What is STP and how it works?

Posted on by Jessy Collins

What is STP and how it works?

What is STP and how does it work? Spanning Tree Protocol (STP) is a Layer 2 network protocol used to prevent looping within a network topology. STP was created to avoid the problems that arise when computers exchange data on a local area network (LAN) that contains redundant paths.

What is STP in CCNA?

Spanning Tree Protocol (STP) is a network protocol designed to prevent layer 2 loops. It is standardized as IEEE 802. D protocol. STP blocks some ports on switches with redundant links to prevent broadcast storms and ensure loop-free topology.

What does STP do on a switch?

The Spanning Tree Protocol (STP) is responsible for identifying links in the network and shutting down the redundant ones, preventing possible network loops. In order to do so, all switches in the network exchange BPDU messages between them to agree upon the root bridge.

What is VLAN and STP?

Spanning Tree Protocol (STP) prevents loops in networks and VLAN (Virtual Local Area Network) is used to create many virtual Local Area Networks. There are certain situations where you need redundant links but not loops. Redundant links are helpful in networks as backups in failover cases.

Why is STP used?

Spanning tree protocol (STP) (IEEE 802.1D) is predominantly used to prevent layer 2 loops and broadcast storms and is also used for network redundancy.

What is BPDU guard?

BPDU Guard is a feature that defends the Layer 2 Spanning Tree Protocol (STP) topology against BPDU-related threats and is designed to protect the switching network. The BPDU guard feature must be activated on ports that should not receive BPDUs from connected devices.

What are the 4 states of the Spanning Tree Protocol?

There are five Spanning Tree Port States :

  • Blocking State : Switch port enters the blocking state at time of election process, when a switch receives a BPDU on a port that indicates a better path to the Root Switch or if a port is not a Root Port.
  • Listening State :
  • Learning State :
  • Forwarding State :
  • Disabled State :

Why do we need STP?

The Spanning Tree Protocol (STP) is a network protocol that builds a loop-free logical topology for Ethernet networks. The basic function of STP is to prevent bridge loops and the broadcast radiation that results from them.

What are the types of STP?

Following are few STP process & System commonly used in India.

  • Activated Sludge Process.
  • Moving Bio Bed Reactor (MBBR)
  • Membrane Bio Reactor (MBR)
  • Electro Coagulation System.
  • Sequential Bio Reactor (SBR)
  • Rotating Bio Reactor (RBC)

Is spanning tree per VLAN?

Per VLAN Spanning Tree (PVST) is a Cisco proprietary protocol that allows a Cisco device to have multiple spanning trees. The Cisco device can interoperate with spanning trees on other PVST devices but cannot interoperate with IEEE 802.1Q devices. An IEEE 802.1Q device has all its ports running a single spanning tree.

What is BPDU in networking?

(Bridge Protocol Data Unit) A spanning tree protocol (STP) message unit that describes the attributes of a switch port such as its MAC address, priority and cost to reach. BPDUs enable switches that participate in a spanning tree protocol to gather information about each other.

Why PortFast is used?

The PortFast feature is introduced to avoid network connectivity issues. These issues are caused by delays in STP enabled ports moving from blocking-state to forwarding-state after transitioning from the listening and learning states.

What is PortFast and BPDU guard?

The PortFast and BPDU. A BPDU is a data message transmitted across a local area network to detect loops in network topologies. Guard features enhance network reliability, manageability, and security for Layer-2 STP. STP is a network protocol that builds a logical loop-free topology for Ethernet networks. .

Who sent BPDU?

Configuration BPDU, sent by root bridges to provide information to all switches. TCN (Topology Change Notification), sent by bridges towards the root bridge to notify changes in the topology, such as port up or port down.

What are the types of BPDU?

There are mainly two types of Bridge Protocol Data Units:

Configuration BPDU. Topology Change Notification (TCN) BPDU.

What is Bpdu guard?

Which VLAN does STP use?

STP runs on the Native VLAN so that it can communicate with both 802.1Q and non-802.1Q compatible switches. This single instance of STP is often referred to as 802.1Q Mono Spanning Tree or Common Spanning Tree (CST).

What are types of BPDU?

What is 802.1 d in networking?

802.1D is the IEEE Media Access Control (MAC) Bridges standard which includes the Spanning Tree Protocol (STP) and Bridging. It details linking to other 802 projects, including the Ethernet and Wi-Fi standards.

What is a BPDU Cisco?

Bridge Protocol Data Units (BPDUs) are frames that contain information about the spanning tree protocol (STP). A switch sends BPDUs using a unique source MAC address from its origin port to a multicast address with destination MAC (01:80:C2:00:00:00, or 01:00:0C:CC:CC:CD for Cisco proprietary Per VLAN Spanning Tree).

What is a BPDU packet?

BPDU – Bridge Protocol Data Unit
BPDUs are data messages that are exchanged across the switches within an extended LAN that uses a spanning tree protocol topology. BPDU packets contain information on ports, addresses, priorities and costs and ensure that the data ends up where it was intended to go.

What is a BPDU filter?

The STP BPDU filter feature allows control of spanning tree participation on a per-port basis. It can be used to exclude specific ports from becoming part of spanning tree operations. A port with the BPDU filter enabled will ignore incoming BPDU packets and stay locked in the spanning tree forwarding state.

What is BPDU guard for?

BPDU Guard prevents switching devices from being accidentally connected to PortFast-enabled ports. If someone tries to connect an L2 device to the network, the BPDU guard ensures that it will be rejected.

Is BPDU a Layer 2?

Definition. BPDUs are Layer 2 protocol packets. As shown in Figure 16-1, BPDUs are encapsulated using IEEE 802.3 and are transmitted in multicast mode. BPDUs are used to transmit Spanning Tree Protocol (STP) and Multiple Spanning Tree Protocol (MSTP) information.

What port does BPDU use?

The port which receives a BPDU is normally a Root Port. For a Non-Root Bridge a port that receives a BPDU, that port leads to the Root Bridge (Root Switch). If a Non-Root Bridge receives BPDUs in two ports, probably the network is in a Layer 2 loop.