tech-invite   World Map     

IETF     RFCs     Groups     SIP     ABNFs    |    3GPP     Specs     Glossaries     Architecture     IMS     UICC    |    search

RFC 1158


Pages: 133
Top     in Index     Prev     Next
 

Management Information Base for network management of TCP/IP-based internets: MIB-II

Part 1 of 4, p. 1 to 27
None       Next RFC Part

Obsoleted by:    1213


Top       Page 1 
Network Working Group                                   M. Rose, Editor
Request for Comments: 1158            Performance Systems International
                                                               May 1990


           Management Information Base for Network Management
                       of TCP/IP-based internets:
                                 MIB-II

1.  Status of this Memo

   This memo defines the second version of the Management Information
   Base (MIB-II) for use with network management protocols in TCP/IP-
   based internets.  In particular, together with its companion memos
   which describe the structure of management information (RFC 1155)
   along with the network management protocol (RFC 1157) for TCP/IP-
   based internets, these documents provide a simple, workable
   architecture and system for managing TCP/IP-based internets and in
   particular the Internet community.

   This document on MIB-II incorporates all of the technical content of
   RFC 1156 on MIB-I and extends it, without loss of compatibilty.
   However, MIB-I as described in RFC 1156 is full Standard Protocol of
   the Internet, while the MIB-II described here is Proposed Standard
   Protocol of the Internet.

   This memo defines a mandatory extension to the base MIB (RFC 1156)
   and is a Proposed Standard for the Internet community.  The
   extensions described here are currently Elective, but when they
   become a standard, they will have the same status as RFC 1156, that
   is, Recommended.  The Internet Activities Board recommends that all
   IP and TCP implementations be network manageable.  This implies
   implementation of the Internet MIB (RFC 1156 and the extensions in
   RFC 1158) and at least one of the two recommended management
   protocols SNMP (RFC 1157) or CMOT (RFC 1095).

   This version of the MIB specification, MIB-II, is an incremental
   refinement of MIB-I.  As such, it has been designed according to two
   criteria: first, changes have been made in response to new
   operational requirements in the Internet; and, second, the changes
   are entirely upwards compatible in order to minimize impact on the
   network as the managed nodes in the Internet transition from MIB-I to
   MIB-II.

   It is expected that additional MIB groups and variables will be
   defined over time to accommodate the monitoring and control needs of
   new or changing components of the Internet.

Top       Page 2 
   Please refer to the latest edition of the "IAB Official Protocol
   Standards" RFC for current information on the state and status of
   standard Internet protocols.

   Distribution of this memo is unlimited.

                             Table of Contents


   1. Status of this Memo ..................................    1
   2. Introduction .........................................    3
   3. Changes from MIB-I ...................................    4
   3.1 Deprecated Objects ..................................    4
   3.2 Display Strings .....................................    5
   3.3 The System Group ....................................    5
   3.4 The Interfaces Group ................................    5
   3.5 The Address Translation Group .......................    6
   3.6 The IP Group ........................................    7
   3.7 The ICMP Group ......................................    7
   3.8 The TCP Group .......................................    7
   3.9 The UDP Group .......................................    7
   3.10 The EGP Group ......................................    8
   3.11 The Transmission Group .............................    8
   3.12 The SNMP Group .....................................    8
   4. Objects ..............................................    8
   4.1 Object Groups .......................................    9
   4.2 Format of Definitions ...............................   10
   5. Object Definitions ...................................   10
   5.1 The System Group ....................................   11
   5.2 The Interfaces Group ................................   14
   5.2.1 The Interfaces table ..............................   15
   5.3 The Address Translation Group .......................   27
   5.4 The IP Group ........................................   30
   5.4.1 The IP Address table ..............................   38
   5.4.2 The IP Routing table ..............................   41
   5.4.3 The IP Address Translation table ..................   48
   5.5 The ICMP Group ......................................   51
   5.6 The TCP Group .......................................   61
   5.6.1 The TCP Connection table ..........................   66
   5.6.2 Additional TCP Objects ............................   69
   5.7 The UDP Group .......................................   70
   5.7.1 The UDP Listener table ............................   72
   5.8 The EGP Group .......................................   73
   5.8.1 The EGP Neighbor table ............................   75
   5.8.2 Additional EGP variables ..........................   83
   5.9 The Transmission Group ..............................   83
   5.10 The SNMP Group .....................................   83
   6. Definitions ..........................................   95

