Displaying Stp Guard Configuration - Dell S6100 Configuration Manual

• 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.
• When used in a PVST+ network, STP loop guard is performed per-port or per-port channel at a VLAN level. If no BPDUs are received
on a VLAN interface, the port or port-channel transitions to a Loop-Inconsistent (Blocking) state only for this VLAN.
To enable a loop guard on an STP-enabled port or port-channel interface, use the following command.
• Enable loop guard on a port or port-channel interface.
INTERFACE mode or INTERFACE PORT-CHANNEL mode
spanning-tree {0 | mstp | rstp | pvst} loopguard
• 0: enables loop guard on an STP-enabled port assigned to instance 0.
• mstp: enables loop guard on an MSTP-enabled port.
• rstp: enables loop guard on an RSTP-enabled port.
• pvst: enables loop guard on a PVST-enabled port.
To disable STP loop guard on a port or port-channel interface, use the no spanning-tree 0 loopguard command in an INTERFACE
configuration mode.
To verify the STP loop guard configuration on a port or port-channel interface, use the show spanning-tree 0 guard
[interface interface] command in a global configuration mode.

Displaying STP Guard Configuration

To display the STP guard configuration, use the following command.
The following example shows an STP network (instance 0) in which:
• Root guard is enabled on a port that is in a root-inconsistent state.
• Loop guard is enabled on a port that is in a listening state.
• BPDU guard is enabled on a port that is shut down (Error Disabled state) after receiving a BPDU.
• Verify the STP guard configured on port or port-channel interfaces.
show spanning-tree 0 guard [interface interface]
Example of Viewing STP Guard Configuration
Dell#show spanning-tree 0 guard
Interface
Name Instance Sts
--------- -------- --------- ----------
Te 1/1/1 0
Te 1/2/1 0
Te 1/3/1 0
Guard type
INCON(Root) Rootguard
LIS Loopguard
EDS (Shut) Bpduguard
Spanning Tree Protocol (STP) 827