CHAPTER
16-1
Cisco ME 3800X and 3600X Switch Software Configuration Guide
OL-23400-01
16
Configuring Resilient Ethernet Protocol
This chapter describes how to use Resilient Ethernet Protocol (REP) on the Cisco ME 3800X and
ME 3600X switch. REP is a Cisco proprietary protocol that provides an alternative to Spanning Tree
Protocol (STP) to control network loops, to respond to link failures, and to 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.
Note REP is not supported on ports configured with service instances.
This chapter includes these sections:
• Understanding REP, page 16-1
• Configuring REP, page 16-6
• Monitoring REP, page 16-14
Understanding REP
A REP segment is a chain of ports connected to each other and configured with a segment ID. Each
segment consists of standard (nonedge) segment ports and two user-configured edge ports. A switch can
have only two ports belonging 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 interfaces.
Figure 16-1 shows an example of a segment consisting of six ports spread across four switches. Ports E1
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 network failure, as shown in the
diagram on the right, the blocked port returns to the forwarding state to minimize network disruption.
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