IEEE 802.3ad link aggregation enables you to group Ethernet interfaces at the physical layer to form a single link layer interface, also known as a link aggregation group (LAG) or bundle. For more information, see IEEE Standard 802.3ad, Link Aggregation.
Some users require more bandwidth in their network than a single Fast Ethernet link can provide, but cannot afford the expense or do not need the bandwidth of a higher-speed Gigabit Ethernet link. Using IEEE 802.3ad link aggregation in this situation provides increased port density and bandwidth at lower cost. For example, if you need 450 Mbps of bandwidth to transmit data and have only a 100-Mbps Fast Ethernet link, creating a LAG bundle containing five 100-Mbps Fast Ethernet links is more cost effective than purchasing a single Gigabit Ethernet link.
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.