Version Description
8.2.1.0 Introduced the hardware shutdown-on-violation
options.
7.6.1.0 Introduced on the S-Series.
7.5.1.0 Introduced on the C-Series.
7.4.1.0 Added the optional bridge port data unit (BPDU) guard.
6.2.1.1 Introduced on the E-Series.
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 tengigabitethernet 4/1
Dell(conf-if-gi-4/0)#spanning-tree rstp edge-port
Dell(conf-if-gi-4/0)#show config
!
interface TenGigabitEthernet 4/1
no ip address
switchport
spanning-tree rstp edge-port
no shutdown
Dell#
1358 Rapid Spanning Tree Protocol (RSTP)