Chapter 13 Spanning Tree Protocol

The following table describes the labels in this screen.

Table 29 Advanced Application > Spanning Tree Protocol > RSTP

LABEL

DESCRIPTION

Status

Click Status to display the RSTP Status screen (see Figure 69 on page

 

159).

 

 

Active

Select this check box to activate RSTP. Clear this checkbox to disable

 

RSTP.

 

Note: You must also activate Rapid Spanning Tree in the

 

Advanced Application > Spanning Tree Protocol >

 

Configuration screen to enable RSTP on the Switch.

Bridge Priority

Bridge priority is used in determining the root switch, root port and

 

designated port. The switch with the highest priority (lowest numeric

 

value) becomes the STP root switch. If all switches have the same

 

priority, the switch with the lowest MAC address will then become the

 

root switch. Select a value from the drop-down list box.

 

The lower the numeric value you assign, the higher the priority for this

 

bridge.

 

Bridge Priority determines the root bridge, which in turn determines

 

Hello Time, Max Age and Forwarding Delay.

 

 

Hello Time

This is the time interval in seconds between BPDU (Bridge Protocol Data

 

Units) configuration message generations by the root switch. The

 

allowed range is 1 to 10 seconds.

 

 

Max Age

This is the maximum time (in seconds) a switch can wait without

 

receiving a BPDU before attempting to reconfigure. All switch ports

 

(except for designated ports) should receive BPDUs at regular intervals.

 

Any port that ages out STP information (provided in the last BPDU)

 

becomes the designated port for the attached LAN. If it is a root port, a

 

new root port is selected from among the switch ports attached to the

 

network. The allowed range is 6 to 40 seconds.

 

 

Forwarding

This is the maximum time (in seconds) a switch will wait before

Delay

changing states. This delay is required because every switch 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 blocking state; otherwise,

 

temporary data loops might result. The allowed range is 4 to 30

 

seconds.

 

As a general rule:

 

Note: 2 * (Forward Delay - 1) >= Max Age >= 2 * (Hello Time + 1)

 

 

Port

This field displays the port number.

*Settings in this row apply to all ports.

Use this row only if you want to make some settings the same for all ports. Use this row first to set the common settings and then make adjustments on a port-by-port basis.

Note: Changes in this row are copied to all the ports as soon as you make them.

 

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XGS4700-48F User’s Guide