NATV2-MIB Table View

Table of subscribers.  As well as the subscriber index, it
provides per-subscriber state and counter objects, a last
discontinuity time object for the counters, and a writable
threshold value and limit on port consumption.

Table of NAT instances.  As well as state and counter
objects, it provides the instance index, instance name, and
the last discontinuity time object that is applicable to
the counters.  It also contains writable thresholds for
reporting of notifications and limits on usage of resources
at the level of the NAT instance.
          
It is assumed that NAT instances can be created and deleted
dynamically, but this MIB module does not provide the means
to do so.  For restrictions on assignment and maintenance of
the NAT index instance, see the description of
natv2InstanceIndex in the table below.  For the requirements
on maintenance of the values of the counters in this table,
see the description of natv2InstanceDiscontinuityTime in
this table.
          
Each NAT instance has its own resources and behavior.  The
resources include memory as reflected in space for map
entries, processing power as reflected in the rate of map
creation and deletion, and mappable addresses in each realm
that can play the role of an external realm for at least
some mappings for that instance.  The NAT instance table
includes limits and notification thresholds that relate to
memory usage for mapping at the level of the whole instance.
The limit on number of subscribers with active mappings is a
limit to some extent on processor usage.
          
The mappable 'external' addresses may or may not be
organized into address pools.  For a definition of address
pools, see the description of natv2PoolTable.  If the instance
does support address pools, it also has a pooling behavior.
Mapping, filtering, and pooling behavior are defined in the
descriptions of the natv2InstancePortMappingBehavior,
natv2InstanceFilteringBehavior, and
natv2InstancePoolingBehavior objects in this table.  The
instance also has a fragmentation behavior, defined in the
description of the natv2InstanceFragmentBehavior object.

Table of protocols with per-protocol counters.  Conceptual
rows of the table are indexed by the combination of the NAT
instance number and the IANA-assigned upper-layer protocol
number as given by the ProtocolNumber Textual Convention
(TC) and contained in the packet IP header.  It is up to the
agent implementation to determine and operate upon only
those upper-layer protocol numbers supported by the NAT
instance.

Table of address pools, applicable only if these are
supported by the NAT instance.  An address pool is a set of
          
addresses and ports in a particular realm, available for
assignment to the 'external' portion of a mapping.  Where more
than one pool has been configured for the realm, policy
determines which subscribers and/or services are mapped to
which pool.  natv2PoolTable provides basic information, state,
statistics, and two notification thresholds for each pool.
natv2PoolRangeTable is an expansion table for natv2PoolTable
that identifies particular address ranges allocated to the
pool.

This table contains address ranges used by pool entries.
It is an expansion of natv2PoolTable.

Table of mappings from the internal to external address.  By
definition, this is a snapshot of NAT instance state at a
given moment.  Indexed by NAT instance, internal realm, and
internal address in that realm.  Provides the mapped external
address and, depending on implementation support, identifies
the address pool from which the external address and port
were taken and the index of the subscriber to which the
mapping has been allocated.
          
In the case of DS-Lite (RFC 6333), the indexing realm and
address are those of the IPv6 encapsulation rather than the
IPv4 inner packet.

Table of port map entries indexed by the NAT instance,
protocol, and external realm and address.  A port map entry
associates an internal upper-layer protocol endpoint with an
endpoint for the same protocol in the given external realm.
By definition, this is a snapshot of NAT instance state at
a given moment.  The table provides the basic mapping
information.
          
In the case of DS-Lite (RFC 6333), the table provides the
internal IPv6 tunnel source address in
natv2PortMapInternalRealmAddress and the IPv4 source address
of the encapsulated packet that is actually translated in
natv2PortMapInternalMappedAddress.  In the general (non-DS-
Lite) case, those two objects will have the same value.