
   discovered on the network.  This group discovers hosts on the network
   by keeping a list of source and destination MAC Addresses seen in
   good packets promiscuously received from the network.  This group
   consists of the hostControlTable, the hostTable, and the
   hostTimeTable.

2.3.6.  The HostTopN Group

   The hostTopN group is used to prepare reports that describe the hosts
   that top a list ordered by one of their statistics.  The available
   statistics are samples of one of their base statistics over an
   interval specified by the management station.  Thus, these statistics
   are rate based.  The management station also selects how many such
   hosts are reported.  This group consists of the hostTopNControlTable
   and the hostTopNTable, and requires the implementation of the host
   group.

2.3.7.  The Matrix Group

   The matrix group stores statistics for conversations between sets of
   two addresses.  As the device detects a new conversation, it creates
   a new entry in its tables.  This group consists of the
   matrixControlTable, the matrixSDTable and the matrixDSTable.

2.3.8.  The Filter Group

   The filter group allows packets to be matched by a filter equation.
   These matched packets form a data stream that may be captured or may
   generate events.  This group consists of the filterTable and the
   channelTable.








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RFC 2819             Remote Network Monitoring MIB              May 2000


2.3.9.  The Packet Capture Group

   The Packet Capture group allows packets to be captured after they
   flow through a channel.  This group consists of the
   bufferControlTable and the captureBufferTable, and requires the
   implementation of the filter group.

2.3.10.  The Event Group

   The event group controls the generation and notification of events
   from this device.  This group consists of the eventTable and the
   logTable.

3.  Control of Remote Network Monitoring Devices

   Due to the complex nature of the available functions in these
   devices, the functions often need user configuration.  In many cases,
   the function requires parameters to be set up for a data collection
   operation.  The operation can proceed only after these parameters are
   fully set up.

   Many functional groups in this MIB have one or more tables in which
   to set up control parameters, and one or more data tables in which to
   place the results of the operation.  The control tables are typically
   read-write in nature, while the data tables are typically read-only.
   Because the parameters in the control table often describe resulting
   data in the data table, many of the parameters can be modified only
   when the control entry is invalid.  Thus, the method for modifying
   these parameters is to invalidate the control entry, causing its
   deletion and the deletion of any associated data entries, and then
   create a new control entry with the proper parameters.  Deleting the
   control entry also gives a convenient method for reclaiming the
   resources used by the associated data.

   Some objects in this MIB provide a mechanism to execute an action on
   the remote monitoring device.  These objects may execute an action as
   a result of a change in the state of the object.  For those objects
   in this MIB, a request to set an object to the same value as it
   currently holds would thus cause no action to occur.

   To facilitate control by multiple managers, resources have to be
   shared among the managers.  These resources are typically the memory
   and computation resources that a function requires.








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RFC 2819             Remote Network Monitoring MIB              May 2000


3.1.  Resource Sharing Among Multiple Management Stations

   When multiple management stations wish to use functions that compete
   for a finite amount of resources on a device, a method to facilitate
   this sharing of resources is required.  Potential conflicts include:

      o  Two management stations wish to simultaneously use resources
         that together would exceed the capability of the device.
      o  A management station uses a significant amount of resources for
         a long period of time.
      o  A management station uses resources and then crashes,
         forgetting to free the resources so others may use them.

   A mechanism is provided for each management station initiated
   function in this MIB to avoid these conflicts and to help resolve
   them when they occur.  Each function has a label identifying the
   initiator (owner) of the function.  This label is set by the
   initiator to provide for the following possibilities:

      o  A management station may recognize resources it owns and no
         longer needs.
      o  A network operator can find the management station that owns
         the resource and negotiate for it to be freed.
      o  A network operator may decide to unilaterally free resources
         another network operator has reserved.
      o  Upon initialization, a management station may recognize
         resources it had reserved in the past.  With this information
         it may free the resources if it no longer needs them.

   Management stations and probes should support any format of the owner
   string dictated by the local policy of the organization.  It is
   suggested that this name contain one or more of the following: IP
   address, management station name, network manager's name, location,
   or phone number.  This information will help users to share the
   resources more effectively.

   There is often default functionality that the device or the
   administrator of the probe (often the network administrator) wishes
   to set up.  The resources associated with this functionality are then
   owned by the device itself or by the network administrator, and are
   intended to be long-lived.  In this case, the device or the
   administrator will set the relevant owner object to a string starting
   with 'monitor'.  Indiscriminate modification of the monitor-owned
   configuration by network management stations is discouraged.  In
   fact, a network management station should only modify these objects
   under the direction of the administrator of the probe.





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RFC 2819             Remote Network Monitoring MIB              May 2000


   Resources on a probe are scarce and are typically allocated when
   control rows are created by an application.  Since many applications
   may be using a probe simultaneously, indiscriminate allocation of
   resources to particular applications is very likely to cause resource
   shortages in the probe.

