Alcatel OmniStack LS 6248 User Manual page 220

3
Configuring the Switch
• 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 is
rerouted.
• Default Path Cost — Indicates if the default path cost of the port is automatically
set by the port speed and the default path cost method.
• Port Fast — Indicates if Fast Link is enabled on the port. If Fast Link mode is
enabled for a port, the Port State is automatically placed in the Forwarding state
when the port link is up. Fast Link optimizes the STP protocol convergence. STP
convergence can take 30-60 seconds in large networks.
• Enable — Port Fast is enabled.
• Disable — Port Fast is disabled.
• Auto — Port Fast mode is enabled a few seconds after the interface becomes
active.
• Root Guard — Used to prevent an unauthorized device from becoming the root of
a spanning tree. It also enables detection and resolution of misconfigurations,
while preventing loops or loss of connectivity.
• BPDU Guard — BPDU Guard is used as a security mechanism to protect the
network from invalid configurations. It is usually used either when fast link ports
(ports connected to clients) are enabled or when STP feature is disabled. When
BPDU guard is enabled on a port, the port is shut down if a BPDU message is
received and an appropriate SNMP trap is generated. The port must then be
reactivated by using the set interface active command. The BPDU Guard
indicates if BPDU is enabled for the selected interface. The possible field values
are:
• Enable — Enables BPDU guard on the selected port or LAG.
• Disable — Disables BPDU guard on the selected port or LAG. This is the default
value.
• Designated Bridge ID — Indicates the bridge priority and the MAC Address of the
designated bridge.
• Designated Port ID — Indicates the selected port 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
Forwarding state to Blocking state.
• LAG — Indicates the LAG to which the port belongs.
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