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12-7
Cisco ASR 901 Series Aggregation Services Router Software Configuration Guide
OL-23826-09
Chapter 12 Configuring Resilient Ethernet Protocol
Configuring Resilient Ethernet Protocol (REP)
Configuring Resilient Ethernet Protocol (REP)
A segment is a collection of ports connected one to the other in a chain and configured with a segment
ID. To configure REP segments, you configure the REP administrative VLAN (or use the default
VLAN 1) and then add the ports to the segment using interface configuration mode. You should
configure a service instance with encapsulation corresponding to the REP admin VLAN and associate it
to arbitratory bridge domain.
Note The explicit configuration of EFP gives you the flexibility to choose the bridge domain of your choice.
You should configure two edge ports in the segment, one as the primary edge port and the other, by
default, the secondary edge port. A segment has only one primary edge port. If you configure two ports
in a segment as the primary edge port, for example ports on different switches, the REP selects one to
serve as the segment primary edge port. You can also optionally configure where to send segment
topology change notices (STCNs) and VLAN load balancing messages.
This section contains the following topics:
• Default REP Configuration, page 12-7
• REP Configuration Guidelines, page 12-7
• Configuring the REP Administrative VLAN, page 12-9
• Configuring REP Interfaces, page 12-10
• Configuring REP as Dual Edge No-Neighbor Port, page 12-15
• Setting up Manual Preemption for VLAN Load Balancing, page 12-20
• Configuring SNMP Traps for REP, page 12-21
• Monitoring REP, page 12-22
Default REP Configuration
By default, REP is disabled on all interfaces. When enabled, the interface is a regular segment port,
unless it is configured as an edge port.
When REP is enabled, the sending of segment topology change notices (STCNs) is disabled, all VLANs
are blocked, and the administrative VLAN is VLAN 1.
When VLAN load balancing is enabled, the default is manual preemption with the delay timer disabled.
If VLAN load balancing is not configured, the default after manual preemption is to block all VLANs at
the primary edge port.
REP Configuration Guidelines
Follow these guidelines when configuring REP:
• We recommend that you begin by configuring one port and then configure the contiguous ports to
minimize the number of segments and the number of blocked ports.
• If more than two ports in a segment fail when no external neighbors are configured, one port goes
into a forwarding state for the data path to help maintain connectivity during configuration. In the
show rep interface command output, the Port Role for this port shows as Fail Logical Open; the