Contents
How does STP choose which port to block?
All switches that are participating in STP exchange BPDU frames to determine which switch has the lowest bridge ID (BID) on the network. After the root bridge has been determined, the STA calculates the shortest path to the root bridge. Each switch uses the STA to determine which ports to block.
What is the first value STP uses to determine port selection?
Default Spanning Tree Port Priority value value is 128 and you may change the Port Priority value in increments of 16. Above topology, omnisecu.com.
Which switch port will be in a blocking state?
Listening state: Only a root or designated port will move to the listening state. The non-designated port will stay in the blocking state.No data transmission occurs at this state for 15 seconds just to make sure the topology doesn’t change in the meantime.
What is root port STP?
Root port: The root port on an STP device has the smallest path cost to the root bridge and is responsible for forwarding data to the root bridge. Among all STP-capable ports on a device, the port with the smallest root path cost is a root port.
What are the STP port roles?
Those roles include root, designated, alternate, backup, and disabled. Root and designated are still the roles that reach the state of forwarding. The role of Desg and Root port is forwarding traffic. The role of Alt is to block the traffic.
What is the STP blocking state?
It’s little said about STP Blocking State. “The Switch Ports will go into a blocking state at the time of election process, when a switch receives a BPDU on a port that indicates a better path to the Root Bridge, and if a port is not a Root Port or a Designated Port.”
How does stp choose the root bridge port?
After electing the root bridge STP has to be choose the root port to the root bridge & the lowest port-priority become the root port & other redundant port will be blocked. So port-priority is used to elect the root port & block the the redundant link in the network.
Which is a blocking port in the STP topology?
– Designated Port (DP) – It is a port that is in the forwarding state. (i.e. port 0/1 0/2 SW2) – Non-Designated Port (NDP) – It is a port that is in a blocking state in the STP topology.
What is the STP designated port in Ethernet?
Selecting STP designated port (DP) We’ve already learned that, on the shared Ethernet segments, the switch with the best path to reach the root switch is placed in forwarding state. That switch is called the designated switch and its port is known as the designated port.
Why are STP buts ports placed in forwarding state?
Another reason why STP buts ports into forwarding state is if a port is the root port on a switch. Each switch has one root port, which is the port that is currently receiving the lowest cost BPDU from the root switch. Same if Switch B, say it receives a low cost on port 26 then that port is placed in forwarding state.