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Cisco IE 2000 Switch Software Configuration Guide
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Chapter 23 Configuring Resilient Ethernet Protocol
Information About Configuring REP
• By entering the neighbor offset number of a port in the segment, which identifies the downstream
neighbor port of an edge port. The neighbor offset number range is –256 to +256; a value of 0 is
invalid. The primary edge port has an offset number of 1; positive numbers above 1 identify
downstream neighbors of the primary edge port. Negative numbers indicate the secondary e dge port
(offset number -1) and its downstream neighbors.
Note You configure offset numbers on the primary edge port by identifying a port’s downstream
position from the primary (or secondary) edge port. You would never enter an offset value of 1
because that is the offset number of the primar y edge port itself.
Figure 23-4 shows neighbor offset numbers for a segment where E1 is the primary edge port and E2
is the secondary edge port. The red numbers inside the ring are numbers offset from the primary
edge port; the black numbers outside of the ring show the offset numbers from the secondary edge
port. Note that you can identify all ports (except the primary edge port) by either a positive offset
number (downstream position from the primary edge port) or a negative offset number (downstream
position from the secondary edge port). If E2 became the primary edge port, its offset number would
then be 1 and E1 would be -1.
• By entering the preferred keyword to select the port that you previously configured as the preferred
alternate port with the rep segment segment-id preferred interface configuration command.
Figure 23-4 Neighbor Offset Numbers in a Segment
When the REP segment is complete, all VLANs are blocked. When you configure VLAN load balancing,
you must also configure triggers in one of two ways:
• Manually trigger VLAN load balancing at any time by entering the rep preempt segment
segment-id privileged EXEC command on the switch that has the primary edge port.
• Configure a preempt delay time by entering the rep preempt delay seconds interface configuration
command. After a link failure and recovery, VLAN load balancing begins after the configured
preemption time period elapses. Note that the delay timer restarts if another port fails before the time
has elapsed.
Note When VLAN load balancing is configured, it does not start working until triggered by either manual
intervention or a link failure and recovery.
E2E1
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E1 = Primary edge port
E2 = Secondary edge port
Offset numbers from the primary edge port
Offset numbers from the secondary edge
port (negative numbers)