rfc1158.txt

<VC++网络游戏建摸与实现>源代码

   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



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   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




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               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.



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          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))



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          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.




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          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




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          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 }











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          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
               }




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          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: