switch as the master switch by choosing “This is Master” from the Ring Master dropdown list
for the desired switch. All other switches in the ring should be set to the default “Automatic”
setting.
RSTP Examples
Example 1: Maximum “Hops” and Switches in a Redundant Ring:
The Max Age setting controls how long RSTP messages may circulate in the network. When
a switch receives a message, it compares the age of the message with the Max Age (also carried
in the message) and if the age has reached the Max Age, the message is discarded. Otherwise,
the message age is incremented before the message is forwarded. Therefore, the maximum
diameter of a RSTP network is controlled by Max Age. Since the largest value allowed for
Max Age is 40, the largest RSTP network hop diameter is also 40.
Number of Hops vs. Recovery Time:
The diagram below shows a typical redundant ring network with 6 managed switches and 5
hops between stations.
The overall recovery time when there is a network segment failure is dependent on the
number of hops. The recovery time is typically less than 50 ms per hop. Therefore, in the
diagram below of a typical ring with 6 managed switches the overall recovery time would be
less than 250 ms (5 hops x <50 ms).
NOTE: When a port is configured as a Ring port, that port cannot be used for communication to or through the Switch.
It can ONLY be connected to another Ring port on a managed Switch or Real-Time Ring Switch.
4-24
Chapter 4 - Managed Switch Software Setup
Stride Industrial Ethernet Switches User Manual 2nd Ed. Rev. A
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