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Dell PowerEdge FN I/O Module Command Line Reference Guide 9.10(0.0)

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spanning-tree rstp

Configure an RSTP interface with one of these settings: port cost, edge port with optional bridge port data unit (BPDU) guard, port priority, loop guard, or root guard.

Syntax

spanning-tree rstp {cost port-cost | edge-port [bpduguard [shutdown-on-violation]] | bpdufilter | priority priority | {rootguard}}

Parameters

cost port-cost	Enter the keyword `cost` then the port cost value. The range is from 1 to 200000. The defaults are: 10-Gigabit Ethernet interface = 2000 Port Channel interface with one 10 Gigabit Ethernet = 2000 Port Channel interface with one 40 Gigabit Ethernet = 1400 Port Channel with two 10 Gigabit Ethernet = 1800 Port Channel with two 40 Gigabit Ethernet = 600
edge-port	Enter the keywords `edge-port` to configure the interface as a rapid spanning tree edge port.
bpduguard	(OPTIONAL) Enter the keyword `portfast` to enable Portfast to move the interface into Forwarding mode immediately after the root fails. Enter the keyword `bpduguard` to disable the port when it receives a BPDU.
shutdown-on-violation	(OPTIONAL) Enter the keywords `shutdown-on-violation` to hardware disable an interface when a BPDU is received and the port is disabled.
bpdufilter	(OPTIONAL) Enter the keyword `bpdufilter` to enable BPDU Filter to stop sending and receiving BPDUs on port enabled interfaces.
priority priority	Enter keyword `priority` then a value in increments of 16 as the priority. The range is from 0 to 240. The default is 128.
rootguard	Enter the keyword `rootguard` to enable root guard on an RSTP port or port-channel interface.

Defaults

Not configured.

Command Modes

INTERFACE

Supported Modes

Full–Switch

Command History

Version	Description
9.9(0.0)	Introduced on the FN IOM.
8.3.16.1	Introduced on the MXL 10/40GbE Switch IO Module.

Usage Information

The BPDU guard option prevents the port from participating in an active STP topology in case a BPDU appears on a port unintentionally, or is misconfigured, or is subject to a DOS attack. This option places the port into an Error Disable state if a BPDU appears and a message is logged so that the administrator can take corrective action.

NOTE: A port configured as an edge port, on an RSTP switch, immediately transitions to the Forwarding state. Only configure ports connected to end-hosts as edge ports. Consider an edge port similar to a port with a spanning-tree portfast enabled.

If you do not enable shutdown-on-violation, BPDUs are still sent to the RPM CPU.

You cannot enable STP root guard and loop guard at the same time on a port. For example, if you configure loop guard on a port on which root guard is already configured, the following error message displays: % Error: RootGuard is configured. Cannot configure LoopGuard.

Enabling Portfast BPDU guard and loop guard at the same time on a port results in a port that remains in a Blocking state and prevents traffic from flowing through it. For example, when Portfast BPDU guard and loop guard are both configured:

If a BPDU is received from a remote device, BPDU guard places the port in an Err-Disabled Blocking state and no traffic is forwarded on the port.
If no BPDU is received from a remote device, loop guard places the port in a Loop-Inconsistent Blocking state and no traffic is forwarded on the port.

Example

Dell(conf)#interface gigabitethernet 4/0
                                             Dell(conf-if-gi-4/0)#spanning-tree rstp edge-port
                                             Dell(conf-if-gi-4/0)#show config
                                             !
                                             interface GigabitEthernet 4/0
                                             no ip address
                                             switchport
                                             spanning-tree rstp edge-port
                                             no shutdown
                                             Dell#