Cisco Catalyst 4500 Series Command Reference Manual page 661

Chapter 2 Cisco IOS Commands for the Catalyst 4500 Series Switches
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You must configure two edge ports on each REP segment, a primary edge port and a port to act as a
secondary edge port. If you configure two ports in a segment as the primary edge port, for example ports
on different switches, the configuration is allowed, but the REP selects one of them to serve as the
segment primary edge port.
REP is supported on EtherChannels, but not on an individual port that belongs to an EtherChannel.
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If you configure two ports in a segment as the primary edge port, for example ports on different switches,
the REP selects one of them to serve as the segment primary edge port. Enter the show rep topology
privileged EXEC command on a port in the segment to verify which port is the segment primary edge
port.
REP interfaces come up in a blocked state and remain in a blocked state until notified that it is safe to
unblock. You need to be aware of this to avoid sudden connection losses.
You should configure REP only in networks with redundancy. Configuring REP in a network without
redundancy causes loss of connectivity.
In networks where ports on a neighboring switch do not support REP, you can configure the non-REP
facing ports as edge no-neighbor ports. These ports inherit all properties of edge ports and you can
configure them as any other edge port, including to send STP or REP topology change notices to the
aggregation switch. In this case, the STP topology change notice (TCN) that is sent is a multiple
spanning-tree (MST) STP message.
Examples
This example shows how to enable REP on a regular (nonedge) segment port:
Switch (config)# interface gigabitethernet1/0/1
Switch (config-if)# rep segment 100
This example shows how to enable REP on a port and identify the port as the REP primary edge port:
Switch (config)# interface gigabitethernet1/1
Switch (config-if)# rep segment 100 edge primary
This example shows how to configure the same configuration when the interface has no external REP
neighbor:
Switch# configure terminal
Switch (config)# interface gigabitethernet1/1
Switch (config-if)# rep segment 100 edge no-neighbor primary
OL-27596 -01
Tunnel port
Access port
REP ports follow these rules:
– There is no limit to the number of REP ports on a switch; however, only two ports on a switch
can belong to the same REP segment.
If only one port on a switch is configured in a segment, the port should be an edge port.
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– If two ports on a switch belong to the same segment, they must be both edge ports, both regular
segment ports, or one regular port and one edge no-neighbor port. An edge port and regular
segment port on a switch cannot belong to the same segment.
If two ports on a switch belong to the same segment and one is configured as an edge port and
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one as a regular segment port (a misconfiguration), the edge port is treated as a regular segment
port.
Catalyst 4500 Series Switch Cisco IOS Command Reference—Release IOS XE 3.4.0SG and IOS 15.1(2)SG)
rep segment
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