Top       Page 3 
   7. Identification of OBJECT instances for use with  the
      SNMP .................................................  126
   7.1 ifTable Object Type Names ...........................  127
   7.2 atTable Object Type Names ...........................  127
   7.3 ipAddrTable Object Type Names .......................  128
   7.4 ipRoutingTable Object Type Names ....................  128
   7.5 ipNetToMediaTable Object Type Names .................  129
   7.6 tcpConnTable Object Type Names ......................  129
   7.7 udpTable Object Type Names ..........................  130
   7.8 egpNeighTable Object Type Names .....................  130
   8.  Acknowledgements ....................................  130
   9.  References ..........................................  131
   10. Security Considerations..............................  133
   11. Author's Address.....................................  133

2.  Introduction

   As reported in RFC 1052, IAB Recommendations for the
   Development of Internet Network Management Standards [1], a
   two-prong strategy for network management of TCP/IP-based
   internets was undertaken.  In the short-term, the Simple
   Network Management Protocol (SNMP) was to be used to manage
   nodes in the Internet community.  In the long-term, the use of
   the OSI network management framework was to be examined.  Two
   documents were produced to define the management information:
   RFC 1065, which defined the Structure of Management
   Information (SMI) [2], and RFC 1066, which defined the
   Management Information Base (MIB) [3].  Both of these
   documents were designed so as to be compatible with both the
   SNMP and the OSI network management framework.

   This strategy was quite successful in the short-term:
   Internet-based network management technology was fielded, by
   both the research and commercial communities, within a few
   months.  As a result of this, portions of the Internet
   community became network manageable in a timely fashion.

   As reported in RFC 1109, Report of the Second Ad Hoc Network
   Management Review Group [4], the requirements of the SNMP and
   the OSI network management frameworks were more different than
   anticipated.  As such, the requirement for compatibility
   between the SMI/MIB and both frameworks was suspended.  This
   action permitted the operational network management framework,
   the SNMP, to respond to new operational needs in the Internet
   community by producing this document.

   As such, the current network management framework for TCP/IP-
   based internets consists of: Structure and Identification of

Top       Page 4 
   Management Information for TCP/IP-based internets, RFC 1155 [13],
   which describes how managed objects contained in the MIB are
   defined; Management Information Base for Network Management of
   TCP/IP-based internets (version 2), this memo, which describes
   the managed objects contained in the MIB; and, the Simple
   Network Management Protocol, RFC 1157 [14], which defines the
   protocol used to manage these objects.

   Consistent with the IAB directive to produce simple, workable
   systems in the short-term, the list ofc objects (e.g., for BSD UNIX)
      were excluded.

   7) It was agreed to avoid heavily instrumenting critical
      sections of code.  The general guideline was one counter
      per critical section per layer.

3.  Changes from MIB-I

   Features of this MIB include:

      1) incremental additions to reflect new operational
         requirements;

      2) upwards compatibility with the SMI/MIB and the SNMP;

      3) improved support for multi-protocol entities; and,

      4) textual clean-up of the MIB to improve clarity and
         readability.

   The objects defined in MIB-II have the OBJECT IDENTIFIER prefix:

               mib-2      OBJECT IDENTIFIER ::= { mgmt 1 }

3.1.  Deprecated Objects

   In order to better prepare implementors for future changes in the
   MIB, a new term "deprecated" may be used when describing an object.
   A deprecated object in the MIB is one which must be supported, but
   one which will most likely be removed from the next version of the
   MIB (e.g., MIB-III).

      MIB-II marks one object as being deprecated:

      atTable

   As a result of deprecating the atTable object, the entire Address
   Translation group is deprecated.

Top       Page 5 
   Note that no functionality is lost with the deprecation of these
   objects: new objects providing equivalent or superior functionality
   are defined in MIB-II.

