Enterasys SmartSwitch 6000 User Manual page 190

Link Aggregation Screen (802.3ad Main Menu Screen)
The STP is able to calculate which ports on a switch can be allowed to forward traffic to eliminate
the possibility of looping in a network. So, if multiple links were attached between two switches,
only one would be used. The remaining links would be placed in a disabled state called
"Blocking."
Link Aggregation
It is desirable to have a way to use multiple interswitch links simultaneously to increase
interswitch bandwidth. This can be done if both sides agree on a set of ports that are being used as
an interswitch link called a "Trunk." As long as both switches agree on which ports are in this
trunk, there are no problems with looping, and the Spanning Tree can treat this trunk as a single
port.
6-26 Port Configuration Menu Screens