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Spanning Tree
Spanning Tree MSTP Summary
Multiple Spanning Tree Protocol (MSTP) allows the creation of MSTIs based upon a VLAN or groups
of VLANs. Configuring MSTIs creates an active topology with a better distribution of network traffic and
an increase in available bandwidth when compared to classic STP.
To display the Spanning Tree MSTP Summary page, click
Switching
>
Spanning Tree
in the naviga-
tion pane, and then click the
MSTP
tab.
Figure 26. Spanning Tree MSTP Summary Page
Table 16. Spanning Tree MSTP Summary Fields
If you modify any settings, click
Apply
to update the switch configuration. The changes take effect
immediately but are not retained across a switch reset unless you click
Save Configuration
.
Field
Description
MSTP ID
The number that identifies the MST instance.
Priority
The bridge priority for the spanning-tree instance. This value affects the likelihood that the
bridge is selected as the root bridge. A lower value increases the probability that the bridge
is selected as the root bridge.
# of Associated VLANs
The number of VLANs that are mapped to the MSTI. This number does not contain any
information about the VLAN IDs that are mapped to the instance.
Bridge Identifier
A unique value that is automatically generated based on the bridge priority value of the MSTI
and the base MAC address of the bridge. When electing the root bridge for an MST instance,
if the bridge priorities for multiple bridges are equal, the bridge with the lowest MAC address
is elected as the root bridge.
Time Since Topology
Change
The amount of time that has passed since the topology of the MSTI has changed.
Designated Root
The bridge identifier of the root bridge for the MST instance. The identifier is made up of the
bridge priority and the base MAC address.
Root Path Cost
The path cost to the designated root for this MST instance. Traffic from a connected device
to the root bridge takes the least-cost path to the bridge. If the value is 0, the cost is
automatically calculated based on port speed.
Root Port
The port on the bridge with the least-cost path to the designated root for the MST instance.