3.2.  Display Strings

   In the past, there have been misinterpretations of the MIB as to when
   a string of octets should contain printable characters, meant to be
   displayed to a human.  As a textual convention in the MIB, the
   datatype

                  DisplayString ::= OCTET STRING

   is introduced.  A DisplayString is restricted to the NVT ASCII
   character set, as defined in pages 10-11 of [7].

   The following objects are now defined in terms of DisplayString:

                  sysDescr
                  ifDescr

   It should be noted that this change has no effect on either the
   syntax nor semantics of these objects.  The use of the DisplayString
   notation is merely an artifact of the explanatory method used in
   MIB-II and future MIBs.

   Further, it should be noted that any object defined in terms of OCTET
   STRING may contain arbitrary binary data, in which each octet may
   take any value from 0 to 255 (decimal).

3.3.  The System Group

   Four new objects are added to this group:

                  sysContact
                  sysName
                  sysLocation
                  sysServices

   These provide contact, administrative, location, and service
   information regarding the managed node.

3.4.  The Interfaces Group

   The definition of the ifNumber object was incorrect, as it required
   all interfaces to support IP.  (For example, devices without IP, such
   as MAC-layer bridges, could not be managed if this definition was
   strictly followed.) The description of the ifNumber object is changed

Top       Page 6 
   accordingly.

   The ifTable object was mistaken marked as read-write, it has been
   (correctly) re-designated as read-only.  In addition, several new
   values have been added to the ifType column in the ifTable object:

                  ppp(23)
                  softwareLoopback(24)
                  eon(25)
                  ethernet-3Mbit(26)
                  nsip(27)
                  slip(28)

   Finally, a new column has been added to the ifTable object:

                  ifSpecific

   which provides information about information specific to the media
   being used to realize the interface.

3.5.  The Address Translation Group

   In MIB-I, this group contained a table which permitted mappings from
   network addresses (e.g., IP addresses) to physical addresses (e.g.,
   MAC addresses).  Experience has shown that efficient implementations
   of this table make two assumptions: a single network protocol
   environment, and mappings occur only from network address to physical
   address.

   The need to support multi-protocol nodes (e.g., those with both the
   IP and CLNP active), and the need to support the inverse mapping
   (e.g., for ES-IS), have invalidated both of these assumptions.  As
   such, the atTable object is declared deprecated.

   In order to meet both the multi-protocol and inverse mapping
   requirements, MIB-II and its successors will allocate up to two
   address translation tables inside each network protocol group.  That
   is, the IP group will contain one address translation table, for
   going from IP addresses to physical addresses.  Similarly, when a
   document defining MIB objects for the CLNP is produced (e.g., [8]),
   it will contain two tables, for mappings in both directions, as this
   is required for full functionality.

   It should be noted that the choice of two tables (one for each
   direction of mapping) provides for ease of implementation in many
   cases, and does not introduce undue burden on implementations which
   realize the address translation abstraction through a single internal
   table.

Top       Page 7 
3.6.  The IP Group

   The access attribute of the variable ipForwarding has been changed
   from read-only to read-write.

   In addition, there is a new column to the ipAddrTable object,

                  ipAdEntReasmMaxSize

   which keeps track of the largest IP datagram that can be re-
   assembled on a particular interface.  There is also a new column in
   the ipRoutingTable object,

                  ipRouteMask

   which is used for IP routing subsystems that support arbitrary subnet
   masks.

   One new object is added to the IP group:

                  ipNetToMediaTable

   which is the address translation table for the IP group (providing
   identical functionality to the now deprecated atTable in the address
   translation group).

3.7.  The ICMP Group

   There are no changes to this group.

3.8.  The TCP Group

   Two new variables are added:

                  tcpInErrs
                  tcpOutRsts

   which keep track of the number of incoming TCP segments in error and
   the number of resets generated by a TCP.

3.9.  The UDP Group

   A new table:

                  udpTable

   is added.

