Brocade TurboIron 24X Series Configuration Guide - Manual (Page 615)

Brocade TurboIron 24X Series Configuration Guide 581
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802.1s Multiple Spanning Tree Protocol
NOTE
MSTP is not operational however until the mstp start command is issued as described in “Activating
MSTP on a switch” on page 585.
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
“Configuring an MSTP instance” on page 582. 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.
Configuring additional MSTP parameters
To configure a switch for MSTP, you could configure the name and the revision on each switch that
is being configured for MSTP. You must then create an MSTP Instance and assign an ID. VLANs are
then assigned to MSTP instances. These instances must be configured on all switches that
interoperate with the same VLAN assignments. Port cost, priority and global parameters can then
be configured for individual ports and instances. In addition, operational edge ports and
point-to-point links can be created and MSTP can be disabled on individual ports.
Each of the commands used to configure and operate MSTP are described in the following:
• “Setting the MSTP name”
• “Setting the MSTP revision number”
• “Configuring an MSTP instance”
• “Configuring bridge priority for an MSTP instance”
• “Setting the MSTP global parameters”
• “Setting ports to be operational edge ports”
• “Setting automatic operational edge ports”
• “Setting point-to-point link”
• “Disabling MSTP on a port”
• “Forcing ports to transmit an MSTP BPDU”
• “Activating MSTP on a switch”
Setting the MSTP name
Each switch that is running MSTP is configured with a name. It applies to the switch which can have
many different VLANs that can belong to many different MSTP regions.
To configure an MSTP name, use a command such as the following at the Global Configuration
level.