Cisco Linksys SFE1000P, Reference Manual

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Chapter 11: Configuring Spanning Tree
Defining Interface Settings
SFE1000P Gigabit Ethernet Switch Administration Guide
Chapter
11
• Port State — Displays the current STP state of a port. If enabled, the port state determines
what forwarding action is taken on traffic. Possible port states are:
– Disabled — Indicates that STP is currently disabled on the port. The port forwards traffic
while learning MAC addresses.
– Blocking — Indicates that the port is currently blocked and cannot forward traffic or
learn MAC addresses.
– Listening — Indicates that the port is in Listening mode. The port cannot forward traffic
nor can it learn MAC addresses.
– Learning — Indicates that the port is in Learning mode. The port cannot forward traffic,
however it can learn new MAC addresses.
– Forwarding — Indicates that the port is in Forwarding mode. The port can forward
traffic and learn new MAC addresses.
• Port Role — Displays the port role assigned by the STP algorithm to provide to STP paths.
The possible field values are:
– Root — Provides the lowest cost path to forward packets to the root switch.
– Designated — The port or LAG through which the designated switch is attached to the
LAN.
– Alternate — Provides an alternate path to the root switch from the root interface.
– Backup — Provides a backup path to the designated port path toward the Spanning
Tree leaves. Backup ports occur only when two ports are connected in a loop by a point-
to-point link, or when a LAN has two or more connections connected to a shared
segment.
– Disabled — The port is not participating in the Spanning Tree.
• Path Cost — Indicates the port contribution to the root path cost. The path cost is adjusted to
a higher or lower value, and is used to forward traffic when a path being rerouted.
•
Priority
— Priority value of the port. The priority value influences the port choice when a
bridge has two ports connected in a loop. The priority value is between 0 -240. The priority
value is provided in increments of 16.
• Designated Bridge ID — Indicates the bridge priority and the MAC Address of the
designated bridge.
• Designated Port ID — Indicates the selected port’s priority and interface.
•
Designated Cost
— Indicates the cost of the port participating in the STP topology. Ports with
a lower cost are less likely to be blocked if STP detects loops.
• Forward Transitions — Indicates the number of times the port has changed from the
Blocking state to Forwarding state.