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RFC 2670


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Radio Frequency (RF) Interface Management Information Base for MCNS/DOCSIS compliant RF interfaces

Part 1 of 3, p. 1 to 17
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Network Working Group                                   M. St. Johns, Ed.
Request for Comments: 2670                                  @Home Network
Category: Proposed Standard                                   August 1999


       Radio Frequency (RF) Interface Management Information Base
                for MCNS/DOCSIS compliant RF interfaces


Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (1999).  All Rights Reserved.

Abstract

   This memo defines a portion of the Management Information Base (MIB)
   for use with network management protocols in the Internet community.
   In particular, it defines a basic set of managed objects for SNMP-
   based management of MCNS/DOCSIS compliant Radio Frequency (RF)
   interfaces.

   This memo specifies a MIB module in a manner that is compliant to the
   SNMP SMIv2 [5][6][7].  The set of objects are consistent with the
   SNMP framework and existing SNMP standards.

   This memo is a product of the IPCDN working group within the Internet
   Engineering Task Force.  Comments are solicited and should be
   addressed to the working group's mailing list at ipcdn@terayon.com
   and/or the author.

Table of Contents

   1 The SNMP Management Framework ................................... 3
   2 Glossary ........................................................ 4
   2.1 CATV .......................................................... 4
   2.2 Channel ....................................................... 4
   2.3 CM ............................................................ 4
   2.4 CMTS .......................................................... 4
   2.5 Codeword ...................................................... 4
   2.6 Data Packet ................................................... 4

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   2.7 dBmV .......................................................... 4
   2.8 DOCSIS ........................................................ 5
   2.9 Downstream .................................................... 5
   2.10 Head-end ..................................................... 5
   2.11 MAC Packet ................................................... 5
   2.12 MCNS ......................................................... 5
   2.13 Mini-slot .................................................... 5
   2.14 QPSK ......................................................... 5
   2.15 QAM .......................................................... 5
   2.16 RF ........................................................... 5
   2.17 Symbol-times ................................................. 5
   2.18 Upstream ..................................................... 6
   3 Overview ........................................................ 6
   3.1 Structure of the MIB .......................................... 6
   3.1.1 docsIfBaseObjects ........................................... 6
   3.1.2 docsIfCmObjects ............................................. 7
   3.1.3 docsIfCmtsObjects ........................................... 7
   3.2 Relationship to the Interfaces MIB ............................ 7
   3.2.1 Layering Model .............................................. 7
   3.2.2 Virtual Circuits ............................................ 8
   3.2.3 ifTestTable ................................................. 9
   3.2.4 ifRcvAddressTable ........................................... 9
   3.2.5 ifEntry ..................................................... 9
   3.2.5.1 ifEntry for Downstream interfaces ......................... 9
   3.2.5.1.1 ifEntry for Downstream interfaces in Cable Modem
        Termination Systems .......................................... 9
   3.2.5.1.2 ifEntry for Downstream interfaces in Cable Modems ...... 11
   3.2.5.2 ifEntry for Upstream interfaces .......................... 12
   3.2.5.2.1  ifEntry for Upstream interfaces in Cable Modem
        Termination Systems ......................................... 12
   3.2.5.2.2 ifEntry for Upstream interfaces in Cable Modems ........ 14
   3.2.5.3 ifEntry for the MAC Layer ................................ 15
   4 Definitions .................................................... 18
   5 Acknowledgments ................................................ 69
   6 References ..................................................... 69
   7 Security Considerations ........................................ 70
   8 Intellectual Property .......................................... 71
   9 Author's Address ............................................... 71
   10 Full Copyright Statement ...................................... 72

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1.  The SNMP Management Framework

   The SNMP Management Framework presently consists of five major
   components:

   o   An overall architecture, described in RFC 2571 [1].

   o   Mechanisms for describing and naming objects and events for the
       purpose of management. The first version of this Structure of
       Management Information (SMI) is called SMIv1 and described in STD
       16, RFC 1155 [2], STD 16, RFC 1212 [3] and RFC 1215 [4]. The
       second version, called SMIv2, is described in STD 58, RFC 2578
       [5], STD 58, RFC 2579 [6] and STD 58, RFC 2580 [7].

