Network Working Group
Request for Comments: 2513
Category: Standards Track
K. McCloghrie
Cisco Systems, Inc.
J. Heinanen
Telia Finland, Inc.
W. Greene
MCI Telecommunications Corp.
A. Prasad
Cisco Systems, Inc.
February 1999

Managed Objects for Controlling the Collection

and Storage of Accounting Information for

Connection-Oriented Networks

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 © The Internet Society (1999). All Rights Reserved.

Table of Contents

   1 Introduction .................................................... 2
   2 The SNMP Network Management Framework ........................... 2
   3 Overview ........................................................ 3
   3.1 Operational Model ............................................. 3
   3.2 Selection of Accounting Data .................................. 5
   3.3 Format of Collection File ..................................... 6
   4 Definitions ..................................................... 9
   5 Acknowledgements ................................................25
   6 References ......................................................25
   7 Security Considerations .........................................27
   8 IANA Considerations .............................................27
   9 Authors' Addresses ..............................................28
   10 Full Copyright Statement .......................................29

1. Introduction

This memo defines a portion of the Management Information Base (MIB) for use with network management protocols in the Internet community. In particular, it describes managed objects used for controlling the collection and storage of accounting information for connection- oriented networks such as ATM. The accounting data is collected into files for later retrieval via a file transfer protocol. For information on data which can be collected for ATM networks, see [19].

2. The SNMP Network Management Framework

The SNMP Management Framework presently consists of five major components:

   o    An overall architecture, described in RFC 2271 [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 RFC 1902 [5],
        RFC 1903 [6] and RFC 1904 [7].
   
   o    Message protocols for transferring management information.  The
        first version of the SNMP message protocol is called SNMPv1 and
        described in STD 15, 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 2272 [11] and
        RFC 2274 [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 2273 [14] and
        the view-based access control mechanism described in RFC 2275
        [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 (e.g., 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.

3. Overview

In some connection-oriented network environments, there is a need for the network administrator to be able to collect accounting data on the usage of bandwidth/resources by connections (e.g., ATM connections) within the network. Data collection should be available for switched virtual connections (SVCs and SVPs), and permanent virtual connections (PVCs and PVPs), including soft-permanent virtual connections (SPVCCs and SPVPCs). This need exists for ATM networks, and may well exist for other connection-oriented networks, such as Frame Relay.

The potential quantity of such accounting information is such that it is not, in general, feasible to retrieve the information via SNMP. A better method is to store the collected accounting information in a file which can be subsequently retrieved via a file transfer protocol.

It is, however, appropriate to provide management control of the selection and collection of such accounting data via SNMP. This memo describes a MIB module which provides such control in a manner independent of the type of network. One or more other documents provide definitions of particular items of accounting data which can be selected; for example, a particular set of data items which can be collected for ATM networks is specified in [19].

3.1. Operational Model

The requirement is for switches (e.g., ATM switches) to collect data concerning the connections which are routed across some subset of their interfaces (e.g., ATM UNI and/or NNI interfaces). The collected data is stored into one or more "files". The use of multiple files allows, for example, the data collected for PVCs to be different from that collected for SVCs.

In order to retrieve the data currently being stored in a file, the administrator instructs the switch to terminate the collection of data into that file, and start collecting data into a new file.

After this operation, the data in the old file is available for retrieval via file transfer.

A collection file is defined to have a maximum size. When the size of the file currently being collected exceeds a threshold percentage of that maximum size, an SNMP notification (e.g., a trap) can be optionally generated. An SNMP notification might also be generated if the file reaches its maximum size.

The accounting data collected for each connection consists of a set of objects and their values. The set of objects and their values are collected on one or more of the following occasions:

(1) on the release (termination) of a connection optionally

including failed connection attempts;

(2) for each active connection (having a particular minimum age) on

        a periodic basis;

(3) for each active connection (having a particular minimum age)

when so commanded by a management application.

While collecting data to be stored in a particular file, the same set of objects is collected for each connection on each occasion. Having the same set of objects stored on each occasion allows the optimization of storing only the values of those objects. This results in a significantly smaller file size, since it allows the names of the objects to be stored once and only once at the beginning of the file, rather than having to store every value as a (name, value) pair.

Two modes of agent behaviour are allowed on the event of a file reaching its maximum size:

(1) management application in control:

The agent does not automatically swap to a new file; rather, it discards newly collected data until the management application subsequently instructs it to swap to a new file. Before swapping to a new file, the name of the file into which data is currently being collected is an implementation issue of no concern to an NM application; after swapping to a new file, the name of the file available for retrieval is as specified by the controlling MIB objects. This behaviour allows the application to know exactly how many files need to be retrieved and their names without having to perform any type of file directory operation, but also results in the possibility that data will be discarded if the application does not instruct the agent to swap within the required time frame.

(2) agent automatically swaps to new file:

The agent terminates collection into the current (full) file, and begins collecting data into a new version of the same base file name. This behaviour aims to avoid loss of data by assuming that additional storage space is actually available to create a new version of the file. To support this behaviour, files are named using suffixes, such that when the current version of the file becomes full, the agent begins collecting data into a file with the same base file-name but with an incremented (or otherwise modified) suffix. This requires the application to perform file directory operations prior to retrieving completed files in order to know how many and which suffixes have been used.

