Users Guide

Version Description
8.3.11.1 Introduced on the Z9000.
8.4.2.1 Added support for the optional guard keyword on the C-Series, S-Series, and E-
Series TeraScale.
8.3.7.0 Introduced on the S4810.
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 miscongured, 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 congured as an edge port, on an RSTP switch, immediately transitions to the
Forwarding state. Only congure 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 congure
loop guard on a port on which root guard is already congured, 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 trac from owing through it. For example, when Portfast BPDU guard and
loop guard are both congured:
• If a BPDU is received from a remote device, BPDU guard places the port in an Err-Disabled Blocking
state and no trac 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 trac 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#
1312
Rapid Spanning Tree Protocol (RSTP)