Brocade FastIron Ethernet Switch Platform and Layer 2 Switching Configuration Guide - Manual (Page 274)

Assignment of ports on Switch 3
Port2 on Switch 3 directly connects to the Designated port on the root bridge; therefore, it assumes the
Root port role.
The root path cost of the RST BPDUs received on Port4/Switch 3 is inferior to the RST BPDUs
transmitted by the port; therefore, Port4/Switch 3 becomes the Designated port.
Similarly Switch 3 has a bridge priority value inferior to Switch 2. Port3 on Switch 3 connects to Port 3
on Switch 2. This port will be given the Alternate port role, since a Root port is already established on
this bridge.
Assignment of ports on Switch 4
Switch 4 is not directly connected to the root bridge. It has two ports with superior incoming RST
BPDUs from two separate LANs: Port3 and Port4. The RST BPDUs received on Port3 are superior to
the RST BPDUs received on port 4; therefore, Port3 becomes the Root port and Port4 becomes the
Alternate port.
Edge ports and edge port roles
The Brocade implementation of 802.1W allows ports that are configured as Edge ports to be present
in an 802.1W topology. (
Figure 41 ). Edge ports are ports of a bridge that connect to workstations or
computers. Edge ports do not register any incoming BPDU activities.
Edge ports assume Designated port roles. Port flapping does not cause any topology change events
on Edge ports since 802.1W does not consider Edge ports in the spanning tree calculations.
Edge ports and edge port roles
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