Loop Guard Configuration - Dell Force10 C150 Configuration Manual

Loop Guard Configuration

You enable STP loop guard on a per-port or per-port channel basis.
FTOS Behavior: The following conditions apply to a port enabled with loop guard:
• Loop guard is supported on any STP-enabled port or port-channel interface.
• Loop guard is supported on a port or port-channel in any Spanning Tree mode:
•Spanning Tree Protocol
•Rapid Spanning Tree Protocol
•Multiple Spanning Tree Protocol
•Per-VLAN Spanning Tree Plus
• Root guard and loop guard cannot be enabled at the same time on an STP 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.
• C-Series and E-Series only: Loop guard is supported on a C-Series or E-Series switch configured for
hitless STP (see
• 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, enter the
loopguard
command:
Task
Enable loop guard on a port or port-channel interface.
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, enter the
command in an INTERFACE configuration mode.
To verify the STP loop guard configuration on a port or port-channel interface, enter the
spanning-tree 0 guard
(STP)
(RSTP)
(MSTP)
(PVST+)
Configuring Spanning Trees as Hitless on page
[
interface
command in global configuration mode.
interface]
1064).
Command Syntax
spanning-tree 0 mstp
{ | |
pvst loopguard
}
no spanning-tree 0 loopguard
spanning-tree 0
Command Mode
rstp
| INTERFACE
INTERFACE
PORT-CHANNEL
show
Spanning Tree Protocol | 1067