9 Rapid Spanning Tree Protocol (RSTP)
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TOEP C730600 0EA Modbus TCP/IP Installation Manual
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9
Rapid Spanning Tree Protocol (RSTP)
Rapid Spanning Tree Protocol (RSTP) is a mechanism that allows an Ethernet network to
be configured as a ring or other topology that may have more than one pathway to each
node. The RSTP protocol automatically determines the most efficient pathway to each
node and disables any redundant pathways.
If one path fails, RSTP activates another pathway to keep the network traffic flowing.
After restoring the failed path, RSTP disables any redundant paths without disrupting
network traffic.
◆
Convergence Time
Convergence is the process that RSTP performs to identify the root node and which
pathways to disable. Convergence occurs on power up and when the network changes (e.
g., path failures and restorations).
Take special care when using parameter
F7-16 [Timeout Value]
, Communication Timeout
Loss, and be sure to give RSTP enough time for convergence. When
F7-16
is set too
short, convergence will not be able to complete before it expires. The complexity of the
network and the number of drives on the network will both factor into the value of the
timeout.
RSTP is unnecessary and should be disabled when using star or line topology network
configurations (RSTP is disabled by default).
◆
Topology
The option is ideal for use in ring topologies. With RSTP enabled, a ring topology
provides redundancy to the network. RSTP determines the fastest paths to each node on
the network and virtually splits the ring by disabling one port on one node to prevent data
from being transmitted endlessly around the ring. If a path on the ring fails, RSTP re-
enables the disabled port and reconnects the split. All nodes on the network remain
accessible without any interruptions.
RSTP is unnecessary and should be disabled when using star or line topology network
configurations (RSTP is disabled by default).
◆
Enabling RSTP
RSTP is enabled from the webpage on the option.
