Specifications

Spanning Tree Algorithm Configuration
2-77
2
CLI – This example enables Spanning Tree Protocol, and then sets the indicated
attributes.
Displaying Interface Settings
The STP Port Information and STP Trunk Information pages display the current
status of ports and trunks in the Spanning Tree.
Command Attributes
The following attributes are read-only and cannot be changed:
• STA Status – Displays current state of this port within the Spanning Tree:
- Discarding - Port receives STA configuration messages, but does not 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 - 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 discarding.
• All ports are discarding when the switch is booted, then some of them change
state to learning, and then to forwarding.
• Forward Transitions – The number of times this port has changed from the
Learning state to the 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 bridge priority and MAC address of the device through
which this port must communicate to reach the root of the Spanning Tree.
• Designated Port – The port priority and number of the port on the designated
bridging device through which this switch must communicate with the root of the
Spanning Tree.
Console(config)#spanning-tree 3-119
Console(config)#spanning-tree mode 3-120
Console(config)#spanning-tree priority 40000 3-123
Console(config)#spanning-tree hello-time 5 3-121
Console(config)#spanning-tree max-age 38 3-122
Console(config)#spanning-tree forward-time 20 3-121
Console(config)#spanning-tree pathcost method long 3-123
Console(config)#spanning-tree transmission-limit 5 3-124
Console(config)#