Ethernet Link Redundancy Overview

You can use 802.3ad Link Aggregation (LAG) to configure Ethernet link redundancy for Fast Ethernet and Gigabit Ethernet interfaces. Ethernet link redundancy enables you to protect against physical link failure and account for network topology changes that redirect network traffic to redundant ports.

The following configurations are available:

• LAG to LAG—Provides redundancy capabilities for two or more ports that are assigned to a LAG. One member link is configured as the backup interface for all other ports in the LAG bundle (1:N). Traffic is not forwarded over the backup member interface; it is disabled until it takes over for an active member interface.
• LAG to non-LAG—Provides redundancy capabilities when redundant ports are connected to a bridged network that has Rapid Spanning Tree Protocol (RSTP) controlling the topology. This configuration supports only two links in the LAG.

For information about the modules that support link aggregation, see ERX Module Guide, Appendix A, Module Protocol Support and E120 and E320 Module Guide, Appendix A, IOA Protocol Support.

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