Description: 
This module contains definitions for performance monitoring of the
packets routed.

This MIB module contains the following tables:
  PKT VCL 15 Minute Current Table
  PKT VCL 15 Minute Interval Table

and the following non-table objects:
  nncDepthOfHistoricalStrata

These tables are heavily influenced by the definition of VPL/VCL
described in rfc1695, and by the statistic table definitions described
in rfc2233. 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. 

Note that IP packets are counted because of rfc1483.

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. For example, on the
  36170 product, M = 1. Refer to a product's NEID document for a
  description of these limits.

  The intervals are 15 minutes and are aligned to
  the quarter of one hour of a wall clock. The current
  interval spans back to the last 15 minute 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