Spanning-Tree Operation
Configuring Rapid Reconfiguration Spanning Tree (RSTP)
Reconfiguring Whole-Switch Spanning Tree Values. You can configure
one or more of the following parameters, which affect the spanning tree
operation of the whole switch:
Table 5-1. Whole-Switch RSTP Parameters
Parameter Default Description
protocol-version RSTP Identifies which of the spanning tree protocols will be used when spanning tree
is enabled on the switch.
force-version rstp-operation Sets the spanning tree compatibility mode. Even if rstp-operation is selected
though, if the switch detects STP BPDU packets on a port, it will communicate
to the attached device using STP BPDU packets.
If errors are encountered, as described in the Note on page 12, the Force-
Version value can be set to stp-compatible, which forces the switch to
communicate out all ports using operations that are compatible with IEEE 802.1D
STP.
priority 32768
(8 as a step value)
Specifies the protocol value used along with the switch MAC address to
determine which device in the spanning tree is the root. The lower the priority
value, the higher the priority.
The value you enter has changed from the STP value. The range is 0 - 61440, but
for RSTP the value is entered as a multiple (a step) of 4096. You enter a value in
the range 0 - 15. The default value of 32768 is derived by the default setting of 8.
Displaying the RSTP configuration (show spanning-tree config) shows 8, but
displaying the RSTP operation (show spanning-tree) shows 32768.
*maximum-age 20 seconds Sets the maximum age of received spanning tree information before it is
discarded. The range is 6 to 40 seconds.
*hello-time 2 seconds Sets the time between transmission of spanning tree messages. Used only when
this switch is the root. The range is 1 to 10 seconds.
*forward-delay 15 seconds Sets the time the switch waits between transitioning ports from listening to
learning and from learning to forwarding states. The range is 4 to 30 seconds.
*These parameters are the same for RSTP as they are for STP. The switch uses its own maximum-age, hello-time, and
forward-delay settings only if it is operating as the root device in the spanning tree. If another device is the root device,
then the switch uses the other device’s settings for these parameters.
5-16
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