Dell Force10 S4820T S4820T Configuration Guide - Page 599

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. FTOS supports only Gigabit, 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). See Chapter 22, Interfaces, Port Channel Interfaces on page 446 for more information.) 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. 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. • Neither the active nor the backup interface may be a member of a LAG. • The active and standby do not have to be of the same type (1G, 10G, etc). • You may not enable any Layer 2 protocol on any interface of a redundant pair or to ports connected to them. In Figure 28-7, interface 3/41 is a backup interface for 3/42, and 3/42 is in the down state, as shown in message Message 1. If 3/41 fails, 3/42 transitions to the up state, which makes the backup link active. A message similar to Message 1 appears whenever you configure a backup port. Message 1 Configuring a Backup Layer 2 Port 02:28:04: %RPM0-P:CP %IFMGR-5-L2BKUP_WARN: Do not run any Layer2 protocols on Gi 3/41 and Gi 3/42 02:28:04: %RPM0-P:CP %IFMGR-5-OSTATE_DN: Changed interface state to down: Gi 3/42 02:28:04: %RPM0-P:CP %IFMGR-5-STATE_ACT_STBY: Changed interface state to standby: Gi 3/42 Layer 2 | 599