Pilz PSSnet SHL 8T MRP - Manual (Page 57)

Rapid Spanning Tree
PSSnet SHL - Redundancy Configuration
Pilz GmbH & Co. KG, Felix- Wankel Str. 2, 73760 Ostfildern
4.1 The Spanning Tree Protocol
57
4.1.4 Root Path Costs
Every path that connects two bridges is assigned costs for the transmission
(path costs). The Switch specifies this value based on the transmission
speed
(see table 10) . It assigns the higher path costs to paths with lower
transmission speeds.
Alternatively, the Administrator can specify the path costs. Like the Switch,
the Administrator assigns the higher path costs to paths with lower transmis-
sion speeds. However, since the Administrator can choose this value freely,
he has a tool with which he can give a certain path an advantage among
redundant paths.
The root path costs are the sum of all the individual path costs for all paths
along which a data packet travels between the connected port of a bridge and
the root bridge.
Figure 29: Path costs
Ethernet (100 Mbit/s)
Ethernet (10 Mbit/s)
PC Path costs
PC = 2 000 000
PC = 200 000
PC = 200 000
Bridge 1
Bridge 2 Bridge 3