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4.3.6.1 RSTP Switch Settings
Select the option RSTP Switch Settings from the Rapid Spanning Tree menu and then
the following screen page appears.
System Priority: When switches on a segment decide which switch becomes a root bridge,
they exchange BPDU frames to determine which switch has the lowest BID. BID mainly
contains two parts. The first part is system priority. Each interface is associated with a port
(number) in the STP code. By default, every switch’s system priority is 32768. You can
change the value by selecting from the pull-down menu but only in increments of 4096. The
Managed Switch with the lowest priority will be selected as the root bridge which is the
“central” bridge in the spanning tree. If switches have the same priority, the other BID
component, MAC address, becomes the deciding factor to determine the root bridge.
Max Age: Maximum age is the length of time that a port saves BPDU configuration
information. By default, the maximum age is set to 20 seconds.
Hello Time: Periodically, a hello packet is sent out to all ports that are not in blocking mode
to communicate information about the topology throughout the entire Bridged Local Area
Network. The default hello time is 2 seconds but can be adjusted between 1 and 10 seconds.
Forward Delay: It is the time spent in each Listening and Learning state before the
Forwarding state is entered. This forward delay occurs when a typology changes (a new
bridge comes onto a busy network). If a switch changes too often, it is possible that not all
network links will be ready to change their state and loops can happen as a result. The
forward delay interval is set to 15 seconds but can be adjusted between 4 and 30 seconds.
Version: Set the Spanning Tree Protocol to be used. Both STP and RSTP have similar
parameters; however, RSTP achieves faster convergence than STP.
NOTE: If you choose STP, you can not enable ports to be edge ports or point to point
ports. The fields for “Edge” and “Point to point” become selectable in RSTP Physical Port
Settings when you select RSTP.
