C
HAPTER
4
| Configuring the Switch
Configuring the Spanning Tree Algorithm
– 141 –
fails, and allowing for faster convergence of a new topology for the failed
instance.
By default all VLANs are assigned to the Common Internal Spanning Tree
(CIST, or MST Instance 0) that connects all bridges and LANs within the
MST region. This switch supports up to 7 instances. You should try to group
VLANs which cover the same general area of your network. However,
remember that you must configure all bridges that exist within the same
MSTI Region with the same set of instances, and the same instance (on
each bridge) with the same set of VLANs. Also, note that RSTP treats each
MSTI region as a single node, connecting all regions to the CIST.
To use multiple spanning trees:
1. Set the spanning tree type to MSTP (page 137).
2. Add the VLANs that will share this MSTI on the MSTI Mapping page.
3. Enter the spanning tree priority for the CIST and selected MST instance
on the MSTI Priorities page.
N
OTE
:
All VLANs are automatically added to the CIST (MST Instance 0).
To ensure that the MSTI maintains connectivity across the network, you
must configure a related set of bridges with the same MSTI settings.
PARAMETERS
These parameters are displayed in the web interface:
Configuration Identification
◆ Configuration Name
2
– The name for this MSTI. (Maximum length:
32 characters; Default: switch’s MAC address)
◆ Configuration Revision
2
– The revision for this MSTI.
(Range: 0-65535; Default: 0)
MSTI Mapping
◆ MSTI – Instance identifier to configure. The CIST is not available for
explicit mapping, as it will receive the VLANs not explicitly mapped.
(Range: 1-7)
◆ VLANs Mapped – VLANs to assign to this MST instance. The VLANs
must be separated with comma and/or space. A VLAN can only be
mapped to one MSTI. (Range: 1-4094)
2. The MST name and revision number are both required to uniquely identify an MST region.
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