Top       Page 8 
3.10.  The EGP Group

   Experience has indicated a need for additional objects that are
   useful in EGP monitoring.  In addition to making several additions to
   the egpNeighborTable object, a new variable is added:

                  egpAs

   which gives the autonomous system associated with this EGP entity.

3.11.  The Transmission Group

   MIB-I was lacking in that it did not distinguish between different
   types of transmission media.  A new group, the Transmission group, is
   allocated for this purpose:

                  transmission OBJECT IDENTIFIER ::= { mib-2 10 }

   When Internet-standard definitions for managing transmission media
   are defined, the transmission group is used to provide a prefix for
   the names of those objects.

   Typically, such definitions reside in the experimental portion of the
   MIB until they are "proven", then as a part of the Internet
   standardization process, the definitions are accordingly elevated and
   a new object identifier, under the transmission group is defined.  By
   convention, the name assigned is:

                  type OBJECT IDENTIFIER    ::= { transmission number }

   where "type" is the symbolic value used for the media in the ifType
   column of the ifTable object, and "number" is the actual integer
   value corresponding to the symbol.

3.12.  The SNMP Group

   The application-oriented working groups of the IETF have been tasked
   to be receptive towards defining MIB variables specific to their
   respective applications.

   For the SNMP, it is useful to have statistical information.  A new
   group, the SNMP group, is allocated for this purpose:

                  snmp   OBJECT IDENTIFIER ::= { mib-2 11 }

4.  Objects

   Managed objects are accessed via a virtual information store, termed

Top       Page 9 
   the Management Information Base or MIB.  Objects in the MIB are
   defined using Abstract Syntax Notation One (ASN.1) [9].

   The mechanisms used for describing these objects are specified the
   companion memo, the SMI.  In particular, each object has a name, a
   syntax, and an encoding.  The name is an object identifier, an
   administratively assigned name, which specifies an object type.  The
   object type together with an object instance serves to uniquely
   identify a specific instantiation of the object.  For human
   convenience, we often use a textual string, termed the OBJECT
   DESCRIPTOR, to also refer to the object type.

   The syntax of an object type defines the abstract data structure
   corresponding to that object type.  The ASN.1 language is used for
   this purpose.  However, the companion memo purposely restricts the
   ASN.1 constructs which may be used.  These restrictions are
   explicitly made for simplicity.

   The encoding of an object type is simply how that object type is
   represented using the object type's syntax.  Implicitly tied to the
   notion of an object type's syntax and encoding is how the object type
   is represented when being transmitted on the network.  This memo
   specifies the use of the basic encoding rules (BER) of ASN.1 [10],
   subject to the additional requirements imposed by the SNMP [14].

4.1.  Object Groups

   Since this list of managed objects contains only the essential
   elements, there is no need to allow individual objects to be
   optional.  Rather, the objects are arranged into the following
   groups:

                  - System
                  - Interfaces
                  - Address Translation (deprecated)
                  - IP
                  - ICMP
                  - TCP
                  - UDP
                  - EGP
                  - Transmission
                  - SNMP

   There are two reasons for defining these groups: to provide a means
   of assigning object identifiers; and, to provide a method for
   implementations of managed agents to know which objects they must
   implement.  This method is as follows: if the semantics of a group is
   applicable to an implementation, then it must implement all objects

Top       Page 10 
   in that group.  For example, an implementation must implement the EGP
   group if and only if it implements the EGP.

4.2.  Format of Definitions

   The next section contains the specification of all object types
   contained in the MIB.  Following the conventions of the companion
   memo, the object types are defined using the following fields:

      OBJECT:
      -------
           A textual name, termed the OBJECT DESCRIPTOR, for the
           object type, along with its corresponding OBJECT
           IDENTIFIER.

      Syntax:
           The abstract syntax for the object type, presented using
           ASN.1.  This must resolve to an instance of the ASN.1
           type ObjectSyntax defined in the SMI.

      Definition:
           A textual description of the semantics of the object
           type.  Implementations should ensure that their
           interpretation of the object type fulfills this
           definition since this MIB is intended for use in multi-
           vendor environments.  As such it is vital that object
           types have consistent meaning across all machines.

