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RFC 1757

 
 
 

Remote Network Monitoring Management Information Base

Part 4 of 4, p. 62 to 91
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          -- The Filter Group

          -- Implementation of the Filter group is optional.
          --
          -- The Filter group allows packets to be captured with an
          -- arbitrary filter expression.  A logical data and
          -- event stream or "channel" is formed by the packets
          -- that match the filter expression.
          --
          -- This filter mechanism allows the creation of an arbitrary
          -- logical expression with which to filter packets.  Each
          -- filter associated with a channel is OR'ed with the others.
          -- Within a filter, any bits checked in the data and status
          -- are AND'ed with respect to other bits in the same filter.
          -- The NotMask also allows for checking for inequality.
          -- Finally, the channelAcceptType object allows for
          -- inversion of the whole equation.
          --
          -- If a management station wishes to receive a trap to alert
          -- it that new packets have been captured and are available
          -- for download, it is recommended that it set up an alarm
          -- entry that monitors the value of the relevant
          -- channelMatches instance.
          --
          -- The channel can be turned on or off, and can also
          -- generate events when packets pass through it.

          filterTable OBJECT-TYPE
              SYNTAX SEQUENCE OF FilterEntry
              ACCESS not-accessible
              STATUS mandatory
              DESCRIPTION
                  "A list of packet filter entries."
              ::= { filter 1 }

          filterEntry OBJECT-TYPE
              SYNTAX FilterEntry
              ACCESS not-accessible
              STATUS mandatory
              DESCRIPTION
                  "A set of parameters for a packet filter applied on a
                  particular interface.  As an example, an instance of
                  the filterPktData object might be named
                  filterPktData.12"
              INDEX { filterIndex }
              ::= { filterTable 1 }

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          FilterEntry ::= SEQUENCE {
              filterIndex                 INTEGER (1..65535),
              filterChannelIndex          INTEGER (1..65535),
              filterPktDataOffset         INTEGER,
              filterPktData               OCTET STRING,
              filterPktDataMask           OCTET STRING,
              filterPktDataNotMask        OCTET STRING,
              filterPktStatus             INTEGER,
              filterPktStatusMask         INTEGER,
              filterPktStatusNotMask      INTEGER,
              filterOwner                 OwnerString,
              filterStatus                EntryStatus
          }

          filterIndex OBJECT-TYPE
              SYNTAX INTEGER (1..65535)
              ACCESS read-only
              STATUS mandatory
              DESCRIPTION
                  "An index that uniquely identifies an entry
                  in the filter table.  Each such entry defines
                  one filter that is to be applied to every packet
                  received on an interface."
              ::= { filterEntry 1 }

          filterChannelIndex OBJECT-TYPE
              SYNTAX INTEGER (1..65535)
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "This object identifies the channel of which this
                  filter is a part.  The filters identified by a
                  particular value of this object are associated with
                  the same channel as identified by the same value of
                  the channelIndex object."
              ::= { filterEntry 2 }

          filterPktDataOffset OBJECT-TYPE
              SYNTAX INTEGER
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "The offset from the beginning of each packet where
                  a match of packet data will be attempted.  This offset
                  is measured from the point in the physical layer
                  packet after the framing bits, if any.  For example,
                  in an Ethernet frame, this point is at the beginning
                  of the destination MAC address.

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                  This object may not be modified if the associated
                  filterStatus object is equal to valid(1)."
              DEFVAL { 0 }
              ::= { filterEntry 3 }

          filterPktData OBJECT-TYPE
              SYNTAX OCTET STRING
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "The data that is to be matched with the input
                  packet.  For each packet received, this filter and
                  the accompanying filterPktDataMask and
                  filterPktDataNotMask will be adjusted for the
                  offset.  The only bits relevant to this match
                  algorithm are those that have the corresponding
                  filterPktDataMask bit equal to one.  The following
                  three rules are then applied to every packet:

                  (1) If the packet is too short and does not have data
                      corresponding to part of the filterPktData, the
                      packet will fail this data match.

                  (2) For each relevant bit from the packet with the
                      corresponding filterPktDataNotMask bit set to
                      zero, if the bit from the packet is not equal to
                      the corresponding bit from the filterPktData,
                      then the packet will fail this data match.

                  (3) If for every relevant bit from the packet with the
                      corresponding filterPktDataNotMask bit set to one,
                      the bit from the packet is equal to the
                      corresponding bit from the filterPktData, then
                      the packet will fail this data match.

                  Any packets that have not failed any of the three
                  matches above have passed this data match.  In
                  particular, a zero length filter will match any
                  packet.

                  This object may not be modified if the associated
                  filterStatus object is equal to valid(1)."
              ::= { filterEntry 4 }

          filterPktDataMask OBJECT-TYPE
              SYNTAX OCTET STRING
              ACCESS read-write
              STATUS mandatory

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              DESCRIPTION
                  "The mask that is applied to the match process.
                  After adjusting this mask for the offset, only those
                  bits in the received packet that correspond to bits
                  set in this mask are relevant for further processing
                  by the match algorithm.  The offset is applied to
                  filterPktDataMask in the same way it is applied to the
                  filter.  For the purposes of the matching algorithm,
                  if the associated filterPktData object is longer
                  than this mask, this mask is conceptually extended
                  with '1' bits until it reaches the length of the
                  filterPktData object.