   o   Message protocols for transferring management information. The
       first version of the SNMP message protocol is called SNMPv1 and
       described in RFC 1157 [8]. A second version of the SNMP message
       protocol, which is not an Internet standards track protocol, is
       called SNMPv2c and described in RFC 1901 [9] and RFC 1906 [10].
       The third version of the message protocol is called SNMPv3 and
       described in RFC 1906 [10], RFC 2572 [11] and RFC 2574 [12].

   o   Protocol operations for accessing management information. The
       first set of protocol operations and associated PDU formats is
       described in STD 15, RFC 1157 [8]. A second set of protocol
       operations and associated PDU formats is described in RFC 1905
       [13].

   o   A set of fundamental applications described in RFC 2573 [14] and
       the view-based access control mechanism described in RFC 2575
       [15].

   Managed objects are accessed via a virtual information store, termed
   the Management Information Base or MIB.  Objects in the MIB are
   defined using the mechanisms defined in the SMI.

   This memo specifies a MIB module that is compliant to the SMIv2. A
   MIB conforming to the SMIv1 can be produced through the appropriate
   translations. The resulting translated MIB MUST be semantically
   equivalent, except where objects or events are omitted because no
   translation is possible (use of Counter64). Some machine readable
   information in SMIv2 will be converted into textual descriptions in
   SMIv1 during the translation process. However, this loss of machine
   readable information is not considered to change the semantics of the
   MIB.

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2.  Glossary

   The terms in this document are derived either from normal cable
   system usage, or from the documents associated with the Data Over
   Cable Service Interface Specification process.

2.1.  CATV

   Originally "Community Antenna Television", now used to refer to any
   cable or hybrid fiber and cable system used to deliver video signals
   to a community.

2.2.  Channel

   A specific frequency allocation with an RF medium, specified by
   channel width in Hertz (cycles per second) and by center frequency.
   Within the US Cable Systems, upstream channels are generally
   allocated from the 5-42MHz range while down stream channels are
   generally allocated from the 50-750MHz range depending on the
   capabilities of the given system.  The typical broadcast channel
   width in the US is 6MHz.  Upstream channel widths for DOCSIS vary.

2.3.  CM   Cable Modem.

   A CM acts as a "slave" station in a DOCSIS compliant cable data
   system.

2.4.  CMTS   Cable Modem Termination System.

   A generic term covering a cable bridge or cable router in a head-end.
   A CMTS acts as the master station in a DOCSIS compliant cable data
   system.  It is the only station that transmits downstream, and it
   controls the scheduling of upstream transmissions by its associated
   CMs.

2.5.  Codeword

   See [16]. A characteristic of the Foward Error Correction scheme used
   above the RF media layer.

2.6.  Data Packet

   The payload portion of the MAC Packet.

2.7.  dBmV

   Decibel relative to one milli-volt. A measure of RF power.

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2.8.  DOCSIS

   "Data Over Cable Interface Specification".  A term referring to the
   ITU-T J.112 Annex B standard for cable modem systems [20].

2.9.  Downstream

   The direction from the head-end towards the subscriber.

2.10.  Head-end

   The origination point in most cable systems of the subscriber video
   signals.

2.11.  MAC Packet

   A DOCSIS PDU.

2.12.  MCNS

   "Multimedia Cable Network System".  Generally replaced in usage by
   DOCSIS.

2.13.  Mini-slot

   See [16].  In general, an interval of time which is allocated by the
   CMTS to a given CM for that CM to transmit in an upstream direction.

2.14.  QPSK   Quadrature Phase Shift Keying.

   A particular modulation scheme on an RF medium. See [19].

2.15.  QAM   Quadrature Amplitude Modulation.

   A particular modulation scheme on on RF medium.  Usually expressed
   with a number indicating the size of the modulation constellation
   (e.g. 16 QAM). See [19], or any other book on digital communications
   over RF for a complete explanation of this.

2.16.  RF

   Radio Frequency.

