rfc1316.txt

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Network Working Group                                 B. Stewart, Editor
Request for Comments: 1316                                  Xyplex, Inc.
                                                              April 1992


                     Definitions of Managed Objects
                      for Character Stream Devices

Status of this Memo

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

1.  Abstract

   This memo defines a portion of the Management Information Base (MIB)
   for use with network management protocols in TCP/IP based internets.
   In particular it defines objects for the management of character
   stream devices.

2.  The Network Management Framework

   The Internet-standard Network Management Framework consists of three
   components.  They are:

   RFC 1155 which defines the SMI, the mechanisms used for describing
   and naming objects for the purpose of management. RFC 1212 defines a
   more concise description mechanism, which is wholly consistent with
   the SMI.

   RFC 1156 which defines MIB-I, the core set of managed objects for the
   Internet suite of protocols.  RFC 1213, defines MIB-II, an evolution
   of MIB-I based on implementation experience and new operational
   requirements.

   RFC 1157 which defines the SNMP, the protocol used for network access
   to managed objects.

   The Framework permits new objects to be defined for the purpose of
   experimentation and evaluation.

3.  Objects

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



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RFC 1316                     Character MIB                    April 1992


   defined using the subset of Abstract Syntax Notation One (ASN.1) [7]
   defined in 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 SMI [3] 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.

   The SMI specifies the use of the basic encoding rules of ASN.1 [8],
   subject to the additional requirements imposed by the SNMP.

3.1.  Format of Definitions

   Section 5 contains the specification of all object types contained in
   this MIB module.  The object types are defined using the conventions
   defined in the SMI, as amended by the extensions specified in [9,10].

4.  Overview

   The Character MIB applies to interface ports that carry a character
   stream, whether physical or virtual, serial or parallel, synchronous
   or asynchronous.  The most common example of a character port is a
   hardware terminal port with an RS-232 interface.  Another common
   hardware example is a parallel printer port, say with a Centronics
   interface.  The concept also includes virtual terminal ports, such as
   a software connection point for a remote console.

   The Character MIB is one of a set of MIBs designed for complementary
   use.  At this writing, the set comprises:

        Character MIB
        PPP MIB
        RS-232-like MIB
        Parallel-printer-like MIB




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RFC 1316                     Character MIB                    April 1992


   The RS-232-like MIB and the Parallel-printer-like MIB represent the
   physical layer, providing service to higher layers such as the
   Character MIB or PPP MIB.  Further MIBs may appear above these.

   The following diagram shows two possible "MIB stacks", each using the
   RS-232-like MIB.

                                               .-----------------.
                    .-----------------.        |  Standard MIB   |
                    |   Telnet MIB    |        | Interface Group |
                    |-----------------|        |-----------------|
                    |  Character MIB  |        |     PPP MIB     |
                    |-----------------|        |-----------------|
                    | RS-232-like MIB |        | RS-232-like MIB |
                    `-----------------'        `-----------------'

   The intent of the model is for the physical-level MIBs to represent
   the lowest level, regardless of the higher level that may be using
   it.  In turn, separate higher level MIBs represent specific
   applications, such as a terminal (the Character MIB) or a network
   connection (the PPP MIB).

   For the most part, character ports are distinct from network
   interfaces (which are already covered by the Interface group).  In
   general, they are attachment points for non-network devices.  The
   exception is a character port that can support a network protocol,
   such as SLIP or PPP.  This implies the existence of a corresponding
   entry in the Interfaces table, with ifOperStatus of 'off' while the
   port is not running a network protocol and 'on' if it is.  The intent
   is that such usage is exclusive of non-network character stream
   usage.  That is, while switched to network use, charPortOperStatus
   would be 'down' and Character MIB operational values such as
   charPortInFlowState and charPortInCharacters would be inactive.

   The Character MIB is mandatory for all systems that offer character
   ports.  This includes, for example, terminal servers, general-purpose
   time-sharing hosts, and even such systems as a bridge with a
   (virtual) console port.  It may or may not include character ports
   that do not support network sessions, depending on the system's
   needs.

