System information

Spanning Tree Algorithm (STA)
3-17
Ports
The parameters shown in the following figure and table are for port STA Information.
Parameter Description
Port Status Displays the current state of this port within the spanning tree:
No Link No link has been established on this port.
Disabled Port has been disabled by the user or has failed diagnostics.
Blocked Port receives STA configuration messages, but does not forward
packets.
Listening Port will leave blocking state due to topology change, starts
transmitting configuration messages, but does not yet forward
packets.
Learning Port has transmitted configuration messages for an interval set by
the Forward Delay parameter without receiving contradictory
information. Port address table is cleared, and the port begins
learning addresses.
Forwarding The port forwards packets, and continues learning addresses.
The rules defining port status are:
• A port on a network segment with no other STA compliant bridging device is
always forwarding.
• If two ports of a switch are connected to the same segment and there is no other
STA device attached to this segment, the port with the smaller ID forwards
packets and the other is blocked.
• All ports are blocked when the switch is booted, then some of them change state
to listening, to learning, and then to forwarding.
Forward Transitions The number of times the port has changed status to forwarding state.
Designated Cost The cost for a packet to travel from this port to the root in the current spanning tree
configuration. The slower the media, the higher the cost.
Designated Bridge The priority and MAC address of the device through which this port must
communicate to reach the root of the spanning tree.
Designated Port The priority and number of the port on the designated bridging device through which
this switch must communicate with the root of the spanning tree.