Configuration Guide User guide

FastIron Configuration Guide 1091
53-1002494-02
Standard STP parameter configuration
Changing STP bridge and port parameters
Table 194 on page 1088 and Table 195 on page 1089 list the default STP parameters. If you need
to change the default value for an STP parameter, use the following procedures.
Changing STP bridge parameters
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 STP specification.
2 * (forward_delay -1) >= max_age
max_age >= 2 * (hello_time +1)
To change a STP bridge priority on a Brocade device to the highest value to make the device the
root bridge, enter the following command.
Brocade(config)#spanning-tree priority 0
The command in this example changes the priority on a device on which you have not configured
port-based VLANs. The change applies to the default VLAN. If you have configured a port-based
VLAN on the device, you can configure the parameters only at the configuration level for individual
VLANs. Enter commands such as the following.
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>] | [maximum-age
<value>] | [priority <value>]
The forward-delay <value> parameter specifies the forward delay and can be a value from 4 – 30
seconds. The default is 15 seconds.
NOTE
You can configure a Brocade device for faster convergence (including a shorter forward delay) using
Fast Span or Fast Uplink Span. Refer to “STP feature configuration” on page 1103.
The hello-time <value> parameter specifies the hello time and can be a value from 1 – 10 seconds.
The default is 2 seconds.
NOTE
This parameter applies only when this device or VLAN is the root bridge for its spanning tree.
The maximum-age <value> parameter specifies the amount of time the device waits for receipt of a
configuration BPDU from the root bridge before initiating a topology change. You can specify from
6 – 40 seconds. The default is 20 seconds.
The priority <value> parameter specifies the priority and can be a value from 0 – 65535. A higher
numerical value means a lower priority. Thus, the highest priority is 0. The default is 32768.