Allied Telesis AT-GS950/16 - Manual (Page 85)

AT-GS950/16 Web Interface User Guide
85
0 to 200,000,000. A setting of 0 indicates Auto (path cost is based
on link negotiation). The path cost is described in “Path Costs and
Port Costs” on page 74.
External Cost - Applies only to MSTP. For information on MSTP,
refer to Chapter 5, “Multiple Spanning Tree Protocol” on page 87.
State - Indicates one of the following port states:
Blocking - A blocking state does not allow network traffic to be
sent or received on a the port, except for BPDU data. A port with
a higher path cost to the root bridge than another on the switch
will cause a switching loop and is placed in the blocking state by
the Spanning Tree algorithm. The port’s state may change to the
forwarding state if the other links in use fail, and the Spanning
Tree algorithm determines the port may transition to the
forwarding state.
Listening - This state occurs on a port during the convergence
process. The port in the listening state processes BPDUs and
awaits new information that would cause the port to return to the
blocking state.
Learning - While the port does not yet forward frames (packets)
in this state, the port does learn source addresses from frames
received and adds them to the filtering (switching) database.
Forwarding - A port that both receives and sends data. This
indicates normal operation. STP continues to monitor the port
for incoming BPDUs that indicate the port should return to the
blocking state to prevent a loop.
Disabled - This state is not strictly part of STP. However, a
network administrator can manually disable a port.
Edge - This parameter applies to RSTP only. Indicates whether or
not a port is connected to an edge device in the network topology.
Auto - Automatic identification of edge ports. By default, Auto is
enabled. With the Auto setting, the port looks for BPDUs for 3
seconds: If there are no BPDUs, the port is connected to an
edge device and is in a forwarding state. If BPDUs are detected,
the port is not connected to an edge device.
ForceTrue - The port is connected to an edge device, and the
port will always be in a forwarding state.
ForceFalse - The port is not connected to an edge device.
P2P - This parameter applies to RSTP only. Indicates if the port is
connected to another network device (point-to-point) in the network
topology.