The Spanning Tree Protocol; The Tasks Of The Stp - Hirschmann RS20 User Manual

Spanning Tree

4.1 The Spanning Tree Protocol

Because RSTP is a further development of the STP, all the following
descriptions of the STP also apply to the RSTP.
4.1.1

The tasks of the STP

The Spanning Tree Algorithm reduces network topologies built with bridges
and containing ring structures due to redundant links to a tree structure. In
doing so, STP opens ring structures according to preset rules by deactivating
redundant paths. If a path is interrupted due to a failure, STP reactivates the
previously deactivated path again. This allows redundant links to increase
the availabiliy of communication.
STP determines a so-called root bridge when building the tree structure. It
will become the STP tree structure's base.
Features of the STP algorithm:
automatic reconfiguration of the tree structure in the case of a bridge
becoming inoperable or the interruption of a data path
the tree structure is stabilized up to the maximum network size (up to
39 hops, depending on the setting for Max Age,
stabilization is achieved within a short time period
topology can be specified and reproduced by the administrator
transparency for the terminal devices
low network load relative to the available transmission capacity due to the
tree structure created
Redundancy L2B
Release 6.0 07/2010
4.1 The Spanning Tree Protocol
(see table 8)
41