With either behaviour, any completed file must be an integral number of connection records (see below). When a file reaches its maximum size, collection into that file is terminated either immediately before or immediately after storing the whole of the current connection record into the file. The former causes the file to be just less than its maximum size, and the latter causes the file to be just greater than its maximum size.

3.2. Selection of Accounting Data

The items of accounting data to be collected are specified as a set of objects. Which objects are contained in such a set is selectable by an administrator through the specification of one or more (subtree, list) tuples, where the set of objects to be collected is the union of the subsets specified by each tuple:

'subtree' specifies an OBJECT IDENTIFIER value such that every

object in the subset is named by the subtree's value appended with a single additional sub-identifier.

'list' specifies an OCTET STRING value, such that if the N-th bit

of the string's value is set then the the subset contains the object named by appending N as a single additional sub- identifier to the subtree.

The rationale for defining each subset as a (subtree,list) tuple is that one and only one OBJECT IDENTIFIER and one OCTET STRING is needed to define the subset of objects. This simplifies the MIB mechanisms needed for selection: an NM application needs to create only one conceptual row in a MIB table for each subset (rather than needing to create a conceptual row in a table for each and every object in the set).

The number of tuples supported by a particular switch is an implementation choice. One possibility is to support two (subtree, list) tuples so that one such tuple can specify a standard 'subtree' (e.g., the atmAcctngDataObjects subtree defined in [19]), and the second tuple can specify an enterprise-specific 'subtree'; this would allow the selected set of objects to be the union of a set of standard objects and a set of enterprise-defined objects.

3.3. Format of Collection File

A collection file generated by this process contains the values of MIB objects defined using the SMIv2. The standard way to encode the values of SNMP MIB objects in a device-independent manner is through the use of ASN.1's Basic Encoding Rules (BER) [18]. Thus, the standard format of an accounting file is defined here using the same adapted subset of ASN.1 [17] as the SMIv2.

The file consists of a set of header information followed by a sequence of zero or more collection records. The header information identifies (via sysName [16]) the switch which collected the data, the date and time at which the collection in to this file started, and the sequence of one or more (subtree, list) tuples identifying the objects whose values are contained in each connection record. The header information also includes a textual description of the data contained in the file.

Each connection record contains a sequence of values for each identified tuple, in the same order as the tuples are identified in the header information. For each tuple, the sequence of values are in ascending order of the sub-identifier which identifies them within the subtree.

Formally, an accounting file is an ASN.1 value with the following syntax:

File ::=

[1]

IMPLICIT SEQUENCE {

                           -- header information
          sysName               -- name of the switch
              DisplayString,
          
          description           -- textual description of the collection
              DisplayString,

startTime -- start time of the collection

DateAndTime,

          SEQUENCE OF {         -- sequence of (subtree, list) tuples
              SEQUENCE {
                  subtree
                      OBJECT IDENTIFIER,
                  list
                      OCTET STRING
              }
          }
                           -- sequence of connection records
          SEQUENCE OF {
                                -- each record containing a sequence
              SEQUENCE OF {     -- per identified tuple
      
                  SEQUENCE OF {     -- each per-tuple sequence containing
                      value         -- a sequence of object values
                          ObjectSyntax
                  }
              }
          }
      }

where:

(1) the value of the sysName component is that of the sysName object

in the System group [16].

(2) each (subtree, list) specifies the set of objects contained in

that tuple's sequence within each and every connection record.

(3) the tuples' sequences within each connection record occur in the

same order as the (subtree, list) tuples occur in the header information.

(4) the object values within each connection record occur in the

same order as they are represented by the bits in the corresponding list value.

(5) ObjectSyntax is defined by the SMIv2 [5].

(6) One particular category of object values deserves special

attention: an object defined to hold the checksum value of an accounting record (e.g., atmAcctngRecordCrc16, defined in [19]). An object in this category will generally have a SYNTAX of a fixed-length OCTET STRING, and have its value initialized to the string of all zeros when composing the accounting record containing it, with the location of these zeros being saved.

Once the record is generated, the checksum is calculated over the whole connection record (including the starting SEQUENCE OF and the trailing end-of-contents octets, if used), and then the zeros are overwritten (at the saved location) by the calculated value of the checksum.

The encoding of the above syntax using the Basic Encoding Rules is the same as defined by the SNMPv2 [10], with the following exception:

  • when encoding the length field for a structured type, i.e., a SEQUENCE or SEQUENCE OF, the indefinite form encoding is permitted.

For example, the file containing the data:

   [1] IMPLICIT SEQUENCE     a1 80
         OCTET STRING        04 09 73 77 69 74 63 68 2d 31 32
         OCTET STRING        04 0a 41 63 63 6f 75 6e 74 69 6e 67
         OCTET STRING        04 08 07 cc 07 14 10 05 00 00
         SEQUENCE OF         30 0e
           SEQUENCE             30 0c
             OBJECT IDENTIFIER     06 07 2b 06 01 03 7f 01 01
             OCTET STRING          04 01 c0
         SEQUENCE OF         30 80
           SEQUENCE OF          30 08
             SEQUENCE OF           30 06
               INTEGER                02 01 00
               INTEGER                02 01 21
           SEQUENCE OF          30 08
             SEQUENCE OF           30 06
               INTEGER                02 01 00
               INTEGER                02 01 22
         end-of-contents     00 00
       end-of-contents       00 00

contains two connection records, each containing one tuple listing two (integer) data items in a (fictitious) subtree: 1.3.6.1.3.127.1.1. Its header indicates it's for "switch-12", with description "Accounting", and was collected at 16:05:00 on 20 July 1996.

