Information Commands

You can also refer to the following port-specific STP information:

•Port number and priority

•Cost

•State

•Port Fast Forwarding state

•Designated bridge

•Designated port

The following table describes the STP parameters.

Table 23 STP parameters

Parameter

Description

 

 

Current Root

Shows information about the root bridge for the Spanning Tree. Information includes

 

the priority (hex) and MAC address of the root.

 

 

Path-Cost

Path-cost is the total path cost to the root bridge. It is the summation of the path cost

 

between bridges (up to the root bridge).

 

 

Port

The current root port refers to the port on the switch that receives data from the current

 

root. Zero (0) indicates the root bridge of the STP.

 

 

Priority (bridge)

The bridge priority parameter controls which bridge on the network will become the

 

STP root bridge.

 

 

Hello

The hello time parameter specifies, in seconds, how often the root bridge transmits a

 

configuration bridge protocol data unit (BPDU). Any bridge that is not the root bridge

 

uses the root bridge hello value.

 

 

MaxAge

The maximum age parameter specifies, in seconds, the maximum time the bridge

 

waits without receiving a configuration bridge protocol data unit before it reconfigures

 

the STP network. If the bridge is not the root bridge, it uses the MaxAge value of the

 

root bridge.

 

 

FwdDel

The forward delay parameter specifies, in seconds, the amount of time that a bridge

 

port has to wait before it changes from learning state to forwarding state. If the bridge

 

is not the root bridge, it uses the FwdDel value of the root bridge.

 

 

Aging

The aging time parameter specifies, in seconds, the amount of time the bridge waits

 

without receiving a packet from a station before removing the station from the

 

Forwarding Database.

 

 

Priority (port)

The port priority parameter helps determine which bridge port becomes the

 

designated port. In a network topology that has multiple bridge ports connected to a

 

single segment, the port with the lowest port priority becomes the designated port for

 

the segment.

 

 

Cost

The port path cost parameter is used to help determine the designated port for a

 

segment. Generally speaking, the faster the port, the lower the path cost.

 

 

State

The State field shows the current state of the port. The State field can be one of the

 

following: BLOCKING, LISTENING, LEARNING, FORWARDING, or DISABLED.

 

 

Designated bridge

Shows information about the bridge connected to each port, if applicable. Information

 

includes the priority (hex) and MAC address of the Designated Bridge.

 

 

Designated port

The port ID of the port on the Designated Bridge to which this port is connected. This

 

information includes the port priority (hex) and the port number (hex).

 

 

 

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