Dell BigIron RX Series, Configuration Manual

Page: 405 / 1458

BigIron RX Series Configuration Guide 329
53-1002253-01
IEEE 802.1D Spanning Tree Protocol (STP)
12
NOTE
If you plan to change STP bridge timers, Brocade recommends 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 * (hell1 )
Table 73 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 BigIron RX’s STP bridge priority to the highest value, so as to make the device the root
bridge, enter the following command.
BigIron RX(config)# vlan 20
BigIron RX(config-vlan-20)# spanning-tree priority 0
To make this change in the default VLAN, enter the following commands.
BigIron RX(config)# vlan 1
BigIron RX(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 72 on page 328.
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 73
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
Gigabit – 4
10 Gigabit – 2
Possible values are 1– 65535
TABLE 72 Default STP bridge parameters (Continued)
Parameter Description Default and valid values