Spanning Tree Protocol

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Spanning Tree Protocol

Spanning Tree Protocol (STP) is a network protocol that ensures a loop-free topology in bridged networks by creating a single active path between any two network devices while providing redundant backup paths. It prevents the formation of loops, which can cause network instability and broadcast storms.

What does Spanning Tree Protocol mean?

Spanning Tree Protocol (STP) is a Layer 2 network protocol that ensures there is only one active path between any two nodes in a network. This prevents network loops, where traffic could endlessly circulate around a network, causing errors and performance degradation.

STP operates by electing a single Switch as the root bridge. All other switches then determine the least cost path to the root bridge and create a spanning tree, where each switch has a single parent switch and a set of designated ports that connect to the other switches in the network.

Applications

STP is essential in any network where there is more than one path between two nodes. This includes:

  • Redundant networks: STP ensures there is always an active path between critical devices, even if one of the links fails.
  • Virtual LANs (VLANs): STP can be used to create multiple VLANs on a single physical network, ensuring that traffic between VLANs is isolated.
  • Data centers: STP is used to create redundant paths between servers and Storage devices, ensuring that data is always available in the event of a failure.

STP is also important in:

  • Preventing network loops: STP’s loop prevention mechanism ensures that traffic does not endlessly circulate around a network.
  • Maximizing Network Performance: By eliminating network loops, STP helps to reduce latency and improve overall network performance.

History

STP was first developed by Digital Equipment Corporation (DEC) in the early 1980s. The original STP, known as DEC Spanning Tree Protocol (DSTP), was a proprietary protocol that operated only on DEC switches.

In 1990, the IEEE published the first standard for STP, IEEE 802.1D. This standard was based on DSTP and added support for other vendor’s switches.

Since then, STP has been revised several times. The current version of STP is IEEE 802.1D-2019. This version includes several enhancements over previous versions, including:

  • Rapid Spanning Tree Protocol (RSTP): RSTP is a faster version of STP that converges more quickly after a network topology change.
  • Multiple Spanning Tree Protocol (MSTP): MSTP allows multiple spanning trees to be created on a single physical network. This can be useful for creating VLANs or for isolating different areas of a network.