User's Manual

Configuration Using Web Based Management and the Command Line Interface
6.5.3 ARP Table Menu Command
Assignment of MAC Address and IP Address
The ARP protocol (Address Resolution Protocol) obtains the corresponding MAC
address of a known IP address. The page of this menu command also indicates
the interface over which a computer can be reached. The last column indicates
how the information was obtained (for example dynamic if it was obtained from ac-
tive data exchange).
6.5.4 Spanning Tree Menu Command
Avoiding Redundant Network Structures
The Spanning Tree protocol identifies physically redundant network structures and
prevents loops occurring by turning off redundant paths. It does this by evaluating
the distance and performance of a connection or by evaluating user settings. Data
is then only exchanged on the remaining connection paths.
If the preferred data path fails, the Spanning Tree algorithm looks for the most effi-
cient path possible with the remaining network nodes.
Root Bridge and Bridge Priority
The identification of the most efficient connection is always related to the root
bridge, a computer that can be considered as a root element of a tree-like network
structure. With the Bridge Priority parameter, you can influence the selection of the
root bridge. The computer with the lowest value for this parameter automatically
becomes the root bridge. If two computers have the same priority value, the com-
puter with the lower MAC address becomes the root bridge.
Response to Changes in the Network Topology
If nodes are added to a network or removed from it, this can influence the selection
of the optimum path for the data packets. To keep on top of this situation, the root
bridge sends configuration messages at regular intervals. You can set the interval
between two configuration messages with the Hello Time parameter.
Operating Instructions SCALANCE W 788-1pro / SCALANCE W 788-2pro
C79000-G8976-C184-01
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