MST Port Configuration

Use MST Port Configuration page to view and configure the Multiple Spanning Tree (MST) settings for each interface on the device. To configure MST settings for an interface and to view additional information about the interface's role in the MST topology, first select the appropriate MST instance from the MST ID menu. Then, select the interface to view or configure and click Edit.

To access this page, click Switching > Spanning Tree > MST Port in the navigation menu.

Note

If no MST instances have been configured on the switch, the page displays a No MSTs Available message and does not display the fields shown in Spanning Tree MST Port Configuration Fields.

Spanning Tree MST Port Configuration Fields

Field	Description
MST ID	The menu contains the ID of each MST instance that has been created on the device.
Interface	The port or LAG (Link Aggregation Group) associated with the rest of the data in the row. When configuring MST settings for an interface, this field identifies the interface being configured.
Port Role	The role of the port within the MST, which is one of the following: Root: A port on the non-root bridge that has the least-cost path to the root bridge. Designated: A port that has the least-cost path to the root bridge on its segment. Alternate: A blocked port that has an alternate path to the root bridge. Backup: A blocked port that has a redundant path to the same network segment as another port on the bridge. Master: The port on a bridge within an MST instance that links the MST instance to other STP (Spanning Tree Protocol) regions. Disabled: The port is administratively disabled and is not part of the spanning tree.
Port Forwarding State	Blocking: The port discards user traffic and receives, but does not send, BPDU (Bridge Protocol Data Unit) units. During the election process, all ports are in the blocking state. The port is blocked to prevent network loops. Listening: The port sends and receives BPDUs and evaluates information to provide a loop-free topology. This state occurs during network convergence and is the first state in transitioning to the forwarding state. Learning: The port learns the MAC addresses of frames it receives and begins to populate the MAC address table. This state occurs during network convergence and is the second state in transitioning to the forwarding state. Forwarding: The port sends and receives user traffic. Disabled: The port is administratively disabled and is not part of the spanning tree.
Port Priority	The priority for the port within the MSTI (Multiple Spanning Tree Instances). This value is used in determining which port on a switch becomes the root port when two ports have the same least-cost path to the root. The port with the lower priority value becomes the root port. If the priority values are the same, the port with the lower interface index becomes the root port.
Port Path Cost	The path cost from the port to the root bridge.
Description	A user-configured description of the port. After you select an interface and click Edit, a window opens and allows you to edit the MST port settings and view additional MST information for the interface. The following information describes the additional fields available in this window.
Auto-calculate Port Path Cost	Shows whether the path cost from the port to the root bridge is automatically determined by the speed of the interface (Enabled) or configured manually (Disabled).
Port ID	A unique value that is automatically generated based on the port priority value and the interface index.
Port Up Time Since Counters Last Cleared	The amount of time that the port has been up since the counters were cleared.
Port Mode	The administrative mode of spanning tree on the port.
Designated Root	The bridge ID of the root bridge for the MST instance.
Designated Cost	The path cost offered to the LAN by the designated port.
Designated Bridge	The bridge ID of the bridge with the designated port.
Designated Port	The port ID of the designated port.
Loop Inconsistent State	Identifies whether the interface is currently in a loop inconsistent state. An interface transitions to a loop inconsistent state if loop guard is enabled and the port stops receiving BPDUs. In this state, the interface does not transmit frames.
Transitions Into LoopInconsistent State	The number of times this interface has transitioned into loop inconsistent state.
Transitions Out Of LoopInconsistent State	The number of times this interface has transitioned out of loop inconsistent state.

If you make any configuration changes, click Submit to apply the new settings to the switch.
Click Refresh to update the screen with most recent data.

Published October 2018prev | next

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