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IEEE 802.1Q-2005
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IEEE 802.1w
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IEEE 802.1D
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IEEE 802.1s
EXPLANATION
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. Spanning tree also allows a
network design to include backup links to provide
fault tolerance if an active link fails.
As the name suggests, STP creates a
spanning tree within a network of connected layer-2
bridges,
and disables those links that are not part of the spanning tree,
leaving a single active path between any two network nodes. STP is based
on an algorithm that was invented by
Radia Perlman while she was working for
Digital Equipment Corporation.
[1][2]
In 2001, the
IEEE introduced
Rapid Spanning Tree Protocol (
RSTP)
as 802.1w. RSTP provides significantly faster recovery in response to
network changes or failures, introducing new convergence behaviors and
bridge port roles to do this. RSTP was designed to be
backwards-compatible with standard STP.
STP was originally standardized as
IEEE 802.1D but the functionality of spanning tree (802.1D), rapid spanning tree (802.1w), and
multiple spanning tree (802.1s) has since been incorporated into
IEEE 802.1Q-2014.
[3]
