Brocade BigIron RX Series Configuration Guide - Manual (Page 407)

BigIron RX Series Configuration Guide 329
53-1002484-04
IEEE 802.1D Spanning Tree Protocol (STP)
12
Default STP bridge and port parameters
Table 75 lists the default STP bridge parameters. The bridge parameters affect the entire spanning
tree. If you are using MSTP, the parameters affect the VLAN. If you are using SSTP, the parameters
affect all VLANs that are members of the single spanning tree.
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 * (hello_time +1 )
Table 76 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.
TABLE 75 Default STP bridge parameters
Parameter Description Default and valid values
Forward Delay The period of time a bridge will wait (the listen and learn
period) before beginning to forward data packets. 15 seconds
Possible values: 4 – 30
seconds
Maximum Age The interval a bridge will wait for a hello packet from the
root bridge before initiating a topology change. 20 seconds
Possible values: 6 – 40
seconds
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 76 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: 0 – 240,
configurable in multiples of 16
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