Brocade FastIron Ethernet Switch Platform and Layer 2 Switching Configuration Guide - Manual (Page 273)

The topology in the following figure contains four bridges. Switch 1 is the root bridge since it has the
lowest bridge priority. Switch 2 through Switch 4 are non-root bridges.
FIGURE 40 Simple 802.1W topology
Assignment of ports on Switch 1
All ports on Switch 1, the root bridge, are assigned Designated port roles.
Assignment of ports on Switch 2
Port2 on Switch 2 directly connects to the root bridge; therefore, Port2 is the Root port.
The bridge priority value on Switch 2 is superior to that of Switch 3 and Switch 4; therefore, the ports on
Switch 2 that connect to Switch 3 and Switch 4 are given the Designated port role.
Furthermore, Port7 and Port8 on Switch 2 are physically connected. The RST BPDUs transmitted by
Port7 are superior to those Port8 transmits. Therefore, Port8 is the Backup port and Port7 is the
Designated port.
Spanning Tree Protocol
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