Brocade BigIron RX Series Configuration Guide - Manual (Page 410)

332 BigIron RX Series Configuration Guide
53-1002484-04
IEEE 802.1D Spanning Tree Protocol (STP)
12
Reconfiguring the timeout period
The timeout period timer is activated whenever a port encounters a superior BPDU, which then
results in a Root Guard violation. If the timeout period is reconfigured while a timer is in use, the
timer on that port is set to the new timeout period, minus the time elapsed since the superior BPDU
was received.
For example, the original timeout period on a device was configured for 60 seconds. The port
encounters a superior BPDU and the timer starts. Issuing a show span root-protect command
displays the following information.
BigIron RX(config)# show span root-protect
Port VLAN Current State
1/4 1 Inconsistent state (56 seconds left on timer)
While the timer is in use, the timeout period is changed to 30 seconds through the issue of the
following command.
BigIron RX(config)# spanning-tree root-protect timeout 30
The timer continues the countdown and minus the time that have already elapsed (about 10
seconds) since the superior BPDU was detected. Issuing a show span root-protect command
displays the following information.
BigIron RX(config)# show span root-protect
Port VLAN Current State
1/4 1 Inconsistent state (20 seconds left on timer)
Next, the timeout period is increased to 120 seconds.
BigIron RX(config)# spanning-tree root-protect timeout 120
Since the timer has not expired, it continues the countdown. The remaining time left is adjusted by
the time that has already elapsed (about 18 seconds) since the superior BPDU was detected.
Issuing a show span root-protect command displays the following information.
BigIron RX(config)# show span root-protect
Port VLAN Current State
1/4 1 Inconsistent state (102 seconds left on timer)
Sample Syslog messages
A Syslog message such as the following is generated after the Root Guard blocks a port.
STP: Root Guard Port 12/21, VLAN 10 inconsistent (Received superior BPDU)
A Syslog message such as the following is generated after the Root Guard unblocks a port.
STP: Root Guard Port 12/21, VLAN 10 consistent (Timeout)
Spanning Tree Protocol (STP) BPDU guard
STP protection provides the ability to prohibit an end station from initiating or participating in an
STP topology. The STP BPDU Guard is used to keep all active network topologies predictable.