As well as the standard format defined above, the MIB allows other enterprise-specific formats to be used.

4. Definitions

ACCOUNTING-CONTROL-MIB DEFINITIONS ::= BEGIN

IMPORTS

    MODULE-IDENTITY, OBJECT-TYPE, NOTIFICATION-TYPE,
    mib-2, Integer32                              FROM SNMPv2-SMI
    TEXTUAL-CONVENTION, RowStatus, TestAndIncr,
    DisplayString, TruthValue                     FROM SNMPv2-TC
    MODULE-COMPLIANCE, OBJECT-GROUP, NOTIFICATION-GROUP
                                                  FROM SNMPv2-CONF
    ifIndex                                       FROM IF-MIB;

accountingControlMIB MODULE-IDENTITY

    LAST-UPDATED "9809281000Z"
    ORGANIZATION "IETF AToM MIB Working Group"
    CONTACT-INFO "Keith McCloghrie
                  Cisco Systems, Inc.
                  170 West Tasman Drive,
                  San Jose CA 95134-1706.
                  Phone: +1 408 526 5260
                  Email: kzm@cisco.com"
    DESCRIPTION
            "The MIB module for managing the collection and storage of
            accounting information for connections in a connection-
            oriented network such as ATM."
    ::= { mib-2 60 }

acctngMIBObjects OBJECT IDENTIFIER ::= { accountingControlMIB 1 }

acctngSelectionControl OBJECT IDENTIFIER ::= { acctngMIBObjects 1 }
acctngFileControl      OBJECT IDENTIFIER ::= { acctngMIBObjects 2 }
acctngInterfaceControl OBJECT IDENTIFIER ::= { acctngMIBObjects 3 }
acctngTrapControl      OBJECT IDENTIFIER ::= { acctngMIBObjects 4 }

-- Textual Conventions

DataCollectionSubtree ::= TEXTUAL-CONVENTION

    STATUS       current
    DESCRIPTION
            "The subtree component of a (subtree, list) tuple.  Such a
            (subtree, list) tuple defines a set of objects and their
            values to be collected as accounting data for a connection.
            The subtree specifies a single OBJECT IDENTIFIER value such
            that each object in the set is named by the subtree value
    
            appended with a single additional sub-identifier."
    SYNTAX       OBJECT IDENTIFIER

DataCollectionList ::= TEXTUAL-CONVENTION

    STATUS       current
    DESCRIPTION
            "The list component of a (subtree, list) tuple.  Such a
            (subtree, list) tuple defines a set of objects and their
            values to be collected as accounting data for a connection.
            The subtree specifies a single OBJECT IDENTIFIER value such
            that each object in the set is named by the subtree value
            appended with a single additional sub-identifier.  The list
            specifies a set of data items, where the presence of an item
            in the list indicates that the item is (to be) present in
            the data collected for a connection; the absence of an item
            from the list indicates that the item is not (to be) present
            in the data collected for a connection.  Each data item is
            represented by an integer which when appended (as as
            additional sub-identifier) to the OBJECT IDENTIFIER value of
            the subtree identified by the tuple, is the name of an
            object defining that data item (its description and its
            syntax).
    
            The list is specified as an OCTET STRING in which each data
            item is represented by a single bit, where data items 1
            through 8 are represented by the bits in the first octet,
            data items 9 through 16 by the bits in the second octet,
            etc.  In each octet, the lowest numbered data item is
            represented by the most significant bit, and the highest
            numbered data item by the least significant bit.  A data
            item is present in the list when its bit is set, and absent
            when its bit is reset.  If the length of an OCTET STRING
            value is too short to represent one or more data items
            defined in a subtree, then those data items are absent from
            the set identified by the tuple of that subtree and that
            OCTET STRING value."
    SYNTAX       OCTET STRING (SIZE(0..8))

FileIndex ::= TEXTUAL-CONVENTION

    STATUS       current
    DESCRIPTION
            "An arbitrary integer value identifying a file into which
            accounting data is being collected."
    SYNTAX       Integer32 (1..65535)

-- The Accounting Information Selection table

acctngSelectionTable OBJECT-TYPE

    SYNTAX      SEQUENCE OF AcctngSelectionEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "A list of accounting information selection entries.
    