                  This object may not be modified if the associated
                  filterStatus object is equal to valid(1)."
              ::= { filterEntry 5 }

          filterPktDataNotMask OBJECT-TYPE
              SYNTAX OCTET STRING
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "The inversion mask that is applied to the match
                  process.  After adjusting this mask for the offset,
                  those relevant bits in the received packet that
                  correspond to bits cleared in this mask must all be
                  equal to their corresponding bits in the
                  filterPktData object for the packet to be accepted.
                  In addition, at least one of those relevant bits in
                  the received packet that correspond to bits set in
                  this mask must be different to its corresponding bit
                  in the filterPktData object.

                  For the purposes of the matching algorithm, if the
                  associated filterPktData object is longer than this
                  mask, this mask is conceptually extended with '0'
                  bits until it reaches the length of the
                  filterPktData object.

                  This object may not be modified if the associated
                  filterStatus object is equal to valid(1)."
              ::= { filterEntry 6 }

          filterPktStatus OBJECT-TYPE
              SYNTAX INTEGER
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION

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                  "The status that is to be matched with the input
                  packet.  The only bits relevant to this match
                  algorithm are those that have the corresponding
                  filterPktStatusMask bit equal to one.  The following
                  two rules are then applied to every packet:

                  (1) For each relevant bit from the packet status
                      with the corresponding filterPktStatusNotMask bit
                      set to zero, if the bit from the packet status is
                      not equal to the corresponding bit from the
                      filterPktStatus, then the packet will fail this
                      status match.

                  (2) If for every relevant bit from the packet status
                      with the corresponding filterPktStatusNotMask bit
                      set to one, the bit from the packet status is
                      equal to the corresponding bit from the
                      filterPktStatus, then the packet will fail this
                      status match.

                  Any packets that have not failed either of the two
                  matches above have passed this status match.  In
                  particular, a zero length status filter will match any
                  packet's status.

                  The value of the packet status is a sum.  This sum
                  initially takes the value zero.  Then, for each
                  error, E, that has been discovered in this packet,
                  2 raised to a value representing E is added to the
                  sum. The errors and the bits that represent them are
                  dependent on the media type of the interface that
                  this channel is receiving packets from.

                  The errors defined for a packet captured off of an
                  Ethernet interface are as follows:

                      bit #    Error
                          0    Packet is longer than 1518 octets
                          1    Packet is shorter than 64 octets
                          2    Packet experienced a CRC or Alignment
                               error

                  For example, an Ethernet fragment would have a
                  value of 6 (2^1 + 2^2).

                  As this MIB is expanded to new media types, this
                  object will have other media-specific errors
                  defined.

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                  For the purposes of this status matching algorithm,
                  if the packet status is longer than this
                  filterPktStatus object, this object is conceptually
                  extended with '0' bits until it reaches the size of
                  the packet status.

                  This object may not be modified if the associated
                  filterStatus object is equal to valid(1)."
              ::= { filterEntry 7 }

          filterPktStatusMask OBJECT-TYPE
              SYNTAX INTEGER
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "The mask that is applied to the status match
                  process.  Only those bits in the received packet
                  that correspond to bits set in this mask are
                  relevant for further processing by the status match
                  algorithm.  For the purposes of the matching
                  algorithm, if the associated filterPktStatus object
                  is longer than this mask, this mask is conceptually
                  extended with '1' bits until it reaches the size of
                  the filterPktStatus.  In addition, if a packet
                  status is longer than this mask, this mask is
                  conceptually extended with '0' bits until it reaches
                  the size of the packet status.

                  This object may not be modified if the associated
                  filterStatus object is equal to valid(1)."
              ::= { filterEntry 8 }

          filterPktStatusNotMask OBJECT-TYPE
              SYNTAX INTEGER
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "The inversion mask that is applied to the status
                  match process.  Those relevant bits in the received
                  packet status that correspond to bits cleared in
                  this mask must all be equal to their corresponding
                  bits in the filterPktStatus object for the packet to
                  be accepted.  In addition, at least one of those
                  relevant bits in the received packet status that
                  correspond to bits set in this mask must be
                  different to its corresponding bit in the
                  filterPktStatus object for the packet to be
                  accepted.

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                  For the purposes of the matching algorithm, if the
                  associated filterPktStatus object or a packet status
                  is longer than this mask, this mask is conceptually
                  extended with '0' bits until it reaches the longer
                  of the lengths of the filterPktStatus object and the
                  packet status.

                  This object may not be modified if the associated
                  filterStatus object is equal to valid(1)."
              ::= { filterEntry 9 }

          filterOwner OBJECT-TYPE
              SYNTAX OwnerString
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "The entity that configured this entry and is
                  therefore using the resources assigned to it."
              ::= { filterEntry 10 }

          filterStatus OBJECT-TYPE
              SYNTAX EntryStatus
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "The status of this filter entry."
              ::= { filterEntry 11 }

          channelTable OBJECT-TYPE
              SYNTAX SEQUENCE OF ChannelEntry
              ACCESS not-accessible
              STATUS mandatory
              DESCRIPTION
                  "A list of packet channel entries."
              ::= { filter 2 }

          channelEntry OBJECT-TYPE
              SYNTAX ChannelEntry
              ACCESS not-accessible
              STATUS mandatory
              DESCRIPTION
                  "A set of parameters for a packet channel applied on a
                  particular interface.  As an example, an instance of
                  the channelMatches object might be named
                  channelMatches.3"
              INDEX { channelIndex }
              ::= { channelTable 1 }

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          ChannelEntry ::= SEQUENCE {
              channelIndex               INTEGER (1..65535),
              channelIfIndex             INTEGER (1..65535),
              channelAcceptType          INTEGER,
              channelDataControl         INTEGER,
              channelTurnOnEventIndex    INTEGER (0..65535),
              channelTurnOffEventIndex   INTEGER (0..65535),
              channelEventIndex          INTEGER (0..65535),
              channelEventStatus         INTEGER,
              channelMatches             Counter,
              channelDescription         DisplayString (SIZE (0..127)),
              channelOwner               OwnerString,
              channelStatus              EntryStatus
          }

          channelIndex OBJECT-TYPE
              SYNTAX INTEGER (1..65535)
              ACCESS read-only
              STATUS mandatory
              DESCRIPTION
                  "An index that uniquely identifies an entry in the
                  channel table.  Each such entry defines one channel,
                  a logical data and event stream.

