Please find attached diagram on this.
Hi, can you clarify this?
Imagine my "root" bridge has been identified. Please find attached diagram. Then I have two switches "Switch2" and "Switch3". I understand that at that point a root port for each switch should be determined determined based on the lowest cost to get to root bridge. If I look at "Switch3", what happens if I have two paths with same cost to get to "Root"?
Which path the STP algorithm would take at that point thus making that the "Root Port" and the path with the highest cost the "blocked" port??
STP uses the following order sequence to decide on its parameters
Step 1. Lowest Root BID
Step 2. Lowest Path Cost to Root Bridge
Step 3. Lowest Sender BID
Step 4. Lowest Port ID
In your case the step 1 & 2 would yield the same result and hence the deciding factor would be the 3 point which is the lowest sender bridge ID (which could be either be the root or the swith2 in your case)
If you had both the links terminated on the same root switch directly, then the deciding factor would have been the port ID and the lowest port would be in forwarding state by default.
HTH, rate if it does