BigIron RX Series Configuration Guide 32753-1001986-01IEEE 802.1D Spanning Tree Protocol (STP) 12NOTEIf you plan to change STP bridge timers, Brocade recommends that you stay within the followingranges, from section 8.10.2 of the IEEE specification.– 2 * (forward_delay -1) >= max_age– max_age >= 2 * (hello_time +1 )Table 73 lists the default STP port parameters. The port parameters affect individual ports and areseparately configurable on each port.Changing STP bridge parametersTo change a BigIron RX’s STP bridge priority to the highest value, so as to make the device the rootbridge, enter the following command.BigIron RX(config)# vlan 20BigIron RX(config-vlan-20)# spanning-tree priority 0To make this change in the default VLAN, enter the following commands.BigIron RX(config)# vlan 1BigIron RX(config-vlan-1)# spanning-tree priority 0Syntax: [no] spanning-tree [forward-delay ] | [hello-time ] | [max-age ] |[priority ]You can specify some or all of the parameters on the same command line. For information onparameters, possible values and defaults, refer to Table 72 on page 326.Hello Time The interval of time between each configuration BPDUsent by the root bridge.2 secondsPossible values: 1 – 10secondsPriority A parameter used to identify the root bridge in a spanningtree (instance of STP). The bridge with the lowest valuehas the highest priority and is the root.A higher numerical value means a lower priority; thus, thehighest priority is 0.32768Possible values: 0 – 65535TABLE 73 Default STP port parametersParameter Description Default and valid valuesPriority The preference that STP gives this port relative to otherports for forwarding traffic out of the spanning tree.A higher numerical value means a lower priority; thus, thehighest priority is 8.128Possible values: 8 – 252,configurable in incrementsof 4Path Cost The cost of using the port to reach the root bridge. Whenselecting among multiple links to the root bridge, STPchooses the link with the lowest path cost and blocks theother paths. Each port type has its own default STP pathcost.10 Mbps – 100100 Mbps – 19Gigabit – 410 Gigabit – 2Possible values are 1– 65535TABLE 72 Default STP bridge parameters (Continued)Parameter Description Default and valid values
