Description: 
  This module contains definitions for performance monitoring of the
  ATM layer and it's circuits.

  This MIB module contains the following tables:
    ATM VPL 15 Minute Current Table
    ATM VPL 15 Minute Interval Table
    ATM VPL 1 Hour Current Table
    ATM VPL 1 Hour Interval Table
    ATM VPL Stat Table
    ATM VPL Stat Counter Table

    ATM VCL 15 Minute Current Table
    ATM VCL 15 Minute Interval Table
    ATM VCL 1 Hour Current Table
    ATM VCL 1 Hour Interval Table
    ATM VCL Stat Table
    ATM VCL Stat Counter Table

    nncDepthOfHistoricalStrata

These tables are heavily influenced by the definition of VPL/VCL
described in rfc1695, and by the statistic table definitions described
for Sonet in rfc1595. The number of intervals supported is dependent
upon resource availibility on any given product, but should nominally
be 32. To avoid building in massive amounts of storage, some products
may adopt a bulk collection scheme. 

Intervals:
Statistics on the performance of VPL/VCLs are collected over a
    historical stratum of up to a maximum of M intervals. The value of M
    is a function of a product's storage capability.

    The intervals can be either 15 minutes or 1 hour and are aligned to
    the quarter or one hour, respectively, of a wall clock. The current
    interval spans back to the last 15 minute or 1 hour tick on the wall
    clock. Continuing along the timeline from that point is the most
    recently completed interval and has an index of 1. The previous
    interval has an index of 2 and so on. Note that the oldest interval
    may be incomplete since the statistic collection may have been
    enabled offset to the quarter or one hour tick.

               t
               0          -1i         -2i         -3i
    ===========|===========|===========|===========|===========
      current      N = 1       N = 2       N = 3       N = 4    ... N = M
      interval

 
Counters:
    The following is understood for each counter in this MIB:
      - OAM cells are included in counts
      - idle and unassigned cells are not counted
      - valid cells are those that have passed HEC and have assigned VPI/VCI
      - admitted cells have a connection
      
 This module also contains definitions for performance monitoring of 
 Virtual Path Aggregation (VPA) - also known as VCC to VPC Traffic
 Aggregation - and implemented as Shaped Trunk Group.
 Only egress VPA statistics are provided.
  
 The following tables have been added :
    ATM VPA Short (15 minutes) Current Table
    ATM VPA Short (15 Minutes) Interval Table
    ATM VPA Long  (1 Hour) Current Table
    ATM VPA Long  (1 Hour) Interval Table
 
 Intervals:
 two 15-minute intervals are provided : current and previous
 two 1-hour intervals are provided : current and previous.