Cisco Catalyst 4500 Series, Software Configuration Manual

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Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
Chapter 25 Configuring Resilient Ethernet Protocol
Configuring REP
Configuring 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 should configure the REP administrative VLAN and then add the
ports to the segment using interface configuration mode. You should configure two edge ports in the
segment, with one of them 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 of them 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.
This section includes this information:
• Default REP Configuration, page 25-7
•
REP Configuration Guidelines, page 25-7
• Configuring the REP Administrative VLAN, page 25-8
•
Configuring REP Interfaces, page 25-10
• Setting Manual Preemption for VLAN Load Balancing, page 25-13
•
Configuring SNMP Traps for REP, page 25-14
Default REP Configuration
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 task of sending segment topology change notices (STCNs) is disabled, all the
VLANs are blocked, and the default administrative VLAN is VLAN 1.
When VLAN load balancing is enabled, the default is manual pre-emption with the delay timer disabled.
If VLAN load balancing is not configured, the default after manual pre-emption is to block all the
VLANs in 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 privileged EXEC command output, the Port Role for this port shows as Fail
Logical Open ; the Port Role for the other failed port shows as Fail No Ext Neighbor . When the
external neighbors for the failed ports are configured, the ports go through the alternate port state
transitions and eventually go to an open state or remain as the alternate port, based on the alternate
port election mechanism.
• REP ports must be Layer 2 dot1Q trunk or PVLAN promiscuous trunk ports.
•
Be careful when configuring REP through a Telnet connection. Because REP blocks all VLANs
until another REP interface sends a message to unblock it, you might lose connectivity to the switch
if you enable REP in a Telnet session that accesses the switch through the same interface.