      Access:
           A keyword, one of read-only, read-write, write-only, or
           not-accessible.  Note that this designation specifies the
           minimum level of support required.  As a local matter,
           implementations may support other access types (e.g., an
           implementation may elect to permitting writing a variable
           marked herein as read-only).  Further, protocol-specific
           "views" (e.g., those implied by an SNMP community) may
           make further restrictions on access to a variable.

      Status:
           A keyword, one of mandatory, optional, obsolete, or
           deprecated.  Use of deprecated implies mandatory status.

5.  Object Definitions

               RFC1158-MIB

               DEFINITIONS ::= BEGIN

Top       Page 11 
               IMPORTS
                       mgmt, OBJECT-TYPE, NetworkAddress, IpAddress,
                       Counter, Gauge, TimeTicks
                           FROM RFC1155-SMI;

               DisplayString ::=
                           OCTET STRING


               mib-2      OBJECT IDENTIFIER ::= { mgmt 1 }    -- MIB-II

               system     OBJECT IDENTIFIER ::= { mib-2 1 }
               interfaces OBJECT IDENTIFIER ::= { mib-2 2 }
               at         OBJECT IDENTIFIER ::= { mib-2 3 }
               ip         OBJECT IDENTIFIER ::= { mib-2 4 }
               icmp       OBJECT IDENTIFIER ::= { mib-2 5 }
               tcp        OBJECT IDENTIFIER ::= { mib-2 6 }
               udp        OBJECT IDENTIFIER ::= { mib-2 7 }
               egp        OBJECT IDENTIFIER ::= { mib-2 8 }
               -- cmot    OBJECT IDENTIFIER ::= { mib-2 9 }
               transmission OBJECT IDENTIFIER ::= { mib-2 10 }
               snmp       OBJECT IDENTIFIER ::= { mib-2 11 }
               END

5.1.  The System Group

   Implementation of the System group is mandatory for all systems.


          OBJECT:
          -------
               sysDescr { system 1 }

          Syntax:
               DisplayString (SIZE (0..255))

          Definition:
               A textual description of the entity.  This value should
               include the full name and version identification of the
               system's hardware type, software operating-system, and
               networking software.  It is mandatory that this only
               contain printable ASCII characters.

          Access:
               read-only.

          Status:
               mandatory.

Top       Page 12 
          OBJECT:
          -------
               sysObjectID { system 2 }

          Syntax:
               OBJECT IDENTIFIER

          Definition:
               The vendor's authoritative identification of the network
               management subsystem contained in the entity.  This value
               is allocated within the SMI enterprises subtree
               (1.3.6.1.4.1) and provides an easy and unambiguous means
               for determining "what kind of box" is being managed.  For
               example, if vendor "Flintstones, Inc." was assigned the
               subtree 1.3.6.1.4.1.4242, it could assign the identifier
               1.3.6.1.4.1.4242.1.1 to its "Fred Router".

          Access:
               read-only.

          Status:
               mandatory.


          OBJECT:
          -------
               sysUpTime { system 3 }

          Syntax:
               TimeTicks

          Definition:
               The time (in hundredths of a second) since the network
               management portion of the system was last re-initialized.

          Access:
               read-only.

          Status:
               mandatory.


          OBJECT:
          -------
               sysContact { system 4 }

          Syntax:
               DisplayString (SIZE (0..255))

Top       Page 13 
          Definition:
               The textual identification of the contact person for this
               managed node, together with information on how to contact
               this person.

          Access:
               read-write.

          Status:
               mandatory.


          OBJECT:
          -------
               sysName { system 5 }

          Syntax:
               DisplayString (SIZE (0..255))

          Definition:
               An administratively-assigned name for this managed node.
               By convention, this is the node's fully-qualified domain
               name.

          Access:
               read-write.

          Status:
               mandatory.


          OBJECT:
          -------
               sysLocation { system 6 }

          Syntax:
               DisplayString (SIZE (0..255))

          Definition:
               The physical location of this node (e.g., "telephone
               closet, 3rd floor").

          Access:
               read-only.

          Status:
               mandatory.

