Alcatel OmniStack LS 6248 User Manual page 219

configuring STP on an interface:
• A port on a network segment with no other STP compliant bridging device is always
forwarding.
• If two ports of a switch are connected to the same segment and there is no other
STP 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.
Command Attributes
• Unit No. — Indicates the stacking member for which the STP settings information
is displayed.
• Query by Interface — Queries the interface configuration table either by: All ports,
All Lags, Active Ports or Blocked Ports.
• Interface — The interface for which the information is displayed.
• STP — Indicates if STP is enabled on the port. The possible field values are:
• Enable — Indicates that STP is enabled on the port.
• Disable — Indicates that STP is disabled on the port.
• Priority — Indicates the 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 determined in increments of 16.
• 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. Blocking is displayed when Classic STP is enabled.
• Forwarding — Indicates the port is currently in the 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 to
a shared segment.
• Disabled — The port is not participating in the Spanning Tree.
• Speed — Indicates the speed at which the port is operating.
Configuring Spanning Tree
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