Chapter 47 Configuration Mode Commands

where

 

 

spanning-tree

=

Enables STP on the Switch.

mrstp <treeIndex>

 

Enables a specific tree configuration.

priority <0-61440>

=

Specifies the bridge priority for the Switch. The lower the

 

 

numeric value you assign, the higher the priority for this bridge.

 

 

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.

 

 

Bridge Priority determines the root bridge, which in turn

 

 

determines Hello Time, Max Age and Forwarding Delay.

hello-time <1-10>

=

Specifies the time interval in seconds between BPDU (Bridge

 

 

Protocol Data Units) configuration message generations by the

 

 

root switch.

maximum-age <6-40>

=

Specifies 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.

forward-delay <4- 30>

=Specifies the maximum time (in seconds) the 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.

<port-list> path-

= Enables STP on the specified ports.

cost <1-65535>

Specifies the cost of transmitting a frame on to a LAN through

 

 

that port. It is assigned according to the speed of the bridge.

<port-list>

= Specifies the priority for each port.

priority <0-255>

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.

<port-list>

= Specifies which STP configuration these ports will participate

treeIndex <1-4>

in. (mrstp command only).

An example using spanning-treecommand is shown next.

•Enable STP on the Switch.

•Set the bridge priority of the Switch to 0.

•Set the Hello Time to 4, Maximum Age to 20 and Forward Delay to 15 on the Switch.

386

 

GS-4012F/4024 User’s Guide