Top       Page 14 
          OBJECT:
          -------
               sysServices { system 7 }

          Syntax:
               INTEGER (0..127)

          Definition:
               A value which indicates the set of services that this
               entity potentially offers.  The value is a sum.  This
               sum initially takes the value zero, Then, for each layer,
               L, in the range 1 through 7, that this node performs
               transactions for, 2 raised to (L - 1) is added to the
               sum.  For example, a node which performs only routing
               functions would have a value of 4 (2^(3-1)).  In
               contrast, a node which is a host offering application
               services would have a value of 72 (2^(4-1) + 2^(7-1)).
               Note that in the context of the Internet suite of
               protocols, values should be calculated accordingly:

                    layer  functionality
                    1      physical (e.g., repeaters)
                    2      datalink/subnetwork (e.g., bridges)
                    3      internet (e.g., supports the IP)
                    4      end-to-end  (e.g., supports the TCP)
                    7      applications (e.g., supports the SMTP)

               For systems including OSI protocols, layers 5 and 6 may
               also be counted.

          Access:
               read-only.

          Status:
               mandatory.

5.2.  The Interfaces Group

   Implementation of the Interfaces group is mandatory for all systems.


          OBJECT:
          -------
               ifNumber { interfaces 1 }

          Syntax:
               INTEGER

Top       Page 15 
          Definition:
               The number of network interfaces (regardless of their
               current state) present on this system.

          Access:
               read-only.

          Status:
               mandatory.

5.2.1.  The Interfaces table

   The Interfaces table contains information on the entity's interfaces.
   Each interface is thought of as being attached to a "subnetwork".
   Note that this term should not be confused with "subnet" which refers
   to an addressing partitioning scheme used in the Internet suite of
   protocols.


          OBJECT:
          -------
               ifTable { interfaces 2 }

          Syntax:
               SEQUENCE OF IfEntry

          Definition:
               A list of interface entries.  The number of entries is
               given by the value of ifNumber.

          Access:
               read-only.

          Status:
               mandatory.


          OBJECT:
          -------
               ifEntry { ifTable 1 }

Top       Page 16 
          Syntax:
               IfEntry ::= SEQUENCE {
                    ifIndex
                        INTEGER,
                    ifDescr
                        DisplayString,
                    ifType
                        INTEGER,
                    ifMtu
                        INTEGER,
                    ifSpeed
                        Gauge,
                    ifPhysAddress
                        OCTET STRING,
                    ifAdminStatus
                        INTEGER,
                    ifOperStatus
                        INTEGER,
                    ifLastChange
                        TimeTicks,
                    ifInOctets
                        Counter,
                    ifInUcastPkts
                        Counter,
                    ifInNUcastPkts
                        Counter,
                    ifInDiscards
                        Counter,
                    ifInErrors
                        Counter,
                    ifInUnknownProtos
                        Counter,
                    ifOutOctets
                        Counter,
                    ifOutUcastPkts
                        Counter,
                    ifOutNUcastPkts
                        Counter,
                    ifOutDiscards
                        Counter,
                    ifOutErrors
                        Counter,
                    ifOutQLen
                        Gauge,
                    ifSpecific
                        OBJECT IDENTIFIER
               }

Top       Page 17 
          Definition:
               An interface entry containing objects at the subnetwork
               layer and below for a particular interface.

          Access:
               read-only.

          Status:
               mandatory.


          We now consider the individual components of each interface
          entry:


          OBJECT:
          -------
               ifIndex { ifEntry 1 }

          Syntax:
               INTEGER

          Definition:
               A unique value for each interface.  Its value ranges
               between 1 and the value of ifNumber.  The value for each
               interface must remain constant at least from one re-
               initialization of the entity's network management system
               to the next re-initialization.

          Access:
               read-only.

          Status:
               mandatory.


          OBJECT:
          -------
               ifDescr { ifEntry 2 }

          Syntax:
               DisplayString (SIZE (0..255))

          Definition:
               A textual string containing information about the
               interface.  This string should include the name of the
               manufacturer, the product name and the version of the
               hardware interface.

Top       Page 18 
          Access:
               read-only.

