Filter
Top Products
21-11
Software Configuration Guide—Release 15.0(2)SG
OL-23818-01
Chapter 21 Configuring Optional STP Features
About UplinkFast
Note For PVST+ information, see Chapter 18, “Configuring STP and MST.”
To enable PortFast BPDU filtering, perform this task:
This example shows how to enable PortFast BPDU filtering on port 4/4:
Switch(config)# interface fastethernet 4/4
Switch(config-if)# spanning-tree bpdufilter enable
Switch(config-if)# ^Z
This example shows how to verify that PortFast BPDU filtering is enabled:
Switch# show spanning-tree interface fastethernet 4/4
Vlan Role Sts Cost Prio.Nbr Status
---------------- ---- --- --------- -------- --------------------------------
VLAN0010 Desg FWD 1000 160.196 Edge P2p
This example shows more detail on the port:
Switch# show spanning-tree interface fastEthernet 4/4 detail
Port 196 (FastEthernet4/4) of VLAN0010 is forwarding
Port path cost 1000, Port priority 160, Port Identifier 160.196.
Designated root has priority 32768, address 00d0.00b8.140a
Designated bridge has priority 32768, address 00d0.00b8.140a
Designated port id is 160.196, designated path cost 0
Timers:message age 0, forward delay 0, hold 0
Number of transitions to forwarding state:1
The port is in the portfast mode by portfast trunk configuration
Link type is point-to-point by default
Bpdu filter is enabled
BPDU:sent 0, received 0
Switch#
About UplinkFast
Note UplinkFast is most useful in wiring-closet switches. This feature might not be useful for other types of
applications.
Spanning Tree UplinkFast provides fast convergence after a direct link failure and uses uplink groups to
achieve load balancing between redundant Layer 2 links. Convergence is the speed and ability of a group
of internetworking devices running a specific routing protocol to agree on the topology of an
internetwork after a change in that topology. An uplink group is a set of Layer 2 interfaces (per VLAN),
only one of which is forwarding at any given time. Specifically, an uplink group consists of the root port
(which is forwarding) and a set of blocked ports, except for self-looping ports. The uplink group provides
an alternate path in case the currently forwarding link fails.
Command Purpose
Step 1
Switch(config)# interface fastEthernet 4/4
Selects the interface to configure.
Step 2
Switch(config-if)# spanning-tree bpdufilter enable
Enables BPDU filtering.
Step 3
Switch# show spanning-tree interface fastethernet 4/4
Verifies the configuration.