Allied Telesis AT-8000GS User's Guide download pdf (Page 112)

Configuring Spanning Tree

Configuring Classic Spanning Tree

Page 112

• 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. The possible values are:

– 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 — Prevents devices outside the network core from being assigned the spanning tree root.

• 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 trunk 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.

• 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.

• Priority — Indicates the priority value of the port connected to the selected port. A lower priority increases

the probability of connecting to a root port. The priority value is between 0-240. The priority value is

determined 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 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.

• Trunk — Indicates the trunk to which the port belongs.

3. Select the Unit, in the STP Interface Configuration section.

4. Click Modify. The Spanning Tree Configuration Page for ports or for trunks opens:

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Allied Telesis AT-8000GS User's Guide Page 112