            Note that additions, modifications and deletions of entries
            in this table can occur at any time, but such changes only
            take effect on the next occasion when collection begins into
            a new file.  Thus, between modification and the next 'swap',
            the content of this table does not reflect the current
            selection."
    ::= { acctngSelectionControl 1 }

acctngSelectionEntry OBJECT-TYPE

    SYNTAX      AcctngSelectionEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "An entry identifying an (subtree, list) tuple used to
            select a set of accounting information which is to be
            collected."
    INDEX   { acctngSelectionIndex }
    ::= { acctngSelectionTable 1 }

AcctngSelectionEntry ::=

    SEQUENCE {
        acctngSelectionIndex     Integer32,
        acctngSelectionSubtree   DataCollectionSubtree,
        acctngSelectionList      DataCollectionList,
        acctngSelectionFile      FileIndex,
        acctngSelectionType      BITS,
        acctngSelectionRowStatus RowStatus
    }

acctngSelectionIndex OBJECT-TYPE

    SYNTAX      Integer32 (1..65535)
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "An arbitrary integer value which uniquely identifies a
            tuple stored in this table.  This value is required to be
            the permanent 'handle' for an entry in this table for as
            long as that entry exists, including across restarts and
            power outages."
    ::= { acctngSelectionEntry 1 }

acctngSelectionSubtree OBJECT-TYPE

    SYNTAX      DataCollectionSubtree
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
            "The combination of acctngSelectionSubtree and
            acctngSelectionList specifies one (subtree, list) tuple
            which is to be collected."
    ::= { acctngSelectionEntry 2 }

acctngSelectionList OBJECT-TYPE

    SYNTAX      DataCollectionList
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
            "The combination of acctngSelectionSubtree and
            acctngSelectionList specifies one (subtree, list) tuple
            which is to be collected."
    ::= { acctngSelectionEntry 3 }

acctngSelectionFile OBJECT-TYPE

    SYNTAX      FileIndex
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
            "An indication of the file into which the accounting
            information identified by this entry is to be stored.  If
            there is no conceptual row in the acctngFileTable for which
            the value of acctngFileIndex has the same value as this
            object, then the information selected by this entry is not
            collected."
    ::= { acctngSelectionEntry 4 }

acctngSelectionType OBJECT-TYPE

    SYNTAX      BITS { svcIncoming(0),
                       svcOutgoing(1),
                       svpIncoming(2),
                       svpOutgoing(3),
                       pvc(4),
                       pvp(5),
                       spvcOriginator(6),
                       spvcTarget(7),
                       spvpOriginator(8),
                       spvpTarget(9) }
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
            "Indicates the types of connections for which the
            information selected by this entry are to be collected."
    DEFVAL      { { svcIncoming, svcOutgoing,
                    svpIncoming, svpOutgoing } }
    ::= { acctngSelectionEntry 5 }

acctngSelectionRowStatus OBJECT-TYPE

    SYNTAX      RowStatus
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
            "The status of this conceptual row.  An agent may refuse to
            create new conceptual rows and/or modify existing conceptual
            rows, if such creation/modification would cause multiple
            rows to have the same values of acctngSelectionSubtree and
            acctngSelectionList.

A conceptual row can not have the status of 'active' until values have been assigned to the acctngSelectionSubtree, acctngSelectionList and acctngSelectionFile columnar objects within that row.

            An agent must not refuse to change the values of the
            acctngSelectionSubtree, acctngSelectionList and
            acctngSelectionFile columnar objects within a conceptual row
            even while that row's status is 'active'.  Similarly, an
            agent must not refuse to destroy an existing conceptual row
            while the file referenced by that row's instance of
            acctngSelectionFile is in active use, i.e., while the
            corresponding instance of acctngFileRowStatus has the value
            'active'.  However, such changes only take effect upon the
            next occasion when collection begins into a new (version of
            the) file."
    ::= { acctngSelectionEntry 6 }

-- The Accounting File table

acctngFileTable OBJECT-TYPE

    SYNTAX      SEQUENCE OF AcctngFileEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "A list of files into which accounting information is to be
            stored."
    ::= { acctngFileControl 1 }

acctngFileEntry OBJECT-TYPE

    SYNTAX      AcctngFileEntry
    MAX-ACCESS  not-accessible
    
    STATUS      current
    DESCRIPTION
            "An entry identifying a file into which accounting
            information is to be collected."
    INDEX   { acctngFileIndex }
    ::= { acctngFileTable 1 }

AcctngFileEntry ::=

    SEQUENCE {
        acctngFileIndex                 FileIndex,
        acctngFileName                  DisplayString,
        acctngFileNameSuffix            DisplayString,
        acctngFileDescription           DisplayString,
        acctngFileCommand               INTEGER,
        acctngFileMaximumSize           Integer32,
        acctngFileCurrentSize           Integer32,
        acctngFileFormat                INTEGER,
        acctngFileCollectMode           BITS,
        acctngFileCollectFailedAttempts BITS,
        acctngFileInterval              Integer32,
        acctngFileMinAge                Integer32,
        acctngFileRowStatus             RowStatus
    }

acctngFileIndex OBJECT-TYPE

    SYNTAX      FileIndex
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "A unique value identifying a file into which accounting
            data is to be stored.  This value is required to be the
            permanent 'handle' for an entry in this table for as long as
            that entry exists, including across restarts and power
            outages."
    ::= { acctngFileEntry 1 }

acctngFileName OBJECT-TYPE

    SYNTAX      DisplayString (SIZE(1..32))
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
            "The name of the file into which accounting data is to be
            stored.  If files are named using suffixes, then the name of
            the current file is the concatenation of acctngFileName and
            acctngFileNameSuffix.

An agent will respond with an error (e.g., 'wrongValue') to a management set operation which attempts to modify the value of this object to the same value as already held by another instance of acctngFileName. An agent will also respond with an error (e.g., 'wrongValue') if the new value is invalid for use as a file name on the local file system (e.g., many file systems do not support white space embedded in file names).

