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Page 69
LGB5028A User‘s Manual
Chapter 6: Configuration
Parameter Description
Port: The switch port number of the logical STP port.
STP Enabled: Control whether STP is enabled on this switch port.
Path Cost: Controls the path cost incurred by the port. The Auto setting will set the path cost as appropriate by the physical link
speed, using the 802.1D recommended values. Using the Specific setting, you can enter a user-defined value. The path cost is
used when establishing the active topology of the network. Lower path cost ports are chosen as forwarding ports in favor of
higher path cost ports. Valid values are in the range 1 to 200000000.
Priority: Control the port priority. This can be used to control priority of ports having identical path cost. (See above).
operEdge (state flag): Show the Operational flag describing whether the port is connecting directly to edge devices. (No
Bridges attached). Transition to the forwarding state is faster for edge ports (having operEdge true) than for other ports.The value
of this flag is based on AdminEdge and AutoEdge fields. This flag is displayed as Edge in Monitor->Spanning Tree -> STP Detailed
Bridge Status.
AdminEdge: Control whether the operEdge flag should start as set or cleared. (The initial operEdge state when a port is
initialized.)
AutoEdge: Control whether the bridge should enable automatic edge detection on the bridge port. This allows operEdge to be
derived from whether BPDUs are received on the port or not.
Restricted Role: If enabled, causes the port not to be selected as Root Port for the CIST or any MSTI, even if it has the best
Spanning Tree priority vector. Such a port will be selected as an Alternate Port after the Root Port has been selected. If set, it can
cause lack of Spanning Tree connectivity. It can be set by a network administrator to prevent bridges external to a core region of
the network from influencing the Spanning Tree active topology, possibly because those bridges are not under the full control of
the administrator. This feature is also known as Root Guard.
Restricted TCN: If enabled, causes the port not to propagate received topology change notifications and topology changes to
other ports. If set, it can cause temporary loss of connectivity after changes in a Spanning Tree's active topology as a result of
persistently incorrect learned station location information. It is set by a network administrator to prevent bridges external to a core
region of the network, causing address flushing in that region, possibly because those bridges are not under the full control of the
administrator or the physical link state of the attached LANs transits frequently.
BPDU Guard:
If enabled, causes the port to disable itself upon receiving valid BPDUs. Contrary to the similar bridge setting, the port edge status
does not affect this setting. A port entering error-disabled state due to this setting is also subject to the bridge Port Error Recovery
setting.
Point to Point: Control whether the port connects to a point-to-point LAN rather than to a shared medium. This can be
automatically determined, or forced either true or false. Transition to the forwarding state is faster for point-to-point LANs than
for shared media.
Buttons
Save: Click to save changes.
Reset: Click to undo any changes made locally and revert to previously saved values.
6.4.5 MSTI Ports
The section describes how to inspect and/or change the current STP MSTI port configurations.
An MSTI port is a virtual port that is initialized separately for each active CIST (physical) port for each MSTI instance configured
on and applicable to the port. The MSTI instance must be selected before displaying actual MSTI port configuration options. It
contains MSTI port settings for physical and aggregated ports.