SMC Networks SMC6824M manual Configuring Multiple Spanning Trees, 172

CONFIGURING THE SWITCH

CLI – This example sets STA attributes for port 5.

Console(config)#interface ethernet 1/5
Console(config-if)#spanning-tree port-priority 0	4-221
Console(config-if)#spanning-tree cost 50	4-220
Console(config-if)#spanning-tree link-type auto	4-223
Console(config-if)#no spanning-tree edge-port	4-221
Console(config-if)#spanning-tree protocol-migration	4-226
Console(config-if)#spanning-tree spanning-disabled	4-214
Console(config-if)#

Configuring Multiple Spanning Trees

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 65 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 3-163)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.

To use multiple spanning trees:

1.Set the spanning tree type to MSTP (STA Configuration, page 3-160).

2.Enter the spanning tree priority for the selected MST instance (MSTP VLAN Configuration).

3.Add the VLANs that will share this MSTI (MSTP VLAN Configuration).

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.

3-172