Brocade TurboIron 24X Series Configuration Guide - Manual (Page 596)

562 Brocade TurboIron 24X Series Configuration Guide
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Configuring STP related features
802.1W Draft 3
As an alternative to full 802.1W, you can configure 802.1W Draft 3. 802.1W Draft 3 provides a
subset of the RSTP capabilities described in the 802.1W STP specification.
802.1W Draft 3 support is disabled by default. When the feature is enabled, if a root port on a
device that is not the root bridge becomes unavailable, the device can automatically Switch over to
an alternate root port, without reconvergence delays. 802.1W Draft 3 does not apply to the root
bridge, since all the root bridge ports are always in the forwarding state.
Figure 87 shows an example of an optimal STP topology. In this topology, all the non-root bridges
have at least two paths to the root bridge (Switch 1 in this example). One of the paths is through
the root port. The other path is a backup and is through the alternate port. While the root port is in
the forwarding state, the alternate port is in the blocking state.
Machine States The current states of the various state machines on the port:
•
PIM – State of the Port Information state machine.
•
PRT – State of the Port Role Transition state machine.
•
PST – State of the Port State Transition state machine.
•
TCM – State of the Topology Change state machine.
•
PPM – State of the Port Protocol Migration.
•
PTX – State of the Port Transmit state machine.
Refer to the section “State machines” on page 530 for details on state
machines.
Received Shows the number of BPDU types the port has received:
•
RST BPDU – BPDU in 802.1W format.
•
Config BPDU – Legacy configuration BPDU (802.1D format).
•
TCN BPDU – Legacy topology change BPDU (802.1D format).
TABLE 92 CLI display of show spanning-tree 802.1W (Continued)
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