ES-2048 User’s Guide

The following table describes the labels in this screen.

Table 25 Spanning Tree Protocol: Configuration

LABEL

DESCRIPTION

 

 

Status

Click Status to display the Rapid Spanning Tree Protocol Status screen (see

 

Figure 45 on page 107).

Active

Select this check box to activate STP on the switch. Clear this checkbox to disable

 

an STP tree.

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 Delay

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

Active

Select this check box to activate STP on this port.

 

 

Priority

Configure the priority for each port here.

 

Priority decides which port should be disabled when more than one port forms a

 

loop in a switch. Ports with a higher priority numeric value are disabled first. The

 

allowed range is between 0 and 255 and the default value is 128.

Path Cost

Path cost is the cost of transmitting a frame on to a LAN through that port. It is

 

assigned according to the speed of the bridge. The slower the media, the higher

 

the cost - see Table 22 on page 105 for more information.

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Chapter 11 Spanning Tree Protocol