rfc1471.txt

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

Network Working Group                                      F. Kastenholz
Request for Comments: 1471                            FTP Software, Inc.
                                                               June 1993


                 The Definitions of Managed Objects for
                      the Link Control Protocol of
                      the Point-to-Point Protocol

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.

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 describes managed objects used for managing the
   Link Control Protocol and Link Quality Monitoring on subnetwork
   interfaces that use the family of Point-to-Point Protocols [8, 9, 10,
   11, & 12].

Table of Contents

   1. The Network Management Framework ......................    2
   2. Objects ...............................................    2
   2.1 Format of Definitions ................................    2
   3. Overview ..............................................    2
   3.1 Object Selection Criteria ............................    2
   3.2 Structure of the PPP .................................    3
   3.3 MIB Groups ...........................................    4
   3.4 Relationship to Interface and Interface Extensions
       Groups ...............................................    5
   4. Definitions ...........................................    6
   4.1 PPP Link Group .......................................    7
   4.2 PPP LQR Group ........................................   16
   4.3 PPP LQR Extensions Group .............................   21
   4.4 PPP Tests ............................................   22
   4.4.1 PPP Echo Test ......................................   22
   4.4.2 PPP Discard Test ...................................   23
   5. Acknowledgements ......................................   23
   6. Security Considerations ...............................   23
   7. References ............................................   24
   8. Author's Address ......................................   25



Kastenholz                                                      [Page 1]

RFC 1471                      PPP/LCP MIB                      June 1993


1.  The Network Management Framework

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

      STD 16/RFC 1155 which defines the SMI, the mechanisms used for
      describing and naming objects for the purpose of management.  STD
      16/RFC 1212 defines a more concise description mechanism, which is
      wholly consistent with the SMI.

      STD 17/RFC 1213 which defines MIB-II, the core set of managed
      objects for the Internet suite of protocols.

      STD 15/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.

2.  Objects

   Managed objects are accessed via a virtual information store, termed
   the Management Information Base or MIB.  Objects in the MIB are
   defined using the subset of Abstract Syntax Notation One (ASN.1) [3]
   defined in the SMI.  In particular, each object type is named by an
   OBJECT IDENTIFIER, an administratively assigned name.  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 descriptor, to refer to the
   object type.

2.1.  Format of Definitions

   Section 4 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 [5,6].

3.  Overview

3.1.  Object Selection Criteria

   To be consistent with IAB directives and good engineering practice,
   an explicit attempt was made to keep this MIB as simple as possible.
   This was accomplished by applying the following criteria to objects
   proposed for inclusion:

      (1)  Require objects be essential for either fault or
           configuration management.  In particular, objects for



Kastenholz                                                      [Page 2]

RFC 1471                      PPP/LCP MIB                      June 1993


           which the sole purpose was to debug implementations were
           explicitly excluded from the MIB.

      (2)  Consider evidence of current use and/or utility.

      (3)  Limit the total number of objects.

      (4)  Exclude objects which are simply derivable from others in
           this or other MIBs.

3.2.  Structure of the PPP

   This section describes the basic model of PPP used in developing the
   PPP MIB. This information should be useful to the implementor in
   understanding some of the basic design decisions of the MIB.

   The PPP is not one single protocol but a large family of protocols.
   Each of these is, in itself, a fairly complex protocol.  The PPP
   protocols may be divided into three rough categories:

   Control Protocols
      The Control Protocols are used to control the operation of the
      PPP. The Control Protocols include the Link Control Protocol
      (LCP), the Password Authentication Protocol (PAP), the Link
      Quality Report (LQR), and the Challenge Handshake Authentication
      Protocol (CHAP).

   Network Protocols
      The Network Protocols are used to move the network traffic over
      the PPP interface.  A Network Protocol encapsulates the datagrams
      of a specific higher-layer protocol that is using the PPP as a
      data link.  Note that within the context of PPP, the term "Network
      Protocol" does not imply an OSI Layer-3 protocol; for instance,
      there is a Bridging network protocol.

   Network Control Protocols (NCPs)
      The NCPs are used to control the operation of the Network
      Protocols. Generally, each Network Protocol has its own Network
      Control Protocol; thus, the IP Network Protocol has its IP Control
      Protocol, the Bridging Network Protocol has its Bridging Network
      Control Protocol and so on.

   This document specifies the objects used in managing one of these
   protocols, namely the Link Control Protocol and Link Quality
   Monitoring Protocol.






Kastenholz                                                      [Page 3]

RFC 1471                      PPP/LCP MIB                      June 1993


3.3.  MIB Groups

   Objects in this MIB are arranged into several MIB groups.  Each group
   is organized as a set of related objects.

   These groups are the basic unit of conformance: if the semantics of a
   group are applicable to an implementation then all objects in the
   group must be implemented.

   The PPP MIB is organized into several MIB Groups, including, but not
   limited to, the following groups:

          o The PPP Link Group
          o The PPP LQR Group
          o The PPP LQR Extensions Group
          o The PPP IP Group
          o The PPP Bridge Group
          o The PPP Security Group

   This document specifies the following groups:

   The PPP Link Group
      This group represents the lowest "level" of the PPP protocol.

