Dell Command Line Reference Guide for the S4048–ON System 9.14.2.5

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spanning-tree

Assigns a Layer 2 interface to STP instance 0 and configures a port cost or port priority, or enables loop guard, root guard, or the Portfast feature on the interface.

Syntax
spanning-tree stp-id {cost cost | {loopguard | rootguard} | portfast [bpduguard [shutdown-on-violation]] | priority priority}

To disable Spanning Tree group on an interface, use the no spanning-tree stp-id {cost cost | {loopguard | rootguard} | portfast [bpduguard [shutdown-on-violation]] | priority priority} command.

Parameters
stp-id
Enter the STP instance ID. The range is 0.
cost cost
Enter the keyword cost then a number as the cost. The range is from 1 to 65535. The defaults are:
  • 1-Gigabit Ethernet interface = 4.
  • 10-Gigabit Ethernet interface = 2.
  • Port Channel interface with 100 Mb/s Ethernet = 18.
  • Port Channel interface with 1 Gigabit Ethernet = 3.
  • Port Channel interface with 10 Gigabit Ethernet = 1.
loopguard
Enter the keyword loopguard to enable STP loop guard on a port or port-channel interface.
rootguard
Enter the keyword rootguard to enable STP root guard on a port or port-channel interface.
portfast [bpduguard [shutdown-on-viol ation]]

Enter the keyword portfast to enable Portfast to move the interface into Forwarding mode immediately after the root fails.

Enter the optional keyword bpduguard to disable the port when it receives a BPDU.

Enter the optional keyword shutdown-on-violation to hardware disable an interface when a BPDU is received and the port is disabled.

priority priority
Enter keyword priority then a number as the priority. The range is from zero (0) to 15. The default is 8.
Defaults
cost = depends on the interface type; priority = 8
Command Modes
INTERFACE
Command History

This guide is platform-specific. For command information about other platforms, see the relevant Dell EMC Networking OS Command Line Reference Guide.

Version
Description
9.10(0.1)
Introduced on the S6010-ON and S4048T-ON.
9.10(0.0)
Introduced on the S3148.
9.10(0.0)
Introduced on the S6100–ON.
9.8(2.0)
Introduced on the S3100 series.
9.8(1.0)
Introduced on the Z9100–ON.
9.8(0.0P5)
Introduced on the S4048-ON.
9.8(0.0P2)
Introduced on the S3048-ON.
9.7(0.0)
Introduced on the S6000-ON.
9.2(1.0)
Introduced on the Z9500.
9.0.2.0
Introduced on the S6000.
8.3.19.0
Introduced on the S4820T.
8.3.11.1
Introduced on the Z9000.
8.3.10.1
Introduced the loopguard and rootguard options on the S4810.
8.4.2.1
Introduced the loopguard and rootguard options on the E-Series, C-Series, and S-Series.
8.3.7.0
Introduced on the S4810.
8.2.1.0
Introduced the shutdown-on-violation option.
7.7.1.0
Introduced on the S-Series.
7.5.1.0
Introduced on the C-Series.
6.2.1.1
Introduced on the E-Series.
Usage Information

If you enable portfast bpduguard on an interface and the interface receives a BPDU, the software disables the interface and sends a message stating that fact. The port is in ERR_DISABLE mode, yet appears in the show interface commands as enabled. If you do not enable shutdown-on-violation, BPDUs are still sent to the RPM CPU.

STP loop guard and root guard are supported on a port or port-channel enabled in any Spanning Tree mode: Spanning Tree Protocol (STP), Rapid Spanning Tree Protocol (RSTP), Multiple Spanning Tree Protocol (MSTP), and Per-VLAN Spanning Tree Plus (PVST+).

Root guard is supported on any STP-enabled port or port-channel except when used as a stacking port. When enabled on a port, root guard applies to all VLANs configured on the port.

STP root guard and loop guard cannot be enabled 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 is displayed: % Error: RootGuard is configured. Cannot configure LoopGuard.

Do not enable Portfast BPDU guard and loop guard at the same time on a port. Enabling both features may result 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.

To display the type of STP guard (Portfast BPDU, root, or loop guard) enabled on a port, enter the show spanning-tree 0 command.


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