Configuring per-port spanning tree

Syntax:

spanning-tree <port-list> admin-edge-port

no spanning-tree <port-list> admin-edge-port

Enables admin-edge-port on ports connected to end nodes. During spanning tree establishment, ports with admin-edge-port enabled transition immediately to the forwarding state. If a bridge or switch is detected on the segment, the port automatically operates as non-edge, not enabled.

If admin-edge-port is disabled on a port and auto-edge-port has not been disabled, the auto-edge-port setting controls the behavior of the port.

Default: No - disabled

The no form of the command disables edge-port operation on the specified ports.

Syntax:

spanning tree <port-list> auto-edge-port

no spanning tree <port-list> auto-edge-port

Enables or disables the automatic identification of edge ports. The port will look for BPDUs for 3 seconds. If there are none, it begins forwarding packets. If admin-edge-port is enabled for a port, the setting for auto-edge-port is ignored whether set to yes or no. If admin-edge-port is set to No, and auto-edge-port has not been disabled (set to No), then the auto-edge-port setting controls the behavior of the port.

Default: Yes - enabled

The no form of the command disables auto-edge-port operation on the specified ports

Syntax:

spanning tree <port-list> bpdu-filter

no spanning tree <port-list> bpdu-filter

Enables or disables BPDU filtering on the specified ports. The bpdu-filter option forces a port to always stay in the forwarding state and be excluded from standard STP operation.

Default: Disabled

See Configuring BPDU filtering.

Syntax:

spanning tree <port-list> bpdu-protection

no spanning tree <port-list> bpdu-protection

Enables or disables BPDU protection on the specified ports.

Syntax:

spanning tree <port-list> point-to-point-mac [ true | false | auto ]

Informs the switch of the type of device to which a specific port connects.

true (default)

Indicates a point-to-point link to a device such as a switch, bridge, or end-node.

false

Indicates a connection to a hub (which is a shared LAN segment).

auto

Causes the switch to set Force-False on the port if it is not running at full duplex. (Connections to hubs are half-duplex.)

Syntax:

spanning tree <port-list> root-guard

This feature is available in RPVST+ only. When a port is enabled as root-guard, it cannot be selected as the root port even if it receives superior STP BPDUs. The port is assigned an “alternate” port role and enters a blocking state if it receives superior STP BPDUs. (A superior BPDU contains “better” information on the root bridge and/or path cost to the root bridge, which would normally replace the current root bridge selection.)

The superior BPDUs received on a port enabled as root-guard are ignored. All other BPDUs are accepted and the external devices may belong to the spanning tree as long as they do not claim to be the Root device. Use the following command on RPVST+ switch ports that are connected to devices located in other administrative network domains to ensure the stability of the core RPVST+ network topology so that undesired or damaging influences external to the network do not enter.

Default: Disabled.

Syntax:

spanning-tree <port-list> tcn-guard

When tcn-guard is enabled for a port, it causes the port to stop processing or propagating received topology change notifications and topology changes to other ports.

Default: Disabled.