Configuration Guide User guide

1092 FastIron Configuration Guide
53-1002494-02
Standard STP parameter configuration
You can specify some or all of these parameters on the same command line. If you specify more
than one parameter, you must specify them in the order shown above, from left to right.
Changing STP port parameters
To change the path and priority costs for a port, enter commands such as the following.
Brocade(config)#vlan 10
Brocade(config-vlan-10)#spanning-tree ethernet 5 path-cost 15 priority 64
Syntax: spanning-tree ethernet <port> path-cost <value> | priority <value> | disable | enable
Specify the port variable in one of the following formats:
• FWS, FCX, and ICX stackable switches – stack-unit/slotnum/portnum
• FSX 800 and FSX 1600 chassis devices – slotnum/portnum
• ICX devices – slotnum/portnum
• FESX compact switches – portnum
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 priority <value> 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 | 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.
NOTE
When you enable or disable STP auto negotiated combo ports on FESX devices, the ports may flap
for a few seconds before the link is up
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.