Reduced occurrences of mstp reconvergence, Example application of mstp reconvergence – Brocade FastIron Ethernet Switch Platform and Layer 2 Switching Configuration Guide User Manual
Page 333
Syntax: [no] mstp scope all
NOTE
MSTP is not operational however until the mstp start command is issued as described in
on page 338.
Once the system is configured into MSTP mode, CIST (sometimes referred to as "instance 0") is
created and all existing VLANs inside the MSTP scope are controlled by CIST. In addition, whenever
you create a new VLAN inside MSTP scope, it is put under CIST control by default. In the Brocade
MSTP implementation however, a VLAN ID can be pre-mapped to another MSTI as described in
on page 336. A VLAN whose ID is pre-mapped, will attach to the
specified MSTI instead of to the CIST when created.
NOTE
Once under MSTP mode, CIST always controls all ports in the system. If you do not want a port to run
MSTP, configure the no spanning-tree command under the specified interface configuration.
Using the no option on a system that is configured for MSTP mode changes the system to non-MSTP
mode. When this switch is made, all MSTP instances are deleted together with all MSTP configurations.
ALL VLANs inside the original MSTP scope will not run any Layer-2 protocols after the switch.
Reduced occurrences of MSTP reconvergence
When a VLAN is deleted, the Brocade device retains the associated VLAN to MSTI mapping instead of
deleting it from the configuration. This way, a VLAN can be pre-mapped to an MSTI and MSTP
reconvergence may not be necessary when a VLAN is added to or deleted from the configuration. As
long as the VLAN being created or deleted is pre-mapped to an MSTI, and the VLAN to MSTI mapping
has not changed, MSTP reconvergence will not occur.
NOTE
MSTP reconvergence occurs when the VLAN to MSTI mapping is changed using the mstp instance
command.
You can optionally remove VLAN to MSTI mappings from the configuration. Refer to
The following shows an example application.
Example application of MSTP reconvergence
The following example shows the running configuration file before and after deleting a VLAN from the
configuration. The VLAN to MSTI mapping is retained in the running configuration, even after the VLAN
is deleted.
device(config-vlan-20)#show run
Current configuration:
!
ver 04.2.00bT3e1
!
!
vlan 1 name DEFAULT-VLAN by port
no spanning-tree
!
vlan 10 by port
Reduced occurrences of MSTP reconvergence
FastIron Ethernet Switch Platform and Layer 2 Switching Configuration Guide
333
53-1003086-04