                  It is suggested that before creating a channel, an
                  application should scan all instances of the
                  filterChannelIndex object to make sure that there
                  are no pre-existing filters that would be
                  inadvertently be linked to the channel."
              ::= { channelEntry 1 }

          channelIfIndex OBJECT-TYPE
              SYNTAX INTEGER (1..65535)
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "The value of this object uniquely identifies the
                  interface on this remote network monitoring device
                  to which the associated filters are applied to allow
                  data into this channel.  The interface identified by
                  a particular value of this object is the same
                  interface as identified by the same value of the
                  ifIndex object, defined in RFC 1213 and RFC 1573
                  [4,6].

                  The filters in this group are applied to all packets
                  on the local network segment attached to the
                  identified interface.

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                  An agent may or may not be able to tell if
                  fundamental changes to the media of the interface
                  have occurred and necessitate an invalidation of
                  this entry.  For example, a hot-pluggable ethernet
                  card could be pulled out and replaced by a
                  token-ring card.  In such a case, if the agent has
                  such knowledge of the change, it is recommended that
                  it invalidate this entry.

                  This object may not be modified if the associated
                  channelStatus object is equal to valid(1)."
              ::= { channelEntry 2 }

          channelAcceptType OBJECT-TYPE
              SYNTAX INTEGER {
                  acceptMatched(1),
                  acceptFailed(2)
              }
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "This object controls the action of the filters
                  associated with this channel.  If this object is equal
                  to acceptMatched(1), packets will be accepted to this
                  channel if they are accepted by both the packet data
                  and packet status matches of an associated filter.  If
                  this object is equal to acceptFailed(2), packets will
                  be accepted to this channel only if they fail either
                  the packet data match or the packet status match of
                  each of the associated filters.

                  In particular, a channel with no associated filters
                  will match no packets if set to acceptMatched(1)
                  case and will match all packets in the
                  acceptFailed(2) case.

                  This object may not be modified if the associated
                  channelStatus object is equal to valid(1)."
              ::= { channelEntry 3 }

          channelDataControl OBJECT-TYPE
              SYNTAX INTEGER {
                  on(1),
                  off(2)
              }
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION

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                  "This object controls the flow of data through this
                  channel.  If this object is on(1), data, status and
                  events flow through this channel.  If this object is
                  off(2), data, status and events will not flow
                  through this channel."
              DEFVAL { off }
              ::= { channelEntry 4 }

          channelTurnOnEventIndex OBJECT-TYPE
              SYNTAX INTEGER (0..65535)
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "The value of this object identifies the event
                  that is configured to turn the associated
                  channelDataControl from off to on when the event is
                  generated.  The event identified by a particular value
                  of this object is the same event as identified by the
                  same value of the eventIndex object.  If there is no
                  corresponding entry in the eventTable, then no
                  association exists.  In fact, if no event is intended
                  for this channel, channelTurnOnEventIndex must be
                  set to zero, a non-existent event index.

                  This object may not be modified if the associated
                  channelStatus object is equal to valid(1)."
              ::= { channelEntry 5 }

          channelTurnOffEventIndex OBJECT-TYPE
              SYNTAX INTEGER (0..65535)
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "The value of this object identifies the event
                  that is configured to turn the associated
                  channelDataControl from on to off when the event is
                  generated.  The event identified by a particular value
                  of this object is the same event as identified by the
                  same value of the eventIndex object.  If there is no
                  corresponding entry in the eventTable, then no
                  association exists.  In fact, if no event is intended
                  for this channel, channelTurnOffEventIndex must be
                  set to zero, a non-existent event index.

                  This object may not be modified if the associated
                  channelStatus object is equal to valid(1)."
              ::= { channelEntry 6 }

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          channelEventIndex OBJECT-TYPE
              SYNTAX INTEGER (0..65535)
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "The value of this object identifies the event
                  that is configured to be generated when the
                  associated channelDataControl is on and a packet
                  is matched.  The event identified by a particular
                  value of this object is the same event as identified
                  by the same value of the eventIndex object.  If
                  there is no corresponding entry in the eventTable,
                  then no association exists.  In fact, if no event is
                  intended for this channel, channelEventIndex must be
                  set to zero, a non-existent event index.

                  This object may not be modified if the associated
                  channelStatus object is equal to valid(1)."
              ::= { channelEntry 7 }

          channelEventStatus OBJECT-TYPE
              SYNTAX INTEGER {
                  eventReady(1),
                  eventFired(2),
                  eventAlwaysReady(3)
              }
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "The event status of this channel.

