MSTP Interface Settings

The MSTP Interface Settings page enables you to configure the port MSTP settings for every MST instance, and to view information that has currently been learned by the protocol, such as the designated bridge per MST instance.

To configure the ports in an MST instance, follow these steps:

Procedure

Step 1

Click Spanning Tree > MSTP > MSTP Interface Settings.

Step 2

Enter the parameters.

  • Instance equals to—Select the MSTP instance to be configured.

  • Interface Type equals to—Select whether to display the list of ports or LAGs.

Step 3

Click Go. The MSTP parameters for the interfaces on the instance are displayed.

Step 4

Select an interface, and click Edit.

Step 5

Enter the parameters.

OptionDescription

Instance ID

Select the MST instance to be configured.

Interface

Select the interface for which the MSTI settings are to be defined.

Interface Priority

Set the port priority for the specified interface and MST instance.

Path Cost

Enter the port contribution to the root path cost in the User Defined textbox or select Use Default to use the default value.

Port State

Displays the MSTP status of the specific port on a specific MST instance. The parameters are defined as:

  • Disabled—STP is currently disabled.

  • Learning—The port on this instance is in Learning mode. The port cannot forward traffic, but it can learn new MAC addresses.

  • Blocking—The port is currently blocked, and can’t forward traffic (except for BPDU data) or learn MAC addresses.

  • Forwarding—The port on this instance is in Forwarding mode. The port can forward traffic and learn new MAC addresses.

Port Role

Displays the port or LAG role, per port or LAG per instance, assigned by the MSTP algorithm to provide STP paths:

  • Master—A Master port provides connectivity from an MSTP region to the outlying CIST root

  • Root—Forwarding packets through this interface provides the lowest cost path for forwarding packets to the root device.

  • Designated Port—The interface through which the bridge is connected to the LAN, which provides the lowest root path cost from the LAN to the Root Bridge for the MST instance.

  • Alternate—The interface provides an alternate path to the Root Bridge from the root port.

  • Backup—The interface provides a backup path to the designated port path toward the Spanning Tree leaves. Backup ports occur when two ports are connected in a loop by a point-to-point link. Backup ports also occur when a LAN has two or more established connections to a shared segment.

  • Disabled—The interface does not participate in the Spanning Tree.

Mode

Displays the current interface Spanning Tree mode.

  • If the link partner is using MSTP or RSTP, the displayed port mode is RSTP.

  • If the link partner is using STP, the displayed port mode is STP.

Type

Displays the MST type of the port.

  • Boundary—A Boundary port attaches MST bridges to a LAN in a remote region. If the port is a boundary port, it also indicates whether the device on the other side of the link is working in RSTP or STP mode.

  • Internal—The port is an internal port.

Designated Bridge ID

Displays the ID number of the bridge that connects the link or shared LAN to the root.

Designated Port ID

Displays the Port ID number on the designated bridge that connects the link or the shared LAN to the root.

Designated Cost

Displays the cost of the port participating in the STP topology. Ports with a lower cost are less likely to be blocked if STP detects loops.

Remain Hops

Displays the hops remaining to the next destination.
Step 6

Click Apply. The Running Configuration file is updated.