      This group contains two tables, one containing status information
      and the other configuration information.  The configuration table
      is split off of the status so that it may be placed in a separate
      MIB View for security purposes.

      Implementation of this group is mandatory for all PPP
      implementations.

   The PPP LQR Group
      This group provides the basic MIB variables that apply to the PPP
      LQR Protocol.  This group provides MIB access to the information
      required for LQR processing. This group contains two tables, one
      containing status information and the other configuration
      information.  The configuration table is split off of the status
      so that it may be placed in a separate MIB View for security
      purposes.

      Implementation of the PPP LQR Group is mandatory for all PPP
      implementations that implement LQR.

   The PPP LQR Extensions Group
      The PPP LQR Extensions group contains the most recently received
      LQR packet, as well as the "save" fields that are "logically
      appended" [12] to received LQR packets.  This is done in order to



Kastenholz                                                      [Page 4]

RFC 1471                      PPP/LCP MIB                      June 1993


      facilitate external implementations of the Link Quality Monitoring
      policies.

      It is not practical to examine the relevant MIB objects which are
      used to generate LQR packets since LQR policies may require
      synchronization of the values of all data used to determine Link
      Quality; i.e., the values of the relevant counters must all be
      taken at the same instant in time.  Thus, by recording the last
      received LQR packet, a synchronized record of the relevant data is
      available.

      As this information may not be efficiently maintained on all PPP
      implementations, implementation of this group is optional.

3.4.  Relationship to Interface and Interface Extensions
      Groups

   The PPP Mib is a medium-specific extension to the standard MIB-2
   interface group [2] and to the Interface Extensions MIB [7].  This
   section discusses certain components of these groups when the
   interface is a PPP interface.

   The PPP interface represents a single interface in the sense used in
   [2] and thus has a single entry in the ifTable.

   Furthermore, the PPP interface may be operating over a lower layer
   hardware interface (such as an RS-232 port).  It is important to
   capture the relationship between the PPP interface and the lower-
   layer interface over which it operates.  This MIB presumes that the
   lower-layer interface has an ifEntry associated with it.  The lower-
   layer ifEntry is identified via the pppLinkStatusPhysicalIndex
   object, which contains the value of ifIndex for the lower-layer
   ifEntry.

   For example, suppose that you run PPP over a RS-232 port.  This would
   use two entries in the ifTable.  Let's suppose that entry number 123
   is for the PPP "interface" and entry number 987 is for the RS-232
   port.  So, ifSpecific.123 would contain the ppp OBJECT IDENTIFIER,
   pppLinkStatusPhysicalIndex.123 would contain 987, and ifSpecific.987
   would contain the rs_232 OBJECT IDENTIFIER (or whatever it is).

   All PPP packets are defined in [8] as being broadcast packets.  Thus,
   the packets are counted as non-unicast packets in the ifTable
   (ifInNUcastPkts and ifOutNUCastPkts) and as broadcasts in the
   ifExtnsTable (ifExtnsBroadcastsReceivedOks and
   ifExtnsBroadcastsTransmittedOks).





Kastenholz                                                      [Page 5]

RFC 1471                      PPP/LCP MIB                      June 1993


   ifSpecific
      Contains the OBJECT IDENTIFIER ppp.

   ifAdminStatus
      Setting this object to up will inject an administrative open event
      into the LCP's finite state machine.  Setting this object to down
      will inject an administrative close event into the LCP's finite
      state machine.

      The use of the testing value is beyond the scope of this document.

   ifOperStatus
      Represents the state of the LCP Finite State Machine.  If the
      Finite State Machine is in the Opened state then the value of
      ifOperStatus is up, otherwise the value of ifOperStatus is down.

      The meaning of the testing value is beyond the scope of this
      document.

   Per the SNMP Protocol Specification [13], the linkUp and linkDown
   traps apply to the PPP Protocol entity.  When the LCP's Finite State
   Machine attains the Opened state, a linkUp trap should be sent. When
   the Finite State Machine leaves the Opened state, a linkDown trap
   should be sent.

   Some tests for the link are defined in this document.  Execution of
   these tests does not place the link's ifOperStatus in the testing
   state as these tests do not prevent normal data transmission from
   occuring over the link.

4.  Definitions

          PPP-LCP-MIB DEFINITIONS ::= BEGIN

          IMPORTS
               Counter
                    FROM RFC1155-SMI
               ifIndex, transmission
                    FROM RFC1213-MIB
               OBJECT-TYPE
                    FROM RFC-1212;

               --  PPP MIB

               ppp  OBJECT IDENTIFIER ::= { transmission 23 }

               pppLcp OBJECT IDENTIFIER ::= { ppp 1 }




Kastenholz                                                      [Page 6]

RFC 1471                      PPP/LCP MIB                      June 1993


               -- The individual groups within the PPP-LCP-MIB

               pppLink      OBJECT IDENTIFIER ::= { pppLcp 1 }
               pppLqr       OBJECT IDENTIFIER ::= { pppLcp 2 }
               pppTests     OBJECT IDENTIFIER ::= { pppLcp 3 }


          -- 4.1.  PPP Link Group