Brocade FastIron Ethernet Switch Platform and Layer 2 Switching Configuration Guide - Manual (Page 308)

802.1W Draft 3 support is disabled by default. When the feature is enabled, if a root port on a Brocade
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.
The following figure 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.
FIGURE 63 802.1W Draft 3 RSTP ready for failover
If the root port on a Switch becomes unavailable, 802.1W Draft 3 immediately fails over to the
alternate port, as shown in the following figure.
Spanning Tree Protocol
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