50
Table of Contents
Linksys
50
Table of Contents
Linksys
1 Set the STP Operation Mode to MSTP as described in the Spanning
Tree page
2 Define MSTP instances Each MSTP instance calculates and builds a
loop free topology to bridge packets from the VLANs that map to the
instance Refer to the MSTP Properties page
3 Decide which MSTP instance be active in what VLAN, and associate
these MSTP instances to VLAN(s) accordingly
4 Configure the MSTP attributes by the following pages:
•
MSTP Properties
•
MSTP Instance Status
•
MSTP Instance Interface
MSTP Interfaces
The global MSTP configures a separate Spanning Tree for each VLAN
group and blocks all but one of the possible alternate paths within each
spanning tree instance MSTP enables formation of MST regions that can run
multiple MST instances (MSTI) Multiple regions and other STP bridges are
interconnected using one single common spanning tree (CST)
MSTP is fully compatible with RSTP bridges, in that an MSTP BPDU can
be interpreted by an RSTP bridge as an RSTP BPDU This not only enables
compatibility with RSTP bridges without configuration changes, but also
causes any RSTP bridges outside of an MSTP region to see the region as a
single RSTP bridge, regardless of the number of MSTP bridges inside the
region itself
Up to three MST instances (predefined from 1-3) can be defined on Smart
switches, in addition to instance zero
VLAN to MSTP Instance Mapping
For two or more switches to be in the same MST region, they must have
the same VLANs to MST instance mapping, the same configuration revision
number, and the same region name
VLAN to MSTP Instance Mapping For two or more switches to be in the same
MST region, they must have the same VLANs to MST instance mapping, the
same configuration revision number, and the same region name Formatted:
Font: 18 pt Formatted: Indent: Left: 0” Managed Switch Administration Guide
57 Switches intended to be in the same MST region are never separated by
switches from another MST region If they are separated, the region becomes
two separate regions
The VLAN to MSTP instance mapping is done in the MSTP Properties page
Each VLAN can be mapped to a MSTP instance For devices to be in the same
region, they must have the same mapping of VLANs to MSTP instances
Configuration on this page (and all of the MSTP pages) applies if the system
STP mode is MSTP
NOTE:
The same MSTI can be mapped to more than one VLAN, but each VLAN can
only have one MST Instance attached to it
For those VLANs that are not explicitly mapped to one of the MST instances,
the device automatically maps them to the CIST (Core and Internal Spanning
Tree) instance The CIST instance is MST instance 0
To configure MSTP:
STEP 1 Click Configuration > Spanning Tree Management> Spanning Tree
Enable MSTP
STEP 2 Click Configuration > Spanning Tree Management> MSTP Properties
The following field is a display only field:
•
IST Master—Displays the regions master
STEP 3 Enter the parameters
•
Region Name—Define an MSTP region name
•
Revision—Define an unsigned 16-bit number that identifies the revision
of the current MST configuration The field range is from 0 to 65535
•
Maximum Hops—Set the total number of hops that occur in a specific
region before the BPDU is discarded Once the BPDU is discarded, the
port information is aged out The field range is from 1 to 40
STEP 4 Click Apply The MSTP properties are defined, and the Running
Configuration file is updated To configure an MSTP:
STEP 5 Click Configuration > Spanning Tree Management> MSTP Properties
STEP 6 Select the MST instance and click Edit
STEP 7 Enter the parameters
•
MST Instance ID—Select an MST instance to be displayed and defined