                  If this channel is configured to generate events
                  when packets are matched, a means of controlling
                  the flow of those events is often needed.  When
                  this object is equal to eventReady(1), a single
                  event may be generated, after which this object
                  will be set by the probe to eventFired(2).  While
                  in the eventFired(2) state, no events will be
                  generated until the object is modified to
                  eventReady(1) (or eventAlwaysReady(3)).  The
                  management station can thus easily respond to a
                  notification of an event by re-enabling this object.

                  If the management station wishes to disable this
                  flow control and allow events to be generated
                  at will, this object may be set to
                  eventAlwaysReady(3).  Disabling the flow control
                  is discouraged as it can result in high network

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                  traffic or other performance problems."
              DEFVAL { eventReady }
              ::= { channelEntry 8 }

          channelMatches OBJECT-TYPE
              SYNTAX Counter
              ACCESS read-only
              STATUS mandatory
              DESCRIPTION
                  "The number of times this channel has matched a
                  packet. Note that this object is updated even when
                  channelDataControl is set to off."
              ::= { channelEntry 9 }

          channelDescription OBJECT-TYPE
              SYNTAX DisplayString (SIZE (0..127))
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "A comment describing this channel."
              ::= { channelEntry 10 }

          channelOwner OBJECT-TYPE
              SYNTAX OwnerString
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "The entity that configured this entry and is
                  therefore using the resources assigned to it."
              ::= { channelEntry 11 }

          channelStatus OBJECT-TYPE
              SYNTAX EntryStatus
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "The status of this channel entry."
              ::= { channelEntry 12 }


          -- The Packet Capture Group

          -- Implementation of the Packet Capture group is optional.
          --
          -- The Packet Capture Group requires implementation of the
          -- Filter Group.
          --
          -- The Packet Capture group allows packets to be captured

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          -- upon a filter match.  The bufferControlTable controls
          -- the captured packets output from a channel that is
          -- associated with it.  The captured packets are placed
          -- in entries in the captureBufferTable.  These entries are
          -- associated with the bufferControlEntry on whose behalf they
          -- were stored.

          bufferControlTable OBJECT-TYPE
              SYNTAX SEQUENCE OF BufferControlEntry
              ACCESS not-accessible
              STATUS mandatory
              DESCRIPTION
                  "A list of buffers control entries."
              ::= { capture 1 }

          bufferControlEntry OBJECT-TYPE
              SYNTAX BufferControlEntry
              ACCESS not-accessible
              STATUS mandatory
              DESCRIPTION
                  "A set of parameters that control the collection of
                  a stream of packets that have matched filters.  As
                  an example, an instance of the
                  bufferControlCaptureSliceSize object might be named
                  bufferControlCaptureSliceSize.3"
              INDEX { bufferControlIndex }
              ::= { bufferControlTable 1 }

          BufferControlEntry ::= SEQUENCE {
              bufferControlIndex                INTEGER (1..65535),
              bufferControlChannelIndex         INTEGER (1..65535),
              bufferControlFullStatus           INTEGER,
              bufferControlFullAction           INTEGER,
              bufferControlCaptureSliceSize     INTEGER,
              bufferControlDownloadSliceSize    INTEGER,
              bufferControlDownloadOffset       INTEGER,
              bufferControlMaxOctetsRequested   INTEGER,
              bufferControlMaxOctetsGranted     INTEGER,
              bufferControlCapturedPackets      INTEGER,
              bufferControlTurnOnTime           TimeTicks,
              bufferControlOwner                OwnerString,
              bufferControlStatus               EntryStatus
          }

          bufferControlIndex OBJECT-TYPE
              SYNTAX INTEGER (1..65535)
              ACCESS read-only
              STATUS mandatory

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              DESCRIPTION
                  "An index that uniquely identifies an entry
                  in the bufferControl table.  The value of this
                  index shall never be zero.  Each such
                  entry defines one set of packets that is
                  captured and controlled by one or more filters."
              ::= { bufferControlEntry 1 }

          bufferControlChannelIndex OBJECT-TYPE
              SYNTAX INTEGER (1..65535)
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "An index that identifies the channel that is the
                  source of packets for this bufferControl table.
                  The channel identified by a particular value of this
                  index is the same as identified by the same value of
                  the channelIndex object.

                  This object may not be modified if the associated
                  bufferControlStatus object is equal to valid(1)."
              ::= { bufferControlEntry 2 }

          bufferControlFullStatus OBJECT-TYPE
              SYNTAX INTEGER {
                      spaceAvailable(1),
                      full(2)
              }
              ACCESS read-only
              STATUS mandatory
              DESCRIPTION
                  "This object shows whether the buffer has room to
                  accept new packets or if it is full.

                  If the status is spaceAvailable(1), the buffer is
                  accepting new packets normally.  If the status is
                  full(2) and the associated bufferControlFullAction
                  object is wrapWhenFull, the buffer is accepting new
                  packets by deleting enough of the oldest packets
                  to make room for new ones as they arrive.  Otherwise,
                  if the status is full(2) and the
                  bufferControlFullAction object is lockWhenFull,
                  then the buffer has stopped collecting packets.