2.17.  Symbol-times

   See [16]. A characteristic of the RF modulation scheme.

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2.18.  Upstream

   The direction from the subscriber towards the head-end.

3.  Overview

   This MIB provides a set of objects required for the management of
   MCNS/DOCSIS compliant Cable Modem (CM) and Cable Modem Termination
   System (CMTS) RF interfaces.  The specification is derived in part
   from the parameters and protocols described in DOCSIS Radio Frequency
   Interface Specification [16].

3.1.  Structure of the MIB

   This MIB is structured as three groups:

   o    Management information pertinent to both Cable Modems (CM) and
        Cable Modem Termination Systems (CMTS) (docsIfBaseObjects).

   o    Management information pertinent to Cable Modems only
        (docsIfCmObjects).

   o    Management information pertinent to Cable Modem Termination
        Systems only (docsIfCmtsObjects).

   Tables within each of these groups group objects functionally - e.g.
   Quality of Service, Channel characteristics, MAC layer management,
   etc.  Rows created automatically (e.g. by the device according to the
   hardware configuration) may and generally will have a mixture of
   configuration and status objects within them.  Rows that are meant to
   be created by the management station are generally restricted to
   configuration (read-create) objects.

3.1.1.  docsIfBaseObjects

   docsIfDownstreamChannelTable - This table describes the active
   downstream channels for a CMTS and the received downstream channel
   for a CM.

   docsIfUpstreamChannelTable - This table describes the active upstream
   channels for a a CMTS and the current upstream transmission channel
   for a CM.

   docsIfQosProfileTable - This table describes the valid Quality of
   Service service profiles for the cable data system.

   docsIfSignalQualityTable - This table is used to monitor RF signal
   quality characteristics of received signals.

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3.1.2.  docsIfCmObjects

   docsIfCmMacTable - This table is used to monitor the DOCSIS MAC
   interface and can be considered an extension to the ifEntry.

   docsIfCmServiceTable - This table describes the upstream service
   queues available at this CM.  There is a comparable table at the
   CMTS, docsIfCmtsServiceEntry, which describes the service queues from
   the point of view of the CMTS.

3.1.3.  docsIfCmtsObjects

   docsIfCmtsStatusTable - This table provides a set of aggregated
   counters which roll-up values and events that occur on the underlying
   sub-interfaces.

   docsIfCmtsCmStatusTable - This table is used to hold information
   about known (e.g. registered) cable modems on the system serviced by
   this CMTS.

   docsIfCmtsServiceEntry - This table provides access to the
   information related to upstream service queues.

   docsIfCmtsModulationTable - This table allows control over the
   modulation profiles for RF channels associated with this CMTS.

   docsIfCmtsMacToCmTable - This table allows fast access into the
   docsIfCmtsCmTable via a MAC address (of the CM) interface.

3.2.  Relationship to the Interfaces MIB

   This section clarifies the relationship of this MIB to the Interfaces
   MIB [17].  Several areas of correlation are addressed in the
   following subsections.  The implementor is referred to the Interfaces
   MIB document in order to understand the general intent of these
   areas.

3.2.1.  Layering Model

   An instance of ifEntry exists for each RF Downstream interface, for
   each RF Upstream interface, and for each RF MAC layer.  The
   ifStackTable [17] MUST be implemented to identify relationships among
   sub-interfaces.

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   The following example illustrates a MAC interface with one downstream
   and two upstream channels.

                               | <== to network layer
                 +-------------+--------------+
                 |           RF MAC           |
                 +----+---------+-----------+-+
                      |         |           |
            +---------+---+ +---+-------+ +-+---------+
            | Downstream1 | | Upstream1 | | Upstream2 |
            +-------------+ +-----------+ +-----------+

   As can be seen from this example, the RF MAC interface is layered on
   top of the downstream and upstream interfaces.