          Status:
               mandatory.


          OBJECT:
          -------
               ifType { ifEntry 3 }

          Syntax:
               INTEGER {
                    other(1),          -- none of the following
                    regular1822(2),
                    hdh1822(3),
                    ddn-x25(4),
                    rfc877-x25(5),
                    ethernet-csmacd(6),
                    iso88023-csmacd(7),
                    iso88024-tokenBus(8),
                    iso88025-tokenRing(9),
                    iso88026-man(10),
                    starLan(11),
                    proteon-10Mbit(12),
                    proteon-80Mbit(13),
                    hyperchannel(14),
                    fddi(15),
                    lapb(16),
                    sdlc(17),
                    t1-carrier(18),
                    cept(19),          -- european equivalent of T-1
                    basicISDN(20),
                    primaryISDN(21),
                                        -- proprietary serial
                    propPointToPointSerial(22),
                    ppp(23),
                    softwareLoopback(24),
                    eon(25),            -- CLNP over IP [12]
                    ethernet-3Mbit(26)
                    nsip(27),           -- XNS over IP
                    slip(28)            -- generic SLIP
               }

          Definition:
               The type of interface, distinguished according to the
               physical/link protocol(s) immediately "below" the network
               layer in the protocol stack.

Top       Page 19 
          Access:
               read-only.

          Status:
               mandatory.


          OBJECT:
          -------
               ifMtu { ifEntry 4 }

          Syntax:
               INTEGER

          Definition:
               The size of the largest datagram which can be
               sent/received on the interface, specified in octets.  For
               interfaces that are used for transmitting network
               datagrams, this is the size of the largest network
               datagram that can be sent on the interface.

          Access:
               read-only.

          Status:
               mandatory.


          OBJECT:
          -------
               ifSpeed { ifEntry 5 }

          Syntax:
               Gauge

          Definition:
               An estimate of the interface's current bandwidth in bits
               per second.  For interfaces which do not vary in
               bandwidth or for those where no accurate estimation can
               be made, this object should contain the nominal
               bandwidth.

          Access:
               read-only.

          Status:
               mandatory.

Top       Page 20 
          OBJECT:
          -------
               ifPhysAddress { ifEntry 6 }

          Syntax:
               OCTET STRING

          Definition:
               The interface's address at the protocol layer immediately
               "below" the network layer in the protocol stack.  For
               interfaces which do not have such an address (e.g., a
               serial line), this object should contain an octet string
               of zero length.

          Access:
               read-only.

          Status:
               mandatory.


          OBJECT:
          -------
               ifAdminStatus { ifEntry 7 }

          Syntax:
               INTEGER {
                    up(1),       -- ready to pass packets
                    down(2),
                    testing(3)   -- in some test mode
               }

          Definition:
               The desired state of the interface.  The testing(3) state
               indicates that no operational packets can be passed.

          Access:
               read-write.

          Status:
               mandatory.


          OBJECT:
          -------
               ifOperStatus { ifEntry 8 }

Top       Page 21 
          Syntax:
               INTEGER {
                    up(1),       -- ready to pass packets
                    down(2),
                    testing(3)   -- in some test mode
               }

          Definition:
               The current operational state of the interface.  The
               testing(3) state indicates that no operational packets
               can be passed.

          Access:
               read-only.

          Status:
               mandatory.


          OBJECT:
          -------
               ifLastChange { ifEntry 9 }

          Syntax:
               TimeTicks

          Definition:
               The value of sysUpTime at the time the interface entered
               its current operational state.  If the current state was
               entered prior to the last re-initialization of the local
               network management subsystem, then this object contains a
               zero value.

          Access:
               read-only.

          Status:
               mandatory.


          OBJECT:
          -------
               ifInOctets { ifEntry 10 }

          Syntax:
               Counter

Top       Page 22 
          Definition:
               The total number of octets received on the interface,
               including framing characters.

          Access:
               read-only.

          Status:
               mandatory.


          OBJECT:
          -------
               ifInUcastPkts  { ifEntry 11 }

          Syntax:
               Counter

          Definition:
               The number of subnetwork-unicast packets delivered to a
               higher-layer protocol.