                  When this object is set to full(2) the probe must
                  not later set it to spaceAvailable(1) except in the
                  case of a significant gain in resources such as
                  an increase of bufferControlOctetsGranted.  In

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                  particular, the wrap-mode action of deleting old
                  packets to make room for newly arrived packets
                  must not affect the value of this object."
              ::= { bufferControlEntry 3 }

          bufferControlFullAction OBJECT-TYPE
              SYNTAX INTEGER {
                      lockWhenFull(1),
                      wrapWhenFull(2)    -- FIFO
              }
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "Controls the action of the buffer when it
                  reaches the full status.  When in the lockWhenFull(1)
                  state and a packet is added to the buffer that
                  fills the buffer, the bufferControlFullStatus will
                  be set to full(2) and this buffer will stop capturing
                  packets."
              ::= { bufferControlEntry 4 }

          bufferControlCaptureSliceSize OBJECT-TYPE
              SYNTAX INTEGER
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "The maximum number of octets of each packet
                  that will be saved in this capture buffer.
                  For example, if a 1500 octet packet is received by
                  the probe and this object is set to 500, then only
                  500 octets of the packet will be stored in the
                  associated capture buffer.  If this variable is set
                  to 0, the capture buffer will save as many octets
                  as is possible.

                  This object may not be modified if the associated
                  bufferControlStatus object is equal to valid(1)."
              DEFVAL { 100 }
              ::= { bufferControlEntry 5 }

          bufferControlDownloadSliceSize OBJECT-TYPE
              SYNTAX INTEGER
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "The maximum number of octets of each packet
                  in this capture buffer that will be returned in
                  an SNMP retrieval of that packet.  For example,

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                  if 500 octets of a packet have been stored in the
                  associated capture buffer, the associated
                  bufferControlDownloadOffset is 0, and this
                  object is set to 100, then the captureBufferPacket
                  object that contains the packet will contain only
                  the first 100 octets of the packet.

                  A prudent manager will take into account possible
                  interoperability or fragmentation problems that may
                  occur if the download slice size is set too large.
                  In particular, conformant SNMP implementations are not
                  required to accept messages whose length exceeds 484
                  octets, although they are encouraged to support larger
                  datagrams whenever feasible."
              DEFVAL { 100 }
              ::= { bufferControlEntry 6 }

          bufferControlDownloadOffset OBJECT-TYPE
              SYNTAX INTEGER
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "The offset of the first octet of each packet
                  in this capture buffer that will be returned in
                  an SNMP retrieval of that packet.  For example,
                  if 500 octets of a packet have been stored in the
                  associated capture buffer and this object is set to
                  100, then the captureBufferPacket object that
                  contains the packet will contain bytes starting
                  100 octets into the packet."
              DEFVAL { 0 }
              ::= { bufferControlEntry 7 }

          bufferControlMaxOctetsRequested OBJECT-TYPE
              SYNTAX INTEGER
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "The requested maximum number of octets to be
                  saved in this captureBuffer, including any
                  implementation-specific overhead. If this variable
                  is set to -1, the capture buffer will save as many
                  octets as is possible.

                  When this object is created or modified, the probe
                  should set bufferControlMaxOctetsGranted as closely
                  to this object as is possible for the particular probe
                  implementation and available resources.  However, if

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                  the object has the special value of -1, the probe
                  must set bufferControlMaxOctetsGranted to -1."
              DEFVAL { -1 }
              ::= { bufferControlEntry 8 }

          bufferControlMaxOctetsGranted OBJECT-TYPE
              SYNTAX INTEGER
              ACCESS read-only
              STATUS mandatory
              DESCRIPTION
                  "The maximum number of octets that can be
                  saved in this captureBuffer, including overhead.
                  If this variable is -1, the capture buffer will save
                  as many octets as possible.

                  When the bufferControlMaxOctetsRequested object is
                  created or modified, the probe should set this object
                  as closely to the requested value as is possible for
                  the particular probe implementation and available
                  resources.
                  However, if the request object has the special value
                  of -1, the probe must set this object to -1.
                  The probe must not lower this value except as a result
                  of a modification to the associated
                  bufferControlMaxOctetsRequested object.

                  When this maximum number of octets is reached
                  and a new packet is to be added to this
                  capture buffer and the corresponding
                  bufferControlFullAction is set to wrapWhenFull(2),
                  enough of the oldest packets associated with this
                  capture buffer shall be deleted by the agent so
                  that the new packet can be added.  If the
                  corresponding bufferControlFullAction is set to
                  lockWhenFull(1), the new packet shall be discarded.
                  In either case, the probe must set
                  bufferControlFullStatus to full(2).

                  When the value of this object changes to a value less
                  than the current value, entries are deleted from
                  the captureBufferTable associated with this
                  bufferControlEntry.  Enough of the
                  oldest of these captureBufferEntries shall be
                  deleted by the agent so that the number of octets
                  used remains less than or equal to the new value of
                  this object.

                  When the value of this object changes to a value

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                  greater than the current value, the number of
                  associated captureBufferEntries may be allowed to
                  grow."
              ::= { bufferControlEntry 9 }

          bufferControlCapturedPackets OBJECT-TYPE
              SYNTAX INTEGER
              ACCESS read-only
              STATUS mandatory
              DESCRIPTION
                  "The number of packets currently in this
                  captureBuffer."
              ::= { bufferControlEntry 10 }

          bufferControlTurnOnTime OBJECT-TYPE
              SYNTAX TimeTicks
              ACCESS read-only
              STATUS mandatory
              DESCRIPTION
                  "The value of sysUpTime when this capture buffer was
                  first turned on."
              ::= { bufferControlEntry 11 }

          bufferControlOwner OBJECT-TYPE
              SYNTAX OwnerString
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "The entity that configured this entry and is
                  therefore using the resources assigned to it."
              ::= { bufferControlEntry 12 }

          bufferControlStatus OBJECT-TYPE
              SYNTAX EntryStatus
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "The status of this buffer Control Entry."
              ::= { bufferControlEntry 13 }

          captureBufferTable OBJECT-TYPE
              SYNTAX SEQUENCE OF CaptureBufferEntry
              ACCESS not-accessible
              STATUS mandatory
              DESCRIPTION
                  "A list of packets captured off of a channel."
              ::= { capture 2 }

