ZyXEL Communications VES-1616 Support Notes page 96

ZyXEL VES-1616/24FA-5x Series Support Notes
1. Switch A bridge ID = 8000:00A0:C511:1111, Switch B bridge ID =
8000:00A0:C522:2222, Switch C bridge ID = 0001:00A0:C533:3333. Switch C
has the lowest bridge ID, so Switch C is the root bridge. All ports of the root bridge
are designated ports, so Port 1 is designated port.
2. For non-root bridge Switch A, Port 1 path cost to root bridge is 19, Port 2 path
cost is 119, 100 (Switch A Port 2) + 19 (Switch B Port 1). For Switch B, Port 1 path
cost is 19, Port 2 path cost is 119. Root port = Port 1 of Switch A and Switch B
because it has the lowest path cost to the root bridge Switch C.
3. On Segment A, both Port 2 of Switch A and Switch B have the same path cost
to root bridge. Since Switch A has lower bridge ID than Switch B, the designated
port is selected on Switch A. So Port 2 of Switch A is designated port.
Blocking = Port 2 of Switch B, the non designated port on the segment.
Forwarding = All designated ports and root ports.
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