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.