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          captureBufferEntry OBJECT-TYPE
              SYNTAX CaptureBufferEntry
              ACCESS not-accessible
              STATUS mandatory
              DESCRIPTION
                  "A packet captured off of an attached network.  As an
                  example, an instance of the captureBufferPacketData
                  object might be named captureBufferPacketData.3.1783"
              INDEX { captureBufferControlIndex, captureBufferIndex }
              ::= { captureBufferTable 1 }

          CaptureBufferEntry ::= SEQUENCE {
              captureBufferControlIndex   INTEGER (1..65535),
              captureBufferIndex          INTEGER (1..2147483647),
              captureBufferPacketID       INTEGER,
              captureBufferPacketData     OCTET STRING,
              captureBufferPacketLength   INTEGER,
              captureBufferPacketTime     INTEGER,
              captureBufferPacketStatus   INTEGER
          }

          captureBufferControlIndex OBJECT-TYPE
              SYNTAX INTEGER (1..65535)
              ACCESS read-only
              STATUS mandatory
              DESCRIPTION
                  "The index of the bufferControlEntry with which
                  this packet is associated."
              ::= { captureBufferEntry 1 }

          captureBufferIndex OBJECT-TYPE
              SYNTAX INTEGER (1..2147483647)
              ACCESS read-only
              STATUS mandatory
              DESCRIPTION
                  "An index that uniquely identifies an entry
                  in the captureBuffer table associated with a
                  particular bufferControlEntry.  This index will
                  start at 1 and increase by one for each new packet
                  added with the same captureBufferControlIndex.

                  Should this value reach 2147483647, the next packet
                  added with the same captureBufferControlIndex shall
                  cause this value to wrap around to 1."
              ::= { captureBufferEntry 2 }

          captureBufferPacketID OBJECT-TYPE
              SYNTAX INTEGER

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              ACCESS read-only
              STATUS mandatory
              DESCRIPTION
                  "An index that describes the order of packets
                  that are received on a particular interface.
                  The packetID of a packet captured on an
                  interface is defined to be greater than the
                  packetID's of all packets captured previously on
                  the same interface.  As the captureBufferPacketID
                  object has a maximum positive value of 2^31 - 1,
                  any captureBufferPacketID object shall have the
                  value of the associated packet's packetID mod 2^31."
              ::= { captureBufferEntry 3 }

          captureBufferPacketData OBJECT-TYPE
              SYNTAX OCTET STRING
              ACCESS read-only
              STATUS mandatory
              DESCRIPTION
                  "The data inside the packet, starting at the
                  beginning of the packet plus any offset specified in
                  the associated bufferControlDownloadOffset,
                  including any link level headers.  The length of the
                  data in this object is the minimum of the length of
                  the captured packet minus the offset, the length of
                  the associated bufferControlCaptureSliceSize minus
                  the offset, and the associated
                  bufferControlDownloadSliceSize.  If this minimum is
                  less than zero, this object shall have a length of
                  zero."
              ::= { captureBufferEntry 4 }

          captureBufferPacketLength OBJECT-TYPE
              SYNTAX INTEGER
              ACCESS read-only
              STATUS mandatory
              DESCRIPTION
                  "The actual length (off the wire) of the packet stored
                  in this entry, including FCS octets."
              ::= { captureBufferEntry 5 }

          captureBufferPacketTime OBJECT-TYPE
              SYNTAX INTEGER
              ACCESS read-only
              STATUS mandatory
              DESCRIPTION
                  "The number of milliseconds that had passed since
                  this capture buffer was first turned on when this

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                  packet was captured."
              ::= { captureBufferEntry 6 }

          captureBufferPacketStatus OBJECT-TYPE
              SYNTAX INTEGER
              ACCESS read-only
              STATUS mandatory
              DESCRIPTION
                  "A value which indicates the error status of this
                  packet.

                  The value of this object is defined in the same way as
                  filterPktStatus.  The value is a sum.  This sum
                  initially takes the value zero.  Then, for each
                  error, E, that has been discovered in this packet,
                  2 raised to a value representing E is added to the
                  sum.

                  The errors defined for a packet captured off of an
                  Ethernet interface are as follows:

                      bit #    Error
                          0    Packet is longer than 1518 octets
                          1    Packet is shorter than 64 octets
                          2    Packet experienced a CRC or Alignment
                               error
                          3    First packet in this capture buffer after
                               it was detected that some packets were
                               not processed correctly.
                          4    Packet's order in buffer is only
                               approximate (May only be set for packets
                               sent from the probe)

                  For example, an Ethernet fragment would have a
                  value of 6 (2^1 + 2^2).

