Cisco PORT QOS MIB - Overview
        
This MIB module is for the management of Cisco's    
per port rate-limiting and traffic shaping on L3    
switch/Router Platform(s).    
        
Per-port rate-limiting is a traffic control method.    
A set of rate limits are applied to the traffic    
traversing an interface. Each rate limit has a    
configurable action that is taken when rate    
limiting criteria is met.    
        
Per-port traffic shaping is a traffic control    
method. The user can restrict the amount of traffic    
coming out of a physical port. Excess traffic is     
buffered within the router/switch to the extent     
possible. 
        
A class represents a class of traffic. It is defined 
via the specification of the packet matching criteria 
that identifies packets that are to belong to the class.
        
Class-default: In addition to user defined classes, 
a pre-existing class named 'class-default' exists to 
represent all packets that do not match any of the user 
defined classes. This class-default exists so that 
policies can be defined for this group of packets that 
do not match any user defined classes.
        
Actions are individual policies (e.g.: policing) that 
can be applied to a traffic class.
        
A policy represents a set of actions that are to be 
applied to a set of traffic classes. The policy is 
associated with a target (like a port) and the direction 
of traffic on that target to which the policy is to be 
applied.
        
A hierarchical policy is one in which an entire policy 
is directly assigned to a class of traffic. Thus, a 
hierarchical policy is a nested policy that contains 
a set of the pair of a child-policy and the 
traffic-class to which it is applied.
        
DSCP (Differentiated Services Code Point) is the six 
most significant bits of the ToS field in a IP packet 
header.
        
CoS (Class of Service) is the three bits in the layer 2 
header that indicates user priority value assigned to 
this packet. 
        
This MIB module also provides per port QoS statistics.