LevelOne GSW-4876 - Manual (Page 132)

C HAPTER 4 | Configuring the Switch
Configuring the Spanning Tree Algorithm
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C ONFIGURING
M ULTIPLE S PANNING
T REES
Use the MSTI Mapping page to add VLAN groups to an MSTP instance
(MSTI), or to designate the name and revision of the VLAN-to-MSTI
mapping used on this switch.
P ATH
Basic/Advanced Configuration, Spanning Tree, MSTI Mapping
C OMMAND U SAGE
MSTP generates a unique spanning tree for each instance. This provides
multiple pathways across the network, thereby balancing the traffic load,
preventing wide-scale disruption when a bridge node in a single instance
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 128 ).
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.
P ARAMETERS
These parameters are displayed:
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)
2. The MST name and revision number are both required to uniquely identify an MST region.