                  As this MIB is expanded to new media types, this
                  object will have other media-specific errors defined."
              ::= { captureBufferEntry 7 }


          -- The Event Group

          -- Implementation of the Event group is optional.
          --
          -- The Event group controls the generation and notification
          -- of events from this device.  Each entry in the eventTable
          -- describes the parameters of the event that can be

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          -- triggered. Each event entry is fired by an associated
          -- condition located elsewhere in the MIB.  An event entry
          -- may also be associated- with a function elsewhere in the
          -- MIB that will be executed when the event is generated.  For
          -- example, a channel may be turned on or off by the firing
          -- of an event.
          --
          -- Each eventEntry may optionally specify that a log entry
          -- be created on its behalf whenever the event occurs.
          -- Each entry may also specify that notification should
          -- occur by way of SNMP trap messages.  In this case, the
          -- community for the trap message is given in the associated
          -- eventCommunity object.  The enterprise and specific trap
          -- fields of the trap are determined by the condition that
          -- triggered the event.  Two traps are defined: risingAlarm
          -- and fallingAlarm.  If the eventTable is triggered by a
          -- condition specified elsewhere, the enterprise and
          -- specific trap fields must be specified for traps
          -- generated for that condition.

          eventTable OBJECT-TYPE
              SYNTAX SEQUENCE OF EventEntry
              ACCESS not-accessible
              STATUS mandatory
              DESCRIPTION
                  "A list of events to be generated."
              ::= { event 1 }

          eventEntry OBJECT-TYPE
              SYNTAX EventEntry
              ACCESS not-accessible
              STATUS mandatory
              DESCRIPTION
                  "A set of parameters that describe an event to be
                  generated when certain conditions are met.  As an
                  example, an instance of the eventLastTimeSent object
                  might be named eventLastTimeSent.6"
              INDEX { eventIndex }
              ::= { eventTable 1 }

          EventEntry ::= SEQUENCE {
              eventIndex          INTEGER (1..65535),
              eventDescription    DisplayString (SIZE (0..127)),
              eventType           INTEGER,
              eventCommunity      OCTET STRING (SIZE (0..127)),
              eventLastTimeSent   TimeTicks,
              eventOwner          OwnerString,
              eventStatus         EntryStatus

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          }

          eventIndex OBJECT-TYPE
              SYNTAX INTEGER (1..65535)
              ACCESS read-only
              STATUS mandatory
              DESCRIPTION
                  "An index that uniquely identifies an entry in the
                  event table.  Each such entry defines one event that
                  is to be generated when the appropriate conditions
                  occur."
              ::= { eventEntry 1 }

          eventDescription OBJECT-TYPE
              SYNTAX DisplayString (SIZE (0..127))
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "A comment describing this event entry."
              ::= { eventEntry 2 }

          eventType OBJECT-TYPE
              SYNTAX INTEGER {
                      none(1),
                      log(2),
                      snmp-trap(3),    -- send an SNMP trap
                      log-and-trap(4)
              }
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "The type of notification that the probe will make
                  about this event.  In the case of log, an entry is
                  made in the log table for each event.  In the case of
                  snmp-trap, an SNMP trap is sent to one or more
                  management stations."
              ::= { eventEntry 3 }

          eventCommunity OBJECT-TYPE
              SYNTAX OCTET STRING (SIZE (0..127))
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "If an SNMP trap is to be sent, it will be sent to
                  the SNMP community specified by this octet string.
                  In the future this table will be extended to include
                  the party security mechanism.  This object shall be
                  set to a string of length zero if it is intended that

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                  that mechanism be used to specify the destination of
                  the trap."
              ::= { eventEntry 4 }

          eventLastTimeSent OBJECT-TYPE
              SYNTAX TimeTicks
              ACCESS read-only
              STATUS mandatory
              DESCRIPTION
                  "The value of sysUpTime at the time this event
                  entry last generated an event.  If this entry has
                  not generated any events, this value will be
                  zero."
              ::= { eventEntry 5 }

          eventOwner OBJECT-TYPE
              SYNTAX OwnerString
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "The entity that configured this entry and is
                  therefore using the resources assigned to it.

                  If this object contains a string starting with
                  'monitor' and has associated entries in the log
                  table, all connected management stations should
                  retrieve those log entries, as they may have
                  significance to all management stations connected to
                  this device"
              ::= { eventEntry 6 }

          eventStatus OBJECT-TYPE
              SYNTAX EntryStatus
              ACCESS read-write
              STATUS mandatory
              DESCRIPTION
                  "The status of this event entry.

                  If this object is not equal to valid(1), all
                  associated log entries shall be deleted by the
                  agent."
              ::= { eventEntry 7 }

          --
          logTable OBJECT-TYPE
              SYNTAX SEQUENCE OF LogEntry
              ACCESS not-accessible
              STATUS mandatory

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              DESCRIPTION
                  "A list of events that have been logged."
              ::= { event 2 }

          logEntry OBJECT-TYPE
              SYNTAX LogEntry
              ACCESS not-accessible
              STATUS mandatory
              DESCRIPTION
                  "A set of data describing an event that has been
                  logged.  For example, an instance of the
                  logDescription object might be named
                  logDescription.6.47"
              INDEX { logEventIndex, logIndex }
              ::= { logTable 1 }

          LogEntry ::= SEQUENCE {
              logEventIndex           INTEGER (1..65535),
              logIndex                INTEGER (1..2147483647),
              logTime                 TimeTicks,
              logDescription          DisplayString (SIZE (0..255))
          }

          logEventIndex OBJECT-TYPE
              SYNTAX INTEGER (1..65535)
              ACCESS read-only
              STATUS mandatory
              DESCRIPTION
                  "The event entry that generated this log
                  entry.  The log identified by a particular
                  value of this index is associated with the same
                  eventEntry as identified by the same value
                  of eventIndex."
              ::= { logEntry 1 }

          logIndex OBJECT-TYPE
              SYNTAX INTEGER (1..2147483647)
              ACCESS read-only
              STATUS mandatory
              DESCRIPTION
                  "An index that uniquely identifies an entry
                  in the log table amongst those generated by the
                  same eventEntries.  These indexes are
                  assigned beginning with 1 and increase by one
                  with each new log entry.  The association
                  between values of logIndex and logEntries
                  is fixed for the lifetime of each logEntry.
                  The agent may choose to delete the oldest

