Two-Rate Three-Color Policing - Cisco Catalyst 4500 Series Configuration Manual

Layer 2 Software Features
Software Release 12.2(40)SG complies to MQC for configuration of QoS features on the Supervisor
Engine 6-E. MQC enables rapid deployment of new features and technology innovations and facilitates
the management of network performance with respect to bandwidth, delay, jitter, and packet loss,
enhancing the performance of mission-critical business applications. The rich and advanced QoS
features are enabled using Cisco MQC.

Two-Rate Three-Color Policing

The Two-Rate Three-Color Policing feature (also termed Hierarchical QoS) limits the input or output
transmission rate of a class of traffic based on user-defined criteria and marks or colors packets by setting
the applicable differentiated services code point (DSCP) values. This feature is often configured on the
interfaces at the edge of a network to limit the rate of traffic entering or leaving the network. Using this
feature, traffic that conforms to user-defined criteria can be sent through the interfaces, while traffic that
exceeds or violates these criteria is sent out with a decreased priority setting or even dropped.
For information on QoS and Auto QoS, see
Resilient Ethernet Protocol
Resilient Ethernet Protocol (REP) is a Cisco proprietary protocol that provides an alternative to
Spanning Tree Protocol (STP) to control network loops, handle link failures, and improve convergence
time. REP controls a group of ports connected in a segment, ensures that the segment does not create any
bridging loops, and responds to link failures within the segment. REP provides a basis for constructing
more complex networks and supports VLAN load balancing.
For information on REP, see
SmartPort Macros
SmartPort macros provide a convenient way to save and share common configurations. You can use
SmartPort macros to enable features and settings based on the location of a switch in the network and
for mass configuration deployments across the network.
For information on configuring SmartPort macros, see
Spanning Tree Protocol
The Spanning Tree Protocol (STP) allows you to create fault-tolerant internetworks that ensure an active,
loop-free data path between all nodes in the network. STP uses an algorithm to calculate the best
loop-free path throughout a switched network.
For information on configuring STP, see
The Catalyst 4500 series switch supports the following STP enhancements:
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Software Configuration Guide—Release IOS XE 3.3.0SG and IOS 15.1(1)SG
1-8
Chapter 22, "Configuring Resilient Ethernet Protocol."
Spanning tree PortFast—PortFast allows a port with a directly attached host to transition to the
forwarding state directly, bypassing the listening and learning states.
Spanning tree UplinkFast—UplinkFast provides fast convergence after a spanning-tree topology
change and achieves load balancing between redundant links using uplink groups. Uplink groups
provide an alternate path in case the currently forwarding link fails. UplinkFast is designed to
decrease spanning-tree convergence time for switches that experience a direct link failure.
Chapter 40, "Configuring Quality of Service."
Chapter 18, "Configuring SmartPort Macros."
Chapter 20, "Configuring STP and MST."
Chapter 1 Product Overview
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