Cross-stack EtherChannel

Multiple physical switch combined to create a single logical (LAG) Link aggregation

This is recommended to prevent single point of failure.

Since PortChannel allows up to 8 links. Imagine we have 2 switches, which give us total of 16 links with 8 active and 8 inactive

Note: when using this you cannot use PAgP (Port Aggregation Protocol) but only can use LACP (Link Aggregation Control Protocol)