Accton Technology 24/48-Port, ES4548D, ES4524D manual Displaying Global Settings, Field Attributes

Displaying Global Settings 22

MSTP connects all bridges and LAN segments with a single Common and Internal Spanning Tree (CIST). The CIST is formed as a result of the running spanning tree algorithm between switches that support the STP, RSTP, MSTP protocols.

Displaying Global Settings

You can display a summary of the current bridge STA information that applies to the entire switch using the STA Information screen.

Field Attributes

•Spanning Tree State – Shows if the switch is enabled to participate in an STA-compliant network.

•Bridge ID – A unique identifier for this bridge, consisting of the bridge priority, the MST Instance ID 0 for the Common Spanning Tree when spanning tree mode is set to MSTP (page 22-6), and MAC address (where the address is taken from the switch system).

•Max Age – The maximum time (in seconds) a device can wait without receiving a configuration message before attempting to reconfigure. All device ports (except for designated ports) should receive configuration messages at regular intervals. Any port that ages out STA information (provided in the last configuration message) becomes the designated port for the attached LAN. If it is a root port, a new root port is selected from among the device ports attached to the network. (References to “ports” in this section mean “interfaces,” which includes both ports and trunks.)

•Hello Time – Interval (in seconds) at which the root device transmits a configuration message.

•Forward Delay – The maximum time (in seconds) the root device will wait before changing states (i.e., discarding to learning to forwarding). This delay is required because every device must receive information about topology changes before it starts to forward frames. In addition, each port needs time to listen for conflicting information that would make it return to a discarding state; otherwise, temporary data loops might result.

•Designated Root – The priority and MAC address of the device in the Spanning Tree that this switch has accepted as the root device.

-Root Port – The number of the port on this switch that is closest to the root. This switch communicates with the root device through this port. If there is no root port, then this switch has been accepted as the root device of the Spanning Tree network.

-Root Path Cost – The path cost from the root port on this switch to the root device.

•Configuration Changes – The number of times the Spanning Tree has been reconfigured.

•Last Topology Change – Time since the Spanning Tree was last reconfigured.

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