Dell C9000 Series Networking Configuration Manual page 646

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 71. 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.
The system supports only 10 Gigabit and 40-Gigabit ports and port channels as primary/backup interfaces in
redundant pairs. (A port channel is also referred to as a link aggregation group (LAG). For more information,
refer to Interfaces) If the interface is a member link of a LAG, the 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.
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