Root Path Cost - Hirschmann RS20 User Manual

Spanning Tree
6.1.4

Root Path Cost

Each path that connects 2 bridges is assigned a cost for the transmission
(path cost). The Switch determines this value based on the transmission
speed (see table
transmission speeds.
Alternatively, the Administrator can set the path cost. Like the Switch, the
Administrator assigns a higher path cost to paths with lower transmission
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 cost is the sum of all individual costs of those paths that a data
packet has to traverse from a connected bridge's port to the root bridge.
PC = 200 000
PC = 200 000
2
Figure 44: Path costs
Data rate Recommended value
≤100 Kbit/s 200,000,000
1 Mbit/s 20,000,000
10 Mbit/s 2,000,000
100 Mbit/s 200,000
1 Gbit/s 20,000
10 Gbit/s 2,000
100 Gbit/s 200
1 TBit/s 20
10 TBit/s 2
Table 13: Recommended path costs for RSTP based on the data rate.
UM RedundConfig L2P
Release 8.0 05/2013
13). It assigns a higher path cost to paths with lower
1
PC = 200 000 000
3
Recommended range
a
20,000,000-200,000,000 1-200,000,000
a
2,000,000-200,000,000
a
200,000-20,000,000
a
20,000-2,000,000
2,000-200,000
200-20,000
20-2,000
2-200
1-20
6.1 The Spanning Tree Protocol
Path costs
PC
Ethernet (100 Mbit/s)
Ethernet (10 Mbit/s)
Possible range
1-200,000,000
1-200,000,000
1-200,000,000
1-200,000,000
1-200,000,000
1-200,000,000
1-200,000,000
1-200,000,000
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