Configuring Flex Links - Cisco Catalyst 4500 Series Software Configuration Manual

Chapter 24 Configuring Flex Links and MAC Address-Table Move Update

Configuring Flex Links

These sections contain this configuration information:
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Default Configuration
The following is the default Flex Links configuration:
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Configuration Guidelines
Follow these guidelines to configure Flex Links and associated features:
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Follow these guidelines to configure VLAN load balancing on the Flex Links feature. For Flex Links
VLAN load balancing, you must choose the preferred VLANs on the backup interface.
Default Configuration, page 24-5
Configuration Guidelines, page 24-5
Configuring Flex Links, page 24-6
Configuring VLAN Load Balancing on Flex Links, page 24-8
Flex Links are not configured on any interface.
Preemption mode is off.
If preemption is enabled, preemption delay is 35 seconds.
You can configure only one Flex Link backup link for any active link, and it must be a different
interface from the active interface.
An interface can belong to only one Flex Links pair. An interface can be a backup link for only one
active link, but an active link cannot belong to another Flex Links pair.
Neither of the links can be a port that belongs to an EtherChannel. However, you can configure two
port channels (EtherChannel logical interfaces) as Flex Links. Moreover, you can configure a port
channel and a physical interface as Flex Links, with either the port channel or the physical interface
as the active link.
The types (Fast Ethernet, Gigabit Ethernet, or port channel) of the backup link and the active link
can differ. However, you should configure both Flex Links with similar characteristics so that no
loops exist or changes occur in behavior if the standby link begins to forward traffic.
STP is disabled on Flex Links ports. A Flex Links port does not participate in STP, even if the
VLANs present on the port are configured for STP. When STP is not enabled, ensure that no loops
exist in the configured topology.
Configure any static MAC addresses on a Flex Links member interface after enabling Flex Links.
Set switchport backup interface interface-id preemption mode to forced. A default value of 35
seconds is used as the delay timeout. You cannot configure switchport backup interface
interface-id preemption mode on the interface. So, mode bandwidth and off cannot be configured.
Adjust the delay time with the switchport backup interface interface-id preemption delay
delay-time command.
Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
Configuring Flex Links
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