Brocade Communications Systems Brocate Ethernet Access Switch 6910 - Manual (Page 824)

774 Brocade 6910 Ethernet Access Switch Configuration Guide
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Configuring Multiple Spanning Trees
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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.
CLI References
• “Spanning Tree Commands” on page 333
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 763 ) 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 ( page 763 ).
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.
Parameters
These parameters are displayed:
• MST ID – Instance identifier to configure. (Range: 0-4094)
• VLAN ID – VLAN to assign to this MST instance. (Range: 1-4093)
• 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)
Interface
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.