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Cisco IE 2000 Switch Software Configuration Guide
OL-25866-01
Chapter 23 Configuring Resilient Ethernet Protocol
REP Segments
• REP ports follow these rules:
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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.
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If only one port on a switch is configured in a segment, the p ort should be an edge port.
–
If two ports on a switch belong to the same segment, they must be both edge port s, 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
one as a regular segment port (a misconfiguration), the edge port is treated as a regular segment
port.
• REP interfaces come up in a blocked state and remains in a blocked state until notified that it is safe
to unblock. You need to be aware of this to avoid sudden connection losses.
• REP sends all LSL PDUs in untagged frames on the native VLAN. The BPA message sent to the
Cisco multicast address is sent on the administration VLAN, which is VLAN 1 by default.
• You can configure how long a REP interface remains up without receiving a hello from a neighbor.
You can use the rep lsl-age-timer value interface configuration command to set the time from
120 ms to 10000 ms. The LSL hello timer is then set to the age-timer value divided by 3. In normal
operation, three LSL hellos are sent before the age timer on the peer switch expires and checks for
hello messages.
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In Cisco IOS Release 12.2(52)SE, the LSL age-timer range chang ed from 3000 to 10000 ms in
500-ms increments to 120 to 10000 ms in 40-ms increments. If the REP neighbor device is not
running Cisco IOS release 12.2(52)SE or later, do not configure a timer value less than 3000 ms.
Configuring a value less than 3000 ms causes the port to shut down because the neighbor switch
does not respond within the requested time period.
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EtherChannel port channel interfaces do not support LSL age-timer values less than 1000 ms.
If you try to configure a value less than 1000 ms on a port chann el, you receive an error message
and the command is rejected.
• When configuring the REP LSL age timer, make sure that both ends of the link have the same time
value configured. Configuring different values on ports at each end of the link results in a REP link
flap.
• REP ports cannot be configured as one of these port types:
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SPAN destination port
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Tunnel port
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Access port
• REP is supported on EtherChannels, but not on an individual port that belongs to an EtherChannel.
• There is a maximum of 64 REP segments per switch.
REP Administrative VLAN
To avoid the delay introduced by relaying messages in software for link-failure or VLAN-blocking
notification during load balancing, REP floods packets at the hardware flood layer (HFL) to a regular
multicast address. These messages are flooded to the whole network, not just the REP segment. You can
control flooding of these messages by configuring an administrative VLAN for the whole domain.
Follow these guidelines when configuring the REP administrative VLAN: