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Configuring STP Bridge Parameters Configuring Spanning Tree Parameters
page 6-26 OmniSwitch AOS Release 7 Network Configuration Guide June 2013
snapshot file. In addition, explicit commands are captured for both flat and per-VLAN mode configura-
tions.
Configuring STP Bridge Parameters
The Spanning Tree software is active on all switches by default and uses default bridge and port
parameter values to calculate a loop free topology. It is only necessary to configure these parameter values
if it is necessary to change how the topology is calculated and maintained.
Note the following when configuring Spanning Tree bridge parameters:
•
When a switch is running in the per-VLAN Spanning Tree mode, each VLAN is in essence a virtual
bridge with its own Spanning Tree instance and configurable bridge parameters.
•
When the switch is running in the flat mode and STP (802.1D) or RSTP (802.1w) is the active
protocol, bridge parameter values are only configured for the flat mode instance.
•
If MSTP (802.1s) is the active protocol, then the priority value is configurable for each Multiple
Spanning Tree Instance (MSTI). All other parameters, however, are still only configured for the flat
mode instance and are applied across all MSTIs.
•
Bridge parameter values for a VLAN instance are not active unless Spanning Tree is enabled on the
VLAN and at least one active port is assigned to the VLAN. Use the
spantree vlan admin-state
command to enable or disable a VLAN Spanning Tree instance.
•
If Spanning Tree is disabled on a VLAN, active ports associated with that VLAN are excluded from
Spanning Tree calculations and remain in a forwarding state.
•
Note that when a switch is running in the flat mode, disabling Spanning Tree on VLAN 1 disables the
instance for all VLANs and all active ports are then excluded from any Spanning Tree calculations and
remain in a forwarding state.
The following is a summary of Spanning Tree bridge configuration commands. For more information
about these commands, see the
OmniSwitch CLI Reference Guide.
Commands Used for ...
spantree protocol Configuring the protocol for the flat mode CIST instance or a per-
VLAN mode VLAN instance.
spantree priority Configuring the priority value for the flat mode CIST instance, a
Multiple Spanning Tree Instance (MSTI), or a per-VLAN mode
VLAN instance.
spantree hello-time Configuring the hello time value for the flat mode CIST instance or
a per-VLAN mode VLAN instance.
spantree max-age Configuring the maximum age time value for the flat mode CIST
instance or a per-VLAN mode VLAN instance.
spantree forward-delay Configuring the forward delay time value for the flat mode CIST
instance or a per-VLAN mode VLAN instance.
spantree bpdu-switching Configuring the BPDU switching status for a VLAN.