This MIB module defines objects that describe Performance
Routing (PfR).  Standard routing protocols base routing
decisions on reachability and the number of hops between the
source and destination networks.  PfR collects and analyzes
other performance data, such as delay, loss, jitter, MOS, and
link utilization, which allows it to make routing decisions
based on policies defined by the network administrator.

Glossary
========

PfR               Performance Routing.
MC                PfR Master Controller.
BR                PfR Border Router.
DRIP              Dynamic Router Interaction Protocol.
TC                PfR Traffic Class.
IPSLA             IP Service Level Agreement (active probing).
Exit              PfR external interface.
Link Group        PfR logical grouping of exits to narrow down
                  potential exits for a TC to use.
Cost Minimization PfR feature that assigns costs to exits and
                  minimizes the overall monetary cost for a TC
Rollup            Data collection for monetary cost calculation
                  for all available exits.
DSCP              Diff-Serv Control Point.
PfR Policy        Global PfR policy defined under PfR master.
                  TC policy defined under PfR map.
PfR Map           Container for a PfR policy.
MOS               Mean opinion score
PBR               Policy based routing. PBR uses route map to
                  enforce the routing decision made by PfR.    



PfR Elements
============

A PfR system consists of a Master Controller (MC) and one or
more Border Routers (BRs).  The MC is a hardware or software
entity that is not in the data path.  A BR is a software entity
in the data path, typically running on an edge router. 

The MC and BRs communicate with each other over a socket
interface using the Dynamic Router Interaction Protocol (DRIP).
The MC sends commands to the BRs related to PfR Policies and
the monitoring of PfR traffic classes (TCs).  The BRs send
performance data gathered using either 'passive data' provided
by NetFlow, 'active data' provided by sending artificial probes
that are created using IPSLA APIs, or both, depending on the
PfR policies configured on the MC.

This MIB module describes a MC object as a single row in the
cpfrMCTable and the BR object as a single row in the
cpfrBRTable.

PfR Exits
=========

A PfR system must have at least two interfaces (i.e., exits)
configured as 'external interfaces' over which a TC's
destination network is reachable in order for PfR to function.
These two exits can be on the same BR or on different BRs.


        +------+      +------+      |----> Exit 1
        |  MC  | ---- |  BR  | ---- |
        +------+      +------+      |----> Exit 2

                           **** OR ****

                             +------+
                      | ---- |  BR  | ----> Exit 1
        +------+      |      +------+
        |  MC  | ---- |
        +------+      |      +------+
                      | ---- |  BR  | ----> Exit 2
                             +------+


PfR can assign these exits to different PfR Link Groups.  A PfR
exit can be in at most three Link Groups at one time. (See 'PfR
Policies' below).

This MIB module describes a PfR exit as a single row in the
cpfrExitTable and a cost minimization policy of an exit as a
single row of the cpfrExitCostTierTable.

PfR Traffic Classes
===================

A traffic class is a generic term for a set of traffic flows
coming into or going out of a network that have a common
characteristic, such as destination address, source address,
application, or DSCP value.

The simplest form of a TC is 'all traffic going to the same
destination prefix'.  Additional parameters defines more
specific TCs.

PfR monitors the TCs that are specified either by enabling PfR
learn mode or by direct configuration in a PfR map.  PfR
can learn TCs with the highest throughput, with the highest
delay, with a destination address inside the PfR network, or
TCs
that matches a configured PfR Learn List.  The BRs use iBGP to
obtain information about 'inside TCs'.  A PfR map specifies TCs
to which the policy applies by configuring match clause.

This MIB module describes a PfR TC as a single row in the
cpfrTrafficClassTable and current status of a TC as a single
row of the cpfrTrafficClassStatusTable, and performance metrics
gathered for a specific TC as a single row of the
cpfrTrafficClassMetricsTable.

PfR Policies
============

A PfR policy describes the performance metrics the router is to
gather, how to gather these metrics, how frequently it should
gather these metrics, and how these metrics influence routing
decisions.  Once enabled, PfR provides a global default PfR
policy.  

A PfR policy can be configured to use one link group as a
'primary' and one as a 'fallback' link group.  If PfR
determines that a TC has gone 'Out of Policy' based on the
current PfR policy, it attempts to move the TC to an exit in
the same primary link group, and only moves it to an exit in
the fallback link group, if configured, if no exit in the
primary link group is 'In Policy'.

This MIB module describes a PfR map policy in a single row of
the cpfrMapTable and a match clause configured for a specific
PfR map as a single row of the cpfrMatchTable.