Your step 1 is fine. Step 2 should be "the root bridge (just like any other bridge in the network) checks to see if it has more than one port on any given, single LAN segment, and if it does, makes the port with the highest port priority the designated port for that segment, putting all other ports on that segment into blocking mode." Step 2.5 should be: "Each non-Root Bridge looks to see if it should have a Root Port. It does so by checking all BPDUs it has received on all ports, and selects among those, the ports that have the best Root Path Cost. Among those ports, the port with the lowest Port ID becomes the Root Port." That is, if it's a bridge. If it's a Cisco switch, instead, step 2.5 should read: "Each non-Root Bridge looks to see if it should have a Root Port. It does so by checking all BPDUs it has received on all ports, and selects among those, the ports having the lowest Root Path Cost. Among those ports with the lowest root path cost, it selects the port that has received the lowest port ID as the Root Port; the other ports on that LAN segment are put into blocking mode." Step 3 is close enough; good by me. Likewise, step 4. The answers below are pretty much correct, but the response from Raveesh needs some further explanation. The figures he has enlarged are not the root path cost for that bridge. For that, you have to look further up int the screen dump to see the section that says "Root ID" and under that, "cost." The root path cost to the root bridge, meaning the fastest path to the root bridge is that cost figure, 23. You can ignore all the path costs associated with the various ports and interfaces as the "least-cost-path" has already been factored into the "cost" figure representing the bridge's root path cost. Cost is only calculated on ports incoming in relationship to the root bridge, and the port costs don't tell you which one of those ports is the root port. All you CAN know is the individual port path costs, and the bridge's total root path cost. The Root path is stated in the output as Fa2/0/27, with a cost of 19, a 100 Mbps port. Likewise, the bridge's designated port has a cost of 4, making it a gigabit port. The cost of port Fa2/0/27 is already factored into the root path cost of 23, so no higher math required. We can also state that if the bridge was directly connected to the Root Bridge, the "cost" for the root bridge would be zero. So, we can conclude that if 19 is the cost of the root port, and 23 is the root path cost for the bridge, then there is another bridge between this bridge and the Root Bridge, and it connects to the Root Bridge (23-19=4) via a 1 Gbps link, or perhaps two 10 Gbps links. I'd bet on the single 1 Gbps link, though. Paul  ... View more