            The value of this object can not be modified while the
            corresponding instance of acctngFileRowStatus is 'active'."
    ::= { acctngFileEntry 2 }

acctngFileNameSuffix OBJECT-TYPE

    SYNTAX      DisplayString (SIZE(0..8))
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "The suffix, if any, of the name of a file into which
            accounting data is currently being stored.  If suffixes are
            not used, then the value of this object is the zero-length
            string.  Note that if a separator, such as a period, is used
            in appending the suffix to the file name, then that
            separator appears as the first character of this value."
    ::= { acctngFileEntry 3 }

acctngFileDescription OBJECT-TYPE

    SYNTAX      DisplayString
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
            "The textual description of the accounting data which will
            be stored (on the next occasion) when header information is
            stored in the file.  The value of this object may be
            modified at any time."
    DEFVAL      { "" }
    ::= { acctngFileEntry 4 }

acctngFileCommand OBJECT-TYPE

    SYNTAX      INTEGER {
                    -- the following two values are states:
                    -- they may be read but not written
                    idle(1),
                    cmdInProgress(2),
                    -- the following two values are actions:
                    -- they may be written, but are never read
                    swapToNewFile(3),
                    collectNow(4)
                }
    MAX-ACCESS  read-create
    
    STATUS      current
    DESCRIPTION
            "A control object for the collection of accounting data.
            When read the value is either 'idle' or 'cmdInProgress'.
            Writing a value is only allowed when the current value is
            'idle'.  When a value is successfully written, the value
            changes to 'cmdInProgress' until completion of the action,
            at which time the value reverts to 'idle'.  Actions are
            invoked by writing the following values:

'swapToNewFile' - the collection of data into the current

file is terminated, and collection continues into a new (version of the) file.

               'collectNow' - the agent creates and stores a connection
                      record into the current file for each active
                      connection having a type matching
                      acctngSelectionType and an age greater than
                      acctngFileMinAge."
    DEFVAL      { idle }
    ::= { acctngFileEntry 5 }

acctngFileMaximumSize OBJECT-TYPE

    SYNTAX      Integer32 (100..2147483647)
    UNITS       "bytes"
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
            "The maximum size of the file (including header
            information).  When the file of collected data reaches this
            size, either the agent automatically swaps to a new version
            (i.e., a new value acctngFileNameSuffix) of the file, or new
            records are discarded.  Since a file must contain an
            integral number of connection records, the actual maximum
            size of the file may be just less OR Just greater than the
            value of this object.
    
            The value of this object can not be modified while the
            corresponding instance of acctngFileRowStatus is 'active'.
            The largest value of the maximum file size in some agents
            will be less than 2147483647 bytes."
    DEFVAL      { 5000000 }
    ::= { acctngFileEntry 6 }

acctngFileCurrentSize OBJECT-TYPE

    SYNTAX      Integer32 (0..2147483647)
    UNITS       "bytes"
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "The current size of the file into which data is currently
            being collected, including header information."
    ::= { acctngFileEntry 7 }

acctngFileFormat OBJECT-TYPE

    SYNTAX      INTEGER { other(1), ber(2) }
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
            "An indication of the format in which the accounting data is
            to be stored in the file.  If the value is modified, the new
            value takes effect after the next 'swap' to a new file.  The
            value ber(2) indicates the standard format."
    DEFVAL      { ber }
    ::= { acctngFileEntry 8 }

acctngFileCollectMode OBJECT-TYPE

    SYNTAX      BITS { onRelease(0), periodically(1) }
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
            "An indication of when accounting data is to be written into
            this file.  Note that in addition to the occasions indicated
            by the value of this object, an agent always writes
            information on appropriate connections to the file when the
            corresponding instance of acctngFileCommand is set to
            'collectNow'.

- 'onRelease' - whenever a connection (or possibly,

connection attempt) is terminated, either through a Release message or through management removal, information on that connection is written.

- 'periodically' - information on appropriate connections

is written on the expiry of a periodic timer,

            This value may be modified at any time."
    DEFVAL      { { onRelease } }
    ::= { acctngFileEntry 9 }

acctngFileCollectFailedAttempts OBJECT-TYPE

    SYNTAX      BITS { soft(0), regular(1) }
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
            "An indication of whether connection data is to be collected

for failed connection attempts when the value of the corresponding instance of acctngFileCollectMode includes 'onRelease'. The individual values have the following meaning:

              'soft' - indicates that connection data is to be collected
            for failed Soft PVCs/PVPs which originate or terminate at
            the relevant interface.
            
              'regular' - indicates that connection data is to be
            collected for failed SVCs, including Soft PVCs/PVPs not
            originating or terminating at the relevant interface.
    
