Brocade Communications Systems 53-1001761-01 Converged Enhanced Ethernet Administrator’s Guide

6 Link aggregation overview

On each port, link aggregation control:

•Maintains configuration information to control port aggregation.

•Exchanges configuration information with other devices to form LAGs.

•Attaches ports to and detaches ports from the aggregator when they join or leave a LAG.

•Enables or disables an aggregator’s frame collection and distribution functions.

Each link in the Brocade FCoE hardware can be associated with a LAG; a link cannot be associated with more than one LAG. The process of adding and removing links to and from a LAG is controlled either statically, dynamically, or through LACP.

Each LAG consists of the following components:

•A MAC address that is different from the MAC addresses of the LAG’s individual member links.

•An interface index for each link to identify the link to neighboring devices.

•An administrative key for each link. Only links having the same administrative key value can be aggregated into a LAG. On each link configured to use LACP, LACP automatically configures an administrative key value equal to the port-channel identification number.

Figure 7 and Figure 8 show typical IP SAN configurations using LAGs. In a data center the Brocade 8000 switch fits into the top-of-the-rack use case where all the servers in a rack are connected to the Brocade 8000 switch through Twinax copper or optical fiber cable. The database server layer connects to the top-of-the-rack Brocade 8000 switch which is located in the network access layer.

The Brocade 8000 switch connects to Layer 2/Layer 3 aggregation routers which provide access into the existing LAN. This connectivity is formed in a standard V-design or square-design. Both designs use the LAG as the uplink to provide redundancy and improved bandwidth.

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