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ES-3148 User’s Guide
98 Chapter 11 Spanning Tree Protocol
The following table describes the labels in this screen.
Table 23 Spanning Tree Protocol: Configuration
LABEL DESCRIPTION
Status Click Status to display the Spanning Tree Protocol Status screen (see Figure 41
on page 95).
Active Select this check box to activate STP. Clear this checkbox to disable STP.
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.
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 20 on page 93 for more information.
Apply Click Apply to save your changes back to the switch.
Cancel Click Cancel to begin configuring this screen afresh.