            This value may be modified at any time."
    DEFVAL      { { soft, regular } }
    ::= { acctngFileEntry 10 }

acctngFileInterval OBJECT-TYPE

    SYNTAX      Integer32 (60..86400)
    UNITS       "seconds"
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
            "The number of seconds between the periodic collections of
            accounting data when the value of the corresponding instance
            of acctngFileCollectMode includes 'periodically'.  Some
            agents may impose restrictions on the range of this
            interval.  This value may be modified at any time."
    DEFVAL     { 3600 }
    ::= { acctngFileEntry 11 }

acctngFileMinAge OBJECT-TYPE

    SYNTAX      Integer32 (60..86400)
    UNITS       "seconds"
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
            "The minimum age of a connection, as used to determine the
            set of connections for which data is to be collected at the
            periodic intervals and/or when acctngFileCommand is set to
            'collectNow'.  The age of a connection is the elapsed time
            since it was last installed.

When the periodic interval expires for a file or when acctngFileCommand is set to 'collectNow', accounting data is collected and stored in the file for each connection having a type matching acctngSelectionType and whose age at that time is greater than the value of acctngFileMinAge

            associated with the file.  This value may be modified at any
            time."
    DEFVAL     { 3600 }
    ::= { acctngFileEntry 12 }

acctngFileRowStatus OBJECT-TYPE

    SYNTAX      RowStatus
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
            "The status of this conceptual row.
    
            This object can not be set to 'active' until a value has
            been assigned to the corresponding instance of
            acctngFileName.  Collection of data into the file does not
            begin until this object has the value 'active' and one or
            more (active) instances of acctngSelectionFile refer to it.
            If this value is modified after a collection has begun,
            collection into this file terminates and a new (or new
            version of the) file is immediately made ready for future
            collection (as if acctngFileCommand had been set to
            'swapToNewFile'), but collection into the new (or new
            version of the) file does not begin until the value is
            subsequently set back to active."
    ::= { acctngFileEntry 13 }

-- Overall Control

acctngAdminStatus OBJECT-TYPE

    SYNTAX      INTEGER { enabled(1), disabled(2) }
    MAX-ACCESS  read-write
    STATUS      current
    DESCRIPTION
            "A control object to indicate the administratively desired
            state of the collection of accounting records across all
            interfaces.
    
            Modifying the value of acctngAdminStatus to 'disabled' does
            not remove or change the current configuration as
            represented by the active rows in the acctngSelectionTable,
            acctngFileTable and acctngInterfaceTable tables."
    ::= { acctngInterfaceControl 1 }

acctngOperStatus OBJECT-TYPE

    SYNTAX      INTEGER { enabled(1), disabled(2) }
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION

"A status object to indicate the operational state of the collection of accounting records across all interfaces.

When the value of acctngAdminStatus is modified to be 'enabled', the value of this object will change to 'enabled' providing it is possible to begin collecting accounting records.

            When the value of acctngAdminStatus is modified to be
            'disabled', the value of this object will change to
            'disabled' as soon as the collection of accounting records
            has terminated."
    ::= { acctngInterfaceControl 2 }

acctngProtection OBJECT-TYPE

    SYNTAX      TestAndIncr
    MAX-ACCESS  read-write
    STATUS      current
    DESCRIPTION
            "A control object to protect against duplication of control
            commands.  Over some transport/network protocols, it is
            possible for SNMP messages to get duplicated.  Such
            duplication, if it occurred at just the wrong time could
            cause serious disruption to the collection and retrieval of
            accounting data, e.g., if a SNMP message setting
            acctngFileCommand to 'swapToNewFile' were to be duplicated,
            a whole file of accounting data could be lost.
    
            To protect against such duplication, a management
            application should retrieve the value of this object, and
            include in the Set operation needing protection, a variable
            binding which sets this object to the retrieved value."
    ::= { acctngInterfaceControl 3 }

acctngAgentMode OBJECT-TYPE

    SYNTAX      INTEGER { swapOnCommand(1), swapOnFull(2) }
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "An indication of the behaviour mode of the agent when a
            file becomes full:

'swapOnCommand' - the agent does not automatically swap

to a new file; rather, it discards newly collected data until a management application subsequently instructs it to swap to a new file.

'swapOnFull' - the agent terminates collection into the

                      current file as and when that file becomes full."
    ::= { acctngInterfaceControl 4 }

-- Per-interface control table

acctngInterfaceTable OBJECT-TYPE

    SYNTAX      SEQUENCE OF AcctngInterfaceEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "A table controlling the collection of accounting data on
            specific interfaces of the switch."
    ::= { acctngInterfaceControl 5 }

acctngInterfaceEntry OBJECT-TYPE

    SYNTAX      AcctngInterfaceEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "An entry which controls whether accounting data is to be
            collected on an interface.  The types of interfaces which
            are represented in this table is implementation-specific."
    INDEX   { ifIndex }
    ::= { acctngInterfaceTable 1 }

AcctngInterfaceEntry ::=

    SEQUENCE {
        acctngInterfaceEnable     TruthValue
    }

acctngInterfaceEnable OBJECT-TYPE

    SYNTAX      TruthValue
    MAX-ACCESS  read-write
    STATUS      current
    DESCRIPTION
            "Indicates whether the collection of accounting data is
            enabled on this interface."
    ::= { acctngInterfaceEntry 1 }