   When a network management station wishes to utilize a function in a
   monitor, it is encouraged to first scan the control table of that
   function to find an instance with similar parameters to share.  This
   is especially true for those instances owned by the monitor, which
   can be assumed to change infrequently.  If a management station
   decides to share an instance owned by another management station, it
   should understand that the management station that owns the instance
   may indiscriminately modify or delete it.

   It should be noted that a management application should have the most
   trust in a monitor-owned row because it should be changed very
   infrequently.  A row owned by the management application is less
   long-lived because a network administrator is more likely to re-
   assign resources from a row that is in use by one user than from a
   monitor-owned row that is potentially in use by many users.  A row
   owned by another application would be even less long-lived because
   the other application may delete or modify that row completely at its
   discretion.

3.2.  Row Addition Among Multiple Management Stations

   The addition of new rows is achieved using the method described in
   RFC 1905 [13].  In this MIB, rows are often added to a table in order
   to configure a function.  This configuration usually involves
   parameters that control the operation of the function.  The agent
   must check these parameters to make sure they are appropriate given
   restrictions defined in this MIB as well as any implementation
   specific restrictions such as lack of resources.  The agent
   implementor may be confused as to when to check these parameters and
   when to signal to the management station that the parameters are
   invalid.  There are two opportunities:

      o  When the management station sets each parameter object.

      o  When the management station sets the entry status object to
         valid.

   If the latter is chosen, it would be unclear to the management
   station which of the several parameters was invalid and caused the
   badValue error to be emitted.  Thus, wherever possible, the
   implementor should choose the former as it will provide more
   information to the management station.



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RFC 2819             Remote Network Monitoring MIB              May 2000


   A problem can arise when multiple management stations attempt to set
   configuration information simultaneously using SNMP.  When this
   involves the addition of a new conceptual row in the same control
   table, the managers may collide, attempting to create the same entry.
   To guard against these collisions, each such control entry contains a
   status object with special semantics that help to arbitrate among the
   managers.  If an attempt is made with the row addition mechanism to
   create such a status object and that object already exists, an error
   is returned.  When more than one manager simultaneously attempts to
   create the same conceptual row, only the first can succeed.  The
   others will receive an error.

   When a manager wishes to create a new control entry, it needs to
   choose an index for that row.  It may choose this index in a variety
   of ways, hopefully minimizing the chances that the index is in use by
   another manager.  If the index is in use, the mechanism mentioned
   previously will guard against collisions.  Examples of schemes to
   choose index values include random selection or scanning the control
   table looking for the first unused index.  Because index values may
   be any valid value in the range and they are chosen by the manager,
   the agent must allow a row to be created with any unused index value
   if it has the resources to create a new row.

   Some tables in this MIB reference other tables within this MIB.  When
   creating or deleting entries in these tables, it is generally
   allowable for dangling references to exist.  There is no defined
   order for creating or deleting entries in these tables.

4.  Conventions

   The following conventions are used throughout the RMON MIB and its
   companion documents.

   Good Packets

   Good packets are error-free packets that have a valid frame length.
   For example, on Ethernet, good packets are error-free packets that
   are between 64 octets long and 1518 octets long.  They follow the
   form defined in IEEE 802.3 section 3.2.all.

   Bad Packets

   Bad packets are packets that have proper framing and are therefore
   recognized as packets, but contain errors within the packet or have
   an invalid length.  For example, on Ethernet, bad packets have a
   valid preamble and SFD, but have a bad CRC, or are either shorter
   than 64 octets or longer than 1518 octets.




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RFC 2819             Remote Network Monitoring MIB              May 2000


5.  Definitions

 RMON-MIB DEFINITIONS ::= BEGIN

     IMPORTS
         MODULE-IDENTITY, OBJECT-TYPE, OBJECT-IDENTITY,
         NOTIFICATION-TYPE, mib-2, Counter32,
         Integer32, TimeTicks                   FROM SNMPv2-SMI

         TEXTUAL-CONVENTION, DisplayString      FROM SNMPv2-TC

         MODULE-COMPLIANCE, OBJECT-GROUP,
         NOTIFICATION-GROUP                     FROM SNMPv2-CONF;


 --  Remote Network Monitoring MIB

 rmonMibModule MODULE-IDENTITY
     LAST-UPDATED "200005110000Z"  -- 11 May, 2000
     ORGANIZATION "IETF RMON MIB Working Group"
     CONTACT-INFO
         "Steve Waldbusser
         Phone: [phone]
         Fax:   [phone]
         Email: [e-mail]"
     DESCRIPTION
         "Remote network monitoring devices, often called
         monitors or probes, are instruments that exist for
         the purpose of managing a network. This MIB defines
         objects for managing remote network monitoring devices."

     REVISION "200005110000Z"    -- 11 May, 2000
     DESCRIPTION
         "Reformatted into SMIv2 format.

         This version published as RFC 2819."