   In this example, the assignment of index values could be as follows:

      ifIndex ifType                   Description

      1    docsCableMaclayer(127)   CATV MAC Layer
      2    docsCableDownstream(128) CATV Downstream interface
      3    docsCableUpstream(129)   CATV Upstream interface
      4    docsCableUpstream(129)   CATV Upstream interface

      The corresponding ifStack entries would then be:

           | IfStackHigherLayer | ifStackLowerLayer |
           |         0          |         1         |
           |         1          |         2         |
           |         1          |         3         |
           |         1          |         4         |
           |         2          |         0         |
           |         3          |         0         |
           |         4          |         0         |

   The same interface model can also be used in Telephony or Telco
   Return systems.  A pure Telco Return system (Cable Modem as well as
   Cable Modem Termination System) would not have upstream, but only
   downstream cable channels.  Systems supporting both Telco Return and
   cable upstream channels can use the above model without modification.

   Telco Return Upstream channel(s) are handled by the appropriate MIBs,
   such as PPP or Modem MIBs.

3.2.2.  Virtual Circuits

   This medium does not support virtual circuits and this area is not
   applicable to this MIB.

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3.2.3.  ifTestTable

   The ifTestTable is not supported by this MIB.

3.2.4.  ifRcvAddressTable

   The ifRcvAddressTable is not supported by this MIB.

3.2.5.  ifEntry

   This section documents only the differences from the requirements
   specified in the Interfaces MIB.  See that MIB for columns omitted
   from the descriptions below.

3.2.5.1.  ifEntry for Downstream interfaces

   The ifEntry for Downstream interfaces supports the
   ifGeneralInformationGroup and the ifPacketGroup of the Interfaces
   MIB.  This is an output only interface at the CMTS and all input
   status counters - ifIn* - will return zero.  This is an input only
   interface at the CM and all output status counters - ifOut* - will
   return zero.

3.2.5.1.1.  ifEntry for Downstream interfaces in Cable Modem Termination
            Systems

   ifTable           Comments
   ==============    ===========================================
   ifIndex           Each RF Cable Downstream interface is represented
                     by an ifEntry.

   ifType            The IANA value of docsCableDownstream(128).

   ifSpeed           Return the speed of this downstream channel.
                     The returned value the raw bandwidth in bits/s
                     of this interface. This is the symbol rate
                     multiplied with the number of bits per symbol.

   ifPhysAddress     Return an empty string.

   ifAdminStatus     The administrative status of this interface.

   ifOperStatus      The current operational status of this interface.

   ifMtu             The size of the largest frame which can be
                     sent on this interface, specified in octets.
                     The value includes the length of the MAC header.

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   ifInOctets        Return zero.

   ifInUcastPkts     Return zero.

   ifInMulticastPkts Return zero.

   ifInBroadcastPkts Return zero.

   ifInDiscards      Return zero.

   ifInErrors        Return zero.

   ifInUnknownProtos Return zero.

   ifOutOctets       The total number of octets transmitted on this
                     interface. This includes MAC packets as well as
                     data packets, and includes the length of the MAC
                     header.

   ifOutUcastPkts    The number of Unicast packets transmitted on this
                     interface. This includes MAC packets as well as
                     data packets.

   ifOutMulticastPkts
                     Return the number of Multicast packets transmitted
                     on this interface.
                     This includes MAC packets as well as data packets.

   ifOutBroadcastPkts
                     Return the number of broadcast packets transmitted
                     on this interface.
                     This includes MAC packets as well as data packets.

   ifOutDiscards     The total number of outbound packets which
                     were discarded. Possible reasons are:
                     buffer shortage.

   ifOutErrors       The number of packets which could not be
                     transmitted due to errors.

   ifPromiscuousMode Return false.

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3.2.5.1.2.  ifEntry for Downstream interfaces in Cable Modems

   ifTable           Comments
   ==============    ===========================================
   ifIndex           Each RF Cable Downstream interface is represented
                     by an ifEntry.

   ifType            The IANA value of docsCableDownstream(128).

   ifSpeed           Return the speed of this downstream channel.
                     The returned value the raw bandwidth in bits/s
                     of this interface. This is the symbol rate
                     multiplied with the number of bits per symbol.

   ifPhysAddress     Return an empty string.

   ifAdminStatus     The administrative status of this interface.

   ifOperStatus      The current operational status of this interface.

