18-8
Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
OL-9639-07
Chapter 18 Configuring Flex Links and the MAC Address-Table Move Update Feature
Configuring Flex Links and MAC Address-Table Move Update
Configuration Guidelines
Follow these guidelines to configure Flex Links:
• You can configure up to 16 backup links.
• 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 Link pair. An interface can be a backup link for only one
active link. An active link cannot belong to another Flex Link 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, and 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.
• A backup link does not have to be the same type (Fast Ethernet, Gigabit Ethernet, or port channel)
as the active link. However, you should configure both Flex Links with similar characteristics so that
there are no loops or changes in behavior if the standby link begins to forward traffic.
• STP is disabled on Flex Link ports. If STP is configured on the switch, Flex Links do not participate
in STP in all VLANs in which STP is configured. With STP not running, be sure that there are no
loops in the configured topology.
Note STP is available only on NNIs or ENIs.
Follow these guidelines to configure VLAN load balancing on the Flex Links feature:
• For Flex Link VLAN load balancing, you must choose the preferred VLANs on the backup interface.
• You cannot configure a preemption mechanism and VLAN load balancing for the same Flex Links
pair.
Follow these guidelines to configure MAC address-table move update feature:
• You can enable and configure this feature on the access switch to send the MAC address-table move
updates.
• You can enable and configure this feature on the uplink switches to get the MAC address-table move
updates.
Configuring Flex Links
Beginning in privileged EXEC mode, follow these steps to configure a pair of Flex Links:
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
interface interface-id Specify the interface, and enter interface configuration
mode. The interface can be a physical Layer 2 interface or
a port channel (logical interface). The port-channel range
is 1 to 48.
Step 3
no shutdown Enable the port, if necessary. By default, UNIs and ENIs
are disabled, and network NNIs are enabled.
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