Brocade FastIron Ethernet Switch Platform and Layer 2 Switching Configuration Guide - Manual (Page 261)

CLI display of STP information (Continued) TABLE 46
Field Description
State The port STP state. The state can be one of the following:
• BLOCKING - STP has blocked Layer 2 traffic on this port to prevent a loop. The device or
VLAN can reach the root bridge using another port, whose state is FORWARDING. When a
port is in this state, the port does not transmit or receive user frames, but the port does
continue to receive STP BPDUs.
• DISABLED - The port is not participating in STP. This can occur when the port is
disconnected or STP is disabled on the port.
• FORWARDING - STP is allowing the port to send and receive frames.
• LISTENING - STP is responding to a topology change and this port is listening for a BPDU
from neighboring bridges in order to determine the new topology. No user frames are
transmitted or received during this state.
• LEARNING - The port has passed through the LISTENING state and will change to the
FORWARDING state, depending on the results of STP reconvergence. The port does not
transmit or receive user frames during this state. However, the device can learn the MAC
addresses of frames that the port receives during this state and make corresponding entries
in the MAC table.
• DESIGNATED INCONSISTENT - This shows as DESI-INCONS in the output. You can
disallow the designated forwarding state on a port in STP 802.1d or 802.1w with the
spanning-tree designated-protect command. If STP tries to put this port into the
designated forwarding role, the device would put this port into a designated inconsistent
STP state. This is effectively equivalent to the listening state in STP in which a port cannot
transfer any user traffic. When STP no longer marks this port as a designated port, the
device automatically removes the port from the designated inconsistent state.
Fwd Trans The number of times STP has changed the state of this port between BLOCKING and
FORWARDING.
Design Cost The cost to the root bridge as advertised by the designated bridge that is connected to this
port. If the designated bridge is the root bridge itself, then the cost is 0. The identity of the
designated bridge is shown in the Design Bridge field.
Designated Root The root bridge as recognized on this port. The value is the same as the root bridge ID listed in
the Root ID field.
Designated Bridge The designated bridge to which this port is connected. The designated bridge is the device that
connects the network segment on the port to the root bridge.
Displaying the STP state of a port-based VLAN
When you display information for a port-based VLAN, that information includes the STP state of the
VLAN.
To display information for a port-based VLAN, enter a command such as the following at any level of
the CLI. The STP state is shown in bold type in this example.
device#show vlans
Total PORT-VLAN entries: 2
Maximum PORT-VLAN entries: 16
legend: [S=Slot]
PORT-VLAN 1, Name DEFAULT-VLAN, Priority level0, Spanning tree On
Untagged Ports: (S3) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Displaying the STP state of a port-based VLAN
FastIron Ethernet Switch Platform and Layer 2 Switching Configuration Guide 261
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