Configuring Mstp - Allied Telesis SwitchBlade x908 Series Software Reference Manual

Spanning Tree Introduction: STP, RSTP, and MSTP

Configuring MSTP

By default, RSTP is enabled with default settings on all switch ports. To configure MSTP, see the
configuration procedure in
To configure other modes, see
page
For detailed configuration examples, see the How To Note How To Configure Basic Switching
Functionality at http://www.alliedtelesis.com/resources/literature/howto_plus.aspx.
Configuration
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guidelines for
MSTP
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Before Before configuring MSTP, configure VLANs and associate them with switch

configuring MSTP

Service" on page 14.18
network:
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Table 18-9: Configuration procedure for MSTP
Enable MSTP
awplus#
awplus(config)#
awplus(config)#
Configure MSTP region, revision, and instances
All MSTP devices in this region of the network must have the same region name, revision number, and VLAN to MSTI
mappings.
awplus(config)#
18.18
Table
18.5.
Switches must have the same MST configuration identification elements (region name,
revision level and VLAN to MSTI mapping) to be in the same MST region. When
configuring multiple MST regions for MSTP, MSTIs are locally significant within an MST
region. MSTIs will not span from one region to another region.
Common and Internal Spanning Tree (CIST) is the default spanning tree instance for
MSTP. This means that all VLANs that are not explicitly configured into another MSTI are
members of the CIST.
The software supports a single instance of the MSTP Algorithm consisting of the CIST and
up to 15 MSTIs.
A VLAN can only be mapped to one MSTI or to the CIST. One VLAN mapped to
multiple spanning trees is not allowed. All the VLANs are mapped to the CIST by default.
Once a VLAN is mapped to a specified MSTI, it is removed from the CIST.
An MSTI is locally significant within an MST region. An MSTI cannot span across multiple
MST regions. The CIST is the spanning tree instance for connecting different MST regions
and single spanning tree entities, such as RSTP and STP switches.
MSTP is compatible with RSTP and STP. An MST region appears as a virtual bridge
connecting to single spanning tree entities.
To avoid unnecessary STP processing, a port that attaches to a LAN that is known to have
no other bridges/switches attached can be configured as an edge port.
and Chapter 17, VLAN
which MSTP regions, revision level and instances are required
which VLANs and switch ports will belong to which MSTIs,
which devices you want to be root bridges for each MSTI
Command
configure terminal
spanning-tree mode mstp
spanning-tree {stp|rstp|mstp} enable
spanning-tree mst configuration
Software Reference for SwitchBlade® x908, x900 and x600 Series Switches
TM
AlliedWare Plus Operating System - Software Version 5.3.1
18-9.
"Configuring RSTP" on page 18.8
Commands), and determine for your
Description
Enter Configuration mode.
By default, the device is in RSTP mode. Change to
MSTP mode.
By default, spanning tree is enabled on all switch
ports. If it has been disabled, enable it for MSTP.
Enter MST Configuration mode.
or "Configuring STP" on
ports("Quality of
C613-50007-01 REV B