148
C
HAPTER
11: C
ONFIGURING
S
PANNING
T
REE
■
Root Guard
— Indicates if the interface is acting as the root port of
the switch. The possible field values are:
■
Enable
— Indicates Root Guard is enabled on the port
■
Disable
— Indicates Root Guard is disabled on the port.
■
Port State
— Displays the current STP state of a port. If enabled, the
port state determines what action is taken on traffic. Possible port
states are:
■
Disable
— 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. Blocking is displayed when
Classic STP is enabled.
■
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.
■
Discarding
— Indicates that the port is in Discarding mode. The
port is listening to BPDUs, and discards any other frames it receives.
■
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.
■
Speed
— Indicates the speed at which the port is operating.