Fabric Attach Automatic LAG Creation

When an switch receives Fabric Attach element TLVs on two or more ports that have same System-Id, same SMLT-Id, and have a Connection Type of SMLT, it automatically creates a LAG consisting of those ports. These LAGs:

• Do not persist after a reboot—after a reboot, TLVs must be received again to re-form the LAG.
• Do not require receipt of LACP PDUs—LACP PDUs are not sent.
• Require at least two ports to form the LAG—if a port is removed from the LAG, and the exiting LAG goes down to one port, it is torn down. When a LAG is initially created with two ports, the lowest numbered port is chosen as the master port of the LAG. If there are three or more ports on the LAG, and the port is not the master port, it is simply removed from the LAG. If it is the master port, the lag is torn down, and then re-created with the lowest port number of the remaining ports as the master port.
• Are supported in stacks—the dynamic LAG is checkpointed to support failover, etc.

A port is removed from a LAG under following circumstances:

• Port is administratively disabled—if port is later administratively enabled, it will not automatically be re-added to the LAG, it will take a receipt of a matching TLV.
• TLV with Connection Type other than MLT is received.
• TLV with a System-ID that is different from the one when the LAG was created is received.
• TLV with a SMLT-ID that is different from the one when the LAG was created is received.