Dell Force10 S50-01-GE-48T FTOS 8.4.2.6 Configuraiton Guide for the E-Series T - Page 589

Configuring Redundant Pairs Configuring Redundant Pairs is supported: c e s • On physical interfaces on platforms c e s • On static and dynamic port-channel interfaces on platforms The Redundant Pairs feature allows you to provide redundancy for Layer 2 links without using Spanning Tree (STP). You create redundant links by configuring pairs of Layer 2 (physical or port-channel) interfaces so that only one interface is up and carries user traffic at any time. Interfaces on either side of a link provide backup for the primary link. Redundant pairs are useful in service-provider and enterprise networks in which you do not run STP on switches-for example, networks with Digital Subscriber Line Access Mutiplexers (DSLAM)-to avoid creating switching loops (see Figure 26-7). Note: For details on STP, see Chapter 53, "Spanning Tree Protocol," on page 1063. Figure 26-7. Configuring Redundant Layer 2 Pairs without Spanning Tree Redundant links create a switching loop. Without STP broadcast storms occurs. Use backup interfaces to create redundant links in networks without STP Force10(conf-if-gi-3/41)#switchport Force10(conf-if-gi-3/41)#switchport backup gi 3/42 Force10(conf-if-gi-3/41)#no shutdown R3 3/41 Force10(conf-if-gi-4/31)#switchport Force10(conf-if-gi-4/31)#no shutdown R4 4/31 Backup Link 3/42 4/32 Force10(conf-if-gi-3/42)#switchport Force10(conf-if-gi-3/42)#no shutdown Force10(conf-if-gi-4/32)#switchport Force10(conf-if-gi-4/32)#no shutdown fnC0067mp 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 and 10-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 Port Channel Interfaces on page 444 for more information.) 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 Gigabit interface. Layer 2 | 589