rfc2515.txt

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   AAL5 in a switch is modeled as shown in Figure 7 and 8.  AAL5 will be
   managed in a switch for only those virtual connections that carry
   AAL5 and are terminated at the AAL5 entity in the switch.  Note that,
   the virtual channels within the ATM UNIs carrying AAL5 will be
   switched by the ATM switching fabric (termed as ATM Entity in the
   figure) to the virtual channels on a proprietary internal interface
   associated with the AAL5 process (termed as AAL5 Entity in the
   figure). Therefore, performance management of the AAL5 resource in
   the switch will be modeled using the ifTable through an internal
   (pseudo-ATM) virtual interface and the AAL5 performance management
   per virtual connection will be supported using an additional AAL5
   connection table in the ATM MIB.  The association between the AAL5
   virtual link at the proprietary virtual, internal interface and the
   ATM virtual link at the ATM interface will be derived from the
   virtual channel cross-connect table and the virtual channel link
   table in the ATM MIB. Note that for the proprietary virtual interface
   the traffic transmit and receive conventions in the virtual channel
   link table are as follows:

      Transmitting traffic:  ATM Entity     --->  AAL5 Entity
      Receiving traffic:     ATM Entity     <---  AAL5 Entity

                 ___________________________
                 |                         |
                 |     =============       |
                 |     |    AAL5   |       |
                 |     |   Entity  |       |
                 |     =============       |
                 |           |             |
                 |         -----Prop. Virtual Interface
                 |           |             |
                 |     =============       |
                 |     |   ATM     |       |
                 |     |  Entity   |       |
                 |     =============       |
                 |_____|__|__|__|__|_______|
                       |  |  |  |  |
                      ---------------- ATM UNIs
                       |  |  |  |  |
                       |  |  |  |  |
                       v  v  v  v  v

         Figure 7: Model of an AAL5 Entity in a Switch








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                     __________________
                     |                |
                     |   AAL5         |
                     |________________|
                     |                |
                     | Prop. Virtual  |
                     |  Interface     |
                     |________________|

        Figure 8: AAL5 Entity's Interface Stack in a Switch

7.2.  Managing AAL5 in a Host

   Managing AAL5 in a host involves managing the AAL5 sublayer interface
   as shown in Figure 9 and 10.  The AAL5 sublayer is stacked directly
   over the ATM sublayer.  The ifTable is applied to the AAL5 sublayer
   as defined in Section 10.3.

                 ___________________________
                 |                         |
                 |     =============       |
                 |     |    AAL5   |       |
                 |     |   Entity  |       |
                 |     =============       |
                 |     |   ATM     |       |
                 |     |  Entity   |       |
                 |     =============       |
                 |___________|_____________|
                             |
                           __|__ ATM UNI
                             |
                             |
                             v

         Figure 9: Model of an AAL5 Entity in a Host

                     __________________
                     |                |
                     |   AAL5         |
                     |________________|
                     |                |
                     |   ATM Layer    |
                     |________________|
                     |                |
                     |  Physical Layer|
                     |________________|

          Figure 10: AAL5 Entity's Interface Stack in a Host



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7.3.  Support of AAL5 by ifTable

   The AAL5 entity in an ATM device (e.g., switch or host) is managed
   using the ifTable.  There are additional counters specified for AAL5
   than those specified in the ATM B-ICI document [21].  Specific
   interpretations of ifTable for the AAL5 CPCS layer are as follows.

   Object   Use for AAL5 CPCS layer entity
   ======   ==============================

   ifIndex  Each AAL5 entity is represented by an ifEntry.

   ifDescr  Description of the AAL5 entity.

   ifType   The value that is allocated for AAL5 is 49.

   ifMtu    Set to the largest PDU size for the
            AAL5 CPCS layer that can be processed
            by the AAL5 entity.

   ifSpeed  Set to 0.

   ifPhysAddress   An octet string of zero length.

   ifAdminStatus   See [17].

   ifOperStatus    Assumes the value down(2) if the AAL5
            layer is down.

   ifLastChange    See [17].

   ifInOctets      The number of received AAL5 CPCS PDU octets.

   ifOutOctets     The number of AAL5 CPCS PDU octets
            transmitted.

   ifInUcastPkts   The number of received AAL5 CPCS PDUs passed
            to a higher-layer.

   ifOutUcastPkts  The number of AAL5 CPCS PDUs received from a
            higher-layer for transmission.
            [Note:  The number of AAL5 PDUs actually
            transmitted is the number received from a
            higher-layer for transmission minus any which
            are counted by ifOutErrors and ifOutDiscards.]






