Siemens SCALANCE X-300 Configuration Manual page 14

Network management for industrial networks
2.2 Functionality and properties of a SCALANCE X-300/X-400
Spanning Tree
The spanning tree algorithm (STP) allows network structures to be created in which there
are several connections between two stations. Spanning Tree permits exactly one path and
disables the other (redundant) ports for data traffic. This prevents loops forming in the
network. If there is an interruption, an alternative path is found via which the data is sent.
Spanning Tree is defined in the IEEE 802.1D-1998 standard.
Rapid Spanning Tree
The Rapid Spanning Tree Protocol (RSTP) is an expansion of the Spanning Tree Protocol
(STP). RSTP differs from STP essentially in that the devices are already collecting
information about alternative routes during normal operation and do not need to gather this
information after a disruption has occurred. This means that the reconfiguration time for an
RSTP controlled network can be reduced to a few seconds.
IE switches support both Rapid Spanning Tree and Spanning Tree.
Rapid Spanning Tree is defined in the IEEE 802.1D-2004 standard.
Multiple Spanning Tree
The Multiple Spanning Tree Protocol (MSTP) is a further development of the Rapid
Spanning Tree Protocol. Among other things, MSTP provides the option of operating
separate RSTP instances within different VLANs or VLAN groups. This, for example, makes
paths available within individual VLANs that the simple Rapid Spanning Tree Protocol would
block globally for data traffic.
Multiple Spanning Tree is defined in the IEEE 802.1Q standard.
C-PLUG
The C-PLUG is an exchangeable storage medium on which all configuration information of
an IE switch is stored. When you replace an IE switch, you simply need to insert the C-PLUG
of the previous device in the new device. The new IE switch then starts up with the
configuration of the previous device.
MAC address table
The MAC address table of an IE switch contains information about the port or ports to which
a received frame should be forwarded. This table can contain both static entries (inserted by
the user) as well as dynamic entries (learned based on the frames received by the IE
switch).
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Configuration Manual, 10/2014, C79000-G8976-C187-22
SCALANCE X-300 / X-400