Alcatel-Lucent OmniSwitch 6800 Series - Enabling;Disabling Spanning Tree on a Port; Spanning Tree on Link Aggregate Ports

Configuring STP Port Parameters Configuring Spanning Tree Parameters
page 7-30 OmniSwitch 6800/6850/9000 Network Configuration Guide March 2008
Enabling/Disabling Spanning Tree on a Port
By default, Spanning Tree is enabled on all ports. When Spanning Tree is disabled on a port, the port is
put in a forwarding state for the specified instance. For example, if a port is associated with both VLAN 10
and VLAN 20 and Spanning Tree is disabled on the port for VLAN 20, the port state is set to forwarding
for VLAN 20. However, the VLAN 10 instance still controls the port’s state as it relates to VLAN 10. This
example assumes the switch is running in the 1x1 Spanning Tree mode.
If the switch is running in the flat Spanning Tree mode, then disabling the port Spanning Tree status
applies across all VLANs associated with the port. The flat mode instance is specified as the port’s
instance, even if the port is associated with multiple VLANs.
To change the port Spanning Tree status for a VLAN instance, specify a VLAN ID with the bridge slot/
port command when the switch is running in the 1x1 mode. For example, the following commands enable
Spanning Tree on port 8/1 for VLAN 10 and disable STP on port 6/2 for VLAN 20:
-> bridge 10 8/1 enable
-> bridge 20 6/2 disable
The explicit bridge 1x1 slot/port command configures the priority for a VLAN instance when the switch
is running in either mode (1x1 or flat). For example, the following commands perform the same function
as the commands in the previous example:
-> bridge 1x1 10 8/1 enable
-> bridge 1x1 20 6/2 disable
To change the port Spanning Tree status for the flat mode instance, use either the bridge slot/port
command or the bridge cist slot/port command. Note that both commands are available when the switch
is running in either mode (1x1 or flat) and an instance number is not required. For example, the following
commands disable the Spanning Tree status on port 1/24 for the flat mode instance:
-> bridge 1/24 disable
-> bridge cist 1/24 disable
As in previous releases, it is possible to configure the flat mode instance with the bridge slot/port
command by specifying 1 as the instance number (e.g., bridge 1 1/24 enable). However, this is only avail-
able when the switch is already running in the flat mode and STP or RSTP is the active protocol.
Spanning Tree on Link Aggregate Ports
Physical ports that belong to a link aggregate do not participate in the Spanning Tree Algorithm. Instead,
the algorithm is applied to the aggregate logical link (virtual port) that represents a collection of physical
ports.
To enable or disable the Spanning Tree status for a link aggregate, use the bridge slot/port commands
described above but specify a link aggregate control number instead of a slot and port. For example, the
following command disables Spanning Tree for link aggregate 10 associated with VLAN 755:
-> bridge 755 10 disable
For more information about configuring an aggregate of ports, see Chapter 16, “Configuring Static Link
Aggregation,” and Chapter 17, “Configuring Dynamic Link Aggregation.”