   The Character MIB's central abstraction is a port.  Physical ports
   have a one-to-one correspondence with hardware ports. Virtual ports
   are software entities analogous to physical ports, but with no
   hardware connector.

   Each port supports one or more sessions.  A session represents a
   virtual connection that carries characters between the port and some



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   partner.  Sessions typically operate over a stack of network
   protocols.  A typical session, for example, uses Telnet over TCP.

   The MIB comprises one base object and two tables, detailed in the
   following sections.  The tables contain objects for ports and
   sessions.

   The MIB intentionally contains no distinction between what is often
   called permanent and operational or volatile data bases.  For the
   purposes of this MIB, handling of such distinctions is implementation
   specific.

5.  Definitions

                    RFC1316-MIB DEFINITIONS ::= BEGIN

                    IMPORTS
                            Counter, TimeTicks, Gauge
                                    FROM RFC1155-SMI
                            DisplayString
                                    FROM RFC1213-MIB
                            OBJECT-TYPE
                                    FROM RFC-1212;

            -- this is the MIB module for character stream devices

            char    OBJECT IDENTIFIER ::= { mib-2 19 }

            -- Textual Conventions

                AutonomousType    ::= OBJECT IDENTIFIER

            -- The object identifier is an independently extensible type
            -- identification value.  It may, for example indicate a
            -- particular sub-tree with further MIB definitions, or
            -- define something like a protocol type or type of
            -- hardware.

                InstancePointer   ::= OBJECT IDENTIFIER

            -- The object identifier is a pointer to a specific instance
            -- of a MIB object in this agent's implemented MIB.  By
            -- convention, it is the first object in the conceptual row
            -- for the instance.







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RFC 1316                     Character MIB                    April 1992


            -- the generic Character group

            -- Implementation of this group is mandatory for all
            -- systems that offer character ports

            charNumber OBJECT-TYPE
                SYNTAX INTEGER
                ACCESS read-only
                STATUS mandatory
                DESCRIPTION
                    "The number of entries in charPortTable, regardless
                    of their current state."
                ::= { char 1 }


            -- the Character Port table

            charPortTable OBJECT-TYPE
                SYNTAX SEQUENCE OF CharPortEntry
                ACCESS not-accessible
                STATUS mandatory
                DESCRIPTION
                    "A list of port entries.  The number of entries is
                    given by the value of charNumber."
                ::= { char 2 }

            charPortEntry OBJECT-TYPE
                SYNTAX CharPortEntry
                ACCESS not-accessible
                STATUS mandatory
                DESCRIPTION
                    "Status and parameter values for a character port."
                INDEX { charPortIndex }
                ::= { charPortTable 1 }

            CharPortEntry ::=
                SEQUENCE {
                    charPortIndex
                        INTEGER,
                    charPortName
                        DisplayString,
                    charPortType
                        INTEGER,
                    charPortHardware
                        AutonomousType,
                    charPortReset
                        INTEGER,
                    charPortAdminStatus



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RFC 1316                     Character MIB                    April 1992


                        INTEGER,
                    charPortOperStatus
                        INTEGER,
                    charPortLastChange
                        TimeTicks,
                    charPortInFlowType
                        INTEGER,
                    charPortOutFlowType
                        INTEGER,
                    charPortInFlowState
                        INTEGER,
                    charPortOutFlowState
                        INTEGER,
                    charPortInCharacters
                        Counter,
                    charPortOutCharacters
                        Counter,
                    charPortAdminOrigin
                        INTEGER,
                    charPortSessionMaximum
                        INTEGER,
                    charPortSessionNumber
                        Gauge,
                    charPortSessionIndex
                        INTEGER
                }

            charPortIndex OBJECT-TYPE
                SYNTAX INTEGER
                ACCESS read-only
                STATUS mandatory
                DESCRIPTION
                    "A unique value for each character port.  Its value