Spanning Tree
47
Table 15. Spanning Tree Switch Configuration 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
Spanning Tree Bridge Configuration
Spanning Tree Admin Mode
The administrative mode of STP on the device. When enabled, the device participates in the
root bridge election process and exchanges Bridge Protocol Data Units (BPDUs) with other
switches in the spanning tree to determine the root path costs and maintain topology
information.
Force Protocol Version
The STP version the device uses, which is one of the following:
STP (IEEE 802.1d) – Classic STP provides a single path between end stations, avoiding
and eliminating loops.
RSTP (IEEE 802.1w) – Rapid Spanning Tree Protocol (RSTP) behaves like classic STP
but also has the ability to configure and recognize full-duplex connectivity and ports that
are connected to end stations, resulting in rapid transitioning of the port to the Forward-
ing state and the suppression of Topology Change Notifications.
MSTP (IEEE 802.1s) – Multiple Spanning Tree Protocol (MSTP) includes all the advan-
tages of RSTP and also supports multiple spanning tree instances to efficiently channel
VLAN traffic over different interfaces. MSTP is compatible with both RSTP and STP.
Configuration Name
The name of the MSTP region. Each switch that participates in the same MSTP region must
share the same Configuration Name, Configuration Revision Level, and MST-to-VLAN
mappings.
Configuration Revision
Level
The revision number of the MSTP region. This number must be the same on all switches that
participate in the MSTP region.
Configuration Digest Key
The 16 byte signature of type HMAC-MD5 created from the MST Configuration Table (a VLAN
ID-to-MST ID mapping).
Configuration Format
Selector
The version of the configuration format being used in the exchange of BPDUs.
Spanning Tree Interface Status
Root Bridge Identifier
The bridge identifier of the root bridge for the spanning tree. The identifier is made up of the
bridge priority and the base MAC address. When electing the root bridge for the spanning
tree, if the bridge priorities for multiple bridges are equal, the bridge with the lowest MAC
address is elected as the root bridge.
Root Guarded Interfaces
A list of interfaces currently having the Root Guard parameter set.
TCN Guarded Interfaces
A list of interfaces currently having the TCN Guard parameter set.
BPDU Filtered Interfaces
A list of interfaces currently having the BPDU Filter parameter set.