-- Objects for controlling the use of Notifications

acctngControlTrapThreshold OBJECT-TYPE

    SYNTAX      INTEGER (0..99)
    MAX-ACCESS  read-write
    STATUS      current
    DESCRIPTION
            "A percentage of the maximum file size at which a 'nearly-
    
            full' trap is generated.  The value of 0 indicates that no
            'nearly-full' trap is to be generated."
    ::= { acctngTrapControl 1 }

acctngControlTrapEnable OBJECT-TYPE

    SYNTAX      TruthValue
    MAX-ACCESS  read-write
    STATUS      current
    DESCRIPTION
            "An indication of whether the acctngFileNearlyFull and
            acctngFileFull traps are enabled."
    ::= { acctngTrapControl 2 }

-- notifications

acctngNotifications OBJECT IDENTIFIER ::= { accountingControlMIB 2 }

acctngNotifyPrefix OBJECT IDENTIFIER ::= { acctngNotifications 0 }

acctngFileNearlyFull NOTIFICATION-TYPE

    OBJECTS     { acctngFileName,
                  acctngFileMaximumSize,
                  acctngControlTrapThreshold,
                  acctngFileNameSuffix }
    STATUS      current
    DESCRIPTION
            "An indication that the size of the file into which
            accounting information is currently being collected has
            exceeded the threshold percentage of its maximum file size.
            This notification is generated only at the time of the
            transition from not-exceeding to exceeding."
    ::= { acctngNotifyPrefix 1 }

acctngFileFull NOTIFICATION-TYPE

    OBJECTS     { acctngFileName,
                  acctngFileMaximumSize,
                  acctngFileNameSuffix }
    STATUS      current
    DESCRIPTION
            "An indication that the size of the file into which
            accounting information is currently being collected has
            transistioned to its maximum file size.  This notification
            is generated (for all values of acctngAgentMode) at the time
            of the transition from not-full to full.  If acctngAgentMode
            has the value 'swapOnCommand', it is also generated
            periodically thereafter until such time as collection of
            data is no longer inhibited by the file full condition."
    ::= { acctngNotifyPrefix 2 }

-- conformance information

acctngConformance OBJECT IDENTIFIER ::= { accountingControlMIB 3 }
acctngGroups      OBJECT IDENTIFIER ::= { acctngConformance 1 }
acctngCompliances OBJECT IDENTIFIER ::= { acctngConformance 2 }

acctngCompliance MODULE-COMPLIANCE

    STATUS  current
    DESCRIPTION
            "The compliance statement for switches which implement the
            Accounting Control MIB."
    
    MODULE  -- this module
        MANDATORY-GROUPS { acctngBasicGroup,
                           acctngNotificationsGroup }

OBJECT acctngSelectionType

SYNTAX BITS { svcIncoming(0), svcOutgoing(1) }

DESCRIPTION "The minimal requirement is collection for SVCs."

        OBJECT      acctngSelectionRowStatus
        MIN-ACCESS  read-only
        DESCRIPTION "Write access is not required."
        
        OBJECT      acctngFileName
        MIN-ACCESS  read-only
        DESCRIPTION "Write access is not required."
        
        OBJECT      acctngFileCommand
        MIN-ACCESS  read-only
        DESCRIPTION "Write access is not required."
        
        OBJECT      acctngFileFormat
        SYNTAX      INTEGER { ber(2) }
        MIN-ACCESS  read-only
        DESCRIPTION "Only the standard format is required, and write
                    access is not required."
        
        OBJECT      acctngFileMaximumSize
        MIN-ACCESS  read-only
        DESCRIPTION "Write access is not required."
        
        OBJECT      acctngFileCollectMode
        SYNTAX      BITS { onRelease(0) }
        MIN-ACCESS  read-only
        DESCRIPTION "The minimal requirement is for collection on
                    connection release."
        
        OBJECT      acctngFileInterval
        MIN-ACCESS  read-only
        DESCRIPTION "Write access is not required."
        
        OBJECT      acctngFileCollectFailedAttempts
        MIN-ACCESS  read-only
        DESCRIPTION "Write access is not required."
        
        OBJECT      acctngFileRowStatus
        MIN-ACCESS  read-only
        DESCRIPTION "Write access is not required."
    
    ::= { acctngCompliances 1 }

-- units of conformance

acctngBasicGroup    OBJECT-GROUP
    OBJECTS { acctngSelectionSubtree, acctngSelectionList,
              acctngSelectionFile, acctngSelectionType,
              acctngSelectionRowStatus, acctngFileName,
              acctngFileNameSuffix, acctngFileDescription,
              acctngFileCommand, acctngFileMaximumSize,
              acctngFileCurrentSize, acctngFileRowStatus,
              acctngFileFormat, acctngFileCollectMode,
              acctngFileCollectFailedAttempts, acctngFileInterval,
              acctngFileMinAge,
              acctngAdminStatus, acctngOperStatus,
              acctngProtection, acctngAgentMode,
              acctngInterfaceEnable,
              acctngControlTrapThreshold,
              acctngControlTrapEnable
            }
    STATUS  current
    DESCRIPTION
            "A collection of objects providing control of the basic
            collection of accounting data for connection-oriented
            networks."
    ::= { acctngGroups 1 }

acctngNotificationsGroup NOTIFICATION-GROUP

    NOTIFICATIONS { acctngFileNearlyFull, acctngFileFull }
    STATUS        current
    DESCRIPTION
            "The notifications of events relating to controlling the
            collection of accounting data."
    ::= { acctngGroups 2 }

END

5. Acknowledgements

The comments of the IETF's AToM MIB Working Group are acknowledged.

