How do you configure a switch as a root bridge?
To configure a Switch to become the Spanning Tree Protocol (STP) Root Bridge (Root Switch) for a VLAN, you can use the “spanning-tree vlan root” command from the Global Configuration Mode.
What is a Cisco root bridge?
The Root bridge (switch) is a special bridge at the top of the Spanning Tree (inverted tree). The branches (Ethernet connections) are then branched out from the root switch, connecting to other switches in the Local Area Network (LAN). All Bridges (Switches) are assigned a numerical value called bridge priority.
How does Cisco determine root bridge?
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.
Which switch becomes the root bridge?
Since the BID starts with the Bridge Priority field, essentially, the switch with the lowest Bridge Priority field becomes the Root Bridge. If there is a tie between two switches having the same priority value, then the switch with the lowest MAC address becomes the Root Bridge.
How do you designate a spanning-tree root switch?
You can manipulate the Root Bridge Election by setting Bridge priority on your switches. The default value is 32768, and the lowest number is preferred. In the case of a tie, the switch with the lowest MAC address will be selected.
What is the best method of ensuring that your preferred switch is the root bridge?
The switch with the lowest priority, which means lowest BID, becomes the root bridge (the lower the priority value, the higher the priority). For example, to ensure that a specific switch is always the root bridge, you set the priority to a lower value than the rest of the switches on the network.
What happens when root bridge fails?
But if the root bridge goes down, or if the failure means that some switches no longer have a path to the root bridge, this constitutes a major topology change. A new root bridge needs to be selected. The entire network will freeze during this time and no packets can be forwarded.
What is an advantage of Pvst +?
PVST+ is an enhancement for Common STP which separates 802.1d spanning-tree instance for each VLAN. This protocol is more efficient on the links, however it causes higher CPU and memory usage.
What is root port?
A Root Port is a single selected port that has the lowest Path Cost to the Root Bridge. The root port is a direct link to the single root bridge or we can say it has the shortest path to the root bridge.
Which configuration mode allows to configure a particular port on a switch?
Switch ports can be manually configured with specific duplex and speed settings. Use the duplex interface configuration mode command to manually specify the duplex mode for a switch port. Use the speed interface configuration mode command to manually specify the speed for a switch port.