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   ifInErrors      Number of errored AAL5 CPCS PDUs received.
            The types of errors counted include  CRC-32 errors,
            SAR time-out errors, and oversized SDU errors.

   ifInUnknownProtos Set to 0.

   ifInDiscards    Number of received AAL5 CPCS PDUs discarded.
            Possible reason may be input buffer overflow.

   ifOutErrors     Number of AAL5 CPCS PDUs that could not
            be transmitted due to errors.

   ifOutDiscards   Number of AAL5 CPCS PDUs received for
            transmission that are discarded.
            Possible reason may be output buffer
            overflow.

   ifInMulticastPkts  Set to 0.

   ifInBroadcastPkts  Set to 0.

   ifOutMulticastPkts Set to 0.

   ifOutBroadcastPkts Set to 0.

   ifName   Textual name (unique on this system) of the
            AAL5 entity or an octet string of zero length.

   ifHighSpeed       Set to 0.

   ifConnectorPresent Set to false (2).

   ifPromiscuousMode Set to false(2).

   ifLinkUpDownTrapEnable     Default is disabled (2).

   ifAlias        The non-volatile 'alias' name for the interface
              as specified by a network manager.

7.4.  Support of Proprietary Virtual Interface by ifTable

   Specific interpretations of ifTable for the proprietary virtual,
   internal interface associated with an AAL5 entity in an ATM switch
   are as follows.







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   Object   Use for proprietary virtual, internal interface
            associated with AAL entities
   ======   ===============================================

   ifIndex  Each proprietary virtual, internal interface
            associated with AAL entities is represented by an
            ifEntry.

   ifDescr  Description of the proprietary virtual, internal
            interface associated with AAL entities.

   ifType   The value that is allocated for proprietary
            virtual, internal interface is 53.

   ifSpeed  See [17].  Set to 0 if the speed is not
            known.

   ifPhysAddress   See [17]. An octet string of zero length
            if no address is used for this interface.

   ifAdminStatus   See [17].

   ifOperStatus    See [17].

   ifLastChange    See [17].

   ifName   Textual name (unique on this system) of the
            interface or an octet string of zero length.

   ifHighSpeed     See [17]. Set to 0 if the speed is not known.

   ifConnectorPresent  Set to false (2).

   ifLinkUpDownTrapEnable     Default is disabled (2).

   ifAlias        The non-volatile 'alias' name for the interface
                  as specified by a network manager.

7.5.  AAL5 Connection Performance Statistics Table

   An AAL5 connection table is used to provide AAL5 performance
   information for each AAL5 virtual connection that is terminated at
   the AAL5 entity contained within an ATM switch or host.








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8.  ILMI MIBs and the ATM Managed Objects

   The ILMI MIBs are specified by the ATM Forum as a set of several
   MIBs, all currently defined in the ILMI Specification [23]. The ILMI
   protocols and MIBs allow two connected ATM Interface Management
   Entities (IMEs) to exchange bi-directional parameters, mainly to
   facilitate auto-configuration between ATM peer entities.  The support
   of the ATM management functions by the ILMI MIBs and those contained
   in this memo are compared in Table 1.  In this table, "yes" in the
   "ILMI MIBs"  column indicates that the management functions are
   supported by the ILMI MIBs.  The parenthesized numbers in the "This
   memo" column correspond to the sets of tables enumerated in Section
   6.2.

   For that subset of management information which the ILMI MIBs and
   this memo have in common, every effort has been made to retain
   identical semantics and syntax, even though the MIB objects are
   identified using different OBJECT IDENTIFIERs.

                Table 1 - Structuring of ATM Managed Objects
   ______________________________________________________________
                 |                                 |This   |ILMI|
   ATM Mgmt.Inf. |ATM Managed Objects              |memo   |MIBs|
   ______________|_________________________________|_______|____|

   Local Interface Information:
   _____________________________________________________________
   ATM interface:| (1) port identifier             |ATM MIB|    |
   physical layer| (2) physical transmission types |   (1)*|yes |
   configuration | (3) operational status          |MIB II | *  |
                 | (4) administrative status       |       | ** |
                 | (5) last change status          |       |    |
   _____________________________________________________________
   ATM interface:| (1) active VPI/VCI fields       |ATM MIB|    |
   cell layer    | (2) maximum number of VPCs/VCCs |   (1) |yes |
   configuration | (3) configured VPCs/VCCs        |       | ** |
                 | (4) ILMI VPI/VCI values         |       |    |
                 | (5) Neighbor system info        |       |    |
                 | (6) Max. number of VPI/VCI bits |       |yes |
                 | (7) ATM Subscribed Address      |       |    |
   _____________________________________________________________
   ATM interface:|(1) received/transmitted cells   |       |    |
   cell layer    |(2) cells with HEC error         |MIB II |yes |
   performance   |(3) cell header validation errors|       |    |
   _____________________________________________________________






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RFC 2515                 ATM Management Objects            February 1999