   ifMtu             The size of the largest frame which can be
                     received from this interface, specified in octets.
                     The value includes the length of the MAC header.

   ifInOctets        The total number of octets received on this
                     interface. This includes data packets as well as
                     MAC layer packets, and includes the length of the
                     MAC header.

   ifInUcastPkts     The number of Unicast packets received on this
                     interface. This includes data packets as well as
                     MAC layer packets.

   ifInMulticastPkts Return the number of Multicast packets received
                     on this interface. This includes data packets as
                     well as MAC layer packets.

   ifInBroadcastPkts Return the number of Broadcast packets received
                     on this interface. This includes data packets
                     as well as MAC layer packets.

   ifInDiscards      The total number of received packets which have
                     been discarded.
                     The possible reasons are: buffer shortage.

   ifInErrors        The number of inbound packets that contained
                     errors preventing them from being deliverable
                     to higher layers.

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                     Possible reasons are: MAC FCS error.

   ifInUnknownProtos The number of frames with an unknown packet type.
                     These are MAC frames with an unknown packet type.

   ifOutOctets       Return zero.

   ifOutUcastPkts    Return zero.

   ifOutMulticastPkts
                     Return zero.

   ifOutBroadcastPkts
                     Return zero.

   ifOutDiscards     Return zero.

   ifOutErrors       Return zero.

   ifPromiscuousMode Refer to the Interfaces MIB.

3.2.5.2.  ifEntry for Upstream interfaces

   The ifEntry for Upstream interfaces supports the
   ifGeneralInformationGroup and the ifPacketGroup of the Interfaces
   MIB.  This is an input only interface at the CMTS and all output
   status counters - ifOut* - will return zero.  This is an output only
   interface at the CM and all input status counters - ifIn* - will
   return zero.

3.2.5.2.1.  ifEntry for Upstream interfaces in Cable Modem Termination
            Systems

   ifTable           Comments
   ==============    ===========================================
   ifIndex           Each RF Cable Upstream interface is represented
                     by an ifEntry.

   ifType            The IANA value of docsCableUpstream(129).

   ifSpeed           Return the speed of this upstream channel.
                     The returned value is the raw bandwidth
                     in bits/s of this interface, regarding the
                     highest speed modulation profile that is
                     defined. This is the symbol rate multiplied
                     with the number of bits per symbol for this
                     modulation profile.

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   ifPhysAddress     Return an empty string.

   ifAdminStatus     The administrative status of this interface.

   ifOperStatus      The current operational status of this interface.

   ifMtu             The size of the largest frame which can be
                     received on this interface, specified in octets.
                     The value includes the length of the MAC header.

   ifInOctets        The total number of octets received on this
                     interface. This includes data packets as well as
                     MAC layer packets, and includes the length of the
                     MAC header.

   ifInUcastPkts     The number of Unicast packets received on this
                     interface. This includes data packets as well as
                     MAC layer packets.

   ifInMulticastPkts Return the number of Multicast packets received
                     on this interface. This includes data packets as
                     well as MAC layer packets.

   ifInBroadcastPkts Return the number of Broadcast packets received
                     on this interface. This includes data packets
                     as well as MAC layer packets.

   ifInDiscards      The total number of received packets which have
                     been discarded.
                     The possible reasons are: buffer shortage.

   ifInErrors        The number of inbound packets that contained
                     errors preventing them from being deliverable
                     to higher layers.
                     Possible reasons are: MAC FCS error.

   ifInUnknownProtos The number of frames with an unknown packet type.
                     This are MAC frames with an unknown packet type.

   ifOutOctets       Return zero.

   ifOutUcastPkts    Return zero.

   ifOutMulticastPkts
                     Return zero.

   ifOutBroadcastPkts
                     Return zero.

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   ifOutDiscards     Return zero.

   ifOutErrors       Return zero.

