Cabletron Systems SmartSwitch Router, User'S Reference Manual

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Chapter 3: Bridging Configuration Guide
62 SmartSwitch Router User Reference Manual
The SSR supports per VLAN spanning tree. By default, all the VLANs defined belong to
the default spanning tree. You can create a separate instance of spanning tree using the
following command:
By default, spanning tree is disabled on the SSR. To enable spanning tree on the SSR, you
perform the following tasks on the ports where you want spanning tree enabled..
Adjusting Spanning-Tree Parameters
You may need to adjust certain spanning-tree parameters if the default values are not
suitable for your bridge configuration. Parameters affecting the entire spanning tree are
configured with variations of the bridge global configuration command. Interface-specific
parameters are configured with variations of the bridge-group interface configuration
command.
You can adjust spanning-tree parameters by performing any of the tasks in the following
sections:
• Set the Bridge Priority
• Set an Interface Priority
Note: Only network administrators with a good understanding of how bridges and the
Spanning-Tree Protocol work should make adjustments to spanning-tree
parameters. Poorly chosen adjustments to these parameters can have a negative
impact on performance. A good source on bridging is the IEEE 802.1d
specification.
Setting the Bridge Priority
You can globally configure the priority of an individual bridge when two bridges tie for
position as the root bridge, or you can configure the likelihood that a bridge will be
selected as the root bridge. The lower the bridge's priority, the more likely the bridge will
be selected as the root bridge. This priority is determined by default; however, you can
change it.
Create spanning tree for a VLAN.
pvst create spanningtree vlan-name
<string>
Enable spanning tree on one or
more ports for default spanning
tree.
stp enable port
<port-list>
Enable spanning tree on one or
more ports for a particular VLAN.
pvst enable port
<port-list>
spanning-tree
<string>