6.5. The Address Translation Group

          -- the Address Translation group

          -- Implementation of the Address Translation group is
          -- mandatory for all systems.  Note however that this group
          -- is deprecated by MIB-II. That is, it is being included
          -- solely for compatibility with MIB-I nodes, and will most
          -- likely be excluded from MIB-III nodes.  From MIB-II and
          -- onwards, each network protocol group contains its own
          -- address translation tables.

          -- The Address Translation group contains one table which is
          -- the union across all interfaces of the translation tables
          -- for converting a NetworkAddress (e.g., an IP address) into
          -- a subnetwork-specific address.  For lack of a better term,
          -- this document refers to such a subnetwork-specific address
          -- as a `physical' address.

          -- Examples of such translation tables are: for broadcast
          -- media where ARP is in use, the translation table is
          -- equivalent to the ARP cache; or, on an X.25 network where
          -- non-algorithmic translation to X.121 addresses is
          -- required, the translation table contains the
          -- NetworkAddress to X.121 address equivalences.

          atTable OBJECT-TYPE
              SYNTAX  SEQUENCE OF AtEntry
              ACCESS  not-accessible
              STATUS  deprecated
              DESCRIPTION
                      "The Address Translation tables contain the
                      NetworkAddress to `physical' address equivalences.
                      Some interfaces do not use translation tables for
                      determining address equivalences (e.g., DDN-X.25
                      has an algorithmic method); if all interfaces are
                      of this type, then the Address Translation table
                      is empty, i.e., has zero entries."
              ::= { at 1 }

          atEntry OBJECT-TYPE
              SYNTAX  AtEntry
              ACCESS  not-accessible
              STATUS  deprecated
              DESCRIPTION
                      "Each entry contains one NetworkAddress to
                      `physical' address equivalence."
              INDEX   { atIfIndex,
                        atNetAddress }
              ::= { atTable 1 }

          AtEntry ::=
              SEQUENCE {
                  atIfIndex
                      INTEGER,
                  atPhysAddress
                      PhysAddress,
                  atNetAddress
                      NetworkAddress
              }

          atIfIndex OBJECT-TYPE
              SYNTAX  INTEGER
              ACCESS  read-write
              STATUS  deprecated
              DESCRIPTION
                      "The interface on which this entry's equivalence
                      is effective.  The interface identified by a
                      particular value of this index is the same
                      interface as identified by the same value of
                      ifIndex."
              ::= { atEntry 1 }

          atPhysAddress OBJECT-TYPE
              SYNTAX  PhysAddress
              ACCESS  read-write
              STATUS  deprecated
              DESCRIPTION
                      "The media-dependent `physical' address.

                      Setting this object to a null string (one of zero
                      length) has the effect of invaliding the
                      corresponding entry in the atTable object.  That
                      is, it effectively dissasociates the interface
                      identified with said entry from the mapping
                      identified with said entry.  It is an
                      implementation-specific matter as to whether the
                      agent removes an invalidated entry from the table.
                      Accordingly, management stations must be prepared
                      to receive tabular information from agents that
                      corresponds to entries not currently in use.
                      Proper interpretation of such entries requires
                      examination of the relevant atPhysAddress object."
              ::= { atEntry 2 }

          atNetAddress OBJECT-TYPE
              SYNTAX  NetworkAddress
              ACCESS  read-write
              STATUS  deprecated
              DESCRIPTION
                      "The NetworkAddress (e.g., the IP address)
                      corresponding to the media-dependent `physical'
                      address."
              ::= { atEntry 3 }