58 Converged Enhanced Ethernet Administrator’s Guide
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STP overview
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DRAFT: BROCADE CONFIDENTIAL
•Disabled—The interface is not participating in spanning tree because of a shutdown port, no
link on the port, or no spanning tree instance running on the port.
A port participating in spanning tree moves through these states:
•From initialization to blocking state.
•From blocking to listening or disabled state.
•From listening to learning, blocking, or disabled state.
•From learning to forwarding, blocking, or disabled state.
•From forwarding to blocking or disabled state.
The following STP features are considered optional features although you might use them in your
STP configuration:
•Root guard—For detailed information, see “Enabling the guard root” on page73.
•PortFast BPDU guard and BPDU filter—For detailed information, see “Enabling port fast (STP)”
on page 75.
Configuring STP
To configure STP, perform the following steps from global configuration mode.
1. Enable RSTP using the global protocol spanning-tree command. For details, see “Enabling STP,
RSTP, or MSTP” on page64.
switch(config)#protocol spanning-tree stp
2. Designate the root switch using the bridge-priority command. For details, see “Specifying the
bridge priority” on page 65. The range is 0 through 61440 and the priority values can be set
only in increments of 4096.
switch(conf-stp)#bridge-priority 28672
3. Enable PortFast on switch ports using the spanning-tree portfast command. For details, see
“Enabling port fast (STP)” on page75. Note that this step is optional.
NOTE
PortFast only needs to be enabled on ports that connect to workstations or PCs. Repeat these
commands for every port connected to workstations or PCs. Do not enable PortFast on ports
that connect to other switches.
switch(config)#interface tengigabitethernet 0/10
switch(conf-if-te-0/10)#spanning-tree portfast
switch(conf-if-te-0/10)#exit
switch(config)#interface tengigabitethernet 0/11
switch(conf-if-te-0/11)#spanning-tree portfast
switch(conf-if-te-0/11)#exit
Repeat these commands for every port connected to workstations or PCs.
4. Optional: Enable the guard root feature with the spanning-tree guard root command.
The guard root feature provides a way to enforce the root bridge placement in the network. For
detailed information, refer to“Enabling the guard root” on page73.
All other switch ports connect to other switches and bridges are automatically placed in
blocking mode.