Configuring Resilient Ethernet Protocol - Cisco Catalyst 4500 series Administration Manual

Configuring Resilient Ethernet Protocol

This chapter describes how to use Resilient Ethernet Protocol (REP) on the Catalyst 4500 series switch.
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.
This chapter includes these sections:
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For complete syntax and usage information for the switch commands used in this chapter, see the Cisco
Note
Catalyst 4500 Series Switch Command Reference and related publications at this location:
http://www.cisco.com/en/US/products/hw/switches/ps4324/index.html
If a command is not in the Catalyst 4500 Series Switch Command Reference, you can locate it in the
Cisco IOS library. See the Cisco IOS Command Reference and related publications at this location:
http://www.cisco.com/en/US/products/ps6350/index.html
About REP
One REP segment is a chain of ports connected to each other and configured with a segment ID. Each
segment consists of standard (non-edge) segment ports and two user-configured edge ports. A switch can
have no more than two ports that belong to the same segment, and each segment port can have only one
external neighbor. A segment can go through a shared medium, but on any link only two ports can belong
to the same segment. REP is supported only on Layer 2 trunk and PVLAN promiscuous trunk interfaces.
Figure 24-1
and E2 are configured as edge ports. When all ports are operational (as in the segment on the left), a
single port is blocked, shown by the diagonal line. When there is a failure in the network, as shown in
the diagram on the right, the blocked port returns to the forwarding state to minimize network disruption.
OL_28731-01
About REP, page 24-1
Configuring REP, page 24-7
Monitoring REP, page 24-14
shows an example of a segment consisting of six ports spread across four switches. Ports E1
C H A P T E R
Software Configuration Guide—Release IOS XE 3.6.0E and IOS 15.2(2)E
24
24-1