Reference Guide

Spanning Tree Protocol | 691
To change the port cost or priority of an interface:
View the current values for interface parameters using the
show spanning-tree 0 command from EXEC
privilege mode. See Figure 38-5.
Enabling PortFast
The PortFast feature enables interfaces to begin forwarding traffic approximately 30 seconds sooner.
Interfaces forward frames by default until they receive a BPDU that indicates that they should behave
otherwise; they do not go through the Learning and Listening states. The
bpduguard shutdown-on-violation
option causes the interface hardware to be shutdown when it receives a BPDU. When only
bpduguard is
implemented, although the interface is placed in an Error Disabled state when receiving the BPDU, the
physical interface remains up and spanning-tree will drop
packets in the hardware after a BPDU violation.
BPDUs are dropped in the software after receiving the BPDU violation.
To enable PortFast on an interface:
Verify that PortFast is enabled on a port using the
show spanning-tree command from the EXEC privilege
mode or the
show config command from INTERFACE mode; Dell Networking recommends using the
show config command, as shown in Figure 38-7.
Task Command Syntax Command Mode
Change the port cost of an interface.
Range: 0 to 65535
Default: see Table 38-2.
spanning-tree 0 cost cost INTERFACE
Change the port priority of an interface.
Range: 0 to 15
Default: 8
spanning-tree 0 priority
priority-value
INTERFACE
Caution: Enable PortFast only on links connecting to an end station. PortFast can cause loops if it is enabled on an
interface connected to a network.
Task Command Syntax Command Mode
Enable PortFast on an interface.
spanning-tree stp-id portfast [bpduguard |
[shutdown-on-violation]]
INTERFACE