6. References

   [1]  Harrington, D., Presuhn, R. and B. Wijnen, "An Architecture for
        Describing SNMP Management Frameworks", RFC 2271, January 1998.
   
   [2]  Rose, M. and K. McCloghrie, "Structure and Identification of
        Management Information for TCP/IP-based Internets", STD 16, RFC
        1155, May 1990.
   
   [3]  Rose, M. and K. McCloghrie, "Concise MIB Definitions", STD 16,
        RFC 1212, March 1991.
   
   [4]  Rose, M., "A Convention for Defining Traps for use with the
        SNMP", RFC 1215, March 1991.
   
   [5]  SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M. and S.
        Waldbusser, "Structure of Management Information for Version 2
        of the Simple Network Management Protocol (SNMPv2)", RFC 1902,
        January 1996.
   
   [6]  SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M. and S.
        Waldbusser, "Textual Conventions for Version 2 of the Simple
        Network Management Protocol (SNMPv2)", RFC 1903, January 1996.
   
   [7]  SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M. and S.
        Waldbusser, "Conformance Statements for Version 2 of the Simple
        Network Management Protocol (SNMPv2)", RFC 1904, January 1996.
   
   [8]  Case, J., Fedor, M., Schoffstall, M. and J. Davin, "Simple
        Network Management Protocol", STD 15, RFC 1157, May 1990.
   
   [9]  SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M. and S.
        Waldbusser, "Introduction to Community-based SNMPv2", RFC 1901,
        January 1996.

[10] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M. and S.

Waldbusser, "Transport Mappings for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1906, January 1996.

   [11] Case, J., Harrington D., Presuhn R. and B. Wijnen, "Message
        Processing and Dispatching for the Simple Network Management
        Protocol (SNMP)", RFC 2272, January 1998.
   
   [12] Blumenthal, U. and B. Wijnen, "User-based Security Model (USM)
        for version 3 of the Simple Network Management Protocol
        (SNMPv3)", RFC 2274, January 1998.

[13] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M. and S.

Waldbusser, "Protocol Operations for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1905, January 1996.

   [14] Levi, D., Meyer, P. and B. Stewart, "SNMPv3 Applications", RFC
        2273, January 1998.
   
   [15] Wijnen, B., Presuhn, R. and K. McCloghrie, "View-based Access
        Control Model (VACM) for the Simple Network Management Protocol
        (SNMP)", RFC 2275, January 1998.

[16] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M. and S.

Waldbusser, "Management Information Base for version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1907, January 1996.

[17] Information processing systems - Open Systems Interconnection,

"Specification of Abstract Syntax Notation One (ASN.1)",

International Organization for Standardization, Internation

Standard 8824, December 1987.

[18] Information processing systems - Open Systems Interconnection,

"Specification of Basic Encoding Rules for Abstract Syntax

Notation One (ASN.1)", International Organization for

Standardization, Internation Standard 8825, December 1987.

   [19] McCloghrie, K., Heinanen, J., Greene, W. and A. Prasad,
        "Accounting Information for ATM Networks", RFC 2512, February
        1999.
   
   [20] Noto, M., Spiegel, E., and K. Tesink, "Definitions of Textual
        Conventions and OBJECT-IDENTITIES for ATM Management", RFC 2514,
        February 1999.

7. Security Considerations

The MIB defined in this memo controls and monitors the collection of accounting data. Care should be taken to prohibit unauthorized access to this control capability in order to prevent the disruption of data collection, possibly with fraudulent intent. Example of such disruption are disabling the collection of data, or causing the wrong set of data items to be collected.

SNMPv1 by itself is not a secure environment. Even if the network itself is secure (for example by using IPSec), even then, there is no control as to who on the secure network is allowed to access and GET/SET (read/change/create/delete) the objects in this MIB.

It is recommended that the implementers consider the security features as provided by the SNMPv3 framework. Specifically, the use of the User-based Security Model RFC 2274 [12] and the View-based Access Control Model RFC 2275 [15] is recommended.

It is then a customer/user responsibility to ensure that the SNMP entity giving access to an instance of this MIB, is properly configured to give access to the objects only to those principals (users) that have legitimate rights to indeed GET or SET (change/create/delete) them.

8. IANA Considerations

Prior to publication of this memo as an RFC, IANA is requested to make a suitable OBJECT IDENTIFIER assignment.

9. Authors' Addresses

Keith McCloghrie
Cisco Systems, Inc.
170 West Tasman Drive,
San Jose CA 95134

   Phone: +1 408 526 5260
   EMail: kzm@cisco.com

Juha Heinanen
Telia Finland, Inc.
Myyrmaentie 2
01600 VANTAA
Finland

   Phone +358 303 944 808
   EMail: jh@telia.fi

Wedge Greene
MCI Telecommunications Corporation
901 International Parkway
Richardson, Texas 75081

   Phone: 214-498-1232 or 972-729-1232
   EMail: wedge.greene@mci.com

Anil Prasad
Cisco Systems, Inc.
170 West Tasman Drive,
San Jose CA 95134

   Phone: 408 525-7209
   EMail: aprasad@cisco.com

10. Full Copyright Statement

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

This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English.

The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns.

This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.