User Manual

Moxa’s Managed Switch Next Generation OS (v3.x) User Manual

Layer 2 Redundancy

First select Network Redundancy on the menu and then click Layer 2 Redundancy.

Spanning Tree

Spanning Tree Overview

Spanning Tree Protocol (STP) was designed to help construct a loop-free logical typology on an Ethernet

network, and provide an automatic means of avoiding any network loops. This is particularly important for

networks that have a complicated architecture, since unintended loops in the network can cause broadcast

storms. Moxa switches’ STP feature is disabled by default. To be completely effective, you must enable

STP/RSTP on every Moxa switch connected to your network.

STP (802.1D) is a bridge-based system that is used to implement parallel paths for network traffic. STP uses

a loop-detection process to:

• Locate and then disable less efficient paths (e.g., paths that have lower bandwidth).

• Enable one of the less efficient paths if a more efficient path fails.

How STP Works

The figure below shows a network made up of three LANs separated by three bridges. Each segment uses at

most two paths to communicate with the other segments. Since this configuration can give rise to loops, the

network will overload if STP is not enabled.