          Access:
               read-only.

          Status:
               mandatory.


          OBJECT:
          -------
               ifInNUcastPkts { ifEntry 12 }

          Syntax:
               Counter

          Definition:
               The number of non-unicast (i.e., subnetwork-broadcast or
               subnetwork-multicast) packets delivered to a higher-layer
               protocol.

          Access:
               read-only.

          Status:
               mandatory.

Top       Page 23 
          OBJECT:
          -------
               ifInDiscards { ifEntry 13 }

          Syntax:
               Counter

          Definition:
               The number of inbound packets which were chosen to be
               discarded even though no errors had been detected to
               prevent their being deliverable to a higher-layer
               protocol.  One possible reason for discarding such a
               packet could be to free up buffer space.

          Access:
               read-only.

          Status:
               mandatory.


          OBJECT:
          -------
               ifInErrors { ifEntry 14 }

          Syntax:
               Counter

          Definition:
               The number of inbound packets that contained errors
               preventing them from being deliverable to a higher-layer
               protocol.

          Access:
               read-only.

          Status:
               mandatory.


          OBJECT:
          -------
               ifInUnknownProtos { ifEntry 15 }

          Syntax:
               Counter

Top       Page 24 
          Definition:
               The number of packets received via the interface which
               were discarded because of an unknown or unsupported
               protocol.

          Access:
               read-only.

          Status:
               mandatory.


          OBJECT:
          -------
               ifOutOctets { ifEntry 16 }

          Syntax:
               Counter

          Definition:
               The total number of octets transmitted out of the
               interface, including framing characters.

          Access:
               read-only.

          Status:
               mandatory.


          OBJECT:
          -------
               ifOutUcastPkts { ifEntry 17 }

          Syntax:
               Counter

          Definition:
               The total number of packets that higher-level protocols
               requested be transmitted to a subnetwork-unicast address,
               including those that were discarded or not sent.

          Access:
               read-only.

          Status:
               mandatory.

Top       Page 25 
          OBJECT:
          -------
               ifOutNUcastPkts { ifEntry 18 }

          Syntax:
               Counter

          Definition:
               The total number of packets that higher-level protocols
               requested be transmitted to a non-unicast (i.e., a
               subnetwork-broadcast or subnetwork-multicast) address,
               including those that were discarded or not sent.

          Access:
               read-only.

          Status:
               mandatory.


          OBJECT:
          -------
               ifOutDiscards { ifEntry 19 }

          Syntax:
               Counter

          Definition:
               The number of outbound packets which were chosen to be
               discarded even though no errors had been detected to
               prevent their being transmitted.  One possible reason for
               discarding such a packet could be to free up buffer
               space.

          Access:
               read-only.

          Status:
               mandatory.


          OBJECT:
          -------
               ifOutErrors { ifEntry 20 }

          Syntax:
               Counter

Top       Page 26 
          Definition:
               The number of outbound packets that could not be
               transmitted because of errors.

          Access:
               read-only.

          Status:
               mandatory.


          OBJECT:
          -------
               ifOutQLen { ifEntry 21 }

          Syntax:
               Gauge

          Definition:
               The length of the output packet queue (in packets).

          Access:
               read-only.

          Status:
               mandatory.


          OBJECT:
          -------
               ifSpecific { ifEntry 22 }

          Syntax:
               OBJECT IDENTIFIER

          Definition:
               A reference to MIB definitions specific to the particular
               media being used to realize the interface.  For example,
               if the interface is realized by an ethernet, then the
               value of this object refers to a document defining
               objects specific to ethernet.  If an agent is not
               configured to have a value for any of these variables,
               the object identifier

                    nullSpecific OBJECT IDENTIFIER ::= { 0 0 }

               is returned.  Note that "nullSpecific" is a syntatically
               valid object identifier, and any conformant

Top       Page 27 
               implementation of ASN.1 and BER must be able to generate
               and recognize this value.

          Access:
               read-only.

          Status:
               mandatory.



(page 27 continued on part 2)

Next RFC Part