LAG - Multi-Chassis LAG

Multi-Chassis LAG (MC-LAG) is a term that is used to refer to the application of Link Aggregation LAG across multiple physical devices, typically switches.

There are various ways in which MC-LAG can be achieved, most of which are associated with high availability switching technologies that are able to perform switch virtualization, allowing multiple physical switches to appear as a single logical switch.

With such arrangements, LAGs can be created on ports from different physical devices, but because they are on the same logical switch, MC-LAG is achievable.

Some additional related topics include:

EtherChannel Nexus - what is vPC PAgP LACP