Siemens CP 1515 - Manual (Page 283)

Industrial Ethernet Wireless LAN RLM Manager, CP 1515 Manager
C79000-G8976-C171-01
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3DWK FRVW
An advanced Bridge Setup parameter for Radio Link Module that is
used to determine the preferred data paths between bridges
throughout the network and the root bridge as calculated by the
‘Spanning Tree Algorithm.
The ‘Root Bridge’ transmits BPDU messages throughout the Local
Area Network. When a bridge unit receives a BPDU message at one
of its ports, it will add the value in the “Path Cost” field for that port to
the value in the ‘root path cost field’ of the BPDU message prior to
forwarding the message again. This will help the other bridges to
determine the ‘Total Path Cost’ to the Root Bridge via this port.
A lower ‘Path Cost’ value would typically be used for ports to LAN
segments closer to the Root Bridge. A higher ‘Path Cost’ value would
typically be used for ports to LAN segments that are ‘the leafs’ of the
Spanning Tree.
For example, when you use the Access Point RLM as an access point
for wireless stations to the Ethernet, a high ‘Path Cost’ for the
SIMATIC NET IWL port will minimize unnecessary use of the
bandwidth for the wireless medium (recommended value 500).
3HHUWR3HHU :RUNJURXS
A stand-alone workgroup of wireless stations which participate in a
small (Peer-to-Peer) network. This is typically a SIMATIC NET IWL
network configuration without RLMs that could connect the stations
into a network infrastructure.