Administrator Guide

Assign a backup interface to an interface using the switchport backup command. The backup interface remains in a Down state until
the primary fails, at which point it transitions to Up state. If the primary interface fails, and later comes up, it becomes the backup
interface for the redundant pair. Dell EMC Networking OS supports Gigabit, 10 Gigabit, and 40-Gigabit interfaces as backup interfaces.
Apply all other configurations to each interface in the redundant pair such that their configurations are identical, so that transition to the
backup interface in the event of a failure is transparent to rest of the network.
Figure 65. Configuring Redundant Layer 2 Pairs without Spanning Tree
You configure a redundant pair by assigning a backup interface to a primary interface with the switchport backup interface
command. Initially, the primary interface is active and transmits traffic and the backup interface remains down. If the primary fails for any
reason, the backup transitions to an active Up state. If the primary interface fails and later comes back up, it remains as the backup
interface for the redundant pair.
Following primary/backup interfaces are also supported:
• primary interface is a physical interface, the backup interface can be a physical interface
• primary interface is a physical interface, the backup interface can be a static or dynamic LAG
• primary interface is a static or dynamic LAG, the backup interface can be a physical interface
• primary interface is a static or dynamic LAG, the backup interface can be a static or dynamic LAG
In a redundant pair, any combination of physical and port-channel interfaces is supported as the two interfaces in a redundant pair. For
example, you can configure a static (without LACP) or dynamic (with LACP) port-channel interface as either the primary or backup link in
a redundant pair with a physical interface.
To ensure that existing network applications see no difference when a primary interface in a redundant pair transitions to the backup
interface, be sure to apply identical configurations of other traffic parameters to each interface.
If you remove an interface in a redundant link (remove the line card of a physical interface or delete a port channel with the no
interface port-channel command), the redundant pair configuration is also removed.
Important Points about Configuring Redundant Pairs
• You may not configure any interface to be a backup for more than one interface, no interface can have more than one backup, and a
backup interface may not have a backup interface.
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