How does STP elect the root switch?

How does STP elect the root switch?

The root bridge is selected by manually configuring its bridge priority to a low value. 32768 is the default value out of a range from 0 to 61440. If all switches in a single spanning tree have the same bridge priority, the switch with the lowest MAC address will become the root bridge.

How is root port elected?

STP Root Port Selection

1. Lowest bridge ID (Priority:MAC Address) switch becomes the Root-Bridge.
2. Each non-root bridge should have ONE root port (RP) which is the port having lowest path-cost to Root Bridge.
3. All ports in Root Bridge become Designated Ports (DP)
4. Each segment should have one Designated Port (DP)

What is the sequence when selecting the root port on a switch stack?

The switch with the lowest priority of all the switches will be the root; if there is a tie, then the switch with the lowest priority and lowest MAC address will be the root.

How designated port is elected in STP?

Designated ports are selected on a per-segment basis, based on the cost of each port on either side of the segment and the total cost calculated by STP for that port to get back to the root bridge. If one end of a segment is a root port, then the other end is a designated port.

What is the difference between root port and designated port in STP?

The Designated Port is the port that has the lowest Spanning Tree Path Cost on a particular Local Area Network (LAN) segment. The Root Port is the port on the Bridge (Switch) with the least Spanning Tree Path Cost from the switch to the Root Bridge.

What is the first criteria for selecting the root switch?

Root port – The port which receives the best BPDU on a non-root bridge. Criteria for selecting root port:

• Lowest path cost to reach the root bridge.
• Lowest sender bridge I’d.
• Lowest sender port I’d.

Which of the following bridge is win election as root?

Which of the following bridge IDs wins election as root, assuming that the switches with these bridge IDs are in the same network? C. The smallest numeric bridge ID wins the election.

How is root ports selected in a switch network?

By default, port costs are defined by the speed at which the port operates. Every non-root bridge selects a root port; this is the port with the lowest cost path to the root bridge. Default costs depend on the speed of the link as set by IEEE (individual path cost = 19).

Which attribute is used to elect a root bridge?

What attributes are used to elect a root bridge? The switch with the lowest bridge priority is elected as the root bridge. In the event of a tie, the bridge MAC address is used to elect a root bridge.

What is an alternate port in STP?

Alternate Port is a blocking port that receives better BPDU from another switch. It is the backup of Root Port. Backup Port is a blocking port that receives better BPDU from the same switch. It is the backup of Designated Port.

How many root ports does STP have?

one root port
An STP device has only one root port, and there is no root port on the root bridge. Designated port: The designated port is located on a designated bridge and forwards configuration BPDUs to the device or LAN, as illustrated in Figure 1.

What is a PCIE root port?

The PCI Express Root Port is a port on the root complex — the portion of the motherboard that contains the host bridge. The host bridge allows the PCI ports to talk to the rest of the computer; this allows components plugged into the PCI Express ports to work with the computer.