Dell C9000 series, Справочное руководство

Страница: 2122 / 2286

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.
On PE ports and on VP-LAGs (lags formed with PE ports):
• spanning-tree with
bpdu guard shutdown-on-violation
is enabled by
default.
•
no spanning tree
command is valid
Hence, you cannot issue the
spanning-tree stp-id
command on the PE ports
(peGigE ports) and issuing this command on VP-LAG ports results in a failure.
Spanning Tree Protocol (STP) 2122