Spanning Tree Algorithm
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Instruction Manual - NXA-ENET8-POE+
Configuring Multiple Spanning Trees
Use the Spanning Tree > MSTP (Configure Global) page to create an MSTP instance, or to add VLAN groups to an MSTP instance.
Command Usage
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 Internal Spanning Tree (MST Instance 0) that connects all bridges and LANs within the MST
region. This switch supports up to 33 instances. You should try to group VLANs which cover the same general area of your network.
However, remember that you must configure all bridges within the same MSTI Region (page 104) 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 Common Spanning Tree.
Perform these steps to use multiple spanning trees:
1.
Set the spanning tree type to MSTP (page 104).
2.
Enter the spanning tree priority for the selected MST instance on the Spanning Tree > MSTP (Configure Global - Add) page.
3.
Add the VLANs that will share this MSTI on the Spanning Tree > MSTP (Configure Global - Add Member) page.
NOTE:
All VLANs are automatically added to the IST (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.
The following table lists the options on this page:
Perform these steps to create instances for MSTP:
1.
Click
Spanning Tree
>
MSTP
.
2.
Select
Configure Global
from the Step list.
3.
Select
Add
from the Action list.
4.
Specify the MST instance identifier and the initial VLAN member. Additional member can be added using the Spanning Tree >
MSTP (Configure Global - Add Member) page. If the priority is not specified, the default value 32768 is used.
5.
Click
Apply
.
Perform these steps to show the MSTP instances:
1.
Click
Spanning Tree
>
MSTP
.
2.
Select
Configure Global
from the Step list.
3.
Select
Show
from the Action list.
Spanning Tree - MSTP Options
MST ID
Instance identifier to configure. (Range: 0-4094)
VLAN ID
VLAN to assign to this MST instance. (Range: 1-4094)
Priority
The priority of a spanning tree instance. (Range: 0-61440 in steps of 4096; Options: 0, 4096,
8192, 12288, 16384, 20480, 24576, 28672, 32768, 36864, 40960, 45056, 49152, 53248,
57344, 61440; Default: 32768)
FIG. 121
Creating an MST Instance
FIG. 122
Displaying MST Instances