TOP 10 SPANNING TREE PROTOCOL | STP | INTERVIEW QUESTIONS & ANSWER | PART 1
Explain types of STP Port Roles? Root port – The root port is always the link directly connected to the root bridge, or the shortest path to the root bridge. It is always on Non-Root Bridge. Designated port – A designated port is one that has been determined as having the best (lowest) cost. A designated port will be marked as a forwarding port. It can be on both the root Bridge & non-root Bridge. All ports of root bridge are designated port. Forwarding port – A forwarding port forwards frames. Blocked port – A blocked port is the port that is used to prevent loops. It only listens to BPDUs. Any port other than root port & designated port is a blocked port.
What are the different port states? 1. Disabled – A port in the disabled state does not participate in the STP. 2. Blocking – A blocked port does not forward frames. It only listens to BPDUs. The purpose of the blocking state is to prevent the use of looped paths. 3. Listening – A port in the listening state prepares to forward data frames without populating the MAC address table. The port also sends and listens to BPDUs to make sure no loops occur on the network. 4. Learning – A port in learning state populates the MAC address table but doesn’t forward data frames. The port still sends and receives BPDUs as before. 5. Forwarding – The port now can send and receive data frames, collect MAC addresses in its address table, send and receive BPDUs. The port is now a fully functioning switch port within the spanning-tree topology.
How Root bridge is elected? The bridge ID is used to elect the root bridge in the STP domain. This ID is 8 bytes long and includes both the priority and the MAC address of the device. Switch with the lowest Bridge ID is elected as the root bridge which means switch with the lowest priority will become root bridge if two or more switches have same priority then switch with lowest mac address will become root Bridge.
What is Path Cost or Spanning Tree Path Cost value? The Spanning Tree Cost Value is inversely proportional to the bandwidth of the link and therefore a path with a low cost value is preferable than a path with high cost value. Link Bandwidth Cost Value 10 Gbps 2 1 Gbps 4 100 Mbps 19 10 Mbps 100
What is Root Port? Once the Root Switch is elected, every other Switch in the network must select a single port on itself to reach the Root Switch. The port with the lowest root path cost (lowest cumulative cost to reach the root switch) is elected as the root port and is placed in the forwarding state. Root bridge will never have a root port.
STP Interview Questions:
Spanning Tree protocol is a very important concept to understand in Networking Field. This article is related to “STP Interview Questions”. Here are some most important questions and answer related to STP (Spanning Tree protocol). And these are very helpful for your networking related job interviews.
UDLD aggressive mode is a mode of operation for the Spanning Tree Protocol (STP) that allows for faster detection of unidirectional links. In this mode, STP will immediately place any port that receives UDLD packets from only one direction into a blocking state. This can help to prevent issues caused by unidirectional links, such as data loss or network loops.
In short, the port state is the condition of the port with respect to the Spanning Tree Protocol. There are three possible states that a port can be in: blocking, listening, and learning. In the blocking state, the port cannot forward any traffic. In the listening state, the port can begin forwarding traffic, but it first needs to listen for a period of time to make sure that there are no other active paths. In the learning state, the port can forward traffic, and it is also learning the addresses of the devices on the network.
You can configure VLANs on a Cisco switch using STP by creating a separate VLAN for each switch port. You will then need to configure the switch port to trunk mode so that it can carry traffic for all VLANs. Finally, you will need to enable STP on the switch port.
BPDUFilter is a Spanning Tree Protocol feature that is used to prevent loops in the network. It does this by filtering out BPDUs that are received on ports that have been configured for PortFast. BPDUGuard is a Spanning Tree Protocol feature that is used to protect ports that have been configured for PortFast. It does this by shutting down the port if a BPDU is received on it.
When a switch receives a BPDU from another switch that has a lower priority, it will keep its current port configuration. However, if the BPDU has an equal priority, then the switch will compare the MAC addresses of the two switches. The switch with the lower MAC address will keep its current port configuration, while the switch with the higher MAC address will change its port configuration.
STP Interview Questions and Answers Vol 0
Check the Description below for STP Interview Questions
FAQ
What are the three types of an STP?
- What is STP and Redundant Links? …
- How STP works? …
- What are the different port states? …
- What is STP Timer and Explain different types of STP Timers? …
- Explain types of STP Port Roles? …
- What is BPDU?
Why we use STP protocol?
