Abbreviated
STP, a link management
protocol that is part of the
IEEE 802.1 standard for media access control
bridges. Using the spanning tree
algorithm, STP provides path redundancy while preventing undesirable loops in a
network that are created by multiple active paths between stations. Loops occur when there are alternate routes between
hosts. To establish path redundancy, STP creates a
tree that spans all of the switches in an extended network, forcing redundant paths into a standby, or blocked, state. STP allows only one active path at a time between any two network devices (this prevents the loops) but establishes the redundant links as a backup if the initial link should fail. If STP costs change, or if one network segment in the STP becomes unreachable, the spanning tree algorithm reconfigures the spanning tree
topology and reestablishes the link by activating the standby path. Without spanning tree in place, it is possible that both connections may be simultaneously live, which could result in an endless loop of traffic on the
LAN.
