Brocade FastIron Ethernet Switch Platform and Layer 2 Switching Configuration Guide - Manual (Page 257)

Changing STP port parameters
To change the path and priority costs for a port, enter commands such as the following.
device(config)#vlan 10
device(config-vlan-10)#spanning-tree ethernet 5 path-cost 15 priority 64
Syntax: spanning-tree ethernet port path-cost value | priority value | disable | enable
The path-cost value parameter specifies the port cost as a path to the spanning tree root bridge. STP
prefers the path with the lowest cost. You can specify a value from 0 - 65535.
The default depends on the port type:
• 10 Mbps - 100
• 100 Mbps - 19
• Gbps - 4
• 10 Gbps - 2
• The priorityvalue parameter specifies the preference that STP gives this port relative to other ports
for forwarding traffic out of the spanning tree. If you are upgrading a device that has a configuration
saved under an earlier software release, and the configuration contains a value from 0 - 7 for a port
STP priority, the software changes the priority to the default when you save the configuration while
running the new release.
The disable and enable parameter disables or re-enables STP on the port. The STP state change
affects only this VLAN. The port STP state in other VLANs is not changed.
STP protection enhancement
STP protection provides the ability to prohibit an end station from initiating or participating in an STP
topology change.
The 802.1W Spanning Tree Protocol (STP) detects and eliminates logical loops in a redundant network
by selectively blocking some data paths (ports) and allowing only the best data paths to forward traffic.
In an STP environment, switches, end stations, and other Layer 2 devices use Bridge Protocol Data
Units (BPDUs) to exchange information that STP will use to determine the best path for data flow. When
a Layer 2 device is powered ON and connected to the network, or when a Layer 2 device goes down, it
sends out an STP BPDU, triggering an STP topology change.
In some instances, it is unnecessary for a connected device, such as an end station, to initiate or
participate in an STP topology change. In this case, you can enable the STP Protection feature on the
Brocade port to which the end station is connected. STP Protection disables the connected device
ability to initiate or participate in an STP topology change, by dropping all BPDUs received from the
connected device.
Enabling STP protection
You can enable STP Protection on a per-port basis.
To prevent an end station from initiating or participating in STP topology changes, enter the following
command at the Interface level of the CLI.
device#(config) interface ethernet 2
device#(config-if-e1000-2)#stp-protect
This command causes the port to drop STP BPDUs sent from the device on the other end of the link.
Syntax: [no] stp-protect
Changing STP port parameters
FastIron Ethernet Switch Platform and Layer 2 Switching Configuration Guide 257
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