3.2.5.2.2.  ifEntry for Upstream interfaces in Cable Modems

   ifTable           Comments
   ==============    ===========================================
   ifIndex           Each RF Cable Upstream interface is represented
                     by an ifEntry.

   ifType            The IANA value of docsCableUpstream(129).

   ifSpeed           Return the speed of this upstream channel.
                     The returned value is the raw bandwidth
                     in bits/s of this interface, regarding the
                     highest speed modulation profile that is
                     defined. This is the symbol rate multiplied
                     with the number of bits per symbol for this
                     modulation profile.

   ifPhysAddress     Return an empty string.

   ifAdminStatus     The administrative status of this interface.

   ifOperStatus      The current operational status of this interface.

   ifMtu             The size of the largest frame which can be
                     transmitted on this interface, specified in octets.
                     The value includes the length of the MAC header.

   ifInOctets        Return zero.

   ifInUcastPkts     Return zero.

   ifInMulticastPkts Return zero.

   ifInBroadcastPkts Return zero.

   ifInDiscards      Return zero.

   ifInErrors        Return zero.

   ifInUnknownProtos Return zero.

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   ifOutOctets       The total number of octets transmitted on this
                     interface. This includes MAC packets as well as
                     data packets, and includes the length of the MAC
                     header.

   ifOutUcastPkts    The number of Unicast packets transmitted on this
                     interface. This includes MAC packets as well as
                     data packets.

   ifOutMulticastPkts
                     Return the number of Multicast packets transmitted
                     on this interface.
                     This includes MAC packets as well as data packets.

   ifOutBroadcastPkts
                     Return the number of broadcast packets transmitted
                     on this interface.
                     This includes MAC packets as well as data packets.

   ifOutDiscards     The total number of outbound packets which
                     were discarded. Possible reasons are:
                     buffer shortage.

   ifOutErrors       The number of packets which could not be
                     transmitted due to errors.

   ifPromiscuousMode Return false.

3.2.5.3.  ifEntry for the MAC Layer

   The ifEntry for the MAC Layer supports the ifGeneralInformationGroup
   and the ifPacketGroup of the Interfaces MIB.  This interface provides
   an aggregate view of status for the lower level Downstream and
   Upstream interfaces.

   ifTable           Comments
   ==============    ===========================================
   ifIndex           Each RF Cable MAC layer entity is represented
                     by an ifEntry.

   ifType            The IANA value of docsCableMaclayer(127).

   ifSpeed           Return zero.

   ifPhysAddress     Return the physical address of this interface.

   ifAdminStatus     The administrative status of this interface.

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   ifOperStatus      The current operational status of the MAC
                     layer interface.

   ifHighSpeed       Return zero.

   ifMtu             Return 1500.

   ifInOctets        The total number of data octets received on this
                     interface, targeted for upper protocol layers.

   ifInUcastPkts     The number of Unicast packets received on this
                     interface, targeted for upper protocol layers.

   ifInMulticastPkts Return the number of Multicast packets received
                     on this interface, targeted for upper protocol
                     layers.

   ifInBroadcastPkts Return the number of Broadcast packets received
                     on this interface, targeted for upper protocol
                     layers.

   ifInDiscards      The total number of received packets which have
                     been discarded.
                     The possible reasons are: buffer shortage.

   ifInErrors        The number of inbound packets that contained
                     errors preventing them from being deliverable
                     to higher layers.
                     Possible reasons are: data packet FCS error,
                     invalid MAC header.

   ifInUnknownProtos The number of frames with an unknown packet type.
                     This is the number of data packets targeted for
                     upper protocol layers with an unknown packet type.

   ifOutOctets       The total number of octets, received from upper
                     protocol layers and transmitted on this interface.

   ifOutUcastPkts    The number of Unicast packets, received from upper
                     protocol layers and transmitted on this interface.

   ifOutMulticastPkts
                     Return the number of Multicast packets received
                     from upper protocol layers and transmitted on this
                     interface.

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   ifOutBroadcastPkts
                     Return the number of broadcast packets received
                     from upper protocol layers and transmitted on this
                     interface.

   ifOutDiscards     The total number of outbound packets which
                     were discarded. Possible reasons are:
                     buffer shortage.

   ifOutErrors       The number of packets which could not be
                     transmitted due to errors.

   ifPromiscuousMode Refer to the Interfaces MIB.


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