Enabling/Disabling Spanning Tree For A Vlan; Enabling/Disabling Source Learning - Alcatel-Lucent OmniSwitch 9900 Series Network Configuration Manual

Configuring VLANs

Enabling/Disabling Spanning Tree for a VLAN

The Spanning Tree operating mode for the switch determines how VLAN ports are evaluated to identify
redundant data paths. If the Spanning Tree switch operating mode is set to flat, then VLAN port
connections are checked against other VLAN port connections for redundant data paths.
Note. The single flat mode STP instance is referred to as the CIST (Common and Internal Spanning Tree)
instance.
In the flat mode, if the CIST instance is disabled, then it is disabled for all configured VLANs. However,
disabling STP on an individual VLAN excludes only those VLAN ports from the flat STP algorithm.
If the Spanning Tree operating mode is set to per-vlan mode, there is a single Spanning Tree instance for
each VLAN broadcast domain. Enabling or disabling STP on a VLAN in this mode includes or excludes
the VLAN from the per-vlan STP algorithm.
The spantree vlan admin-state
existing VLAN. In the following examples, Spanning Tree is disabled on VLAN 255 and enabled on
VLAN 755:
-> spantree vlan 255 admin-state disable
-> spantree vlan 755 admin-state enable
STP does not become operationally active on a VLAN unless the VLAN is operationally active, which
occurs when at least one active port is assigned to the VLAN. Also, STP is enabled/disabled on individual
ports. So even if STP is enabled for the VLAN, a port assigned to that VLAN must also have STP
enabled. See Chapter 6, "Configuring Spanning Tree Parameters."

Enabling/Disabling Source Learning

Source learning can be disabled on a VLAN. Disabling source learning can be beneficial in a ring
topology. There is no limit on the number of ports that can belong to a VLAN that has source learning
disabled, but it is recommended to include only the two ports connecting the switch to a ring.
To enable or disable source learning on a VLAN, use the
For example, the following commands disable and enabled source learning on VLAN 10:
-> mac-learning vlan 10 disable
-> mac-learning vlan 10 enable
Disabling source learning on a VLAN causes the VLAN to be flooded with unknown unicast traffic.
OmniSwitch AOS Release 8 Network Configuration Guide
command is used to enable or disable a Spanning Tree instance for an
December 2017
Enabling/Disabling Spanning Tree for a VLAN
mac-learning static mac-address command.
page 4-9