Information About Flex Links And Mac Address-Table Move Update - Cisco Catalyst 2960 series Configuration Manual

Information About Flex Links and MAC Address-Table Move Update

• You can configure only one Flex Links backup link for any active link, and it must be a different interface
• An interface can belong to only one Flex Links pair. An interface can be a backup link for only one
• Neither of the links can be a port that belongs to an EtherChannel. However, you can configure two port
• A backup link does not have to be the same type (Gigabit Ethernet or port channel) as the active link.
• STP is disabled on Flex Links ports. A Flex Links port does not participate in STP, even if the VLANs
Related Topics
Configuring a Preemption Scheme for a Pair of Flex Links , on page 381
Configuring Flex Links , on page 380
Configuring Flex Links: Examples, on page 387
Configuring VLAN Load Balancing on Flex Links , on page 383
Configuring VLAN Load Balancing on Flex Links: Examples, on page 387
Configuring a Switch to Obtain and Process MAC Address-Table Move Update Messages , on page 385
Configuring MAC Address-Table Move Update , on page 384
Configuring the MAC Address-Table Move Update: Examples, on page 389
Information About Flex Links and MAC Address-Table Move Update
Flex Links
Flex Links are a pair of a Layer 2 interfaces (switch ports or port channels) where one interface is configured
to act as a backup to the other. The feature provides an alternative solution to the Spanning Tree Protocol
(STP). Users can disable STP and still retain basic link redundancy. Flex Links are typically configured in
service provider or enterprise networks where customers do not want to run STP on the switch. If the switch
is running STP, Flex Links are not necessary because STP already provides link-level redundancy or backup.
You configure Flex Links on one Layer 2 interface (the active link) by assigning another Layer 2 interface as
the Flex Links or backup link. On switches, the Flex Links can be on the same switch or on another switch
in the stack. When one of the links is up and forwarding traffic, the other link is in standby mode, ready to
begin forwarding traffic if the other link shuts down. At any given time, only one of the interfaces is in the
linkup state and forwarding traffic. If the primary link shuts down, the standby link starts forwarding traffic.
When the active link comes back up, it goes into standby mode and does not forward traffic. STP is disabled
on Flex Links interfaces.
Related Topics
Configuring a Preemption Scheme for a Pair of Flex Links , on page 381
Consolidated Platform Configuration Guide, Cisco IOS Release 15.2(4)E (Catalyst 2960-X Switches)
374
from the active interface.
active link. An active link cannot belong to another Flex Links pair.
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.
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.
present on the port are configured for STP. When STP is not enabled, be sure that there are no loops in
the configured topology.