CIST Ports

This page allows you to inspect the current STP (Spanning Tree Protocol) CIST port configurations, and possibly change them as well. This page contains settings for physical and aggregated ports.

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../Graphics/config_spanning_tree_cist_ports.png
Object Description
Port The switch port number of the logical STP port.
STP Enabled Controls 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, a user-defined value can be entered. 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 1 – 200000000.
Priority Controls the port priority. This can be used to control priority of ports having identical port cost. (See above.)
operEdge (state flag) 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 Controls whether the operEdge flag should start as set or cleared. (The initial operEdge state when a port is initialized.)
AutoEdge Controls whether the bridge should enable automatic edge detection on the bridge port. This allows operEdge to be derived from whether BPDU's 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 influence 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 BPDU's. Contrary to the similar bridge setting, the port Edge status does not effect this setting.

A port entering error-disabled state due to this setting is subject to the bridge Port Error Recovery setting as well.

Point-to-Point Controls 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
../_Common/../Graphics/save_new.png Save changes.
../_Common/../Graphics/reset_new.png Undo any changes and revert to previously saved values.