Explanation/Reference:
Explanation:
RSTP can only achieve rapid transition to the forwarding state on edge ports and on point-to-point links, not on trunk links. The link type is automatically derived from the duplex mode of a port. A port that operates in full-duplex is assumed to be point-to-point, while a half-duplex port is considered as a shared port by default. This automatic link type setting can be overridden by explicit configuration. In switched networks today, most links operate in full-duplex mode and are treated as point-to-point links by RSTP.
This makes them candidates for rapid transition to the forwarding state.
Reference: http://www.cisco.com/c/en/us/support/docs/lan-switching/spanning-tree-protocol/24062-
146.html