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MULTILINK ML1200 MANAGED FIELD SWITCH – INSTRUCTION MANUAL 12–1
Managed Field Switch
Chapter 12: Spanning Tree
Spanning Tree Protocol (STP)
The Spanning Tree Protocol was designed to avoid loops in an Ethernet network. An
Ethernet network using switches can have redundant paths, which may cause loops. To
prevent loops, the MultiLink Switch Software uses the spanning tree protocol (STP).
Controlling the span in which traffic traverses is necessary as a manager of the software. It
is also necessary to specify the parameters of STP. STP is available as the IEEE 802.1d
protocol and is a standard of the IEEE.
12.1.2 Features and Operation
The switch uses the IEEE 802.1d Spanning Tree Protocol (STP). When STP is enabled, it
ensures that only one path at a time is active between any two nodes on the network. In
networks where more than one physical path exists between two nodes, STP ensures only
a single path is active by blocking all redundant paths. Enabling STP is necessary to avoid
loops and duplicate messages. This duplication leads to a “broadcast storm” or other
erratic behavior that can bring down the network.
As recommended in the IEEE 802.1Q VLAN standard, the MultiLink ML1200 Managed Field
Switch uses single-instance STP. This means a single spanning tree is created to make sure
there are no network loops associated with any of the connections to the switch. This
works regardless of whether VLANs are configured on the switch. Thus, these switches do
not distinguish between VLANs when identifying redundant physical links.
The switch automatically senses port identity and type, and automatically defines port
cost and priority for each type. The software allows a manager to adjust the cost, priority,
the mode for each port as well as the global STP parameter values for the switch.