Chapter 13 Spanning Tree Protocol

 

Table 32 Advanced Application > Spanning Tree Protocol > MRSTP (continued)

 

LABEL

DESCRIPTION

 

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) the 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) the 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.

 

 

 

 

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 recommended to assign this value according to the speed of

 

 

the bridge. The slower the media, the higher the cost-see Table 27 on

 

 

page 124 for more information.

 

 

 

 

133

GS2200-24 User’s Guide