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                  instances of logEntry as required because of
                  lack of memory.  It is an implementation-specific
                  matter as to when this deletion may occur."
              ::= { logEntry 2 }

          logTime OBJECT-TYPE
              SYNTAX TimeTicks
              ACCESS read-only
              STATUS mandatory
              DESCRIPTION
                  "The value of sysUpTime when this log entry was
                  created."
              ::= { logEntry 3 }

          logDescription OBJECT-TYPE
              SYNTAX DisplayString (SIZE (0..255))
              ACCESS read-only
              STATUS mandatory
              DESCRIPTION
                  "An implementation dependent description of the
                  event that activated this log entry."
              ::= { logEntry 4 }

          --  These definitions use the TRAP-TYPE macro as
          --  defined in RFC 1215 [10]

          --  Remote Network Monitoring Traps

          risingAlarm TRAP-TYPE
              ENTERPRISE rmon
              VARIABLES { alarmIndex, alarmVariable, alarmSampleType,
                          alarmValue, alarmRisingThreshold }
              DESCRIPTION
                  "The SNMP trap that is generated when an alarm
                  entry crosses its rising threshold and generates
                  an event that is configured for sending SNMP
                  traps."
              ::= 1

          fallingAlarm TRAP-TYPE
              ENTERPRISE rmon
              VARIABLES { alarmIndex, alarmVariable, alarmSampleType,
                          alarmValue, alarmFallingThreshold }
              DESCRIPTION
                  "The SNMP trap that is generated when an alarm
                  entry crosses its falling threshold and generates
                  an event that is configured for sending SNMP
                  traps."

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              ::= 2

          END

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6.  Acknowledgments

   This document was produced by the IETF Remote Network Monitoring
   Working Group.

7.  References

   [1] Cerf, V., "IAB Recommendations for the Development of Internet
       Network Management Standards", RFC 1052, NRI, April 1988.

   [2] Cerf, V., "Report of the Second Ad Hoc Network Management Review
       Group", RFC 1109, NRI, August 1989.

   [3] Rose M., and K. McCloghrie, "Structure and Identification of
       Management Information for TCP/IP-based internets", STD 16, RFC
       1155, Performance Systems International, Hughes LAN Systems, May
       1990.

   [4] McCloghrie K., and M. Rose, Editors, "Management Information Base
       for Network Management of TCP/IP-based internets", STD 17, RFC
       1213, Performance Systems International, March 1991.

   [5] Case, J., Fedor, M., Schoffstall, M., and J. Davin, "Simple
       Network Management Protocol", STD 15, RFC 1157, SNMP Research,
       Performance Systems International, Performance Systems
       International, MIT Laboratory for Computer Science, May 1990.

   [6] McCloghrie, K., and F. Kastenholz, "Evolution of the Interfaces
       Group of MIB-II", RFC 1573, Hughes LAN Systems, FTP Software,
       January 1994.

   [7] Information processing systems - Open Systems Interconnection -
       Specification of Abstract Syntax Notation One (ASN.1),
       International Organization for Standardization.  International
       Standard 8824, (December, 1987).

   [8] Information processing systems - Open Systems Interconnection -
       Specification of Basic Encoding Rules for Abstract Notation One
       (ASN.1), International Organization for Standardization.
       International Standard 8825, (December, 1987).

   [9] Rose, M., and K. McCloghrie, Editors, "Concise MIB Definitions",
       RFC 1212, Performance Systems International, Hughes LAN Systems,
       March 1991.

  [10] Rose, M., Editor, "A Convention for Defining Traps for use with
       the SNMP", RFC 1215, Performance Systems International, March
       1991.

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8.  Security Considerations

   Security issues are not discussed in this memo.

9.  Author's Address

   Steven Waldbusser
   Carnegie Mellon University
   5000 Forbes Ave.
   Pittsburgh, PA 15213

   EMail: waldbusser@cmu.edu

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10.  Appendix: Changes from RFC 1271

   The RMON MIB has not been significantly changed since RFC 1271 was
   issued.

   Two changes were made to object definitions:

  1) A new status bit has been defined for the
     captureBufferPacketStatus object, indicating that the packet
     order within the capture buffer may not be identical to the
     packet order as received off the wire.  This bit may only be used
     for packets transmitted by the probe.  Older NMS applications can
     safely ignore this status bit, which might be used by newer
     agents.

  2) The packetMatch trap has been removed.  This trap was never
     actually 'approved' and was not added to this document along with
     the risingAlarm and fallingAlarm traps. The packetMatch trap
     could not be throttled, which could cause disruption of normal
     network traffic under some circumstances. An NMS should configure
     a risingAlarm threshold on the appropriate channelMatches
     instance if a trap is desired for a packetMatch event. Note that
     logging of packetMatch events is still supported--only trap
     generation for such events has been removed.

   In addition, several clarifications to individual object definitions
   have been added to assist agent and NMS implementors:

     - global definition of "good packets" and "bad packets"

     - more detailed text governing conceptual row creation and
       modification

     - instructions for probes relating to interface changes and
       disruptions

     - clarification of some ethernet counter definitions

     - recommended formula for calculating network utilization

     - clarification of channel and captureBuffer behavior for some
       unusual conditions

     - examples of proper instance naming for each table