Spanning Tree; Understanding Rstp And Mstp - FibroLAN Falcon Gen-3 M-Class User Manual

Falcon M-Class | User Guide
4.17

Spanning Tree

Spanning Tree Protocol was developed in order to protect Ethernet networks from the bad effects
of network loops: a loop is a circular path in the network which causes frame storms that overloads
the Ethernet network.
Spanning Tree Protocol creates a spanning tree within a mesh network of connected Ethernet
bridges and disables the links which are not part of that tree, leaving a single active path between
any two network nodes.
Note: Spanning Tree is available in all uFalcon and Falcon S devices
Spanning Tree Versions:
•
802.1d Legacy Spanning Tree
•
802.1w Rapid Spanning Tree
Faster topology conversion by:
A faster method for temporary loop prevention: STP waits for the new topology to stabilize while
RSTP makes the new root port forwarding immediately once all prior root ports have been made
blocking, and then uses handshaking (on point-to-point links) to make designated ports forwarding
as well.
Improvements in topology change detection, notification, and flushing of the learn tables.
•
802.1s Multiple-Instance Spanning Tree
A newer version supporting more than a single topology: each instance (group of VLANs) can have
its own topology.
4.17.1

Understanding RSTP and MSTP

Understanding RSTP
STP provides basic loop prevention functionality with slow network convergence when topology
changes occur.
RSTP converges faster because a handshake mechanism is deployed, based on P2P links instead of
the timer based process used by STP.
Under RTSP, port assignments change through exchanged messages RSTP device generates
configuration messages once every hello time interval.
An RTSP device will respond to BPDUs sent from the root bridge. The RSTP device will propose its
spanning tree information to its designated ports.
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