Resilient Ethernet Protocol - Cisco Catalyst 4500 series Administration Manual

Layer 2 Software Features

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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For information on the STP enhancements, see
Stateful Switchover
Stateful switchover (SSO) enables you to propagate configuration and state information from the active
to the redundant supervisor engine so that sub-second interruptions in Layer 2 traffic occur when the
active supervisor engine switches over to the redundant supervisor engine.
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Software Configuration Guide—Release IOS XE 3.6.0E and IOS 15.2(2)E
1-10
Chapter 24, "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.
Spanning tree BackboneFast—BackboneFast reduces the time needed for the spanning tree to
converge after a topology change caused by an indirect link failure. BackboneFast decreases
spanning-tree convergence time for any switch that experiences an indirect link failure.
Spanning tree root guard—Root guard forces a port to become a designated port so that no switch
on the other end of the link can become a root switch.
Stateful IGMP Snooping
Chapter 20, "Configuring SmartPort Macros."
Chapter 22, "Configuring STP and MST."
Chapter 25, "Configuring Optional STP Features."
Chapter 1 Product Overview
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