Brocade Multi-Service IronWare Switching Configuration Guide (Supporting R05.6.00) - Manual (Page 351)

Multi-Service IronWare Switching Configuration Guide 321
53-1003036-02
IEEE 802.1D Spanning Tree Protocol (STP)
12
NOTE
If you plan to change STP bridge timers, it is recommended that you stay within the following ranges,
from section 8.10.2 of the IEEE specification:
– 2 * (forward_delay -1) >= max_age
– max_age >= 2 * (hello_time +1 )
Table 51 lists the default STP port parameters. The port parameters affect individual ports and are
separately configurable on each port.
Changing STP bridge parameters
To change a Brocade device’s STP bridge priority to the highest value, so as to make the Brocade
device the root bridge, enter the following command.
Brocade(config)# vlan 20
Brocade(config-vlan-20)# spanning-tree priority 0
To make this change in the default VLAN, enter the following commands.
Brocade(config)# vlan 1
Brocade(config-vlan-1)# spanning-tree priority 0
Syntax: [no] spanning-tree [forward-delay value] | [hello-time value] | [max-age value] | [priority
value]
You can specify some or all of the parameters on the same command line. For information on
parameters, possible values and defaults, refer to
Table 50 .
Hello Time The interval of time between each configuration BPDU sent
by the root bridge. 2 seconds
Possible values: 1 – 10 seconds
Priority A parameter used to identify the root bridge in a spanning
tree (instance of STP). The bridge with the lowest value has
the highest priority and is the root.
A higher numerical value means a lower priority; thus, the
highest priority is 0. 32768
Possible values: 0 – 65535
TABLE 51 Default STP port parameters
Parameter Description Default and valid values
Priority The preference that STP gives this port relative to other ports
for forwarding traffic out of the spanning tree.
A higher numerical value means a lower priority; thus, the
highest priority is 8. 128
Possible values: 8 – 252,
configurable in increments of 4
Path Cost The cost of using the port to reach the root bridge. When
selecting among multiple links to the root bridge, STP
chooses the link with the lowest path cost and blocks the
other paths. Each port type has its own default STP path cost. 10 Mbps – 100
100 Mbps – 19
1 Gigabit – 4
10 Gigabit – 2
40 Gigabit – 1
100 Gigabit – 1
Possible values are 1– 65535
TABLE 50 Default STP bridge parameters (Continued)
Parameter Description Default and valid values